CN1785836A - High efficiency composite flocculant, its preparation method and application - Google Patents

Abstract

The invention relates to a high-efficiency composite flocculant, a preparation method and an application. The flocculant is composed of flocculant and coagulant aid. The flocculant is mainly polyaluminium-iron or polyaluminum. There are two main categories of coagulant aids, one is inorganic substances such as: sodium silicate, calcium hydroxide, calcium carbonate, magnesium hydroxide, polymer inorganic coagulants, etc.; the other is organic substances such as: polyacrylamide, Dodecyl dimethyl tertiary amine, dicyandiamide and modified chitosan, etc. The high-efficiency composite flocculant of the invention can be used for the treatment of printing and dyeing wastewater, and is especially suitable for difficult-to-remove non-water-soluble disperse dyes and paints.

Description

High-efficiency composite flocculant, preparation method and application thereof

technical field

The invention belongs to the technical field of printing and dyeing wastewater treatment. The invention relates to a composite polymer flocculant, a preparation method and an application, which can be used for the treatment of textile printing and dyeing wastewater.

Background technique

With the rapid development of the dye industry, tens of thousands of dyes are currently used in the world. The printing and dyeing wastewater mainly contains dyes, sizing agents, additives, oil agents, acids and bases, fiber impurities and inorganic salts, etc., with complex components, It has the characteristics of high concentration, high chroma, and refractory degradation. It is one of the main harmful wastewater commonly encountered in our country. The treatment of this type of wastewater must first solve the problem of decolorization. At present, the commonly used decolorization methods include neutralization method, oxidation method, adsorption method, reverse osmosis method, coagulation method and so on. Among them, the coagulation method is widely used due to its strong adaptability, simple operation and management, and capital investment. However, there are many kinds of printing and dyeing wastewater, and the coagulation effect of the same coagulant applied to different printing and dyeing wastewater is very different. Especially for the decolorization of disperse dyes and paints, there is still a lack of effective flocculant treatment. Therefore, it is one of the main directions of coagulation technology development to develop high-efficiency composite flocculants through in-depth research on the mechanism of action of various flocculants combined with the molecular structure of dyes.

During the coagulation process, the flocculant first undergoes chemical reactions such as hydrolysis and polymerization in water, and the resulting hydrolyzed polymers then undergo electrostatic neutralization, intergranular bridging, and adhesion sweeping with particles in the water to form coarse flocs and then Removed by precipitation. The above effects may occur at the same time, and a certain effect may be the dominant factor under different conditions. The process control of the coagulation reaction not only through the screening of flocculants, the determination of the conditions of the flocculation reaction, etc., the coagulation reaction can achieve the best treatment effect with the smallest dosage. Therefore, polymer composite flocculants are generally used in the treatment of wastewater, which can take advantage of several flocculants at the same time, making the coagulation method economical and applicable for printing and dyeing wastewater.

Polymer flocculant is a preparation with high molecular weight, which can promote the coagulation of colloidal particles and other suspended particles into amorphous flocs and precipitate them. Polymer flocculants can be divided into inorganic polymer flocculants, organic polymer flocculants and biological polymer flocculants. Due to the possible toxicity and high price of some organic polymer flocculants, it is more cautious to use them in water treatment. At present, the most widely used polymer flocculants in water treatment are polymer aluminum salts (or iron salts) and composite inorganic polymer aluminum salts (or iron salts), and polymer aluminum salts (or iron salts)-organic The use of polymer compound systems in water treatment has also attracted more and more attention.

Aluminum-based and iron-based inorganic flocculants have been developed for decades as two major types of inorganic flocculants. Pure aluminum salts have disadvantages such as slow precipitation and poor decolorization effect, while pure iron salts have fast settling speed and good turbidity removal effect, but iron salts are highly corrosive. Therefore, it has become a new research direction to copolymerize aluminum and iron into new polymers, which have the characteristics of general aluminum salts and iron salts. From the perspective of structural characteristics, polyaluminium-iron is a polymer flocculant obtained by copolymerization of aluminum salts and iron salts. It has a relatively large molecular weight and has a good decolorization effect. It also has certain applications in the treatment of water-soluble dye wastewater. , but the decolorization effect on difficult-to-handle disperse dyes and paints is not obvious. It is generally believed that paints and disperse dyes are in the form of colloids, which are difficult to remove with general flocculants, and a composite flocculant must be prepared. This kind of flocculant introduces a certain proportion of other metal ions into the polymerized organic or inorganic polymers, making them polymerized ions with larger molecular weights. By adsorbing paints, disperse dyes, etc., their colloidal stability is destroyed, and then the colloids can be coagulated and precipitated. According to this principle, the innovative point of the present invention is to introduce polymer flocculant aids into the aluminum-iron flocculant to form a composite flocculant with a larger molecular weight. Reasonable compounding of additives in the flocculant can not only speed up the flocculation speed and improve the flocculation effect, but also reduce the amount of flocculant. The flocculation aid mainly plays the role of adjusting pH value, providing alkalinity, improving the flocculation effect of low temperature and low turbidity, destroying the stability of hydrophilic organic impurities, and reducing the coexistence of impurities.

