CN112520831B

CN112520831B - Method for recovering free starch in papermaking white water

Info

Publication number: CN112520831B
Application number: CN201910889287.0A
Authority: CN
Inventors: 王祥槐; 李志军; 胡维维; 刘波; 张福山
Original assignee: Risingstar Biotech Guangzhou Co ltd
Current assignee: Risingstar Biotech Guangzhou Co ltd
Priority date: 2019-09-19
Filing date: 2019-09-19
Publication date: 2023-03-14
Anticipated expiration: 2039-09-19
Also published as: CN112520831A

Abstract

The invention relates to a method for recovering free starch in papermaking white water, which comprises the following steps of (a): reacting a zwitterionic starch complexing agent with free starch in papermaking white water to modify the free starch; the chemical structure of the zwitterionic starch complexing agent is composed of the following parts: i) One or more hydrophobic groups, wherein at least one hydrophobic group is capable of reacting with starch to form an inclusion complex, and ii) one or more hydrophilic groups, wherein at least one hydrophilic group is an anionic hydrophilic group and at least one hydrophilic group is a cationic hydrophilic group; the hydrophilic groups are connected through chemical bonds to form one tail end of a molecular structure, and the hydrophobic groups and the hydrophilic groups are respectively positioned at two ends of the same molecular structure and are connected through chemical bonds to form an asymmetric and polar structure. The method can effectively reduce the content of free starch in the papermaking white water, thereby reducing the COD discharge amount of the papermaking wastewater.

Description

Method for recovering free starch in papermaking white water

Technical Field

The invention relates to the technical field of pulping and papermaking, in particular to a method for recovering free starch in papermaking white water.

Background

The whole production process of pulping and papermaking industry, including material preparation, paper making, chemical recovery, paper processing and the like, needs a large amount of water for conveying, washing, dispersing materials, cooling equipment and the like. Although the production process also comprises recovery, treatment and reuse, a large amount of waste water is discharged into a water body, so that the water environment is seriously polluted. Paper industry wastewater is an important pollution source in the world, and is classified as one of six public hazards and five public hazards in Japan and United states, respectively.

At present, the discharge amount of the wastewater of the paper industry and the discharge amount of COD in China are the first of the discharge amounts of various industries in China, and the pollution to the water environment is the first problem of pollution control of the paper industry in China and the first problem of standard treatment of industrial wastewater in China. According to statistics, the discharge amount of the industrial wastewater of paper making and paper products in China accounts for 18.6 percent of the total discharge amount of the national industry, the COD in the discharged wastewater accounts for 44.0 percent of the total discharge amount of the COD of the national industry, and the discharge amount after treatment reaches the standard accounts for 49 percent of the total discharge amount of the wastewater of the paper making industry. The papermaking wastewater has high COD concentration and high BOD content, the treatment method is different from that of the common industrial wastewater, at present, the treatment method of the papermaking wastewater mainly comprises a physical method, a chemical method, a biological method and a physical-chemical method, wherein the biological method is most widely applied and becomes one of the main methods for secondary treatment of the papermaking wastewater.

In recent years, with the emphasis on forest resource protection and ecological improvement, the waste paper recycling industry is rapidly developed. According to' year 2016 Chinese paper making annual newspaper in year 2016 published in year 2017 by the Chinese paper making Association in year 5, the total output of Chinese paper and paperboard in year 2016 is 10855 ten thousand tons, wherein four major types of industrial paper such as wrapping paper, white board paper, boxboard paper, corrugated paper and the like are 6655 ten thousand tons and account for 61 percent of the total output, and the recycled waste paper accounts for more than 80 percent of the raw material composition of the production of the four major types of paper products at present. Because the paper produced by the waste paper raw material which is repeatedly utilized in China has low strength and poor quality. In order to meet the requirements of users on paper strength and other properties, a general paper making enterprise applies starch surface sizing to improve various performance indexes of paper and paperboard, including paper strength such as bursting strength, ring crush strength, tensile strength, folding strength and the like, air permeability, smoothness, printability, water resistance, grease/oil resistance and the like. The amount of starch used in the surface sizing of starch is 30-80 kg/ton paper.

When the paper products are recycled, a large amount of waste water is generated through the technological processes of paper shredding, purification, screening, concentration, pulp storage, pulping, net surfing and the like. Through analysis, main pollutants in the wastewater mainly comprise pollutants such as dissolved starch, hemicellulose, lignin and derivatives thereof, fine fibers, inorganic fillers, printing ink, dye and the like. Among them, starch, lignin and its derivative organisms, and hemicellulose are the main components forming COD and BOD. In particular, the surface gum starch is mostly dissolved or dispersed in water during pulping, resulting in a high COD concentration of the wastewater. According to the domestic typical OCC paper mill production data, 30-70% of the wastewater COD is derived from starch. These dissolved or colloidal starches are degraded by amylase from microorganisms in the system, causing the starch chains to become short and even simple sugars, which are difficult to fix on the fibers by fixatives added at the wet end of the paper machine, resulting in an increased concentration of COD contamination in the white water. At present, the COD of papermaking drainage water of enterprises using OCC production in China is over 10000ppm, i.e.,1 percent. In addition, the degraded starch also increases the white water microbial activity during the closed circulation of the white water, producing more VFA, causing paper mill odor pollution.

Therefore, an effective starch retention and recovery technique is of great significance for papermaking. US9091024 describes a method for amylase control using sodium hypochlorite and chloramine. US patent 8758562 describes a method of controlling microorganisms using the weakly oxidizing biocides bromamine and organic biocides, and two fixatives of different molecular weights and charge densities are added to fix starch to the fibers. WO 2012/025228Al kemila describes a method for the synergistic control of microorganisms and amylases using the weakly oxidizing bactericide bromamine and zinc ions.

However, the above techniques all have some disadvantages: in order to prevent the starch chain from shortening, microorganisms must be sufficiently and effectively controlled to prevent the microorganisms from secreting amylase, and the methods need to add a large amount of bactericide, which can affect the subsequent biological treatment of the waste water. In addition, because the starch of the papermaking white water is mainly derived from surface sizing, the starch has low molecular weight and no electric charge and is difficult to retain in paper, so that a large amount of starch is retained in a pulping and papermaking system, the starch not only serves as a nutrient substance of microorganisms to increase the growth of the microorganisms, but also the accumulation of the starch finally causes the problem of 'starch stickies' deposition, causes paper diseases and broken ends and affects the operation efficiency.

So far, the problem of recycling the dissolved starch in the white water of papermaking is not really and effectively solved. The paper industry is eagerly keen to develop an economical and effective technology to reduce the starch dissolution in the process of recycling the fiber and improve the recycling rate of the starch so as to reduce the COD emission, which is a problem in the paper making production for nearly a hundred years.

Disclosure of Invention

Based on the method, the invention provides a method for recovering free starch in papermaking white water, which can effectively reduce the content of the free starch in the papermaking white water, thereby reducing the COD discharge amount of the papermaking wastewater.

The specific technical scheme is as follows:

a process for recovering free starch from papermaking white water comprising the steps of (a): reacting a zwitterionic starch complexing agent with free starch in papermaking white water to modify the free starch;

the chemical structure of the zwitterionic starch complexing agent is composed of the following parts:

i) One or more hydrophobic groups, at least one of which is capable of reacting with starch to form an inclusion complex, and

ii) one or more hydrophilic groups, wherein at least one hydrophilic group is an anionic hydrophilic group and at least one hydrophilic group is a cationic hydrophilic group;

the hydrophobic group and the hydrophilic group are respectively positioned at two ends of the same molecular structure and are connected by chemical bonds to form an asymmetric and polar structure;

the hydrophobic group is a nonpolar group and is selected from substituted or unsubstituted straight-chain aliphatic hydrocarbon, substituted or unsubstituted branched-chain aliphatic hydrocarbon, substituted or unsubstituted aromatic hydrocarbon and substituted or unsubstituted aliphatic and aromatic mixed hydrocarbon;

the hydrophilic group is a polar group;

wherein the anionic hydrophilic group is selected from: at least one of carboxyl group and salt thereof, sulfonic acid group and salt thereof, sulfuric acid group and salt thereof, phosphoric acid group and salt thereof, and phosphorous acid group and salt thereof; and, the anionic hydrophilic group is anionic in water, or generates an anion after undergoing an ionization reaction in water to give a proton; the anion is selected from: at least one of carboxylate, sulfate, sulfonate, phosphate, and phosphite anions;

the cationic hydrophilic group is selected from: at least one of amide group, tertiary amine group and salt thereof, quaternary ammonium group and salt thereof, sulfonium salt group and phosphonium salt type cation; the cationic hydrophilic group is a cation in water, or a cation is generated after an ionization reaction is carried out in water to obtain a proton; the cation is selected from: at least one of an amine salt type cation, a quaternary ammonium salt type cation, a sulfonium salt type cation, and a phosphonium salt type cation.

In some of these embodiments, the zwitterionic starch complexing agent has the following structure:

wherein A is selected from:

b is selected from:

c is selected from:

d is selected from:

r is selected from: substituted or unsubstituted alkyl, substituted or unsubstituted aryl;

each R ₁ Each independently selected from: H. a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group;

each R ₂ 、R ₃ And R ₄ Each independently selected from: H. substituted or unsubstituted alkyl;

m is selected from: H. metal ions, ammonium ions, organic amine cations, or none;

each n is independently: a positive integer between 1 and 10.

In some of these embodiments, R is selected from: 1 or more R ₅ Substituted C ₄ -C ₄₀ Alkyl, alkyl containing a carbon-carbon double bond, 1 or more R ₆ Substituted C ₆ -C ₁₀ Aryl, or the structure:

wherein each R is ₅ Each independently selected from: H. fluorine, C ₁ -C ₂₀ Alkyl, carboxyl, hydroxyl;

each R ₆ Each independently selected from: H. fluorine, carboxyl, hydroxyl, C ₄ -C ₄₀ Alkyl radical, C ₄ -C ₄₀ Alkoxy and at least one R ₆ Is selected from C ₄ -C ₄₀ Alkyl or C ₄ -C ₄₀ An alkoxy group;

each R ₇ Each independently selected from: 1 or more of R ₅ Substituted C ₄ -C ₄₀ Alkyl, alkyl containing a carbon-carbon double bond, 1 or more R ₆ Substituted C ₆ -C ₁₀ An aryl group;

each R ₈ Each independently selected from: H. r ₉ -(C＝O)-O-、C ₁ -C ₆ Alkoxy radical, C ₁ -C ₆ An alkyl group;

each R ₉ Each independently selected from: 1 or more of R ₅ Substituted C ₁ -C ₄₀ Alkyl, alkyl containing a carbon-carbon double bond;

the total number of carbon atoms in each of the alkyl groups containing a carbon-carbon double bond is independently 4 to 40, and the number of carbon-carbon double bonds is independently 1 to 10.

