A soybean protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure

Abstract

The present application relates to the technical field of bio-based water treatment materials, and particularly relates to a soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure, which is prepared through the following steps: step one, preparing carboxylated polyvinyl alcohol; step two, introducing hydrochloric acid dopamine and reacting with the carboxylated polyvinyl alcohol to obtain a dopamine grafted polyvinyl alcohol solution; step three, treating the dopamine grafted polyvinyl alcohol solution through dialysis and rotary evaporation concentration to obtain a dopamine grafted polyvinyl alcohol concentrated solution; step four, adding soy protein isolate into the dopamine grafted polyvinyl alcohol concentrated solution, and freeze-drying to obtain a composite; step five, immersing the composite into a methyltrimethoxysilane n-hexane solution, and finally drying in an oven to obtain a soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure. The material is environmentally friendly, has an elastic and porous structure, can repeatedly adsorb oil, and has selective adsorption of cationic dyes.

Description

Technical Field

[0001] The invention relates to the technical field of bio-based water treatment materials, and in particular to a soybean protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure. Background Art

[0002] Pollution of aquatic systems causes illness and potentially death in humans, plants, and organisms worldwide. To improve environmental sustainability, effective and rational wastewater management is required. Water must be purified to levels that are safe for drinking, washing, and discharge into rivers, lakes, and oceans. Currently, a variety of water purification technologies exist, including adsorption, chemical precipitation, ion exchange, reverse osmosis, and electrochemical treatment. Adsorption has emerged as a promising solution due to its high efficiency, low cost, and ease of operation. Most adsorbents studied are in powder or film form. These two forms have the following drawbacks: First, powder adsorbents have a large surface area but are difficult to recycle, making them unsuitable for practical water treatment applications. Second, film adsorbents are too thin. Although they have a high adsorption capacity per unit weight, they do not have a high adsorption capacity and are prone to breakage in practical applications. Biomass-based adsorbents are more attractive for water treatment due to their effectiveness, low cost, eco-friendliness, and biodegradability, and in line with the American Chemical Society's "Green Chemistry" initiative. Therefore, there is an urgent need to develop a biomass-based adsorbent with large adsorption capacity, simple preparation method, and easy recycling to overcome the limitations of existing adsorbents. Summary of the Invention

[0003] The purpose of the present invention is to avoid the shortcomings of the existing technology and provide a soybean protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure. The material can not only efficiently adsorb oil and dye pollutants, but also be reused, and has the advantages of being environmentally friendly and low cost.

[0004] To achieve the above objectives, the present invention provides the following technical solutions:

[0005] A soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure is provided, which is prepared by the following method, comprising the following steps:

[0006] Step 1: dissolving polyvinyl alcohol in anhydrous dimethyl sulfoxide to obtain a polyvinyl alcohol solution, cooling the solution to room temperature, and then sequentially adding succinic anhydride and triethylamine and mixing to obtain a carboxylated polyvinyl alcohol solution;

[0007] Step 2: adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide to the carboxylated polyvinyl alcohol solution and stirring to react, then adding dopamine hydrochloride and triethylamine, and continuing the reaction at room temperature under nitrogen to obtain a dopamine-grafted polyvinyl alcohol solution;

[0008] Step 3, dialyzing and concentrating the dopamine-grafted polyvinyl alcohol solution through rotary evaporation to obtain a concentrated dopamine-grafted polyvinyl alcohol solution;

[0009] Step 4: adding the soy protein isolate to the dopamine-grafted polyvinyl alcohol concentrated solution, quantitatively adding deionized water, then adding glycerol and mixing evenly, adjusting the pH to 9-11, continuing to stir evenly, and then freeze-drying to obtain a composite;

[0010] Step 5: Evenly mix methyltrimethoxysilane and n-hexane to obtain a mixed soaking solution, add the complex into the mixed soaking solution and soak it, and then dry it in an oven to obtain a soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure.

[0011] In some embodiments, in step 1, the weight ratio of polyvinyl alcohol, anhydrous dimethyl sulfoxide solution, succinic anhydride and triethylamine is 1-3:60-120:0.2-0.8:0.2-0.8.

