A preparation method of polystyrene foam composite material based on hydrolyzed oil

Abstract

The invention discloses a preparation method of a polystyrene foam composite material based on hydrolyzed grease, specifically: porcine pancreatic lipase enzyme powder is mixed with phosphate buffer solution, centrifuged, and lipase solution is obtained; concentrated sulfuric acid, thiosalicylic acid, catechol-O-O-peroxydiacetic acid are put into an ice bath and cooled and stirred, then added into ice water, centrifuged, freeze-dried, and TX-Ct are obtained; the TX-Ct aqueous solution is added dropwise to the surface of a polystyrene foam board, then placed between quartz plates, placed under an ultraviolet high-pressure mercury lamp and irradiated, and Foam-TX-Ct is obtained; polyethylene glycol diacrylate, lipase solution, glycerol, deionized water are mixed, added dropwise to the surface of Foam-TX-Ct, placed between two quartz plates and irradiated under visible light. The composite material obtained has better storage stability and operational stability than free lipase, so that it has a broader application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material preparation, and particularly relates to a method for preparing a polystyrene foam composite material based on hydrolyzed oil. Background Art

[0002] In actual leather production, processes such as degreasing and fleshing generate tens of thousands of tons of waste oil. Discharged without proper treatment not only negatively impacts the natural environment, but also wastes valuable biomass resources and hinders coordinated economic and social development. Traditionally, the treatment of industrial waste oil involves decomposing it under high temperature and high pressure using chemical catalysts. This approach is complex and dangerous, requiring significant energy and wasting resources. It also poses a significant environmental burden, resulting in significant pollution.

[0003] Therefore, there is an urgent need to find a more value-added, greener, and more efficient method to treat the vast amounts of waste oils and fats generated during industrial production. Compared to chemical reagents, lipase hydrolysis of oils and fats is a safe, green, efficient, and clean biotreatment method. Under the action of lipase, oils and fats are specifically hydrolyzed by the lipase system, and the resulting product can be produced into biodiesel. Compared to traditional chemical treatment methods, enzymatic hydrolysis offers a series of significant and valuable advantages, including a clean process, environmental friendliness, high production efficiency, and a high-value-added end product.

[0004] However, in actual production life, the application of lipase in the hydrolysis of industrial waste oils and fats has been greatly hindered by the shortcomings of lipase, such as high cost, poor operational stability, and difficulty in recycling. Enzyme immobilization is a physical or chemical method that restricts or fixes the enzyme in a specific spatial range. It provides a feasible way to solve the high cost and difficulty in recycling of free enzymes. Immobilized enzymes can be separated from the final product very easily and simply, reducing pollution to the product; at the same time, polymer materials such as polystyrene foam will float on the surface of oily wastewater. Therefore, by confining the immobilized enzyme to the surface of polystyrene foam, its own operational stability is extremely significantly improved, which is conducive to long-term use in industrial production. Summary of the Invention

[0005] The object of the present invention is to provide a method for preparing a polystyrene foam composite material based on hydrolyzed oil, which has good immobilization properties and excellent storage stability and cycle stability.

[0006] The technical solution adopted by the present invention is a method for preparing a polystyrene foam composite material based on hydrolyzed oil, which is specifically implemented according to the following steps:

[0007] Step 1: mixing porcine pancreatic lipase powder with a phosphate buffer solution, and centrifuging to remove insoluble lipase to obtain a lipase solution;

[0008] Step 2: Cool concentrated sulfuric acid, thiosalicylic acid, and catechol-0-0-peroxydiacetic acid in an ice bath under light-proof conditions while stirring continuously. After the reaction is completed, slowly add the reaction solution into ice water, centrifuge, and freeze-dry to obtain a yellow powder, which is the initiator TX-Ct.

[0009] Step 3: dripping the TX-Ct aqueous solution onto the surface of the polystyrene foam board, evenly spreading the solution, placing the polystyrene foam board coated with the TX-Ct aqueous solution between the quartz plates and fixing it with a clamp, and then irradiating it under an ultraviolet high-pressure mercury lamp to obtain a polystyrene foam board planted with TX-Ct;

[0010] Step 4: Mix and shake polyethylene glycol diacrylate, lipase solution, glycerol, and deionized water to obtain a mixed solution, and evenly add the mixed solution dropwise onto the surface of the polystyrene foam board planted with TX-Ct. Then, place it between two quartz plates and fix it with clips. Place it under visible light to obtain a polystyrene foam board grafted hydrogel network-encapsulated lipase system, which is a polystyrene foam composite material.