Contents of the invention

The object of the present invention is to provide the above-mentioned composite flocculant.

Another object of the present invention is to provide a method for preparing the above-mentioned composite flocculant.

The object of the present invention is also to provide an application of the above-mentioned composite flocculant, which can be used for the treatment of textile printing and dyeing wastewater. The present invention introduces inorganic and organic coagulants such as sodium silicate, inorganic polymer coagulant Z, polyacrylamide, dodecyl dimethyl tertiary amine, etc. into aluminum and iron copolymers to form flocculants. Printing and dyeing wastewater includes disperse dyes, reactive dyes, acid dyes, direct dyes and paint wastewater to be treated to improve the flocculation and decolorization effect of these dyes in wastewater, reduce the COD _cr and BOD values of printing and dyeing wastewater, and play a role in purifying water quality. Moreover, the present invention has particularly prominent effects on the treatment of disperse dye and paint wastewater, the decolorization rate of wastewater exceeds 85%, and the removal rate of COD _cr is greater than 75%. The composite polymer flocculant, preparation method and application can be used for the treatment of textile printing and dyeing wastewater.

The invention adopts a coagulation method, and uses a compound flocculant to decolorize dyes and paints in printing and dyeing wastewater. Since the hydrolyzate of this kind of flocculant can compress the electric double layer and charge neutralization with the colloidal particles of the suspended matter in the water, so that the colloidal impurities of the suspended matter in the wastewater "stick" and "bridge", so in the process of downward settlement , to "sweep" the impurity particles in the water, so that they can be removed.

The preparation method of the composite flocculant of the present invention is to first prepare aluminum and iron ions into polyaluminium-iron or polyaluminum flocculants, and then combine such flocculants with selected inorganic or organic polymer coagulants in a reactor reflux at a controlled temperature of 40° C. to 70° C. and pH=3 to 5, and stir rapidly for 1 to 3 hours, that is, compound and prepare a polymer composite flocculant.

The high-efficiency composite flocculant of the present invention can be expressed as: X+Y. Wherein, X is a flocculant, and the flocculant is mainly polyaluminium-iron or polyaluminum. Y is a coagulant aid, there are two main categories, one is inorganic substances such as: sodium silicate, calcium hydroxide, calcium carbonate, magnesium hydroxide or polymer inorganic coagulant aid Z, etc.; the other is organic substances such as: Polyacrylamide, dodecyl dimethyl tertiary amine, dicyandiamide or modified chitosan, etc. Composite flocculants with high stability are prepared by reacting or compounding these coagulants with polyaluminium-iron and polyaluminum. Among them, the coagulation aid with more obvious effect is the composite flocculant of polymer inorganic coagulation aid Z and organic dodecyl dimethyl tertiary amine.

The present invention particularly recommends inorganic polymer coagulant Z, which is prepared by using chemical reagents such as inorganic sodium salts, dissolving in distilled water, adjusting to the required pH value with acid, and reacting under reflux for 30-45 minutes at 50-60°C. Forming. It is characterized by accelerating the formation of flocs, making them coarse and dense, and also has good coagulation effect under low water temperature and low alkalinity conditions. The main structure of inorganic polymer coagulant aid Z is as follows:

Wherein: n=5～15.

It can combine with AlO ₄ Al ₁₂ (OH) ₂₄ ⁷⁺ and Fe ³⁺ formed by the hydrolysis of polymerized aluminum and iron to form a large molecular weight flocculant with linear, branched chain or spherical particles, and compress double with suspended solids and colloidal particles in water. Electric layer, electric neutralization, "bridging" and other functions can "sweep" the impurity particles in the water to remove them, especially for the decolorization effect of paint and disperse dyes.