[0012] In some embodiments, in step 2, the weight ratio of the carboxylated polyvinyl alcohol solution, the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, dopamine hydrochloride and triethylamine is 90-120:0.5-10:0.3-0.6:0.5-1:0.2-0.6.

[0013] In some embodiments, in step 4, the ratio of the volume of deionized water after quantification to the volume of glycerol is 10:0.1-0.5.

[0014] In some embodiments, in step 1, the mixing reaction time is 20 to 30 hours.

[0015] In some embodiments, in step 2, the reaction is continued at room temperature for 20 to 30 hours.

[0016] In some embodiments, in step three, the dialyzed dopamine-grafted polyvinyl alcohol solution is concentrated by rotary evaporation to a concentration 4 to 5 times the original concentration of the dopamine-grafted polyvinyl alcohol solution.

[0017] In some embodiments, in step 4, stirring is performed in a magnetic stirrer and the stirring time is 0.5 to 2 hours.

[0018] In some embodiments, the composite is immersed in the mixed soaking solution for 1 to 3 hours.

[0019] In some embodiments, in step five, the drying temperature in the oven is 50-70°C.

[0020] The beneficial effects of the soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure of the present invention are as follows:

[0021] (1) The soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure of the present invention has a soy protein / polyvinyl alcohol-dopamine mixed solution. Since the water molecules in the soy protein / polyvinyl alcohol-dopamine mixed solution gradually move slowly during the freezing process and are orderly aggregated due to the interaction of hydrogen bonds, the soy protein / polyvinyl alcohol-dopamine mixed solution forms an ice crystal structure during the molding process. During the vacuum freeze-drying process, the ice crystals sublime, and pores are formed at the positions of the ice crystals, thereby shaping a three-dimensional interconnected porous material, which is conducive to the adsorption and retention of oil products (toluene, kerosene, hydraulic oil and soybean oil). By regulating the amount of ice crystals, the density of the composite sponge can be achieved to 0.1g / cm 3 , so that the oil can float on the water surface after being adsorbed, which is conducive to the rapid recovery of the composite sponge after water treatment, and also makes the surface area of ​​the composite sponge pores reach 0.75m 2 / g, the porosity can reach 92%, the total pore volume can reach 11mL / g, and the saturation capacity for adsorbing oil is larger.

[0022] (2) The soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure of the present invention has dopamine grafted onto polyvinyl alcohol to obtain an elastic structure. The elastic structure is added to the soy protein isolate, which effectively improves the brittleness of the soy protein isolate itself. The soy protein isolate and polyvinyl alcohol-dopamine components can be prepared into a composite sponge with elastic characteristics, which can be reused after adsorbing oil and squeezing.

[0023] (3) The soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure of the present invention has phenolic hydroxyl and carboxyl functional groups due to the grafting of succinic anhydride and dopamine. The presence of the two acidic groups of carboxyl and phenolic hydroxyl makes the material ionize H in aqueous solution. + Under electrostatic interaction, the anionic functional groups produced have a stronger selective adsorption effect on cationic dyes (methylene blue), which is beneficial to the adsorption of cationic dyes and increases the dye adsorption capacity.

[0024] (4) The invented soybean protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure, wherein the soybean protein isolate is an amphiphilic substance, which is not only lipophilic but also can adsorb dyes dissolved in water medium.

[0025] (5) The invented soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure uses soy protein isolate, polyvinyl alcohol and dopamine as biomass raw materials, does not need to rely on petrochemical products, avoids secondary pollution, is cheap, renewable and easy to degrade, and is suitable for large-scale production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The synthetic flow chart of SPI / PVA-DP composite material with sponge structure;

[0027] Figure 2 Comparison of the adsorption performance of SPI / PVA-DP composite materials with sponge structure to different oils;

[0028] Figure 3 This is the oil-water separation efficiency diagram of the SPI / PVA-DP composite material with sponge structure for different oil products;

[0029] Figure 4 This is the adsorption capacity diagram of methylene blue dye by SPI / PVA-DP composite material with sponge structure;

[0030] Figure 5 is the pore size distribution of three SPI / PVA-DP composite materials with sponge structure;