[0011] The present invention is also characterized in that:

[0012] In step 1, the stirring speed is 6000 r / min and the centrifugation time is 10 min.

[0013] In step 1, the concentration of the lipase solution is 18.3 mg / mL, the concentration of the phosphate buffer solution (PBS) is 0.01 M, and the pH is 7.4.

[0014] In step 2, the cooling temperature is 0°C, the cooling time is 30-35 minutes, and the stirring time is 72 hours.

[0015] In step 2, the mass ratio of concentrated sulfuric acid, thiosalicylic acid, and catechol-0-0-peroxydiacetic acid is 86:1:4.

[0016] In step 3, the wavelength of the ultraviolet high-pressure mercury lamp is 254 nm and the light intensity is 9 mW / cm 2 , the irradiation time is 3min.

[0017] In step 4, the wavelength of visible light is 420nm and the intensity is 3mW / cm 2 , the irradiation time is 50min.

[0018] The beneficial effects of the present invention are:

[0019] Polystyrene foam sheets can better bind to oils and fats, which have a lower density than water, achieving a "waste-to-waste" approach. Lipase is then encapsulated in situ within the PEG three-dimensional "molecular mesh" through a photochemical reaction. Compared to other surface modification methods, such as ozone treatment and high-energy radiation grafting, photochemical reactions are more efficient, greener, and spatially precisely controllable. Furthermore, mild reaction conditions ensure maximum lipase activity. The resulting composite material exhibits better storage and handling stability than free lipase, giving it broader application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 1 is a diagram showing the synthesis mechanism of the polystyrene foam composite material of the present invention;

[0021] Figure 2 It is a graph of hydrolysis yield of free enzyme, immobilized enzyme floating on the surface of substrate solution and immobilized enzyme fixed on the bottom;

[0022] Figure 3 This is a graph showing the relative activity of free enzyme and immobilized enzyme changing with storage time. DETAILED DESCRIPTION

[0023] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] The object of the present invention is to provide a method for preparing a polystyrene foam composite material based on hydrolyzed oil, which is specifically implemented according to the following steps:

[0025] Step 1: mixing porcine pancreatic lipase powder with a phosphate buffer solution, and removing insoluble lipase by centrifugation to obtain a lipase (PPL) solution;

[0026] The stirring speed was 6000 r / min and the centrifugation time was 10 min;

[0027] The concentration of the lipase solution was 18.3 mg / mL, the concentration of the phosphate buffer solution (PBS) was 0.01 M, and the pH was 7.4;

[0028] Step 2: Cool concentrated sulfuric acid, thiosalicylic acid, and catechol-0-0-peroxydiacetic acid in an ice bath under light-proof conditions while stirring continuously. After the reaction is completed, slowly add the reaction solution into ice water, centrifuge, and freeze-dry to obtain a yellow powder, which is the initiator TX-Ct.

[0029] The cooling temperature is 0°C, the cooling time is 30-35 minutes, and the stirring time is 72 hours.

[0030] The mass ratio of concentrated sulfuric acid, thiosalicylic acid, and catechol-OO-peroxydiacetic acid is 86:1:4;

[0031] Step 3: dripping the TX-Ct aqueous solution onto the surface of the polystyrene foam board, evenly spreading the solution, placing the polystyrene foam board coated with the TX-Ct aqueous solution between quartz plates and fixing it with a clamp, and then irradiating it under a high-pressure ultraviolet mercury lamp to obtain a polystyrene foam board planted with TX-Ct (Foam-TX-Ct);

[0032] The wavelength of the ultraviolet high-pressure mercury lamp is 254nm and the light intensity is 9mW / cm 2 , irradiation time is 3min;

[0033] Step 4: polyethylene glycol diacrylate (PEGDA), lipase (PPL) solution, glycerol, and deionized water are mixed and shaken to obtain a mixed solution, which is evenly added dropwise to the surface of Foam-TX-Ct. The solution is then placed between two quartz plates and fixed with a clamp. The plate is then irradiated under visible light to obtain a polystyrene foam board grafted hydrogel network-encapsulated lipase system (Foam-gP(PEGDA)PPL), which is a polystyrene foam composite material.

[0034] The wavelength of visible light is 420nm and the intensity is 3mW / cm 2 , irradiation time is 50min;

[0035] The PPL fixed in the polystyrene foam composite material prepared by the present invention has better adaptability to acid and high temperature resistance; the immobilized PPL is also superior to the free PPL in terms of hydrolysis efficiency; the immobilized PPL also has better storage stability and operational stability.

