CN102174504A - Granular carrier immobilized lipase for treating papermaking white water and preparation method thereof - Google Patents

Abstract

The invention discloses a granular carrier-immobilized lipase for treating papermaking white water and a preparation method thereof. In this method, chitosan powder is dissolved in acetic acid aqueous solution to completely dissolve chitosan, and PVA aqueous solution is added to mix evenly, and then added dropwise to the mixed solution of NaOH aqueous solution and absolute ethanol, and the reaction is solidified into granules, and the obtained The chitosan particles are added to glutaraldehyde aqueous solution with a mass concentration of 0.0025-0.05%, placed in a shaker for cross-linking reaction, washed with deionized water until neutral, and lipase is added. The present invention utilizes PVA to improve the surface structure of chitosan particles, and then utilizes PVA to modify chitosan particles to immobilize lipase. Utilizing this immobilized lipase can not only enhance the removal effect of papermaking white water resin deposits, but also greatly Reduce the cost of white water treatment in factories.

Description

Granular carrier-immobilized lipase for treating papermaking white water and preparation method thereof

technical field

The invention relates to an immobilized biological enzyme for treating papermaking white water, in particular to a granular carrier-immobilized lipase for treating papermaking white water and a preparation method thereof.

Background technique

my country's paper industry is an important industry that is undergoing transformation from traditional industry to modern industry. But at the same time, the paper industry has become more and more serious to the country's energy consumption and environmental pollution. In 2006, the total amount of wastewater discharged by my country's paper industry accounted for about 16% of the total industrial discharge, and the COD discharge accounted for about 33% of the total discharge. The high water consumption and high pollution problems in the paper industry have had an overall impact on my country's energy security and ecological security. With the rapid development of the paper industry for a long period of time in the future, the energy consumption will increase. It is urgent to develop new water recycling technology and energy utilization technology in the paper industry.

For pulp and paper mills that use wood as raw material, especially for paper mills that use masson pine as the main raw material to produce newsprint in southern my country, the problem of resin barriers has always been a major problem. In the pulping and papermaking process, the resin in the pulp will be deposited on the surface of the pulping and papermaking equipment in various ways, resulting in a series of resin barrier problems. The harmful effects of these problems mainly have two aspects: one is that the resin deposition can lead to product The second is that the deposition of resin can affect the pulping and papermaking process and reduce the output of the product. Because the traditional chemical control method, mechanical control method and process control method cannot effectively prevent the problem of resin deposition and frequent end breaks in various parts of the paper machine, resulting in many unplanned shutdowns and cleanings, this has also become a further increase in machine speed. bottleneck. In addition, with the improvement of the closed cycle of water in modern paper mills, the expansion of the types of paper materials and the application of alkaline papermaking technology, the problem of resin barriers will become one of the increasingly prominent problems in the paper industry.

Many studies have shown that triglycerides in white water are the main harmful components that cause resin barriers in the pulp and paper process. Since triglyceride is a non-polar component, it is easy to rely on van der Waals force to adhere to some hydrophobic equipment surfaces during the white water recycling process, thus forming a large amount of resin deposits. The use of biotechnology to control the problem of resin barriers in paper mills is a hot research topic in recent years, and research in this area has been carried out both at home and abroad. This method mainly uses lipase to hydrolyze the esters in the resin into low-viscosity fatty acids and alcohols, so as to achieve the purpose of controlling resin deposition.

Although lipase has a good catalytic decomposition effect on resin deposits in white water, current researchers only add biological enzymes to white water at one time, and seldom consider the recycling of lipase, which will inevitably cause fat The waste of enzymes increases the cost of white water treatment in factories. The prior art does not consider taking measures to change the surface structure of immobilized particles to promote the immobilization effect of lipase.

Contents of the invention

The purpose of the present invention is to overcome the shortcoming of prior art, provide a kind of lipase immobilization effect that strengthens, and can continuously improve the effect of the resin deposit in papermaking white water treatment papermaking white water granular carrier immobilized lipase and its preparation method .

For realizing the purpose of the present invention, the technical scheme adopted is:

A preparation method for immobilizing lipase on a granular carrier for treating papermaking white water, comprising the steps of:

(1) Dissolve chitosan powder in aqueous acetic acid solution, heat to 40-60°C to dissolve chitosan completely, add PVA aqueous solution and mix evenly, then add it dropwise to the mixed solution of NaOH aqueous solution and absolute ethanol, The reaction is solidified into granules, soaked in the mixed solution of NaOH and absolute ethanol for 2-6h, suction filtered, fully washed with distilled water until the pH value is neutral; the mass volume ratio of chitosan to acetic acid is 1g: 1- 5ml; the mass ratio of chitosan to PVA is 100:1-5; the NaOH concentration in NaOH aqueous solution is 1-4mol/L; the volume ratio of NaOH aqueous solution to absolute ethanol is 4-8:1;

(2) Add the chitosan particles obtained in step (1) into the glutaraldehyde aqueous solution with a mass concentration of 0.0025-0.05%, place them in a shaker at room temperature for cross-linking reaction for 10-60min, and wash them with deionized water until medium Add lipase, the mass-volume ratio of chitosan particles to lipase is 1g: 1-4ml; after shaking in a shaker for 1-4h, pour out the remaining lipase solution, and add a mass concentration of 0.5-2 % EDC aqueous solution, placed in a shaker at room temperature after 30-90min activation reaction, washed to neutral with deionized water, added lipase, the mass volume ratio of chitosan particles and lipase is 1g: 1-4ml; Shake in a shaker for 1-4 hours, wash with deionized water to remove residual enzyme solution, and refrigerate for later use.