In some of these embodiments, R is selected from: c ₇ -C ₃₀ Alkyl, alkyl containing a carbon-carbon double bond, 1 or more R ₆ Substituted phenyl, or the structure:

wherein each R is ₆ Each independently selected from: H. c ₇ -C ₃₀ Alkyl radical, C ₇ -C ₃₀ Alkoxy and at least one R ₆ Is selected from C ₇ -C ₃₀ Alkyl or C ₇ -C ₃₀ An alkoxy group;

each R ₇ Each independently selected from: c ₇ -C ₃₀ Alkyl, alkyl containing a carbon-carbon double bond;

each R ₈ Each independently selected from: H. r is ₉ -(C＝O)-O-、C ₁ -C ₆ Alkoxy radical, C ₁ -C ₆ An alkyl group;

each R ₉ Each independently selected from: c ₁ -C ₃₀ Alkyl, alkyl containing a carbon-carbon double bond;

the total number of carbon atoms in each of the alkyl groups containing a carbon-carbon double bond is independently 7 to 30, and the number of carbon-carbon double bonds is independently 1 to 8.

In some of these embodiments, R is selected from: c ₁₀ -C ₂₀ Alkyl, alkyl containing a carbon-carbon double bond, 1 or more R ₆ Substituted phenyl, or the structure:

wherein each R is ₆ Each independently selected from: H. c ₁₀ -C ₂₀ Alkyl radical, C ₁₀ -C ₂₀ Alkoxy and at least one R ₆ Is selected from C ₁₀ -C ₂₀ Alkyl or C ₁₀ -C ₂₀ An alkoxy group;

each R ₇ Each independently selected from: c ₁₀ -C ₂₀ Alkyl, containing carbon-carbonDouble-bonded alkyl;

each R ₉ Each independently selected from: c ₁ -C ₂₀ Alkyl, alkyl containing a carbon-carbon double bond;

the total number of carbon atoms in each alkyl group containing a carbon-carbon double bond is 10 to 20, and the number of carbon-carbon double bonds is 1 to 5.

In some of these embodiments, R is selected from: c ₁₀ -C ₂₀ Alkyl, or the structure:

wherein each R is ₇ Each independently selected from: c ₁₀ -C ₂₀ An alkyl group;

each R ₈ Each independently selected from: H. r is ₉ -(C＝O)-O-、C ₁ -C ₆ An alkoxy group;

each R ₉ Each independently selected from: c ₇ -C ₂₀ An alkyl group.

In some of these embodiments, each R ₁ Each independently selected from: H. hydroxy, C ₁ -C ₆ Alkyl, hydroxy substituted C ₁ -C ₆ Alkyl radical, C ₁ -C ₆ An alkoxy group.

In some of these embodiments, each R ₂ 、R ₃ And R ₄ Each independently selected from: H. c ₁ -C ₆ Alkyl, hydroxy substituted C ₁ -C ₆ Alkyl, carboxy substituted C ₁ -C ₆ Alkyl, sulfuric acid radical substituted C ₁ -C ₆ Alkyl, sulfonic substituted C ₁ -C ₆ Alkyl, phosphate substituted C ₁ -C ₆ Alkyl, phosphityl substituted C ₁ -C ₆ An alkyl group.

In some of these embodiments, each R ₂ 、R ₃ And R ₄ Each independently selected from: H. methyl, carboxymethyl, carboxyethyl, hydroxymethyl, hydroxyethyl, hydroxypropyl.

In some embodiments, each n is independently: a positive integer between 1 and 5.

In some of these embodiments, the zwitterionic starch complexing agent is selected from at least one of the following compounds:

in some of these embodiments, the free starch is selected from the group consisting of: at least one of corn starch, tapioca starch, sweet potato starch, wheat starch, and oxidation modified starch; the oxidation modified starch is oxidation modified corn starch, oxidation modified cassava starch, oxidation modified sweet potato starch or oxidation modified wheat starch.

In some of these embodiments, the method of preparing the oxidatively modified starch comprises the steps of: preparing starch into water solution, heating to 80-100 deg.C, adding starch oxidant or amylase, reacting until viscosity is stable, and cooling to 60-70 deg.C to obtain the final product.

In some of these embodiments, the method of recovering free starch in papermaking white water comprises the steps of:

(a) Adding a zwitterionic starch complexing agent into papermaking white water, and reacting the zwitterionic starch complexing agent with free starch in the papermaking white water to modify the free starch to obtain modified starch;

(b) And adding fiber or paper pulp, and performing adsorption reaction to adsorb the modified starch.

In some of these embodiments, the fiber or pulp has a solids concentration of 1% to 10%.

In some of these embodiments, the fiber or pulp has a solids concentration of 2% to 4%.

In some of these embodiments, the weight ratio of the zwitterionic starch complexing agent to the dry weight of the fiber or pulp is from 0.02 to 20kg/T.

In some of these embodiments, the weight ratio of the zwitterionic starch complexing agent to the dry weight of the fiber or pulp is from 0.15 to 2kg/T.

In some of these embodiments, the weight ratio of the zwitterionic starch complexing agent to the dry weight of the fiber or pulp is from 0.2 to 1.5kg/T.

In some embodiments, the method for recovering free starch in papermaking white water further comprises the step of adding a synergist, and specifically comprises the following steps:

(b) Adding fiber or paper pulp and a synergist, and performing adsorption reaction to adsorb the modified starch;

the synergist is a cationic polymer, a nonionic polymer or a zwitterionic polymer which has an effect of promoting the retention of the modified starch on fibers, and the molecular weight of the cationic polymer, the nonionic polymer or the zwitterionic polymer is 50,000-10,000,0000Dalton.

In some of these embodiments, the potentiator is selected from: at least one of polydiallyldimethylammonium chloride, polyhydroxypropyldimethylammonium chloride, dicyandiamide formaldehyde polycondensation resin, polyvinylamine, polyethyleneimine and polydichloroethyl ether tetramethylethylenediamine.

In some embodiments, the mass ratio of the zwitterionic starch complexing agent to the synergist is 1:0.05-40.

In some embodiments, the mass ratio of the zwitterionic starch complexing agent to the synergist is 1:0.1-10.

In some embodiments, the mass ratio of the zwitterionic starch complexing agent to the synergist is 1:0.2-5.

In some embodiments, the mass ratio of the zwitterionic starch complexing agent to the synergist is 1:0.2-1.

In some of these embodiments, the temperature of the reaction of step a) is 10 to 90 ℃ and the temperature of the adsorption reaction of step b) is 10 to 90 ℃.

In some of these embodiments, the temperature of the reaction of step a) is 10 to 60 ℃ and the temperature of the adsorption reaction of step b) is 10 to 60 ℃.

In some of these embodiments, the temperature of the reaction of step a) is 15 to 50 ℃ and the temperature of the adsorption reaction of step b) is 15 to 50 ℃.

In some of these embodiments, the reaction time of step a) is from 1min to 20h.

In some of these embodiments, the reaction time of step a) is from 25min to 1h.

In some of these embodiments, the time for the adsorption reaction of step b) is from 1min to 120min.

In some of these embodiments, the time for the adsorption reaction of step b) is 5min to 30min.

In some of these embodiments, the reaction of step a) and step b) has a pH of from 4 to 11.

In some of these embodiments, the reaction of step a) and step b) has a pH of 4.5 to 9.5.

The method for recovering the free starch in the papermaking white water has the following advantages and beneficial effects:

the method for recovering the free starch in the papermaking white water of the invention generates the ' starch-compound ' inclusion complex ' by adding the zwitterion complexing agent with special complexing action on the starch into the papermaking white water to react with the starch in the papermaking white water, thereby changing the physical and chemical properties of the starch in the papermaking white water, reducing the solubility of the starch in the papermaking white water, greatly reducing the content of the free starch in the papermaking white water and reducing the COD discharge amount of the papermaking wastewater. The fiber or pulp is further added into the white water treated by the zwitterionic complexing agent, so that the obtained starch-compound can be precipitated or adsorbed in the fiber or pulp, the free starch content in the white water can be further reduced, and the fiber or pulp adsorbed with starch prepared by recovering the white water can be directly used for papermaking, so that the recovery rate of the starch and the utilization rate in papermaking are greatly improved. In the process of recycling treatment by the method, a certain synergist is added, so that the content of free starch in the white water can be further reduced, and the COD discharge amount of the papermaking wastewater is reduced.

Thus, the method of recovering free starch from papermaking white water of the present invention can produce various beneficial effects, including: (1) The COD concentration of papermaking drainage is reduced, organic pollution is reduced, and the environment is improved; (2) The recovery rate of starch is improved, and the production cost is reduced; (3) Reduce the starch consumption of the paper industry and increase the national food safety. Therefore, the method for recovering the free starch in the papermaking white water has great significance for the papermaking production industry.

Detailed Description

The definitions and meanings of technical terms in the present invention include the following.

In the present invention, "Starch Binding reaction" (Starch Binding), "Starch Complexation" (Starch Modification) "and" Starch Modification "(Starch Modification) mean a reaction of Starch with a substance having affinity for Starch in an aqueous phase, forming the Starch into a helix and including the reactant in the helix, and a" Inclusion Complex "(Inclusion Complex). These names are used interchangeably in the present technology. The "inclusion complex" formed is referred to as "modified starch", or "modified starch", i.e. "modified starch" and "modified starch" have the same meaning in the art and are used interchangeably.

In the above reaction, a reactant having a specific affinity for Starch is called "Starch Binding Agents (Starch Binding Agents)" or "Starch complexing Agents (Starch complexing Agents)", and the reactant can react with Starch to form an inclusion complex, and the chemical structure of the reactant is composed of the following components:

i) One or more hydrophobic groups, at least one of which has a strong affinity for starch, capable of reacting with starch to form an "Inclusion Complex" (Inclusion Complex) of a starch-compound, and

ii) one or more hydrophilic groups to allow the compound itself to achieve sufficient aqueous solubility;

the two groups with the structures and the properties which are opposite are positioned at two ends of the same molecular structure and are connected by chemical bonds, so that an asymmetric and polar structure is formed.

