CN102586221A - A kind of porous high mass transfer PVA embedding carrier and preparation method thereof - Google Patents

Abstract

The invention relates to a porous high mass transfer PVA embedding carrier and a preparation method thereof. The method is to add Sodium Bicarbonate (SB) and concentrated hydrochloric acid into PVA to prepare the embedding carrier. According to the invention, sodium bicarbonate and hydrochloric acid are added to enable a reaction system to generate a large amount of bubbles, and the prepared embedding carrier has better pores than the traditional embedding carrier, so that the mass transfer capacity of the carrier and the containing capacity of microorganisms are improved; the consumption of boric acid is reduced, and the harm to microorganisms in an embedding body is reduced; the raw materials are easy to obtain, the production cost is low, the preparation method is simple and convenient in process, and the preparation method is very suitable for wide application of environmental microorganisms and the environmental protection industry and is beneficial to industrial production.

Description

A kind of porous high mass transfer PVA embedding carrier and preparation method thereof

technical field

The invention relates to a novel polyvinyl alcohol embedding carrier and a preparation method thereof, in particular to a porous high mass transfer polyvinyl alcohol embedding carrier.

Background technique

The selection of a suitable embedding carrier can improve the mass transfer efficiency of the carrier, increase the contact opportunity of the nutrients in the environmental solution into the carrier and the microorganisms, so as to make better use of the substrate, and also allow the microbial metabolites to leave the carrier quickly and diffuse into the environment solution, reducing the toxic effect on microbial growth. There are two types of embedding carriers commonly used at present. One is natural synthetic embedding carriers including carrageenan, gelatin, agar, hornin, chitosan, calcium alginate, cellulose acetate, collodion, fibrin, etc. These carriers have poor mechanical strength and durability . The other is a synthetic embedding carrier including polyacrylamide, PVA, polyurethane resin, photosensitive resin, polyethylene oxide, etc. This type of carrier has high mechanical strength and durability, but has poor mass transfer performance. The PVA carrier material is low in price, high in mechanical strength, and has a certain degree of elasticity. The development of a cost-effective, good mass transfer performance, and harmless to microorganisms PVA composite embedding carrier has great market application prospects.

The PVA embedding carrier composed of organic polymer materials and various inorganic materials combines various components together, through chemical and physical effects, and then through curing, the specific surface area of the pores and the carrier is significantly increased, and the microorganisms are increased. The capacity improves the fluidity of the material, increases the opportunity for microorganisms to use the substrate, and reduces the damage to microorganisms caused by metabolic waste.

Contents of the invention

The object of the present invention is to provide a porous high-density composite material with low production cost, good universal applicability, easy preparation and certain mechanical strength on the basis of material price, preparation difficulty, activity recovery rate, immobilization cost and stable performance. Mass transfer PVA embedding carrier and preparation method thereof.

The preparation method of the porous high mass transfer PVA embedding carrier of the present invention comprises the following steps:

①According to mass percentage, mix 7.5% PVA, 0.125～0.5% sodium bicarbonate (SB), 0.15～0.59% concentrated hydrochloric acid and 91.41～92.225% water, 80r/min, and stir for 5min to obtain mixed solution I; The polymerization degree of said PVA is 1700～1800;

②According to the mass percentage, after mixing 3% boric acid, 2% calcium chloride and 95% water, adjust the pH value to 7 with 2mol/L sodium hydroxide aqueous solution to obtain a solidified solution;

③ Add the mixed solution I dropwise to the solidified solution and shake for 12 hours.

In the above preparation method of the present invention, after further optimization, the mass percentage of sodium bicarbonate (SB) is preferably 0.25%.

In the above-mentioned preparation method of the present invention, in order to make the performance of the prepared product better, the PVA is firstly dissolved in water, and heated at 0.1 MPa and 120° C. for 20 minutes.

In the present invention, a more specific technical solution includes the following steps:

①According to mass percentage, mix 7.5% PVA with 91.41-92.225% water, heat at 0.1MPa, 120°C for 20min, cool to room temperature, add 0.125-0.5% sodium bicarbonate and 0.15-0.59% concentrated hydrochloric acid, 80r/ min, stirred for 5min to obtain mixed solution I;

②According to the mass percentage, after mixing 3% boric acid, 2% calcium chloride and 95% water, adjust the pH value to 7 with 2mol/L sodium hydroxide aqueous solution to obtain a solidified solution;

③ Add the mixed solution I dropwise to the solidified solution and shake for 12 hours.

The object of the present invention is to provide a porous high-mass transfer polyvinyl alcohol embedding carrier prepared by any of the methods described above.

Compared with the prior art, the polyvinyl alcohol embedding carrier prepared by the present invention has the following advantages:

(1) By adding SB and hydrochloric acid in the present invention, the reaction system produces a large number of bubbles, and the prepared embedding carrier has better pores than the traditional embedding carrier, which improves the mass transfer capacity of the carrier and the inclusion capacity of microorganisms;

(2) In the present invention, the consumption of boric acid is reduced, and the damage to microorganisms in the embedding body is reduced;

(3) The raw materials used in the present invention are easy to obtain, the production cost is low, and the preparation method is simple and convenient, which is very suitable for the wide application of environmental microorganisms and their environmental protection industries, and is conducive to industrial production.