[0036] The present invention describes a method for preparing a polystyrene foam composite material based on hydrolyzed oils. This method uses a photochemical reaction to in situ encapsulate lipase within a three-dimensional PEG "molecular mesh." Compared to other surface modification methods, such as ozone treatment and high-energy radiation grafting, the photochemical reaction is more efficient, greener, and spatially precisely controllable. Furthermore, the mild reaction conditions ensure maximum lipase activity. The resulting material exhibits improved storage and operational stability compared to free lipase, promising broader application prospects.

[0037] Example 1

[0038] Weigh 0.5 g of porcine pancreatic lipase powder, add 25 mL of phosphate buffer solution (PBS, 0.01 M, pH = 7.4), stir the mixture for 24 hours, centrifuge at 6000 r / min for 10 minutes to remove insoluble lipase, and obtain 18.3 mg / mL PPL solution, which is stored at 4°C; prepare a 50 mL round-bottom flask, place a magnetic bar, add 26.72 mL of concentrated sulfuric acid, cool in an ice bath for 35 minutes and stir continuously, then add 0.57 g of thiosalicylic acid, stir until completely dissolved, and then add 2.4 g of catechol-OO-peroxydiacetic acid. Finally, protect from light, stir magnetically and react for 72 hours. After the reaction, slowly add the reaction solution into 200 mL of ice water (0°C), centrifuge and freeze-dry to obtain a yellow powder, which is the initiator TX-Ct. The TX-Ct solution was dripped onto the surface of the foam plate and the solution was evenly spread. The foam plate coated with the TX-Ct solution was placed between the quartz plates and fixed with a clamp. The system was placed under a UV high-pressure mercury lamp (wavelength 254 nm, light intensity 9 m W / cm 2 ) for 5 min to obtain a polystyrene foam board seeded with TX-Ct (Foam-TX-Ct);

[0039] PEGDA, PPL solution (18.3 mg / mL), glycerol, and deionized water were mixed in a ratio of 25%, 65%, 5%, and 5%. The mixture was shaken for 10 minutes to make it uniform. 10 μL of the mixture was dropped onto the surface of Foam-TX-Ct. The foam plate coated with the mixture was placed between two quartz plates to disperse the mixture evenly and fixed with a clamp. The system was placed under visible light (xenon lamp with filter, light band of 420 nm, light intensity of 3 mW / cm 2 ,) for 50 min to obtain a foam board grafted hydrogel network encapsulated enzyme system (Foam-gP(PEGDA)PPL). The surface coating is smooth and continuous.

[0040] Comparative Example 1

[0041] Comparative Example 1 differs from Example 1 in that PEGDA, PPL solution (18.3 mg / mL), glycerol, and deionized water are mixed in ratios of 25%, 70%, 0%, and 5%. The resulting foam-grafted hydrogel network-encapsulated enzyme system (Foam-gP(PEGDA)PPL) prepared by this method exhibits a smooth but discontinuous surface coating.

[0042] Comparative Example 2

[0043] The difference between Comparative Example 2 and Example 1 is that PEGDA, PPL solution (18.3 mg / mL), glycerol, and deionized water are mixed in proportions of 25%, 75%, 0%, and 0%; the foam board grafted hydrogel network-embedded enzyme system (Foam-gP(PEGDA)PPL) prepared by this method has a sparse and discontinuous surface coating.

[0044] Figure 1 This diagram illustrates the synthesis mechanism of the polystyrene foam composite material of this invention. Using visible light-activated graft polymerization, a simple and mild method for immobilizing lipase was employed. The immobilized lipase system was then characterized and its performance investigated. First, dormant TX-Ct free radicals were seeded on the polystyrene foam surface using UV light. The TX-Ct-seeded foam board then triggered active graft polymerization of PEGDA under visible light. During this process, the enzyme solution was mixed with PEGDA to achieve in situ immobilization of the lipase within the PEGDA three-dimensional network.