The hydrophobic groups are nonpolar groups, and can be classified according to the structure of the hydrophobic groups, such as straight chain/branched chain aliphatic hydrocarbon, aromatic hydrocarbon, mixed aliphatic and aromatic hydrocarbon, mixed hydrocarbon with weak hydrophilic groups, perfluoroalkyl groups, and fluorine-containing mixed hydrocarbon groups.

Wherein the hydrophilic group is a polar group, and is classified into a carboxyl group, a sulfonic group, a sulfuric group, a phosphoric group, a phosphorous group, an amide group, an ester group, a haloformyl group, a carbamoyl group, a cyano group, an aldehyde group, a carbonyl group, an ether group, an alcohol group, a phenol group, a mercapto group, a sulfide group, and the like, according to the structure or chemical properties.

The above-mentioned starch binder may also be referred to as a starch modifier (starch modifier), a starch crystallizing agent (starch crystallizing agent), a starch precipitant (starch precipitating agent), a starch agglomerating agent (starch agglomerating agent), a starch cross-linking agent (starch binder), a starch adsorbent (starch adsorbent), a starch curing agent (starch curing agent), a starch fixing agent (starch fixing agent), and a starch microfibrillating agent (starch microfibrillating agent).

The starch binder of the present invention has the structural characteristics of a "zwitterionic surfactant", which is called a zwitterionic starch binder. The following categories (the following are only some examples and are not intended to limit the scope of the present invention) are mainly defined:

amino acid type zwitterionic starch binder (Y-type)

The positive charge of hydrophilic radical cation of the amino acid type zwitterionic starch binder is carried by amino, and the negative charge can be carried by carboxyl, sulfonic group, sulfuric acid group and the like, wherein the amino carboxylic acid type zwitterionic starch binder is taken as a main material. In the amino carboxylic acid type amphoteric ion starch binder, the anion in the hydrophilic group is carboxyl and the cation is ammonium salt, and the starch binder shows different properties along with the change of the pH value of a medium.

For example, the structural formula of the monoaminocarboxylic acid zwitterionic starch binder is:

wherein R is a substituted or unsubstituted alkyl group with a carbon chain length greater than 7, R ₂ Is H, methyl, carboxymethyl, hydroxyethyl or hydroxypropyl, and n is a positive integer of 1-10.

The structural general formula of the amino dicarboxylic acid type zwitterionic starch binder is as follows:

wherein R is substituted or unsubstituted alkyl with carbon chain length larger than 7, or phenyl substituted by alkyl or alkoxy, and n is a positive integer of 1-10. For example, disodium laurylaminodipropionate (also known as Sodium laurylaminodipropionate) has the formula:

the structural formula of N- [3, 5-m-decyloxy-phenyl ] -N-carboxymethylglycine (N- [3,5-Bis (decyloxy) phenyl ] -N- (carboxymethyethyl) glycine) is:

the negative charge of the hydrophilic group of the amino acid type zwitterionic starch binder can be carried by a sulfonic acid group, a sulfuric acid group, a phosphoric acid group, a phosphorous acid group or the like. For example:

(di) amide-acid type zwitterionic surfactant (Y-type)

The positive charge of hydrophilic radical cation of the amide-acid type zwitterionic starch binder is carried by amide nitrogen, and the negative charge can be carried by carboxyl, sulfonic group, sulfuric acid group and the like, wherein the amide-carboxylic acid type zwitterionic starch binder is taken as the main material. In the amide-carboxylic acid type zwitterionic starch binders, the anion in the hydrophilic group is a carboxyl group, and such starch binders exhibit different properties as the pH of the medium changes. The structural general formula of the monoamide-carboxylic acid zwitterionic starch binder is as follows:

For example, sarcosyl (Sodium lauroylsarcosine) has the formula:

the structural formula of octyl amide glycine (abbreviated as caprylyl glycine, N-octanoyl glycine) is as follows:

tetradecyl amidoglycine (also called myristoyl glycine, N-myristoyl glycine) has the structural formula:

the structure formula of octadecyl amide glycine (also called stearoyl glycine, 2-octadamidoacetic acid) is as follows:

the negative charge of the hydrophilic group of the amide-acid type zwitterionic starch binder may be carried by a sulfonic acid group, a sulfuric acid group, a phosphoric acid group, or a phosphorous acid group, or the like. For example:

(tri) amide-amino acid type zwitterionic surfactant (Y-type)

The positive charge of hydrophilic radical cation of the amide-amino acid type zwitterionic starch binder is carried by amino and amide nitrogen, and the negative charge can be carried by carboxyl, sulfonic group, sulfuric acid group and the like, wherein the amide-amino carboxylic acid type zwitterionic starch binder is taken as a main material. In the amide-aminocarboxylic acid type zwitterionic starch binders, the anion in the hydrophilic group is a carboxyl group, and such starch binders exhibit different properties as the pH of the medium changes.

For example: the general structural formula of the alkyl acyl ethyl hydroxyethyl amine glycine is as follows:

wherein R is a substituted or unsubstituted alkyl group with a carbon chain length greater than 7, R ₂ H, methyl and carboxymethyl.

The general structural formula of the alkyl hydroxyethyl ethyl amido glycine is as follows:

(IV) betaine type zwitterionic starch Binder (Linear or Rib type)

The hydrophilic group in the Betaine type (Betaine type) zwitterionic starch binder is composed of a quaternary ammonium type cation and a carboxylic acid, sulfonic acid, sulfuric acid or phosphate type anion.

(1) Carboxylic betaine amphoteric starch binder

The anion of the hydrophilic group in the molecule of the carboxylic acid based betaine amphoteric starch binding agent is carboxyl, and the cation is quaternary ammonium group. One of the structural general formulas is shown as follows, wherein the carbon number of the hydrocarbyl group R is 12-18. In comparison with amino acid type starch binders, betaine type starch binders are soluble in water in acidic, neutral or alkaline media, do not cause precipitation even at isoelectric points, and can be used in aqueous solutions of any pH.

For example, myristylbetaine, also known as N- (carboxymethyl) -N, N-dimethyl-1-tetradecylammonium inner salt (N, N-dimethylmyristylammonium) acetate, has the structural formula:

lauryl betaine (also known as Lauryldimethylaminoacetic acid betaine) has the structural formula:

the structural formula of 3- (N, N-dimethyldodecylammonium) butyrate (also called 3-butyldodecyldimethyl betaine, (N-Dodecyl-N, N- (dimethyldodecylammonium) butyrate) is as follows:

other carboxylic acid betaine zwitterionic binders with variant structures include amide-substituted or ether-substituted carboxylic acid betaines, wherein the amide-substituted carboxylic acid betaines have the general structural formula:

for example, the chemical structure of lauramidopropyl betaine (lauramidopropyl carboxybetaine (carboxymethyl) dimethyl-3- [ (1-oxodocyl) amino ] propyllammonium hydroxide) is:

the long chain alkyl chain of betaine type amphoteric ion starch binder may be not on nitrogen atom, but on carbon atom of carboxyl group, and its preparation method is that long chain fatty acid reacts with bromine to produce monobromo fatty acid, then reacts with trimethylamine to produce the said material.

(2) Sulfobetaine zwitterionic starch binders

The anion of hydrophilic group in sulfobetaine amphoteric ion starch binder molecule is sulfonic group (SO) ₃ ^- ) The cation is quaternary ammonium group, and one of the structural general formulas is as follows:

in the formula, R ² ,R ³ Is unsubstituted or substituted alkyl, wherein the number of carbon atoms of R alkyl is more than 8; r ¹⁰ Is unsubstituted or substituted alkylene.

Since the cationic and anionic groups of the sulfobetaine are strongly dissociative at any pH, their properties are essentially independent of the pH of the solution, and the "inner salt" formed is neutral.

For example, 3- (N, N-dimethyldodecylammonium) propane sulfonate, 3-sulfopropyldodecyldimethylbetaine (N-Dodecyl-N, N-dimethyl-3-amonio-1-propanesulfonate) has the formula:

3-sulfopropyltetradecyldimethylammonium (also known as tetradecylsulfosuccinate, 3- (N, N-dimethylsulfoammonio) propanesulfonate) has the structural formula:

the structural formula of 3-sulfopropyloctadecyl dimethyl ammonium (also called octadecyl sulfobetaine, N, N-dimethyl sulfobetaine) propanesulfonate3- (N, N-dimethyl sulfobetaine) propanesulfonate is shown as follows:

when the hydrophobic group of the sulfobetaine type zwitterionic starch binder is an alkylamide group, the structural general formula is as follows:

in the formula, R is long-chain aliphatic hydrocarbon, and X is sulfonic group.

For example, cetyl acylpropyl sulfobetaine (also known as 3-sulfopropylcetyl acylpropyl Dimethyl ammonium, 3- [ N, N-Dimethyl (3-palmitylaminopropropyl) amonio ] -propanesulfonate) has the formula

Tetradecanoylpropylsulfobetaine (also called 3-sulfopropyltetradecanoylpropyldimethylammonium, 3- [ N, N-Dimethyl (3-mycesteramidopropyl) amonio ] propanesulfonate) has the structural formula:

the alkyl dimethyl hydroxypropyl sulfobetaine has a structural general formula as follows:

the general structural formula of the alkylamido hydroxypropyl sulfobetaine is as follows:

for example, the structure of dodecylamidopropyl hydroxypropyl sulfobetaine (also known as lauramidopropyl hydroxysulfobetaine, N, N-DIMETHYL-N-DODECYL-N- (2-HYDROXY-3-SULFOPROPYL) aminomethane) is:

(3) Sulfate betaine type zwitterionic starch binder

The anion of hydrophilic group in sulfate betaine amphoteric ion starch binder molecule is sulfate group (SO) ₄ ^- ) The cation is quaternary ammonium group, and the sulfate betaine type zwitterionic starch binder has a typical structure as follows:

wherein n =2,3. For example, the dodecyl propyl sulfate betaine structure is:

(4) Phosphate betaine zwitterionic starch binder

The anion of the hydrophilic group in the molecular structure of the phosphate betaine zwitterionic starch binder is phosphoric acid (PO) ₄ ^- ) The cation is quaternary ammonium group.

For example, the chemical structure of dodecyl dimethyl propyl hydroxy phosphate betaine is:

(V) imidazoline type zwitterionic starch binders

The imidazoline type zwitterionic starch binder has a structure that hydrophilic groups in the molecule of the imidazoline type zwitterionic starch binder comprise a ring and a pentavalent nitrogen atom and are cations, the hydrophobic groups of the imidazoline type zwitterionic starch binder are long-chain alkyl groups connected at the 2 position, the hydrophilic groups are carboxyethyl groups, hydroxyethyl groups and the like, and one of the structural formulas is as follows:

wherein R is a long chain alkyl group, R ² Is H, hydroxyethyl.