Description of drawings

6 pieces of accompanying drawings of the present invention,

Fig. 1 is the picture of the embedding carrier of the present invention, wherein, a is the picture of Comparative Example 2, b is the picture of Example 2, and c is the picture of Comparative Example 1;

Fig. 2 is the specific surface area of the embedding carrier of the present invention; wherein, the relationship diagram between the concentration of methylene blue in the solution and the amount of the carrier, the maximum adsorption amount of the carrier is equal to the reciprocal of the linear relationship k value.

斜率(k)等于π².De.R^-2，那么De等于k.R².π^-2，R是载体直径(cm)，De是传质系数(cm²/s)。Fig. 3 is the embedded carrier mass transfer rate of the present invention; Wherein, according to spherical carrier mass transfer relational expression

The slope (k) is equal to π ² .De.R ^-2 , then De is equal to kR ² .π ^-2 , R is the carrier diameter (cm), and De is the mass transfer coefficient (cm ² /s).

Fig. 4 is the SEM picture of the embedding carrier of the present invention; Wherein, a is the section view of Comparative Example 1, b is the section view of Comparative Example 2, and c is the section view of Example 2;

Fig. 5 is the oxygen absorption rate of the embedding carrier of the present invention; among them, the aerobic respiration rate of three hydrogels embedding the same amount of AOB, MLVSS 0.221g, 200ml system;

Figure 6 shows the ammonia oxidation rate of the embedding carrier of the present invention; among them, the ammonia conversion rate of three hydrogels embedding the same amount of AOB, MLVSS 0.221g, 400ml system.

Detailed ways

The following non-limiting examples can enable those skilled in the art to understand the present invention more fully, but do not limit the present invention in any way.

Part 1: Preparation of embedding carrier

Example 1

①Mix 7.5g PVA and 92.225g water, heat at 0.1MPa, 120°C for 20min, cool to room temperature, add 0.125g SB and 0.15g concentrated hydrochloric acid, 80r/min, stir for 5min, to get the mixture I;

②Add 20g of calcium chloride to 500ml of water, stir to dissolve, add 30g of boric acid, adjust the pH value to 7 with 2mol/L sodium hydroxide aqueous solution, and set the volume to 1000ml to obtain a solidified solution;

③ Drop the mixed liquid I into the solidified liquid solution and shake for 12 hours. The performance parameters of the carrier are shown in Table 1.

Embodiment 2 (PVA-SB) and embodiment 3

Repeat the method of Example 1 according to the content of each component specified in Table 1 below, and the performance parameters of the carrier are shown in Table 1.

Comparative Example 1 (PVA) and Comparative Example 2 (PVA-SA)

Repeat the method of Example 1 according to the content of each component specified in Table 1 below, and the performance parameters of the carrier are shown in Table 1.

Table 1

It can be seen from Table 1 that the specific surface area of the embedding beads prepared by the present invention is 85% and 14% higher than that of the PVA embedding beads and the PVA-sodium alginate embedding beads.

Part II: Application of Embedding Carriers

Example 4

With embodiment 2, the carrier that comparative example 1 and comparative example 2 prepares embeds ammonia oxidizing bacteria (Ammoniaoxidizing bacteria, AOB), detects the oxygen uptake rate (Oxygen uptake rate, OUR) and the ammonia oxidation rate of carrier-embedded bacteria, determines carrier Applicability in sewage treatment: First, the mixed solution I in the preparation steps of Example 2, Comparative Example 1 and Comparative Example 2 was stirred evenly and cooled to 37° C., and an equal amount of AOB bacteria was added, and stirred evenly at a slow speed to obtain the mixed solution II, drop the mixed solution II into the solidified solution, and shake for 12 hours to obtain the embedded bacteria particles. Comparison of OUR and ammonia oxidation rate of carrier-embedded bacteria, performance parameters are shown in Table 2:

Table 2

Claims (5)

1. A preparation method for porous high mass transfer PVA embedding carrier, comprising the steps: ① According to mass percentage, mix 7.5% PVA, 0.125-0.5% sodium bicarbonate, 0.15-0.59% concentrated hydrochloric acid and 91.41-92.225% water, 80r/min, and stir for 5min to obtain mixed solution I; wherein, the PVA The degree of polymerization is 1700-1800; ②According to the mass percentage, after mixing 3% boric acid, 2% calcium chloride and 95% water, adjust the pH value to 7 with 2mol/L sodium hydroxide aqueous solution to obtain a solidified solution; ③ Drop the mixed solution I into the solidified solution and shake for 12 hours. 2. the preparation method of porous high mass transfer PVA embedding carrier according to claim 1, is characterized in that the mass percent of described sodium bicarbonate is 0.25%. 3. The preparation method of the porous high-mass transfer PVA embedding carrier according to claim 1 or 2, characterized in that the PVA in the step ① is mixed with water first, and heated at 0.1MPa and 120°C for 20min. 4. the preparation method of porous high mass transfer PVA embedding carrier according to claim 3 is characterized in that described method comprises the steps: ①According to mass percentage, mix 7.5% PVA with 91.41-92.225% water, heat at 0.1MPa, 120°C for 20min, cool to room temperature, add 0.125-0.5% sodium bicarbonate and 0.15-0.59% concentrated hydrochloric acid, 80r/ min, stirred for 5min to obtain mixed solution I; ②According to the mass percentage, after mixing 3% boric acid, 2% calcium chloride and 95% water, adjust the pH value to 7 with 2mol/L sodium hydroxide aqueous solution to obtain a solidified solution; ③ Add the mixed solution I dropwise to the solidified solution and shake for 12 hours. 5. The porous high mass transfer PVA embedding carrier prepared by the method of claim 1.

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