The preparation method of composite polymer flocculant of the present invention can be specifically divided into two processes:

1. Preparation of polyaluminium-iron flocculant

In water, under the conditions of pH value 2-4 and 40°C-70°C, the weight ratio of aluminum chloride and ferric sulfate is 1:0.5-1.5, and the reaction is refluxed and stirred for 0.5-2 hours; the water is preferably distilled water.

2. Preparation of polymer composite flocculant

In distilled water, pH = 3-5 and 40-70°C, the flocculant and coagulant aid are refluxed and stirred for 1-3 hours, and compounded to obtain a brown-yellow composite flocculant; the weight ratio of polyaluminium-iron to coagulant aid is 1 : 0.03 to 1.0.

The coagulant aid can be an inorganic substance such as: sodium silicate, calcium hydroxide, calcium carbonate, magnesium hydroxide or the above-mentioned polymer inorganic coagulant aid, etc.; or an organic substance, such as: polyacrylamide, dodecyl Dimethyl tertiary amine, dicyandiamide and modified chitosan, etc.

The polymer inorganic coagulation aid is in the aqueous solution, the weight ratio of sodium silicate and silicon oxide is 2: 0.8-1.2, and the pH is adjusted to 3-4 with dilute sulfuric acid, dilute hydrochloric acid or acetic acid, and at 50-60°C Refluxing and stirring for 30-45 minutes; the water is preferably distilled water; the weight ratio of sodium silicate to silicon oxide is recommended to be 2:-1.0.

For example, dissolve 20 grams of sodium silicate and 10 grams of silicon oxide in 100 ml of distilled water, adjust the pH to 3-4 with dilute sulfuric acid, dilute hydrochloric acid or acetic acid, reflux and stir the reaction at 50-60°C for 30-45 minutes, That is, coagulant aids with n=8 are obtained.

The composite flocculant of the present invention has the advantages of simple preparation method, low cost and convenient use, not only has a certain flocculation and decolorization effect on common water-soluble dyes, but also has excellent adsorption and decolorization ability on water-insoluble disperse dyes and coatings. The composite flocculants A, B and C specially developed by the present invention are new composite flocculants, which not only have the functions of aluminum ion and iron ion compressing the electric double layer and electric neutralization, but also have the functions of adsorption and bridging of coagulants, The sweeping function can effectively remove the impurity particles in the wastewater. In the range of pH value 5-8, settling time 2-3h, when the dosage is 100-150ppm, it has a good flocculation effect on water-soluble dyes and difficult-to-remove disperse dyes and paints in printing and dyeing wastewater. Especially for disperse dyes and coatings, the effect is particularly obvious, the chroma decolorization rate is ≥85%, and the removal rate of CODcr is ≥75%.

Detailed ways:

The present invention will be further understood through the following examples, but the content of the present invention cannot be limited.

Example 1 Preparation of composite inorganic polymer flocculant A

1. Preparation of polyaluminium-iron flocculant

According to the ratio of 1:0.7, take 30 grams of aluminum chloride and 21 grams of ferric sulfate respectively, put them in the reaction bottle, add 400 mL of distilled water, reflux and stir at 50 ° C ~ 60 ° C, and the pH value is 2 ~ 3 for 0.5 ~ 1 Hour.

2. Preparation of coagulant aid

Dissolve 20 grams of sodium silicate and 10 grams of silicon oxide in 100 ml of distilled water, adjust the pH to 3-4 with sulfuric acid or hydrochloric acid, reflux and stir at 50-60°C for 30-45 minutes to obtain the coagulation aid . (n=8).

3. Polymerized aluminum-iron flocculant reacts with coagulant aid Z to prepare flocculant A

Put the synthesized polyaluminium-iron in a reaction bottle, and slowly add 0.9 g of coagulation aid (inorganic polymer compound n=8) under the conditions of 40°C-50°C and pH=3-4, and stir under reflux for 1- 1.5 hours. After the reaction is completed, a brown-yellow transparent composite flocculant A is obtained.

Example 2 Preparation of composite polymer flocculant B

1. Preparation of polyaluminium-iron flocculant

According to the ratio of 1:0.7, take 20 grams of aluminum chloride and 14 grams of ferric sulfate respectively, put them in the reaction bottle, add 270 mL of distilled water, and reflux and stir the reaction at 50 ° C ~ 60 ° C and the pH value of 2 ~ 3 for 0.5 ~ 1 Hour.