For example: 2-alkyl-N-carboxymethyl-N' -hydroxyethyl imidazoline, having the following structural formula:

2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazoline, which has the following structural formula

Wherein R is an alkyl group having 12 to 18 carbon atoms.

The structural formula of the 2-alkyl-N-ethanesulfonic acid-N-hydroxyethyl imidazoline zwitterionic starch binder is as follows:

the structural formula of the 2, N' -dialkyl-N-ethyl sulfate imidazoline zwitterionic starch binder is as follows:

the imidazoline borate type zwitterionic starch binder can be prepared by firstly forming an intermediate (HEAI) by fatty acid and hydroxyethyl ethylenediamine, and then carrying out esterification reaction with boric acid to prepare the organic boron system imidazoline zwitterionic starch binder, wherein the structural formula is as follows:

imidazoline betaine is prepared by reacting imidazoline with acrylic acid, and fatty acid and hydroxyethyl ethylenediamine are subjected to condensation reaction to obtain imidazoline, which is then reacted with acrylic acid to obtain imidazoline betaine:

(Hexa) phosphorylcholine type zwitterionic starch binder

Phosphorylcholine (PC) is an amphiphilic molecule in which the aliphatic chain is saturated or unsaturated, and is a nonpolar hydrophobic tail; the phosphorylcholine moiety is a dipolar ion, a polar hydrophilic head. For example, the structural formula is as follows:

in the formula, R ¹ Is an aliphatic hydrocarbon radical having a carbon chain length of at least 10 carbon atoms, R ⁷ Is a short chain hydrocarbyl group having a carbon chain length of 1 to 4 carbon atoms.

The structural formula of 1-O-Octadecyl-2-O-methyl-sn-glycerol-3-phosphorylcholine (1-O-Octadecyl-2-O-methyl-sn-glycerol-3-phosphorylcholine) is as follows:

the structural formula of 1-0-octadecyl-2-O-carboxyl-sn-glycerol-3-phosphorylcholine (beta-Acetyl-gamma-O-octadecel-L-alpha-phosphatydilcholine) is as follows:

when the hydrophobic group is a double long-chain fatty acid, the structural formula is as follows:

in the formula, R ⁷ And R ⁷ Are saturated or unsaturated aliphatic hydrocarbon radicals having a carbon chain length of at least 10 carbon atoms. For example,

1, 2-diacyl-sn-glycero-3-phosphocholine (also known as 3-sn-phosphatidylcholine; L-alpha-lecithin; L-alpha-phosphatidylcholine), having the structural formula:

1, 2-dicoroyl-sn-glycero-3-phosphocholine (Dimyristoyl lecithin, 1, 2-Dimyristoyl-rac-glycerol-3-phosphorylcholine) structural formula:

1, 2-dilauroylamino-2-sn-glycero-3-phosphocholine (dilauroyl lecithin, 1, 2-didecanoyl-rac-glycero-3-phosphorylcholine) has the structural formula:

1-palmitoyl-2-Oleoyl-sn-glycero-3-phosphocholine (1-palmitoyl-2-Oleoyl lecithin, 2-Oleoyl-1-palmitoyl-sn-glycero-3-phosphorylcholine) has the structural formula:

the structural formula of 1-2-Dioleoyl-sn-glycero-3-phosphocholine (Dioleoyl lecithin, 1, 2-Dioleoyl-sn-glycero-3-phosphorylcholine) is shown in the specification,

1, 2-Dipalmitoyl-sn-glycero-3-phosphocholine (Dipalmitoyl lecithin, 1, 2-Dipalmitoyl-rac-glycerol-3-phosphorylcholine) has the structural formula:

(VII) zwitterionic starch Binder with non-Nitrogen atoms as cationic Structure

The cations in the structures of the starch binders are all N atoms, and the positive charges in the cations in the zwitterionic starch binder can also be carried by phosphorus (P) atoms or sulfur (S) atoms. For example, the formula is:

specific compounds are, for example: the octadecyl phosphonic acid phosphorus alkali lactone (octadecene) has the structural formula:

in addition, hydrogen atoms in the hydrophobic groups in the above various starch binder structures may be partially or fully substituted with fluorine atoms into fluorocarbon chains.

Starch. Starch is a polysaccharide of the formula (C) ₆ H ₁₀ O ₅ ) n, starch can be regarded as a high polymer of glucose. The starch includes amylose and amylopectin. Amylose contains several hundred glucose units, and amylopectin contains several thousand glucose units; thus, amylose has a relatively small molecular weight, on the order of 50000, and amylopectin has a much higher molecular weight than amylose, on the order of 60000. The composition of the plant starch generally consists of 10 to 30% amylose and 70 to 90% amylopectin.

The starch has the characteristic of changing into blue when meeting iodine, which is determined by the structural characteristics of the starch. Amylose dissolved in water is coiled into a helix by intramolecular hydrogen bonds. If iodine solution is added, iodine molecules in the iodine solution are inserted into the gaps of the helical structure and are associated with amylose by van der Waals force to form a complex. The complex can uniformly absorb other visible light (with the wavelength range of 400-750 nm) except blue light, so that amylose presents blue when meeting iodine, amylopectin presents purplish red when meeting iodine, and dextrin presents blue purple, orange and other colors when meeting iodine.

The starch content of various plants is high, the rice contains 62-86% of starch, the wheat contains 57-75% of starch, the corn contains 65-72% of starch, and the potato contains more than 90% of starch.

Modified Starch (Modified Starch). In order to improve the performance of the starch and expand the application range of the starch, a physical, chemical or enzymatic treatment is utilized to introduce new functional groups on starch molecules or change the size of the starch molecules and the properties of starch particles, so that the natural characteristics (such as gelatinization temperature, hot viscosity and stability thereof, freeze-thaw stability, gel strength, film forming property, transparency and the like) of the starch are changed, and the starch is more suitable for the requirements of certain applications. This starch that has undergone secondary processing to alter its properties is collectively referred to as destructured starch. Currently, the classification of destructured starch is generally carried out according to the mode of treatment.

Physical denaturation: pregelatinized (alpha-gelatinized) starch, gamma-ray, ultrahigh-frequency radiation-treated starch, mechanical grinding-treated starch, moist heat-treated starch, etc.

Chemical denaturation: the resulting modified starch is treated with various chemical agents. There are two main categories: one is to lower the molecular weight of starch, such as acid hydrolyzed starch, oxidized starch, baked dextrin, etc.; another class is to increase the molecular weight of starches such as crosslinked starches, esterified starches, etherified starches, grafted starches and the like.

Enzymatic denaturation (biological modification): various enzymes treat the starch. Such as alpha, beta, gamma-cyclodextrin, maltodextrin, amylose, etc.

Complex denaturation: modified starch obtained by more than two treatment methods. Such as oxidatively crosslinked starch, crosslinked esterified starch, and the like. The modified starch obtained by composite modification has the respective advantages of two modified starches.

In addition, modified starch can be classified according to production process routes, such as dry methods (such as phosphate starch, acid hydrolyzed starch, cationic starch, carboxymethyl starch and the like), wet methods, organic solvent methods (such as carboxyl starch preparation generally adopts ethanol as a solvent), extrusion methods, roller drying methods (such as natural starch or modified starch as a raw material to produce pregelatinized starch), and the like.

Pregelatinized Starch (Pre-gelatinized Starch). Gelatinizing starch: the function of starch granules swelling, splitting and forming a uniform pasty solution in water at a proper temperature (the temperature required by starch from various sources is different, generally 60-80 ℃) is called gelatinization. The essence of gelatinization is that hydrogen bonds between starch molecules in ordered and disordered (crystalline and amorphous) states in starch grains are broken, and the starch grains are dispersed in water to form a colloidal solution.

The process of gelatinization can be divided into three phases: (1) In the reversible water absorption stage, water enters the amorphous part of the starch grains, the volume is slightly expanded, at the moment, the grains can be recovered after cooling and drying, and the birefringence phenomenon is not changed; (2) In the irreversible water absorption stage, along with the rise of temperature, water enters the clearance of the starch microcrystal and absorbs a large amount of water irreversibly, the birefringence phenomenon is gradually blurred and disappears, namely crystallization 'dissolution', and starch grains expand to 50-100 times of the original volume; (3) The starch grains are finally disintegrated, and the starch molecules are all put into the solution.

The method for determining the gelatinization of starch comprises the following steps: there are optical microscopy, electron microscopy, light propagation, viscometry, swelling and solubility measurements, enzyme analysis, nuclear magnetic resonance, laser light scattering and the like. Viscometry, swelling and solubility measurements are common in the industry.

Acid-denatured Starch (Acidified Starch). The acid-modified starch refers to a modified starch obtained by treating native starch with an inorganic acid at a temperature lower than the gelatinization temperature to change the properties of the native starch.

Typical conditions for the preparation of acid-denatured starch are: the concentration of the starch milk is 36-40%, the temperature is lower than the gelatinization reaction temperature (35-60 ℃), and the reaction time is 0.5h to several hours. When the required viscosity or conversion degree is reached, neutralizing, filtering, washing and drying to obtain the product.

Effect of reaction conditions on acid-denatured starch performance:

1. the temperature reaction temperature is the main factor influencing the performance of the acid-denatured starch, when the temperature is between 40 and 55 ℃, the viscosity changes to the temperature, and the starch is gelatinized when the temperature is raised to 70 ℃. The reaction temperature is therefore generally chosen in the range from 40 to 55 ℃.

2. The kind and amount of the acid are used as catalysts and do not participate in the reaction. Different acids have different catalytic effects, hydrochloric acid is strongest, sulfuric acid and nitric acid are similar, and when the temperature is higher and the acid consumption is larger, the nitric acid modified starch is light yellow due to side reaction, so the nitric acid modified starch is rarely used in actual production. The catalytic action of the acid is related to the amount of acid used, and if the amount of acid is large, the reaction is severe.

3. Starch milk concentration the starch milk concentration should be controlled around 40%.

Esterified Starch (esterified Starch). The esterified starch is modified starch obtained by performing esterification reaction on starch milk and organic acid anhydride (acetic anhydride, succinic anhydride and the like) below gelatinization temperature under certain conditions.