[0031] Figure 6 (a) XPS spectra of PVA, DP and PVA-DP; (b) ATR-FTIR spectra of PVA and PVA-DP; (c), (e) and (g) are the C1s curve fitting results of pure PVA, pure DP and PVA-DP, respectively; (d), (f) and (h) are the N1s curve fitting results of pure PVA, pure DP and PVA-DP, respectively;

[0032] Figure 7 This is the SEM image of the shear surface of SPI / PVA-DP with sponge structure;

[0033] Figure 8 are the compressive stress-strain curves of SPI / PVA and SPI / PVA-DP composites at 50% strain;

[0034] Figure 9 The appearance of SPI / PVA and SPI / PVA-DP under 90% compressive strain. DETAILED DESCRIPTION

[0035] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although preferred embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to make the present invention more thorough and complete and to fully convey the scope of the present invention to those skilled in the art.

[0036] Example

[0037] The soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure disclosed in this embodiment is as follows Figure 1 As shown, it is prepared by the following method, which comprises the following steps:

[0038] Step 1: dissolving polyvinyl alcohol in anhydrous dimethyl sulfoxide to obtain a polyvinyl alcohol solution, cooling the solution to room temperature, and then sequentially adding succinic anhydride and triethylamine and mixing them to obtain a carboxylated polyvinyl alcohol solution;

[0039] First, polyvinyl alcohol (PVA) is dissolved in anhydrous dimethyl sulfoxide (DMSO). Polyvinyl alcohol can be dissolved in DMSO because DMSO is a highly polar solvent that can form hydrogen bonds with the hydroxyl groups in polyvinyl alcohol, helping the polyvinyl alcohol to dissolve.

[0040] The polyvinyl alcohol-DMSO solution obtained above is cooled to room temperature to facilitate the subsequent reaction. Succinic anhydride is added to the cooled mixed solution. Succinic anhydride is a commonly used carboxylic anhydride that can react with the hydroxyl groups in polyvinyl alcohol to introduce carboxyl functional groups. After adding succinic anhydride, triethylamine is further added. Triethylamine may act as a catalyst or acid binding agent here to promote the reaction of succinic anhydride and polyvinyl alcohol to form carboxylated polyvinyl alcohol. After adding triethylamine, the mixed solution needs to be fully stirred to ensure that the reaction is evenly carried out and the completeness of the carboxylation reaction is ensured to obtain the carboxylated polyvinyl alcohol. This modified polyvinyl alcohol has more carboxyl functional groups, which can improve its water solubility and cross-linking reactivity and other properties.

[0041] Step 2: adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide to the carboxylated polyvinyl alcohol solution and stirring to react, then adding dopamine hydrochloride and triethylamine, and continuing the reaction at room temperature under nitrogen to obtain a dopamine-grafted polyvinyl alcohol solution;

[0042] 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC·HCl) and N-hydroxysuccinimide (NHS) are added to carboxylated polyvinyl alcohol. EDC·HCl and NHS are commonly used carboxyl group activation reagents. EDC·HCl reacts with carboxyl groups to form a reactive intermediate, which then reacts with NHS to form an NHS ester intermediate. After the addition of EDC·HCl and NHS, the mixed solution needs to be stirred to promote the reaction. Dopamine hydrochloride and triethylamine are then added to the reaction system. Dopamine hydrochloride provides dopamine molecules, while triethylamine acts as a base catalyst, promoting the reaction of the NHS ester with the primary amine groups in the dopamine molecules to form a stable amide bond. After the addition of dopamine hydrochloride and triethylamine, the reaction is stirred at room temperature under nitrogen to ensure that the dopamine molecules fully react with the NHS ester to form dopamine-grafted polyvinyl alcohol.

[0043] Step 3, dialyzing and concentrating the dopamine-grafted polyvinyl alcohol solution through rotary evaporation to obtain a concentrated dopamine-grafted polyvinyl alcohol solution;

[0044] Dialysis can remove unreacted monomers, low molecular weight polymers and small molecule impurities in the solution. This process usually takes 2 days to ensure the dialysis effect. After the dialysis treatment is completed, the dopamine-grafted polyvinyl alcohol solution is transferred to a rotary evaporator. By reducing the pressure and heating, the solvent (usually water) in the solution will evaporate, thereby increasing the concentration of dopamine-grafted polyvinyl alcohol in the solution. This process can effectively reduce the solution volume and remove unnecessary impurities to obtain a high-concentration dopamine-grafted polyvinyl alcohol solution.