2. Polymerized aluminum iron flocculant and coagulant aid dodecyl dimethyl tertiary amine compound to form flocculant B

Put the synthesized polyaluminium-iron in a reaction bottle, and slowly add 20 grams of coagulant aid dodecyl dimethyl tertiary amine under the conditions of 40°C-50°C and pH=3-4, and stir under reflux for 1.5- 2 hours. After the compound is completed, the light yellow compound flocculant B is obtained.

Example 3 Preparation of composite inorganic-organic polymer flocculant C

1. Preparation of composite inorganic polymer flocculant A

Put 34 grams of polyaluminium-iron in a reaction bottle, add 270 mL of distilled water, and slowly add 2 grams of coagulation aid (inorganic polymer compound n=8) at 40 ° C to 50 ° C and pH = 3 to 4 , reflux and stir for 1 to 1.5 hours. After the reaction is completed, a brown-yellow transparent composite flocculant A is obtained.

2. Flocculant A and dodecyl dimethyl tertiary amine compound to form flocculant C

Put the synthesized flocculant A in a reaction flask, slowly add 20 grams of dodecyldimethyl tertiary amine under the condition of 50-60°C, and stir under reflux for 1.5-2 hours. The brown-yellow composite flocculant C can be obtained.

Example 4 Application of composite flocculant in water-soluble dye wastewater

The dosage of composite flocculant:

Example 1 Flocculant A 100ppm

Example 2 Flocculant B 150ppm

Example 3 Flocculant C 120ppm

Approach:

The composite flocculants A, B, and C with a molar concentration of 0.36mol/L were added to the printing and dyeing wastewater such as acid red 3R dye, reactive blue X-BR dye and direct lake blue 5B dye according to the above dosage (the concentration of the wastewater was equal to 0.04g/L), stirred for 10-15 minutes, settled for 2-3 hours under the condition of pH=5-8, and then measured the decolorization rate.

See Table 1 for the processing results.

Table 1 The flocculation and decolorization effect of flocculants on water-soluble dye wastewater flocculant Decolorization rate/% Acid Red 3R Reactive Blue X-BR Direct Lake Blue 5B Flocculant A Flocculant B 79.677.4 77.875.5 76.074.6 Flocculant C 83.6 82.4 79.3

Example 5 Application of composite flocculant in disperse dye and paint wastewater

The dosage of composite flocculant:

Example 1 Flocculant A 75～100ppm

Example 2 Flocculant B 100～150ppm

Example 3 Flocculant C 100～120ppm

Approach:

Add composite flocculants A, B, and C with a molar concentration of 0.4mol/L to the disperse blue HGL dye and paint blue wastewater (both wastewater concentrations are 0.03-0.04g/L) according to the above dosage, and stir for 10- 15 minutes, under the condition of pH=5-8, settle for 3 hours, and then measure the decolorization rate.

See Table 2 for the processing results.

Table 2 Flocculation and decolorization effects of flocculants on disperse dyes and paint wastewater flocculant Decolorization rate/% Disperse blue HGL paint blue Flocculant A Flocculant B Flocculant C 91.289.190.1 87.585.187.0

Example 6 The influence of coagulant aid Z on the decolorization performance of disperse dyes and paint wastewater

Different forms of coagulation aids can be obtained by changing the amount of sodium silicate and silicon oxide: n is 5, 8, 12 respectively.

The coagulant aid Z (n=5, 8, 12) reacts with polyaluminium-iron to form a composite flocculant A, which is used for the decolorization treatment of disperse dye and paint wastewater.

Approach:

Add the composite flocculant A with a molar concentration of 0.4mol/L in an amount of 75-100ppm to the disperse blue HGL dye and paint blue wastewater (both wastewater concentrations are 0.03-0.04g/L), and stir for 10-15 minutes , under the condition of pH=5-8, settle for 3 hours, and then measure the decolorization rate.

See Table 3 for the processing results.