The acetic acid esterification modified starch is characterized in that an acetyl group is connected to C6 of a glucose unit, the acetyl group belongs to a hydrophilic group, the binding capacity of the starch and water is greatly improved, the water swelling degree of starch particles is improved, the gelatinization temperature is reduced, the peak viscosity is improved, the acetic acid esterification modified starch protein is very low, the fat content is very low, the color is white, the natural fluorescence is realized, the color of a noodle body can be effectively improved, the gelatinization temperature is lower than that of original starch in flour, the gelatinization is prior to gelatinization of the original starch in a noodle cake cooking process, the cooking time is shortened, due to the existence of the acetyl group and the film forming property of the modified starch on the surface of the noodle, the adhesion of oil and the noodle cake can be effectively prevented, the oil absorption rate is reduced, the high peak viscosity of the modified starch indicates that the water swelling degree of the starch particles is large, and great help is brought to the rehydration of the instant noodles.

Oxidized Starch (Oxidized Starch). Many chemical oxidants are capable of oxidizing starch, but the most common in industrial production is alkaline hypochlorite.

Cross-linked Starch (Cross-linked Starch). The concept of crosslinked starch is that the alcoholic hydroxyl group of starch and the multifunctional group of the crosslinking agent form a di-ether bond or a di-ester bond, so that two or more starch molecules are bridged together to form a reaction with a multidimensional network structure, which is called a crosslinking reaction.

The cross-linking is the bridging between molecules to form chemical bonds, which strengthens the hydrogen bonds between molecules. When cross-linked starch is heated in water, the hydrogen bonds can be weakened or even broken, whereas the starch granules will remain unchanged to varying degrees due to the presence of chemical bridges.

The most commonly used crosslinking agents in China are: sodium trimetaphosphate, sodium tripolyphosphate, formaldehyde, phosphorus oxychloride and epichlorohydrin.

Resistant Starch (also known as Resistant Starch and indigestible Starch) is not enzymatically hydrolyzed in the small intestine, but is fermented with volatile fatty acids in the human gastrointestinal colon. Resistant starches are present in certain natural foods, such as potato, banana, rice, etc., which contain resistant starches, and in particular high amylose corn starches contain up to 60% resistant starch. This starch is more resistant to degradation than other starches, is digested more slowly in the body, and is absorbed more slowly and enters the blood stream. The product has the property similar to soluble fiber, and has certain slimming effect.

Starch-Iodine Inclusion Complex (Starch-Iodine Inclusion Complex). Amylose is a long, helical helix formed by the condensation of alpha-glucose molecules, each glucose unit still having its hydroxyl group exposed outside the helix. The iodine molecules act with the hydroxyl groups, so that the iodine molecules are embedded into the axial position of the starch spirochete. This action of iodine and starch is called inclusion, and the product is called inclusion compound.

In the inclusion compound formed by starch and iodine, each iodine molecule is matched with 6 glucose units, starch chain is coiled into a spiral shape with the diameter of 0.13pm, and the iodine molecule is positioned at the axle center of the spiral.

The color of the inclusion compound formed by starch and iodine is related to the polymerization degree or relative molecular mass of starch. Within a certain polymerization degree or relative molecular mass range, the color of the clathrate compound changes from colorless, orange, reddish, purple to blue along with the increase of the polymerization degree or the relative molecular mass. For example, when the polymerization degree of amylose is 200 to 980 or the relative molecular mass range is 32000 to 160000, the color of the clathrate is blue. Amylopectin with a high degree of linear chain average polymerization in the branches of 20 to 28, so that the inclusion compound formed is purple. Dextrin has lower polymerization degree, and shows brownish red, light red and the like.

Amylase (Amylase). Amylases are enzymes that act on α -1, 4-glucans such as soluble starch, amylose, and glycogen to hydrolyze α -1, 4-glucosidic bonds. Depending on the type of isomerism of the enzymatic hydrolysate, a distinction is made between alpha-amylases (EC 3.2.1.1) and beta-amylases (EC 3.2.1.2).

alpha-Amylase (alpha-Amylase), system name 1, 4-alpha-D-Glucan glucanohydrolase, (1, 4-alpha-D-Glucan-glucanohydrolase). The alpha-amylase can hydrolyze alpha-1, 4-glycosidic bonds in the starch, hydrolysis products are dextrin, oligosaccharide and monosaccharide, the viscosity of gelatinized starch can be rapidly reduced after the enzyme action, and the gelatinized starch is changed into liquefied starch, so the alpha-amylase is also called as liquefied amylase, liquefied enzyme and alpha-1, 4-dextrinase.

When the alpha-amylase uses amylose as a substrate, the reaction is generally carried out in two stages. First, amylose is rapidly degraded to produce oligosaccharides, at which stage the viscosity and the ability to undergo a color reaction with iodine rapidly decrease. The second stage is a much slower reaction than the first stage, involving a slow hydrolysis of the oligosaccharides to the final products glucose and maltose. Alpha-amylases, when acted upon by amylopectin, produce glucose, maltose and a series of restricted dextrins (oligosaccharides consisting of 4 or more glucose groups), all of which contain alpha-1, 6-glucosidic linkages.

The alpha-amylase molecule contains a calcium ion which is combined firmly, the calcium ion does not directly participate in the formation of an enzyme-substrate complex, and the function of the calcium ion is to maintain the structure of the enzyme so that the enzyme has the maximum stability and the highest activity.

High temperature resistant alpha-amylases and meso-amylases can be classified according to their thermostability. Among the thermostable alpha-amylases, enzyme preparations produced by Bacillus amyloliquefaciens and Bacillus licheniformis have been widely used in food processing. The temperature has different influences on the activities of the two enzymes, the optimum temperature of the bacillus licheniformis-amylase is 92 ℃, the optimum temperature of the bacillus amyloliquefaciens-amylase is only 70%, and the final products of the two enzymes acting on starch are different except for the difference of thermal stability.

Beta-amylase (β -amylase), also known as amylobeta-1, 4-maltosidase (α -1,4-glucan maltohydrolase), is one of the classes of amylases that can break down amylose into maltose. The only product of β -amylase is maltose, not glucose. Beta-amylase is an exo-amylase which acts on starch by cleaving alternate alpha-1, 4 linkages in sequence from the non-reducing end and the hydrolysis products are all maltose. The amylase is called beta-amylase because the amylase converts the configuration of C1 in a hydrolysate maltose molecule from alpha type to beta type in the hydrolysis process.

Beta-amylase is mainly present in higher plants, particularly in cereals such as barley, wheat, etc., but also in sweet potato, soybean, and in animal bodies. The active center of the beta-amylase contains sulfydryl (-SH), so that certain oxidants, heavy metal ions and sulfydryl reagents can inactivate the beta-amylase, and the reduced glutathione and cysteine have a protection effect on the beta-amylase.

Beta-amylase cannot hydrolyze the alpha-1, 6 bonds of amylopectin and cannot continue to hydrolyze across branch points, so that the hydrolysis of amylopectin is incomplete, leaving beta-limit dextrins of macromolecules. When beta-amylase hydrolyzes amylose, if the starch molecule consists of an even number of glucose units, the final hydrolysate is entirely maltose; if the starch molecule consists of an odd number of glucose units, the final hydrolysate will have a small amount of glucose in addition to maltose. When beta-amylase hydrolyzes starch, viscosity is slowly decreased because macromolecules always exist from the molecular end, and the starch cannot be used as liquefying enzyme, and when beta-amylase hydrolyzes starch hydrolysate such as maltodextrin and malto-oligosaccharide, hydrolysis speed is fast, so the starch hydrolysate is used as saccharifying enzyme.

Gamma-amylase (gamma-amylase). Code e.c.3.2.1.3. The gamma-amylase is an exonuclease, alpha (1 → 4) chain glycosidic bond and alpha (1 → 6) chain glycosidic bond are sequentially cut from the non-reducing end of a starch molecule, glucose residues are cut one by one, and free hemiacetal hydroxyl generated by hydrolysis is subjected to transposition to release beta-glucose. Thus, the final product is glucose, whether it acts on amylose or amylopectin. Therefore, it is also called glucoamylase, glucoamylase.

Isoamylase (isoamyylase). Code e.c.3.2.1.33. Isoamylase hydrolyzes alpha-1, 6-glycosidic bond of amylopectin or glycogen, hydrolyzes only-1, 6 glycosidic chain of glycogen or amylopectin branch point, cuts off whole side branch, and forms amylose with different length. Thus, isoamylases are also known as starch-1, 6-glucosidases. Isoamylase is produced by animals, plants and microorganisms. The source is different, and the name is different, such as: debranching enzymes, Q enzymes, R enzymes, pullulanase, and the like.

Cyclodextrin Glucosyltransferase (CGT). Cyclodextrins (often abbreviated as CD) are a generic name for a class of cyclic compounds formed from starch or polysaccharides by the action of cyclodextrin glucosyltransferases, consisting of D-glucopyranose units linked end-to-end by alpha-1, 4-glycosidic bonds, usually 6-12D-glucopyranose units, and thus, depending on the number of glucose units in the ring, molecules with 6, 7 and 8 glucose units are common, called alpha-, beta-and gamma-Cyclodextrins, respectively. Cyclodextrin glucosyltransferases are most importantly characterized by their ability to catalyze the formation of cyclodextrins from linear starch oligosaccharide chains. The CGT cyclization reaction is a special form of transglycosidation which uses the non-reducing end of the donor chain as an acceptor to form the cyclized product.

Chemical Oxygen Demand (COD). COD is defined as that the water sample is converted into milligrams of oxygen required by oxidizing 1 liter of water sample by using the amount of oxidant consumed by oxidizing reducing substances in the water sample as an index under a certain condition, wherein the milligrams of oxygen are expressed in mg/L (ppm). It reflects the degree of pollution of reducing substances in water, and is an important organic pollution parameter which can be quickly measured as one of the comprehensive indexes of the relative content of organic matters. Therefore, chemical Oxygen Demand (COD) is often used as an index to measure the content of organic substances in water. The larger the chemical oxygen demand, the more serious the water body is polluted by organic matters.

The measurement of Chemical Oxygen Demand (COD) varies depending on the method of measuring the reducing substances in a water sample and the measurement method. The most common methods currently used are an acid potassium permanganate oxidation method and a potassium dichromate oxidation method. Potassium permanganate (KMnO) ₄ ) The method has low oxidation rate, is simple and convenient, and can adopt potassium dichromate (K) when the relative value of the content of organic matters in a water sample is large ₂ Cr ₂ O ₇ ) The method has high oxidation rate and good reproducibility, and is suitable for measuring the total amount of organic matters in a water sample.