[0045] Step 4: adding the soy protein isolate to the dopamine-grafted polyvinyl alcohol concentrated solution, quantitatively adding deionized water, then adding glycerol and mixing evenly, adjusting the pH to 9-11, continuing to stir evenly, and then freeze-drying to obtain a composite;

[0046] A certain amount of deionized water is added to the solution to adjust the concentration and viscosity of the solution to a state suitable for subsequent processing. Glycerol can improve the plasticity of the material by weakening the interaction between polymer molecular chains and increasing the mobility of the molecular chains. After all components are added, the mixed solution needs to be fully stirred to ensure that the components are evenly distributed to form a uniform mixed solution. The pH value of the solution is adjusted to 9-11 by adding alkaline substances (such as sodium hydroxide). This pH range is conducive to the dissolution of proteins and the stability of dopamine-grafted polyvinyl alcohol. After adjusting the pH, continue to stir the solution to ensure that the pH adjuster is evenly distributed and the solution remains uniform. The uniform mixed solution is freeze-dried. Freeze-drying is a method of removing water from the solution under low temperature and vacuum conditions. It can maintain the microstructure and active ingredients of the material and avoid the destruction of heat-sensitive components. At the same time, the removal of water will cause the material to form a porous structure at the location of the original ice crystals.

[0047] Step 5: Evenly mix methyltrimethoxysilane and n-hexane to obtain a mixed soaking solution, add the complex into the mixed soaking solution and soak it, and then dry it in an oven to obtain a soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure.

[0048] After the above steps, a soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure is obtained. This material combines the properties of soy protein, polyvinyl alcohol and dopamine, providing a high specific surface area and porosity through the sponge structure.

[0049] The process involves multiple steps, including surface modification, freeze-drying, soaking, and heat treatment, to create a composite material with a specific structure and properties. The sponge structure of this material may help improve its adsorption properties in water treatment.

[0050] In this embodiment, in step 1, the weight ratio of polyvinyl alcohol, anhydrous dimethyl sulfoxide solution, succinic anhydride and triethylamine is 1-3:60-120:0.2-0.8:0.2-0.8, preferably 2.2:108:0.5:0.5.

[0051] In this embodiment, in step 2, the weight ratio of the carboxylated polyvinyl alcohol solution, the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, dopamine hydrochloride and triethylamine is 90-120:0.5-10:0.3-0.6:0.5-1:0.2-0.6, preferably 111:0.9:0.5:0.9:0.5.

[0052] In this embodiment, in step 4, the ratio of the volume of the quantified deionized water to the volume of the glycerol is 10:0.1 to 0.5, preferably 10:0.2. The specific parameters can be selected according to actual conditions and are not limited here.

[0053] In this embodiment, in step 1, the mixing reaction time is 20 to 30 hours, preferably 24 hours. The specific parameters can be selected according to actual conditions and are not limited here.

[0054] In the embodiment, in step 2, the reaction time at room temperature is 20 to 30 hours, preferably 24 hours. The specific parameters can be selected according to actual conditions and are not limited here.

[0055] In this embodiment, in step 3, the dialyzed dopamine-grafted polyvinyl alcohol solution is concentrated by rotary evaporation to 4 to 5 times its original concentration. Specific parameters can be selected according to actual conditions and are not limited here.

[0056] In this embodiment, in step 4, the stirring time in the magnetic stirrer is 0.5 to 2 hours, preferably 1 hour. The specific parameters can be selected according to actual conditions and are not limited here.

[0057] In this embodiment, the freeze-dried complex is immersed in the mixed immersion solution for 1 to 3 hours, preferably 2 hours. Specific parameters can be selected according to actual conditions and are not limited here.

[0058] In this embodiment, in step 5, the drying temperature in the oven is 50-70° C., preferably 60° C. The specific parameters can be selected according to actual conditions and are not limited here.