Table 3 Flocculation and decolorization effects of flocculants on disperse dyes and paint wastewater flocculant Decolorization rate/% Disperse blue HGL paint blue Flocculant A (n=5 of coagulant) Flocculant A (n=8 of coagulant) Flocculant A (n of coagulant=12) 89.791.287.6 86.587.585.1

Example 7 COD _cr value changes after disperse dyes and coatings are treated with flocculant A

Approach:

In the strongly acidic solution, accurately add excess potassium dichromate standard solution, heat to reflux, and oxidize the reducing substances (mainly organic matter) in the disperse dye and the paint wastewater sample (the amount of wastewater sample taken shall not be less than 5ml), and the excessive Potassium dichromate is made indicator with ferrous iron, back drips with ammonium ferrous sulfate standard solution, calculates water sample chemical oxygen demand according to the consumed potassium dichromate standard solution amount, then calculates COD _cr removal rate:

COD _cr removal rate (%) = (COD _cr0 -COD _cr1 )/COD _cr0 × 100%

See Table 4 for the processing results.

Table 4 COD _cr values of disperse dyes and paint wastewater before and after treatment Dyeing Wastewater COD _cr /mg.L ^-1 COD _cr removal rate% before processing after treatment Disperse Blue HGL Paint Blue 348.5222.4 76.743.2 7881

Claims (7)

1, a kind of high efficiency composite flocculant is characterized in that being composited by flocculation agent and coagulant aids,

Wherein: flocculation agent is polymeric ferric aluminum or poly-aluminium; Coagulant aids is inorganics salt or inorganic coagulant aids of polymer or organic compound; Described inorganics is that water glass, calcium hydroxide, lime carbonate, magnesium hydroxide or structural formula are

The inorganic coagulant aids of polymer, wherein: n=5～15; Described organic compound is polyacrylamide, dodecyl dimethyl tertiary amine, Dyhard RU 100 or modified chitosan; Wherein the weight ratio of aluminium, iron and coagulant aids is 1: 0.5～1.5: 0.03～1.

2, a kind of preparation method of high efficiency composite flocculant as claimed in claim 1 is characterized in that being obtained by following two one step process:

(1) in water and under 40 ℃～70 ℃, the weight ratio of aluminum chloride and ferric sulfate is that 1: 0.5～1.5 o'clock, pH value are back flow reaction acquisition in 0.5～2 hour polymeric ferric aluminum flocculation agent under 2～4 conditions;

Or

(2) with the polymeric ferric aluminum of (1) and coagulant aids under the condition of 40 ℃～70 ℃ and pH=3～5, refluxing to stir obtained pale brown look transparent composite flocculant in 1～3 hour; Wherein: the weight ratio of polymeric ferric aluminum and coagulant aids is 1: 0.03～1.0;

Described coagulant aids is inorganics salt or inorganic coagulant aids of polymer or organic compound; Described inorganics is water glass, calcium hydroxide, lime carbonate or magnesium hydroxide, and the inorganic coagulant aids structural formula of described polymer is

N=5～15 wherein; Described organic compound is polyacrylamide, dodecyl dimethyl tertiary amine, Dyhard RU 100 or modified chitosan.

3, a kind of preparation method of high efficiency composite flocculant as claimed in claim 2, it is characterized in that the inorganic coagulant aids of described polymer is in the aqueous solution, the weight ratio of sodium silicate and silicon oxide is that 2: 0.8～1.2 o'clock usefulness dilute sulphuric acid, dilute hydrochloric acid or acetic acid are regulated pH=3～4, and backflow, stirring reaction are 30～45 minutes under 50～60 ℃.

4, a kind of preparation method of high efficiency composite flocculant as claimed in claim 2 is characterized in that described water is distilled water; Described sodium silicate and silicon oxide weight ratio are 2 :～1.0.

5,, it is characterized in that being used for the flocculation decoloration processing of dyeing waste water as the purposes of claim 4 and 5 described a kind of high efficiency composite flocculants.

6,, it is characterized in that described dyeing waste water is the waste water of the water-soluble dye wastewater of matching stain, reactive dyestuffs and substantive dyestuff as the purposes of claim 4 and 5 described a kind of high efficiency composite flocculants; It perhaps is the water-insoluble dyeing waste water that is difficult to remove of dispersed dye or coating waste-water.

7, the purposes of a kind of high efficiency composite flocculant as claimed in claim 6, it is characterized in that with volumetric molar concentration being that the described composite flocculant of 0.3～0.4mol/L joins in the dyeing waste water, stirred 10～15 minutes, under the condition of pH=5～8, sedimentation 3 hours.