The experimental materials, laboratory instruments and general experimental methods used in the following examples are as follows.

Experimental materials:

starch complexing agent: table 1 lists details of some of the starch complexing agent materials, including english and chinese names, chemical structural formulas, and material numbers (the numbers quoted in the examples correspond to those in table 1). All starch complexing agents are commercially available products, and the purity of the effective components ranges from reagent pure to pharmaceutical pure. In all examples, all starch complexing agents were used as received (as-is) without further purification.

TABLE 1 zwitterionic starch complexing agent

Starch retention synergist: table 2 lists details of the starch retention potentiators used in the following examples, including english and chinese designations, cas, and molecular formulas. All synergists are commercially available products, and their effective composition ranges in purity from reagent pure to pharmaceutical pure. In all examples, all synergists were used as they were (as-is) sold without further purification.

TABLE 2 starch Retention potentiators

Fiber retention aid: table 3 lists details of the fiber retention agents used in the examples below, including names in chinese and english, molecular formulas and molecular weights. The starch retention synergist and the fiber retention aid listed in the invention are cationic polymers, nonionic polymers or zwitterionic polymers which have an effect of promoting the retention of modified starch on fibers, and belong to the category of the synergist disclosed by the invention. All fiber retention aids are commercially available products with effective compositions ranging in purity from reagent pure to pharmaceutical pure. In all examples, all fiber retention agents were used as received (as-is) without further purification.

TABLE 3 fiber Retention aid

The starch is corn starch which is 'XingMao' edible corn starch and purchased from the YongMao corn development Limited company of Zhucheng; cassava starch, wheat starch and sweet potato starch are purchased from Shenzhen zero one biotechnology Limited.

Bleached chemical pulp was obtained from Dongguan white swan paper industry Co., ltd (BKP).

Unbleached chemical pulp: the unbleached chemical pulp is imported North American native coniferous chemical pulp (UKP) from Zhejiang Rongcheng paper industry Co.

OCC waste paper: the base paper is corrugated paper produced by using 100% of OCC national waste, and the surface sizing amount of starch is about 40-60kg/T paper.

The test instrument:

standard fiber disintegrator type CBJ-a: changchun City Yueming mini tester, inc.

CPO1A-3A sheet former: integree precise instruments, inc. of Dongguan city.

BS-30KA electronic balance: shanghai friend Sound Scale, inc.

The COD digestion instrument comprises: XJ-III COD TPTN digestion device produced by Shaoguan Mingtian environmental protection instruments Limited.

Uv-visible spectrophotometer: UVmini-1240 ultraviolet-visible spectrophotometer, manufactured by Shimadzu instruments, japan.

DHG-9070A electric heating constant temperature air drying oven: shanghai Qixin scientific instruments Co., ltd

TDL-80-2B: shanghai' an pavilion scientific instrument factory.

Test method

Preparing standard iodine solution: 11g of iodine and 22g of potassium iodide are weighed, the iodine is completely dissolved by a small amount of distilled water, and finally the volume is determined to be 500ml, and the solution is stored in a brown bottle.

Preparing a dilute iodine solution: weighing 10g of potassium iodide, dissolving the potassium iodide in a small amount of water, sucking 2ml of concentrated iodine solution, metering the volume to a 100ml volumetric flask by using distilled water, and storing the volumetric flask in a brown bottle.

Preparing an original starch solution: preparing a 7% starch solution by taking a starch sample; (2) Heating the starch solution to 95 ℃ (DEG C), and reacting until the viscosity is stable; (3) Cooling to 65 deg.C, and maintaining the starch solution in constant temperature water bath. In the following examples, unless otherwise specified, all starch samples were native starch, and the 7% "standard starch solution" was prepared in this manner.

And (2) preparing an oxidized starch solution, namely putting 465g of deionized water into a magnetic water bath kettle at the temperature of 97 ℃, slowly adding 35g of starch, then adding 0.14g of ammonium persulfate (namely equivalent to 0.4%), boiling for 40 minutes, then cooling to 65 ℃, keeping the starch solution at the temperature of 60 ℃, preparing a 7% standard starch solution (the viscosity of the starch solution is about 30mPa.s), and storing for later use.

Preparing chemical pulp: taking a certain amount of bleached or unbleached chemical pulp board, tearing the bleached or unbleached chemical pulp board into small blocks, weighing 300g of small blocks of pulp, adding 45 ℃ warm water to 2307g, enabling the pulp concentration to be 13%, soaking for a plurality of minutes, pouring the pulp into a PL12-00 type high-concentration hydrapulper, pulping for 15 minutes, and then wringing out water for storage for later use.

Preparing OCC waste paper pulp and white water: taking 300g of waste paper, tearing the waste paper into small pieces, adding tap water to dilute the waste paper to a concentration of 13%, soaking for 5-10min, pouring the waste paper into a PL12-00 type high-concentration hydrapulper, pulping for 15min, taking out the crushed pulp, and adding tap water to dilute the pulp to a concentration of 3%; then separating white water and pulp by using a filter bag to prepare OCC waste paper pulp white water and OCC waste paper pulp which are respectively stored for later use.

Preparing a starch complexing agent solution: firstly, preparing 5% ethanol solution by using high-purity ethanol and purified water, and then dissolving the starch complexing agents listed in tables 1-3 in the prepared 5% ethanol solution, wherein the concentration of the starch complexing agents is between 0.05 and 0.5% (wt.) according to the structure.

Starch retention builders and fiber retention aids are commercial products and are formulated at a concentration of 0.01% (wt.) prior to each use.

Starch complex reaction: (1) Taking 500mL of the prepared starch solution or starch-containing OCC waste paper pulp white water, placing the starch solution or starch-containing OCC waste paper pulp white water into a constant-temperature water bath (the reaction temperature is set according to needs), stirring at a constant speed to reach balance, and adjusting the pH value of the solution according to needs; (2) Adding a starch complexing agent according to the designed dosage, carrying out reaction, taking the solution when the reaction time reaches 5, 10, 15, 30, 60, 90 or 120 minutes, placing the solution in a 30mL test tube, then carrying out centrifugal separation (x4000g.5 minutes), and finally taking the supernatant to analyze the concentration of the starch or COD.

Adsorption/retention test of starch on pulp fibers: (1) Taking 800mL of the prepared starch solution or starch-containing OCC waste paper pulp white water, placing the starch solution or starch-containing OCC waste paper pulp white water into a constant-temperature water bath (the reaction temperature is set according to needs), stirring at a constant speed to reach balance, and adjusting the pH of the solution according to needs; (2) Adding a starch complexing agent according to the designed using amount, reacting, taking the solution when 30, 60 or 120 minutes is reached, and placing the solution in a 30mL test tube; (3) Adding chemical pulp or OCC pulp according to the required pulp concentration, and stirring for adsorption reaction; (4) When the reaction time reaches 10, 30, 60 or 120 minutes, taking the serous fluid and placing the serous fluid in a 30mL test tube; (5) All the solutions taken were analyzed by centrifugation (x 4000g.5 min) and the supernatants were analyzed for starch or COD concentration.

The test procedure of chemical pulp papermaking: (1) Taking 300g of bleached or unbleached chemical pulp, tearing the bleached or unbleached chemical pulp into small blocks, adding tap water to dilute the chemical pulp to 13 percent of concentration, soaking the small blocks for 5 to 10min, pouring the small blocks into a PL12-00 type high-concentration hydrapulper, pulping the small blocks for 15min, taking out the crushed pulp, and storing the crushed pulp for later use; (2) Taking 800g of the prepared starch solution or OCC waste paper pulp white water, adding a test reagent (starch complexing agent) for reacting for 30min; (3) After reacting for 30min, adding the synergist, stirring and reacting for 2-3min, adding the chemical pulp, and stirring and reacting for 10min; (4) Placing the slurry in a 30mL test tube, and after centrifugal treatment, testing the starch concentration and COD content of the supernatant; (5) Immediately pouring the residual pulp into a fiber standard dissociator for defibering 1500r, adding water for diluting to 0.5% after defibering, weighing 640g of pulp with the concentration of 0.5% and papermaking by using a paper sheet former (the paper quantitative is about 100 g); (6) After paper making, the paper sample is placed in a constant temperature and humidity chamber with the temperature of 25 ℃ and the moisture of 50 percent for balancing for 16 hours, and then the physical properties of the paper and the starch content of the finished paper are tested.

The testing steps of white water separation and respective treatment of OCC waste paper and papermaking are as follows: (1) Taking 300g of OCC waste paper, tearing the OCC waste paper into small pieces, adding tap water to dilute the OCC waste paper to a concentration of 13%, soaking for 5-10min, pouring the OCC waste paper into a PL12-00 type high-concentration hydrapulper, pulping for 15min, taking out the crushed pulp, adding tap water to dilute the crushed pulp to a concentration of 3%, separating white water and the pulp by using a filter bag, and respectively storing the white water and the pulp for later use; (2) Taking 800g of the prepared white water, adding a test reagent (starch complexing agent) to react for 30min; (3) After reacting for 30min, adding the synergist, stirring and reacting for 2-3min, adding the OCC slurry prepared above, and stirring and reacting for 10min; (4) Placing the slurry in a 30mL test tube, and testing the starch concentration and the COD content of the supernatant after centrifugal treatment; (5) Immediately pouring the residual pulp into a fiber standard dissociator for defibering 1500r, adding water for diluting to 0.5% after defibering, weighing 730g of the pulp with the concentration of 0.5% and papermaking by using a paper former (the paper ration is about 100 g); (6) After paper making, the paper sample is placed in a constant temperature and humidity chamber with the temperature of 25 ℃ and the moisture of 50 percent for balancing for 16 hours, and then the physical properties of the paper and the starch content of the finished paper are tested.

The primary pulp papermaking experiment of OCC waste paper comprises the following steps: (1) Taking 300g of waste paper, tearing the waste paper into small pieces, adding tap water to dilute the waste paper to a concentration of 13%, soaking for 5-10min, pouring the waste paper into a PL12-00 type high-concentration hydrapulper, pulping for 15min, taking out the crushed pulp, adding tap water to dilute the pulp to a concentration of 3%, and storing for later use; (2) Adding test reagent (starch complexing agent) into 800g of the above 3% OCC raw stock, and reacting for 30min; (3) after reacting for 30min, adding the synergist, stirring and reacting for 10min; (4) Placing the slurry in a 30mL test tube, and testing the starch concentration and the COD content of the supernatant after centrifugal treatment; (5) Immediately pouring the residual pulp into a fiber standard dissociator for defibering 1500r, adding water for diluting to 0.5% after defibering, weighing 730g of the pulp with the concentration of 0.5% and papermaking by using a paper former (the paper ration is about 100 g); (6) After paper making, the paper sample is placed in a constant temperature and humidity chamber with the temperature of 25 ℃ and the moisture of 50 percent for balancing for 16 hours, and then the physical property and the starch content of the finished paper are tested.