[0059] Effect verification:

[0060] In order to further verify the characteristics and functions of the soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure of the present invention, test examples and comparative examples were carried out respectively.

[0061] The abbreviated names of the components are as follows:

[0062] SPI / PVA-DP Soy Protein Isolate / Polyvinyl Alcohol-Dopamine

[0063] SPI / PVA soy protein isolate / polyvinyl alcohol

[0064] SPI Soy Protein Isolate

[0065] PVA polyvinyl alcohol

[0066] DP dopamine

[0067] Test example

[0068] Step 1: Synthesis of carboxylated PVA. PVA (2.2 g, 50 mmol AOH groups) was dissolved in anhydrous DMSO (100 mL) and the solution was cooled to room temperature. Succinic anhydride (0.5 g, 5.0 mmol) and triethylamine (0.5 g, 5.0 mmol) were added sequentially and reacted for 24 h to obtain carboxylated PVA.

[0069] Step 2: 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC HCl) (957.8 mg, 5.0 mmol) and N-hydroxysuccinimide (NHS) (575 mg, 5 mmol) were added to the reaction solution containing carboxyl-functionalized PVA and stirred for 30 min. Then, dopamine hydrochloride (948.20 mg, 5.0 mmol) and triethylamine (505.95 mg, 5.0 mmol) were added and stirred at room temperature under N2 for 24 h to obtain dopamine-grafted polyvinyl alcohol (PVA-DP).

[0070] Step 3: After dialyzing the sample solution for 2 days, the sample solution was concentrated by rotary evaporation to 4-5 times, 2 mL of the sample solution was freeze-dried, and the weight was weighed to determine the concentration of the sample solution;

[0071] Step 4: Weigh SPI at SPI:PVA-DP weight ratios of 100:0, 80:20, 60:40, 40:60, 20:80, and 0:100 into a 25 mL beaker containing a PVA-DP sample solution to a solids content of 0.3 g. Add deionized water to adjust the final volume to 10 mL. Add 0.2 mL of glycerol to each sample solution. Finally, adjust the pH of the solution to 10 with 15% NaOH solution. Stir the sample solution in a magnetic stirrer at room temperature for 1 hour, remove it, and freeze-dry it.

[0072] Step 5: The freeze-dried samples were added to 20 mL of a 1.5% methyltrimethoxysilane (MTMS) / n-hexane solution and soaked for 2 hours. Subsequently, the samples were dried in a 60°C oven to obtain cylindrical SPI / PVA-DP products with a diameter of 30 mm and a height of 15 mm.

[0073] The soy protein / polyvinyl alcohol-dopamine composite water treatment materials with sponge structures (hereinafter referred to as sponge structures) obtained in the test examples, namely the SPI / PVA-DP composite sponges, were used to adsorb toluene, kerosene, hydraulic oil and soybean oil, and their saturated adsorption capacity, adsorption rate and reusability were compared. Figure 2(a) It can be seen that compared with commercial PP oil-absorbing felt, the sponge-structured soybean protein / polyvinyl alcohol-dopamine composite water treatment materials with a ratio of 60:40, 40:60 and 20:80 have a larger oil absorption capacity, reaching a maximum of 9.21g / g. However, the ratios of 100:0, 80:20 and 0:100 are slightly inferior to PP oil-absorbing felt. Figure 2 (b), (c), (d) and (e) show that all composite sponges can almost reach full adsorption within 5 min and reach saturated adsorption capacity within 30 min. Figure 2 (f), (g), (h) and (i) show that the composite sponge is reusable for adsorbing different oils. After being used 10 times, the recovery rate can still reach more than 90%, and its adsorption capacity is even improved compared with the first use. Figure 3 It can be seen that the oil-water separation efficiency of the SPI / PVA-DP composite sponge for toluene, kerosene, hydraulic oil and soybean oil can reach more than 95%, so the composite sponge can be used in practical applications of oil-water separation.