To further realize the object of the present invention, the mass concentration of the PVA aqueous solution is preferably 1-5%.

The glutaraldehyde purity is preferably analytically pure.

The volume ratio of the mixture of NaOH aqueous solution and absolute ethanol is preferably 4-6:1.

A single enzyme immobilized on a granular carrier for treating papermaking white water is prepared by the above method.

Compared with the prior art, the present invention has the following advantages:

Chitosan is a polymer compound extracted from the shells of crustaceans such as shrimps and crabs. It is the most abundant polymer found on the earth except cellulose. However, chitosan is used to immobilize lipase There has never been a report on the treatment of papermaking white water, especially the use of PVA to improve the structure of chitosan surface particles has not been reported. The invention aims at the shortcomings of the current traditional white water treatment technology, uses cheap and easy-to-obtain chitosan immobilized lipase, can greatly reduce the cost of factory white water treatment while enhancing the effect of removing resin deposits in papermaking white water. After papermaking white water is treated with immobilized lipase, the average particle size of colloidal particles decreases from 552 μm to 276 μm, the turbidity of white water decreases from 101 NTU to 80.8 NTU, and the removal rate of resin deposits can reach 66.8%.

Description of drawings

Figure 1 is a graph showing the recycling performance of the immobilized lipase prepared in Example 1 of the present invention.

Detailed ways

Below in conjunction with embodiment the method of the present invention is described in further detail. It should be noted that the protection scope of the present invention shall include but not be limited to the technical content disclosed in this embodiment.

Example 1

(1) First weigh 5g of chitosan powder and dissolve it in 100mL of 5% acetic acid solution, heat to 40°C to completely dissolve chitosan, add 5mL of 1% PVA aqueous solution and mix well, then add it dropwise to 1mol/L In the mixed solution of NaOH aqueous solution and absolute ethanol (volume ratio 4:1), the reaction coagulates into particles, and the addition of PVA makes the surface of chitosan particles present a porous structure, which is beneficial to the immobilization of biological enzymes. Soak in a mixture of NaOH and absolute ethanol for 2 hours, filter with suction, and wash thoroughly with distilled water until the pH value is neutral;

(2) Add 5 g of chitosan particles obtained in step (1) to a glutaraldehyde aqueous solution with a mass concentration of 0.0025%, place it in a shaker at room temperature for cross-linking reaction for 10 minutes, wash with deionized water until neutral, add 5ml of lipase solution; placed in a shaker for 1 hour, poured out the remaining lipase solution, added a 0.5% EDC aqueous solution, placed it in a shaker at room temperature for 30 minutes, and washed it with deionized water until medium Add 5ml of lipase solution; shake in a shaker for 1 hour, wash with deionized water to remove residual enzyme solution, and refrigerate for later use.

Example 2

(1) First weigh 5g of chitosan powder and dissolve it in 100mL of 10% acetic acid solution, heat to 50°C to completely dissolve chitosan, add 5mL of 2% PVA aqueous solution and mix evenly, then add it dropwise to 2mol/L In the mixed solution composed of NaOH aqueous solution and absolute ethanol (volume ratio 6:1), the reaction is solidified into particles, soaked in the mixed solution of NaOH and absolute ethanol for 4 hours, filtered with suction, and fully washed with distilled water until the pH value is neutral ;

(2) Add 5 g of chitosan particles obtained in step (1) to a glutaraldehyde aqueous solution with a mass concentration of 0.005%, place it in a shaker at room temperature for a cross-linking reaction for 30 minutes, wash with deionized water until neutral, add 10ml of lipase solution; placed in a shaker for 2 hours, poured out the remaining lipase solution, added a 1% EDC aqueous solution, placed it in a shaker at room temperature for 60 minutes, and washed it with deionized water until medium Add 10ml of lipase solution; place in a shaker for 2 hours, wash with deionized water to remove residual enzyme solution, and refrigerate for later use.

Example 3

(1) First weigh 5g of chitosan powder and dissolve it in 100mL of 25% acetic acid solution, heat to 60°C to completely dissolve chitosan, add 5mL of 5% PVA aqueous solution and mix evenly, then add it dropwise to 4mol/L In the mixed solution composed of NaOH aqueous solution and absolute ethanol (volume ratio 8:1), the reaction is solidified into particles, soaked in the mixed solution of NaOH and absolute ethanol for 6 hours, filtered with suction, and fully washed with distilled water until the pH value is neutral ;

(2) Add 5 g of chitosan particles gained in step (1) to a glutaraldehyde aqueous solution with a mass concentration of 0.05%, place it in a shaker at room temperature for 60 minutes of cross-linking reaction, wash with deionized water until neutral, add 20ml of lipase solution; placed in a shaker for 4 hours, poured out the remaining lipase solution, added a 2% EDC aqueous solution, placed it in a shaker at room temperature for 90 minutes, and washed it with deionized water to medium Add 20ml of lipase solution; place in a shaker for 4 hours, wash with deionized water to remove residual enzyme solution, and refrigerate for later use.