[0045] Figure 2 The following are the hydrolysis yield curves for the free enzyme, the immobilized enzyme floating on the substrate solution, and the immobilized enzyme fixed to the bottom. It can be seen that both the free and floating immobilized enzymes exhibit high hydrolysis efficiencies at the beginning of the reaction. After 40 minutes, the curves flatten out, and the yield steadily increases. When the reaction stabilizes, the hydrolysis efficiency of the free enzyme is 50 μg / min, while that of the floating immobilized enzyme is 52 μg / min. Furthermore, the hydrolysis yield of the floating immobilized enzyme is always greater than that of the free enzyme at any time during the reaction. Therefore, it can be concluded that under optimal conditions for the autocatalytic reaction and without external constraints, the catalytic activity and hydrolysis efficiency of the immobilized enzyme are higher than those of the free enzyme. This indicates that the immobilized enzyme exhibits superior catalytic activity and hydrolysis efficiency compared to the free enzyme. Furthermore, the yield curve of the immobilized enzyme fixed to the bottom of the test tube shows a relatively smooth increasing trend, without a distinct turning point, as seen in the yield curve of the floating immobilized enzyme. Furthermore, at any point during the reaction, the hydrolysis yield of the immobilized enzyme at the bottom was always lower than that of the floating immobilized enzyme, and also lower than that of the free enzyme. Therefore, it can be inferred that if external forces restrict the relative position of the immobilized enzyme, the expression of the immobilized enzyme's catalytic activity will be affected, and the performance advantages of the immobilized enzyme will not be fully realized. This phenomenon may be caused by the fact that when the immobilized enzyme is at the bottom of the test tube, its physical position is restricted, and it cannot fully contact the substrate, which is not conducive to material flow and activity expression. It cannot expose all catalytic active sites, thus leading to a decrease in hydrolysis efficiency and yield.

[0046] Figure 3The following graph shows the relative activity of the free and immobilized enzymes as a function of storage time. It can be seen that both the free and immobilized enzymes exhibit the same trend with increased storage time, with their relative activity decreasing significantly. This trend may be due to the inherent tendency of lipase to inactivate. However, compared to the free enzyme, the immobilized enzyme inactivates at a significantly slower rate over the same storage time, and its final relative activity is significantly higher. Therefore, the Foam-gP(PEGDA)PPL constructed in the experiment does improve the storage stability of the enzyme.

Claims

1. A method for preparing a polystyrene foam composite material based on hydrolyzed oil, characterized in that: Please follow the steps below to implement it: Step 1: mixing porcine pancreatic lipase powder with a phosphate buffer solution, and centrifuging to remove insoluble lipase to obtain a lipase solution; Step 2: Cool concentrated sulfuric acid, thiosalicylic acid, and catechol-0-0-peroxydiacetic acid in an ice bath under light-proof conditions while stirring continuously. After the reaction is completed, slowly add the reaction solution into ice water, centrifuge, and freeze-dry to obtain a yellow powder, which is the initiator TX-Ct. Step 3: dripping the TX-Ct aqueous solution onto the surface of the polystyrene foam board, evenly spreading the solution, placing the polystyrene foam board coated with the TX-Ct aqueous solution between quartz plates and fixing it with a clamp, and then irradiating it under an ultraviolet high-pressure mercury lamp to obtain a polystyrene foam board planted with TX-Ct; Step 4: Polyethylene glycol diacrylate, lipase solution, glycerol, and deionized water are mixed in proportions of 25%, 65%, 5%, and 5%, and shaken evenly to obtain a mixed solution. The mixed solution is evenly dropped onto the surface of the polystyrene foam board planted with TX-Ct, and then placed between two quartz plates and fixed with clips. The plate is then irradiated under visible light to obtain a polystyrene foam board grafted hydrogel network-encapsulated lipase system, which is a polystyrene foam composite material.

2. The method for preparing a polystyrene foam composite material based on hydrolyzed oil according to claim 1, characterized in that: In step 1, the stirring speed is 6000 r / min and the centrifugation time is 10 min.

3. The method for preparing a polystyrene foam composite material based on hydrolyzed oil according to claim 1, characterized in that: In step 1, the concentration of the lipase solution is 18.3 mg / mL, the concentration of the phosphate buffer solution (PBS) is 0.01 M, and the pH is 7.

4.

4. The method for preparing a polystyrene foam composite material based on hydrolyzed oil according to claim 1, characterized in that: In step 2, the cooling temperature is 0° C., the cooling time is 30-35 min, and the stirring time is 72 h.

5. The method for preparing a polystyrene foam composite material based on hydrolyzed oil according to claim 1, characterized in that: In the step 2, the mass ratio of concentrated sulfuric acid, thiosalicylic acid, and catechol-0-0-peroxydiacetic acid is 86:1:

4.

6. The method for preparing a polystyrene foam composite material based on hydrolyzed oil according to claim 1, characterized in that: In step 3, the wavelength of the ultraviolet high-pressure mercury lamp is 254 nm and the light intensity is 9 mW / cm 2 , the irradiation time is 3min.

7. The method for preparing a polystyrene foam composite material based on hydrolyzed oil according to claim 1, characterized in that: In step 4, the wavelength of visible light is 420 nm and the light intensity is 3 mW / cm 2 , the irradiation time is 50 min.

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