[0074] In 200 μg / mL methylene blue solution, the adsorption value of methylene blue by all composite sponges obtained in the test example can reach more than 48 mg / g ( Figure 4 ), among which the composite sponges with a ratio of 100:0, 80:20 and 60:40 had higher adsorption values, namely 54.5 mg / g, 54.2 mg / g and 54.4 mg / g respectively. At the same time, the adsorption efficiency of the composite sponge for methylene blue can reach more than 85%, which shows that it has effective adsorption for cationic dyes (methylene blue). Compared with cationic dyes, the composite sponge was adsorbed in a 150 μg / mL solution of anionic dye (Acid Blue 92) for two hours, and the results showed that it had no adsorption effect on Acid Blue 92. Obviously, the composite sponge exhibits selective adsorption for cationic dyes due to its rich anionic groups such as phenolic hydroxyl and carboxyl groups.

[0075] Table 1 shows the pore analysis of three SPI / PVA-DP composite sponges;

[0076]

[0077]

[0078] Figure 5The pore size distribution of three SPI / PVA-DP composite sponges with different weight ratios is shown. The 80:20 and 60:40 composite sponges showed similar average pore sizes of 61.95μm and 61.75μm, respectively, while the average pore size of the 40:60 composite sponge was 40.70μm. The porosity of the 80:20, 60:40 and 40:60 composite sponges was 91.88%, 91.15% and 89.00%, respectively. This shows that the composite sponge has a high porosity and large pore structure. Its total pore volume and total pore surface area show that the composite sponge has a large adsorption space and adsorption surface, confirming that the composite sponge is beneficial in various applications of water treatment. As shown in Table 1, the sample density is between 0.08-0.12g / cm 3 , indicating that the composite material can be prepared using a small amount of raw materials and is lightweight and efficient.

[0079] In order to verify whether PVA is successfully grafted with DP, XPS technology ( Figure 6 ) analyzed surface chemical changes and chemical composition. For pure PVA, C1s, O1s, and N1s were detected. C and O accounted for 68.50% and 31.20% of the PVA, respectively, while N accounted for only 0.30%. This suggests that N may be a contaminant or an impure sample. Because DP itself contains N, a very strong N1s peak was detected in DP, which is absent in pure PVA. However, the XPS spectrum of the PVA-DP sample showed a relatively strong N1s peak, with C, O, and N accounting for 63.53%, 21.18%, and 2.2%, respectively. Clearly, the C and O contents of the target sample were lower than those of pure PVA, while the N content was higher. Furthermore, the C1s peak analysis revealed a new peak at 288.1 eV, attributed to C=O. This C=O is introduced by the grafting of succinic anhydride onto PVA, and is also generated when carboxylated polyvinyl alcohol is subsequently grafted onto DP. This shows that the reaction formula is valid and PVA-DP is successfully synthesized.

[0080] In the infrared spectra of PVA and PVA-DP ( Figure 6 b) at 3290 cm -1 There is a broad and strong absorption at 2920 cm, which is attributed to the symmetrical stretching vibration of the -OH group; -1 The peak at 1090 cm is attributed to the CH stretching vibration peak of saturated C; -1 The peak at 1720 cm-1 of the target product PVA-DP is stronger than that of pure PVA, indicating that the addition of phenolic hydroxyl groups of DP increases the total number of hydroxyl groups in the target product. -1 A new peak was generated at 1650 cm-1, which indicates that the target product PVA-DP has an ester bond -COO.-1 The new peaks at 1 and 2 are the C=C stretching vibrations of the aromatic ring. The appearance of the two new peaks further confirms that DP has been successfully grafted onto PVA.

[0081] Depend on Figure 7 As can be seen, all samples have a porous structure. For the composite sponge prepared with soy protein isolate (i.e., 100:0), its pore structure is relatively simple, with fewer holes on the pore walls compared to the 20μm micrographs of other samples. The pore structures of the other samples are very rich, especially 80:20, 60:40, and 40:60, which have very dense holes on the pore walls. Moreover, the higher the protein content, the larger the pores, indicating that the addition of soy protein isolate has a positive effect on the pore structure of the porous composite sponge.