Performance Testing

1. Treatment effect on resin deposits in papermaking white water

For pulp and paper mills that use wood as raw material, especially for paper mills that use masson pine as the main raw material to produce newsprint in southern my country, the problem of resin barriers has always been a major problem. Many studies have shown that triglycerides in white water are the main harmful components that cause resin barriers in the pulp and paper process. Since triglyceride is a non-polar component, it is easy to rely on van der Waals force to adhere to some hydrophobic equipment surfaces during the white water recycling process, thus forming a large amount of resin deposits.

The immobilized lipase prepared in Example 1 was used to treat the white water resin deposits. The paper-making white water was the paper-making white water produced by producing newsprint with Pinus massoniana as the main raw material. The results are shown in Table 1. It can be seen that after white water is treated with immobilized lipase, the average particle size of colloidal particles decreases from 552 μm to 276 μm, the turbidity of white water decreases from 101 NTU to 80.8 NTU, and the removal rate of resin deposits can reach 66.8%. It can be seen that immobilized lipase has a good removal effect on white water resin deposits, mainly because immobilized lipase can crack the ester bonds of resinous substances in white water, degrading them into small molecular fatty acids, etc. substance. In addition, the modified chitosan particle carrier for immobilized lipase itself also has strong adsorption properties, especially after being treated with PVA, the surface of the chitosan particle carrier presents a porous structure, which is conducive to the immobilization of lipase and has a good effect on whitening. The adsorption of resin deposits in water has a certain enhancement effect.

Table 1 Effect of immobilized lipase on white water

2. Stability test

In order to illustrate the recycling performance of the immobilized biological enzyme of the present invention, the operational stability of the immobilized enzyme of the present invention is determined.

For the immobilized lipase prepared in Example 1, 8 batches of papermaking white water produced by producing newsprint with Pine massoniana as the main raw material were continuously operated for 8 batches, and the relative activity after each use was calculated. The results are shown in Figure 1. It can be seen that the relative activity of the immobilized lipase gradually decreased with the increase of the number of reactions, but the activity of the immobilized lipase remained at a high level after 5 consecutive uses, and remained at about 70%; when used 8 times continuously, The immobilized enzyme can also maintain 59% activity. This shows that the immobilized lipase has good operational stability, which provides a prerequisite for repeated use in the actual production process.

Claims (5)

1. a preparation method who handles mthod of white water from paper making with the granular carrier immobilized lipase is characterized in that comprising the steps:

(1) the chitosan powder is dissolved in the acetic acid aqueous solution, being heated to 40-60 ℃ dissolves chitosan fully, and adding PVA aqueous solution is even, become to be added dropwise in the mixed solution of the NaOH aqueous solution and dehydrated alcohol then, reaction is frozen into particle, soak 2-6h in the mixed solution of NaOH and dehydrated alcohol, suction filtration is neutral with distilled water thorough washing to pH value; The mass volume ratio of described chitosan and acetate is 1g: 1-5ml; The mass ratio of chitosan and PVA is 100: 1-5; NaOH concentration is 1-4mol/L in the NaOH aqueous solution; The volume ratio of the NaOH aqueous solution and dehydrated alcohol is 4-8: 1;

(2) step (1) gained chitosan particle is added in the glutaraldehyde water solution that mass concentration is 0.0025-0.05%, after placing shaking table crosslinking reaction 10-60min under the room temperature, be washed till neutrality with deionized water, add lipase, the mass volume ratio of chitosan particle and lipase is 1g: 1-4ml; After placing shaking table vibration 1-4h, topple over and remaining lipase liquid, adding mass concentration is the EDC aqueous solution of 0.5-2%, after placing shaking table priming reaction 30-90min under the room temperature, be washed till neutrality with deionized water, add lipase, the mass volume ratio of chitosan particle and lipase is 1g: 1-4ml; Place the shaking table 1-4h that vibrates,, refrigerate standby with deionized water flush away residual enzyme liquid.

2. the processing mthod of white water from paper making according to claim 1 preparation method of granular carrier immobilized lipase, it is characterized in that: the mass concentration of the described PVA aqueous solution is 1-5%.

3. the processing mthod of white water from paper making according to claim 1 preparation method of granular carrier immobilized lipase, it is characterized in that: described glutaraldehyde purity is analytical pure.

4. the processing mthod of white water from paper making according to claim 1 preparation method of granular carrier immobilized lipase, it is characterized in that: the volume ratio of the mixed solution of the described NaOH aqueous solution and dehydrated alcohol is 4-6: 1.

5. handle mthod of white water from paper making granular carrier immobilized lipase for one kind, it is characterized in that by the described method preparation of claim 1.

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