The iodine color development starch test method comprises the following steps: taking 0.5ml of centrifuged sample, adding 4ml of diluted iodine solution, measuring absorbance at 600nm, and determining the starch concentration according to the absorbance concentration scale line.

And (3) testing the COD content by a digestion method: accurately transferring 3.00mL of a sample to be detected into a digestion tube, accurately adding 1.00mL of a masking agent (1.00 mL of 10% sulfuric acid is added to a water sample without chloride ions), then adding 3.00mL of digestion solution and 5.00mL of a catalyst, screwing a sealing cover (the water sample without chloride ions and low-boiling-point organic matters can be tested by opening the tube, and the method is the same), and sequentially putting the digestion tube into a digestion device at the temperature of 160 ℃ for digestion for 25 minutes. After the digestion process is finished, cooling, taking out the digestion tubes in sequence, and measuring the COD value by a colorimetric method.

The method for testing the starch content of the finished paper comprises the following steps: (1) Taking a paper sample, placing the paper sample in an oven for drying for 15min, crushing the paper sample by using a plant micro crusher after drying, and then placing the crushed paper sample in the oven for drying for 15min; (2) Placing 1g of the dried pulverized paper pattern in a 100ml beaker, adding 70-80ml of boiled water, and placing in a 100 ℃ constant temperature water bath kettle for 40min; (3) Taking out after 40min, adding water to 100g, taking the slurry, centrifuging, and testing the starch content of the supernatant.

The starch reduction amount (also called starch precipitation amount, or starch retention amount) refers to the difference between the starch concentration (St) in the starch solution after the reaction with the starch complexing agent and the initial starch concentration (So), i.e., starch retention amount = So-St (mg/L).

Starch retention (also called starch deposition rate) is the percentage of starch retention in the total amount of the original starch, i.e. the percentage of starch retention

Starch retention (%) = (So-St)/So × 100

The COD degradation amount (also called COD deposition amount) refers to the difference between the COD concentration (COD 1) in the solution and the initial COD concentration (CODo) after the starch solution reacts with the starch complexing agent, namely

COD degradation = CODo-COD1 (mg/L)

The COD reduction rate (also called COD deposition rate) is the percentage of starch retention in the total amount of the initial starch, i.e. the percentage

COD reduction rate (%) = (CODo-COD 1)/CODo × 100.

Example 1 Effect of the Structure of the starch Binder on the reaction of the Binder with starch

This example tests the reaction of starch binders of different structure with native starch (only cooked, unmodified).

The experimental steps are as follows: (1) Preparing a 7% 'standard starch solution' by taking a corn starch sample; (2) Taking a proper amount of standard starch solution, adding deionized water to dilute the starch solution until the concentration of the starch is 1600mg/L, wherein the pH of the obtained solution is between 6.7 and 7.1; (3) Taking 500mL of starch solution with the prepared concentration, placing the starch solution in a beaker, and placing the beaker in a constant-temperature water bath with the preset temperature of 45 ℃; (4) According to the concentration of the prepared starch complexing agent, 3-30mg/L of the starch complexing agent is added, so that the weight ratio of the starch: the weight ratio of the complexing agent is 50:1, then reacting for 30 minutes to obtain a modified starch solution; (5) Samples were centrifuged (4000 Xg) for 5 minutes and the supernatant was tested for starch content (results correspond to the reduction in dissolved starch in Table 4); (6) Adding bleached hardwood chemical pulp (eucalyptus, BKP) into the residual modified starch solution according to the pulp solid concentration of 2.5% (the weight ratio of the starch complexing agent to the BKP dry weight is 1.2 kg/T), and keeping stirring; (7) Reacting for 10 minutes, taking the slurry, centrifuging (4000 x g) for 5 minutes, taking the supernatant, and testing the concentration of the starch in the white water to obtain the starch retention rate without the starch retention synergist (the result corresponds to the addition of BKP in the table 4); (8) And adding a starch retention synergist Y2 (with the dosage of 6mg/L and 0.24kg/T absolute dry pulp) into the reacted pulp, reacting for 5 minutes, taking the pulp, centrifuging (4000 x g) for 5 minutes, taking supernate, and testing the starch concentration and the COD concentration in the white water to obtain the starch retention rate of the added starch retention synergist (the result corresponds to the addition of BKP and Y2 in the table 4).

TABLE 4 influence of the Structure of the zwitterionic starch Binders on starch Retention

The data in Table 4 show that the zwitterionic starch binder of the present invention can effectively modify starch, change the solubility properties of starch, and greatly reduce the concentration of dissolved starch in solution, with starch retention as a parameter. The modified starch can be effectively fixed on the fiber, and can be more effectively attached on the fiber after the starch retention synergist Y2 is added, so that the concentration of the dissolved starch in the white water is greatly reduced, the corresponding COD concentration is also correspondingly reduced, the removal rate of the COD is basically consistent with the retention rate of the starch, and the modified dissolved starch can be effectively retained on the fiber after being modified by the zwitterionic starch complexing agent.

Example 2 Effect of reaction pH on the reaction of starch Binders with starch and on the adsorption Effect of modified starch

This example examines the effect of solution pH on the reaction of the starch binder with starch and the properties of the modified starch (reaction product, modified starch).

The experimental steps are as follows: (1) Preparing a 7% 'standard starch solution' by taking a corn starch sample; (2) Adding deionized water into a proper amount of standard starch solution to dilute until the concentration of starch is 600mg/L, wherein the pH value of the obtained local solution is 6.7-7.1; (3) 500mL of the prepared starch solution with the concentration is taken and placed in a beaker, and is placed in a preset constant-temperature water bath at 45 ℃, and the pH value of the starch solution is adjusted by adding hydrochloric acid or sodium hydroxide; (4) Adding a zwitterionic starch complexing agent until the solution concentration reaches 30mg/L (namely the mass ratio of the starch to the starch complexing agent is 20; (5) Sampling and centrifuging (4000 x g) for 5 minutes, and taking supernatant to test the starch content and COD concentration; (6) Adding chemical pulp (BKP) (the weight ratio of a starch complexing agent to the BKP dry weight is 1.2kg/T oven-dried pulp) into the residual modified starch solution according to the pulp solid concentration of 2.5%, stirring for 3 minutes, and adding a starch retention synergist Y4 (800 g/T oven-dried pulp); (7) Then the reaction is carried out for 10 minutes, the slurry is taken out and centrifuged (4000 Xg) for 5 minutes, and the supernatant is taken to test the concentration of starch and the concentration of COD in the white water.

The results of the different reaction pH on starch retention are shown in Table 5. It can be seen that some of the starch complexing agent reacts with starch substantially independently of pH, and that only T2 and T4 have a lower starch retention at alkaline pH relative to acidic and neutral pH without the addition of the starch retention synergist Y4.

Table 5 starch retention of zwitterionic starch binders (dosage =1.2kg/T oven dried pulp) at different pH conditions

Example 3 Effect of reaction temperature on starch binding reaction and on adsorption Effect of modified starch

The experimental steps are as follows: (1) Preparing a 7% 'standard starch solution' from a corn starch sample; (2) Taking a proper amount of standard starch solution, adding deionized water and diluting to the concentration of starch of about 600mg/L; (3) Taking 500mL of starch solution with the prepared concentration, placing the starch solution into a beaker, placing the beaker into a constant-temperature water bath with the preset required test temperature, and balancing the starch solution to the specified temperature; (4) Adding a starch binding agent to a solution concentration of 30mg/L (namely the mass ratio of the starch to the starch complexing agent is 20: 1) according to the test requirement, and reacting for 60 minutes to obtain a modified starch solution (the reaction pH is 6.5-7.0); (5) Sampling and centrifuging (4000 x g) for 5 minutes, and taking supernatant to test the starch content; (6) Adding chemical pulp (BKP) (the dosage of the starch binding agent is equivalent to 1000g/T of oven dry stock) into the residual modified starch solution according to the pulp solid concentration of 2.5 percent, then adding a synergist Y1, and keeping stirring; (7) After 10 minutes of reaction, the slurry was centrifuged (4000 Xg) for 5 minutes and the supernatant was tested for starch concentration in the white water.

Table 6 shows the effect of starch binder and reaction with starch on retention of starch in chemical pulp at different temperatures. It can be seen that without the addition of the slurry, the reaction of the binder with the starch decreases with increasing temperature; but the adsorption of the modified starch on the fiber surface remains essentially unchanged in the presence of the pulp within the temperature range tested.

Table 6 starch retention of zwitterionic starch binders (dosage =1kg/T oven dried pulp) at different temperatures

Example 4 comparison of starch modified with different starch binders to paper strength improvement

This example examines the retention in fiber and the paper strength of starch modified with zwitterionic starch binders.

The experimental steps are as follows: preparing starch: boiling the corn starch solution in a water bath at 95 ℃ for 60 minutes to prepare a 7 percent standard starch solution, cooling to 60 ℃, and preserving heat for later use; (2) preparing a slurry: weighing 400g of bleached broadleaf chemical pulp (BKP), adding water at 55 ℃ to 3077g (13% concentration), soaking for 60 minutes, pouring the pulp into a pulper, and pulping for 20 minutes; weighing 200g of absolutely dry pulp, pouring into a horizontal (Wally) beater, adding water to dilute to 23L, untwining for 3 minutes without adding weight, adding 5kg of weight, and beating for 2 minutes until the beating degree is about 30 DEG SR; wringing the pulped pulp, dispersing, and testing the pulp concentration to 29%; taking the pulp according to the required amount of the pulp, adding water to dilute the pulp to 3 percent, pouring the pulp into a fluffer to be fluffed for 3 minutes for standby; (3) preparation of medicine: preparing a starch binding agent and a starch retention synergist Y4 into 1% solution respectively by using deionized water for later use; (4) Modification reaction of starch and reaction of modified starch and slurry: weighing 120g of 7% starch solution prepared in the step (1), adding deionized water to dilute by 200 times, namely, the concentration of starch is 350mg/L, the pH of the solution is 6.7-7.1, and reacting with the 1% starch binding agent solution prepared in the step (3) for 30 minutes at the temperature of 45 ℃, wherein the dosage range is 0.25-1.0kg/T (absolute dry pulp) to obtain modified starch; meanwhile, 3 percent of the slurry prepared in the step (2) is put into a water bath at the temperature of 45 ℃, and is stirred for 30 minutes; pouring the modified starch solution into the slurry, wherein the dosage of the starch is 30kg/T, and continuously stirring for 3 min; adding 1% starch retention synergist solution Y4 (the dosage is 0.8 kg/T) prepared in the step (3) according to the experiment requirement, continuously stirring for 7min, sampling after the reaction is finished, and performing centrifugal test to obtain the concentration of starch and COD in the reacted solution; (5) sheet making: pouring the slurry reacted in the step (4) into a fluffer, adding water to dilute the slurry until the slurry is scribed, fluffing for 30 seconds, diluting the fluffed slurry to 0.5 percent, weighing 750g of diluted slurry and making sheets; all sheets were pressed at 0.4MPa for 5 minutes and then dried in a sheet machine for 5 minutes. And (3) placing the paper sample in a constant temperature and humidity chamber with the temperature of 25 ℃ and the moisture of 50% for balancing for 16h, then testing the physical properties of the paper and the starch content of the finished paper, and completing sheet making and testing according to a TAPPI standard method.