[0082] Comparative Example

[0083] To illustrate the effect of adding dopamine in the present invention, a comparative example of a soy protein / polyvinyl alcohol composite sponge for water treatment is provided as follows:

[0084] At 90°C, PVA was dissolved in 10 mL of deionized water. After complete dissolution, SPI was added into a 25 mL beaker (the weight ratio of SPI:PVA was 100:0, 80:20, 60:40, 40:60, 20:80, and 0:100), with a solid content of 0.3 g. The pH of the sample solution was adjusted to 10 with 15% NaOH solution. The solution was stirred in a magnetic stirrer at room temperature for 1 h, taken out, and freeze-dried to obtain a cylindrical SPI / PVA product with a diameter of 30 mm and a height of 15 mm.

[0085] Depend on Figure 8 The results show that the height of the SPI / PVA composite sponge has decreased by more than 20% after the fifth compression under 50% strain and cannot be restored. After 10 times of 50% compression strain, the composite sponge is severely deformed, proving that it has no elasticity. However, the composite sponge grafted with dopamine only deforms slightly after 50 times of 50% compression strain and can almost recover to its original height when the external force is released. Figure 9 It can be seen that among the composite sponges of the same batch and size, the SPI / PVA composite sponge has become flattened after 90% strain. However, except for the 100:0 composite sponge, the other SPI / PVA-DP composite sponges can almost recover to their original height, indicating that most SPI / PVA-DP composite sponges have good elasticity and compression properties.

[0086] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A soybean protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure, characterized in that: It is prepared by the following method, which comprises the following steps: Step 1: dissolving polyvinyl alcohol in anhydrous dimethyl sulfoxide to obtain a polyvinyl alcohol solution, cooling the solution to room temperature, and then sequentially adding succinic anhydride and triethylamine and mixing them to obtain a carboxylated polyvinyl alcohol solution; Step 2: adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide to the carboxylated polyvinyl alcohol solution and stirring to react, then adding dopamine hydrochloride and triethylamine, and continuing the reaction at room temperature under nitrogen to obtain a dopamine-grafted polyvinyl alcohol solution; Step 3, dialyzing and concentrating the dopamine-grafted polyvinyl alcohol solution through rotary evaporation to obtain a concentrated dopamine-grafted polyvinyl alcohol solution; Step 4: adding the soy protein isolate to the dopamine-grafted polyvinyl alcohol concentrated solution, quantitatively adding deionized water, then adding glycerol and mixing evenly, adjusting the pH to 9-11, continuing to stir evenly, and then freeze-drying to obtain a composite; Step 5: Evenly mix methyltrimethoxysilane and n-hexane to obtain a mixed soaking solution, add the complex into the mixed soaking solution and soak it, and then dry it in an oven to obtain a soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure.

2. The soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure according to claim 1, characterized in that: In step 1, the weight ratio of polyvinyl alcohol, anhydrous dimethyl sulfoxide solution, succinic anhydride and triethylamine is 1-3:60-120:0.2-0.8:0.2-0.

8.

3. The soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure according to claim 1, characterized in that: In step 2, the weight ratio of the carboxylated polyvinyl alcohol solution, the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, dopamine hydrochloride and triethylamine is 90-120:0.5-10:0.3-0.6:0.5-1:0.2-0.

6.

4. The soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure according to claim 1, characterized in that: In step 4, the ratio of the volume of the quantified deionized water to the volume of the glycerol is 10:0.1-0.

5.

5. The soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure according to claim 1, characterized in that: In step 1, the mixing reaction time is 20 to 30 hours.

6. The soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure according to claim 1, characterized in that: In step 2, the reaction is continued at room temperature for 20 to 30 hours.

7. The soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure according to claim 1, characterized in that: In step 3, the dialyzed dopamine-grafted polyvinyl alcohol solution is concentrated by rotary evaporation to a concentration of 4 to 5 times the original concentration of the dopamine-grafted polyvinyl alcohol solution.

8. The soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure according to claim 1, characterized in that: In step 4, stirring is performed in a magnetic stirrer for 0.5 to 2 hours.

9. The soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure according to claim 1, characterized in that: The composite is immersed in the mixed immersion solution for 1 to 3 hours.

10. The soy protein / polyvinyl alcohol-dopamine composite water treatment material with a sponge structure according to claim 1, characterized in that: In step 5, the drying temperature in the oven is 50-70°C.

Images