The results of the experiment are shown in Table 7. Therefore, the starch modified by the starch binder can be effectively retained on the fiber, and the content of the starch in the finished paper is increased along with the increase of the dosage of the binder; the retained starch greatly improves the physical strength of the paper, and each index of the paper is increased along with the increase of the starch retention, and the structure of the starch binding agent also has influence on the physical strength of the paper.

TABLE 7 influence of different starch binders on the improvement of the paper index of the modified starch (starch usage =30 kg/T)

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is specific and detailed, but not to be understood as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent should be subject to the appended claims.

Claims

1. A method for recovering free starch from papermaking white water, comprising the steps of (a): reacting a zwitterionic starch complexing agent with free starch in papermaking white water to modify the free starch to obtain modified starch;

(b) Adding fiber or paper pulp, and performing adsorption reaction to adsorb the modified starch;

ii) a plurality of hydrophilic groups, wherein at least one hydrophilic group is an anionic hydrophilic group and at least one hydrophilic group is a cationic hydrophilic group;

the hydrophilic group is a polar group;

wherein the anionic hydrophilic group is selected from: at least one of carboxyl group and salt thereof, sulfonic acid group and salt thereof, sulfuric acid group and salt thereof, phosphoric acid group and salt thereof, and phosphorous acid group and salt thereof; and, the anionic hydrophilic group is anionic in water, or generates an anion after undergoing an ionization reaction in water to give a proton; the anion is selected from: at least one of carboxylate anion, sulfate anion, sulfonate anion, phosphate anion, and phosphite anion;

the cationic hydrophilic group is selected from: at least one of amide group, tertiary amine group and salt thereof, quaternary ammonium group and salt thereof, sulfonium salt group and phosphonium salt type cation; and the cationic hydrophilic group is a cation in water, or a cation is generated after an ionization reaction is carried out in water to obtain a proton; the cation is selected from: at least one of an amine salt type cation, a quaternary ammonium salt type cation, a sulfonium salt type cation, and a phosphonium salt type cation;

the zwitterionic starch complexing agent has the following structure:

wherein A is selected from:

；

b is selected from:

；

c is selected from:

；

d is selected from:

；

each n is independently: a positive integer between 1 and 10;

r is selected from: 1 or more R ₅ Substituted C ₄ -C ₄₀ Alkyl, alkyl containing a carbon-carbon double bond, 1 or more R ₆ Substituted C ₆ -C ₁₀ Aryl, or the structure:

；

each R ₇ Each independently selected from: 1 or more R ₅ Substituted C ₄ -C ₄₀ Alkyl, alkyl containing a carbon-carbon double bond, 1 or more R ₆ Substituted C ₆ -C ₁₀ An aryl group;

each R ₈ Each independently selected from: H. r ₉ -(C=O)-O-、C ₁ -C ₆ Alkoxy radical, C ₁ -C ₆ An alkyl group;

each R ₉ Each independently selected from: 1 or more R ₅ Substituted C ₁ -C ₄₀ Alkyl, alkyl containing a carbon-carbon double bond;

2. The method for recovering free starch from papermaking white water according to claim 1, wherein R is selected from the group consisting of: c ₇ -C ₃₀ Alkyl, alkyl containing a carbon-carbon double bond, 1 or more R ₆ Substituted phenyl, or the structure:

；

3. The method for recovering free starch from papermaking white water according to claim 2, wherein R is selected from the group consisting of: c ₁₀ -C ₂₀ Alkyl, alkyl containing a carbon-carbon double bond, 1 or more R ₆ Substituted phenyl, or the structure:

；

each R ₇ Each independently selected from: c ₁₀ -C ₂₀ Alkyl, alkyl containing a carbon-carbon double bond;

4. The method for recovering free starch from papermaking white water according to claim 3, wherein R is selected from the group consisting of: c ₁₀ -C ₂₀ Alkyl, or the structure:

；

each R ₈ Each independently selected from: H. r is ₉ -(C=O)-O-、C ₁ -C ₆ An alkoxy group;

each R ₉ Each independently selected from: c ₇ -C ₂₀ An alkyl group.

5. The method for recovering free starch from papermaking white water according to claim 1, wherein each R is selected from the group consisting of ₁ Each independently selected from: H. hydroxy, C ₁ -C ₆ Alkyl, hydroxy-substituted C ₁ -C ₆ Alkyl radical, C ₁ -C ₆ An alkoxy group.

6. The method of recovering free starch from papermaking white water according to claim 1, wherein each R is R ₂ 、R ₃ And R ₄ Each independently selected from: H. c ₁ -C ₆ Alkyl, hydroxy substituted C ₁ -C ₆ Alkyl, carboxy substituted C ₁ -C ₆ Alkyl, sulfuric acid radical substituted C ₁ -C ₆ Alkyl, sulfonic substituted C ₁ -C ₆ Alkyl, phosphate substituted C ₁ -C ₆ Alkyl, phosphityl substituted C ₁ -C ₆ An alkyl group.

7. The method of recovering free starch from papermaking white water according to claim 6, wherein each R is R ₂ 、R ₃ And R ₄ Each independently selected from: H. methyl, carboxymethyl, carboxyethyl, hydroxymethyl, hydroxyethylAnd hydroxypropyl.

8. The method for recovering free starch from papermaking white water according to claim 1, wherein each n is independently: a positive integer between 1 and 5.

9. The method for recovering free starch from papermaking white water according to claim 1, wherein the zwitterionic starch complexing agent is selected from at least one of the following compounds:

。

10. the method for recovering free starch from papermaking white water according to any one of claims 1 to 9, characterized in that the free starch is selected from the group consisting of: at least one of corn starch, tapioca starch, sweet potato starch, wheat starch, and oxidation modified starch; the oxidation modified starch is oxidation modified corn starch, oxidation modified cassava starch, oxidation modified sweet potato starch or oxidation modified wheat starch.

11. The method for recovering free starch from papermaking white water according to claim 10, characterized in that the method for preparing oxidatively modified starch comprises the following steps: preparing starch into water solution, heating to 80-100 deg.C, adding starch oxidant, reacting until viscosity is stable, and cooling to 60-70 deg.C.

12. The method for recovering free starch from papermaking white water according to claim 1, characterized in that the fiber or pulp has a solid concentration of 1-10%.

13. The method for recovering free starch from papermaking white water according to claim 12, characterized in that the fiber or pulp has a solids concentration of 2-4%.

14. The method of recovering free starch from paper making white water according to claim 1, wherein the weight ratio of the zwitterionic starch complexing agent to the dry weight of the fibers or pulp is 0.02-20kg/t.

15. The method of recovering free starch from papermaking white water according to claim 14, characterized in that the weight ratio of the zwitterionic starch complexing agent to the dry weight of the fibers or pulp is 0.15-2kg/t.

16. The method for recovering free starch from papermaking white water according to claim 1, further comprising the step of adding a synergist, specifically comprising:

(b) Adding fiber or paper pulp and a synergist into the mixture to perform adsorption reaction so as to adsorb the modified starch;

the synergist is a cationic polymer, a nonionic polymer or a zwitterionic polymer which has an effect of promoting the retention of the modified starch on fibers, and the molecular weight of the cationic polymer, the nonionic polymer or the zwitterionic polymer is 50,000-10,000,0000 Dalton.

17. The method of recovering free starch from papermaking white water as claimed in claim 16, wherein said builder is selected from the group consisting of: at least one of polydiallyldimethylammonium chloride, polyhydroxypropyldimethylammonium chloride, dicyandiamide formaldehyde polycondensation resin, polyvinylamine, polyethyleneimine and polydichloroethyl ether tetramethylethylenediamine.

18. The method for recovering free starch from papermaking white water according to claim 17, wherein the mass ratio of the zwitterionic starch complexing agent to the synergist is 1:0.05-40.

19. The method of recovering free starch in papermaking white water according to claim 18, wherein the mass ratio of the zwitterionic starch complexing agent to the synergist is 1:0.1-10.

20. The method for recovering free starch from papermaking white water according to claim 19, wherein the mass ratio of the zwitterionic starch complexing agent to the synergist is 1:0.2-5.

21. The method for recovering free starch from paper making white water according to claim 1 or 16, wherein the temperature of the reaction in step (a) is 10-90 ℃ and the temperature of the adsorption reaction in step (b) is 10-90 ℃.

22. The method for recovering free starch from paper making white water according to claim 21, wherein the temperature of the reaction in the step (a) is 10-60 ℃ and the temperature of the adsorption reaction in the step (b) is 10-60 ℃.

23. The method for recovering free starch from papermaking white water according to claim 1 or claim 16, characterized in that the reaction time of step (a) is 1min-20h.

24. The method of recovering free starch in papermaking white water according to claim 23, characterized in that the reaction time of step (a) is 25min-1h.

25. The method for recovering free starch from papermaking white water according to claim 1 or claim 16, wherein the adsorption reaction time of step (b) is 1min to 120min.

26. The method for recovering free starch from papermaking white water according to claim 25, wherein the adsorption reaction time in the step (b) is 5min to 30min.

27. The method for recovering free starch from papermaking white water according to claim 1 or claim 16, wherein the pH of the reaction in step (a) and step (b) is 4-11.

28. The method for recovering free starch from paper making white water according to claim 27, wherein the pH of the reaction in step (a) and step (b) is 4.5-9.5.