Water purifying agent based on bionic adsorption principle and preparation process thereof

Abstract

The present application relates to the technical field of water treatment, and particularly relates to a water purifying agent based on a biomimetic adsorption principle and a preparation process thereof, wherein the water purifying agent is obtained by a composite framework of an inner layer, an intermediate layer and an outer layer; the inner layer is a polydopamine nanofiber network; the intermediate layer is a spider silk protein-paraffin composite layer; and the outer layer is a spider silk protein-polydopamine macroporous framework structure; through the multi-layer composite structure, the spider silk protein-polydopamine macroporous framework is the outer layer, the spider silk protein-paraffin composite layer is the intermediate layer, and the polydopamine nanofiber network is the inner layer, so that gradient capture of pollutants from micron to nanometer is realized, and through biomimetic tough framework design, dynamic pore size regulation mechanism, hierarchical adsorption synergistic effect and biomimetic adhesion enhancement technology, the limitation of traditional adsorbents is broken through.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and more specifically, to a water purification agent based on the principle of biomimetic adsorption and its preparation process. Background Technology

[0002] Major pollutants in water bodies include heavy metal ions (such as lead, cadmium, and mercury), organic pollutants (such as pesticides and dyes), microorganisms (such as bacteria and viruses), and microplastics. Traditional water purification technologies (such as coagulation, sedimentation, filtration, and disinfection) suffer from low efficiency, high cost, and secondary pollution when dealing with complex pollutants. There is an urgent need to develop new and efficient water purification materials. In recent years, the development of bionics and materials science has provided new ideas for the research and development of water purification agents. The principle of bionic adsorption is to imitate the adsorption process in living organisms and improve adsorption efficiency by designing materials with specific microstructures and functional groups.

[0003] However, the existing adsorbent framework suffers from insufficient mechanical strength during dynamic filtration, leading to particle breakage and increasing the risk of system blockage. At the same time, conventional biomimetic adsorbents are prone to pollutant deposition in the pores of the water purification agent during dynamic filtration or long-term operation, causing the pores to gradually become blocked. In view of this, we propose a water purification agent based on the principle of biomimetic adsorption and its preparation process. Summary of the Invention

[0004] The purpose of this invention is to provide a water purification agent based on the principle of biomimetic adsorption and its preparation process, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides a water purification agent based on the principle of biomimetic adsorption, comprising the following components: the water purification agent is obtained by a composite structure of an inner layer, a middle layer and an outer layer;

[0006] The inner layer is a polydopamine nanofiber network;

[0007] The middle layer is a spider silk protein-paraffin composite layer;

[0008] The outer layer is a spider silk protein-polydopamine macroporous framework structure;

[0009] The water purifier achieves its adsorption efficiency through a multi-layered composite structure. The specific structure of the water purifier is as follows: the outer layer is a macroporous framework constructed by spider silk protein / polydopamine to pre-filter suspended solids; the middle layer is a spider silk protein-paraffin (C18-C22 short-chain alkane paraffin) composite layer to intercept colloidal pollutants; and the inner layer is a polydopamine nanofiber network to chelate heavy metal ions and small molecule organic matter.

[0010] Spider silk protein is a unique fibrous protein. Its β-sheets composed of alanine and proline-rich A-helices, along with its tightly packed secondary structure, create a semi-crystalline molecular spring structure, giving it high strength and toughness. Therefore, spider silk protein is used as the adsorbent's framework. However, high strength is not enough; a certain degree of toughness is also needed to maintain the integrity of the adsorbent particles. Thus, polydopamine is added to impart flexibility, ensuring the particles remain intact in high-speed water flow. The surface of polydopamine is rich in phenolic hydroxyl and amino groups, which can efficiently capture heavy metal ions through chelation, adsorbing heavy metals in water and achieving purification. Furthermore, it acts as a "binder" to bind the structures together.

[0011] Paraffin is a phase change material. During the phase change process, its volume changes. When it melts and expands, it compresses the protein network, causing the pore size to shrink. When it solidifies and shrinks, it releases stress and the pore size recovers. Therefore, it can act as a "micro-valve" to adjust the pore size in a small way. Although the pore size change rate is small, when pollutants are adsorbed and blocked, the paraffin solidifies and shrinks to release stress and the pore size recovers. It can actively "pop out" the adsorbed pollutants, reduce pore blockage, and improve anti-blocking ability.

[0012] By constructing the above-mentioned multi-layer composite structure and leveraging the synergistic effect between layers, it is possible to classify and adsorb pollutants according to changes in ambient temperature and different water environments, thereby improving adsorption efficiency.

[0013] On the other hand, the present invention provides a preparation process for a water purification agent based on the biomimetic adsorption principle, used in any one of the above-mentioned water purification agents based on the biomimetic adsorption principle, comprising the following steps:

[0014] S1.1. Dissolve dopamine hydrochloride in Tris-HCl buffer solution with pH 8.5-9 to obtain a 10-15 wt% dopamine hydrochloride solution. Perform oxidative polymerization at room temperature for 24-48 h with magnetic stirring at 800-1000 rpm and dissolved oxygen concentration of 8-10 ppm to obtain a polydopamine solution. Mix the polydopamine solution with polyvinyl alcohol and prepare fiber structure by electrospinning. Set the electrospinning parameters and vacuum dry at 60-80℃ for 10-12 h to obtain a polydopamine nanofiber network, i.e., the inner layer.

[0015] S1.2 Mix molten short-chain alkane paraffin with a composite emulsifier and homogenize at 15000-16000 rpm for 5-10 min to form a nano-paraffin emulsion with a particle size of 50-200 nm. Dissolve spider silk protein in choline chloride / urea solvent, wherein the molar ratio of choline chloride / urea solvent is 1:2. Stir at 55-60℃ for 5-6 h to obtain a 12-14% (w / v) spider silk protein solution. Add the nano-paraffin emulsion and ultrasonically emulsify for 20-30 min to obtain an intermediate layer solution.

[0016] S1.3. The intermediate layer solution is coated onto the inner layer surface using the dip-spin coating method, and then kept in an oven at 45-50℃ for 1.5-2 hours, then transferred to an environment at 20-25℃ for 8-12 hours, and then sprayed with a 0.5-0.8% dopamine hydrochloride solution. Oxidative polymerization is carried out for 12-16 hours to obtain the inner layer-intermediate layer composite.

[0017] S1.4. Dissolve spider silk protein in choline chloride / urea solvent to obtain a 10-12 wt% spider silk protein solution. Add 2-4 wt% polydopamine solution and mix and stir for 3-4 hours. Then add NaCl and ultrasonically disperse for 20-30 minutes. Shape the mixture by freeze casting, set the program, and obtain a porous block. Finally, put the porous block into a mold, hold it under 3-5 MPa pressure for 30 minutes to fix it, and soak it in 0.5-1 wt% genipin for crosslinking for 4-6 hours. Wash it with phosphate buffer until the pH is 7.2-7.4 to obtain the spider silk protein-polydopamine macroporous framework structure, i.e., the outer layer.

[0018] The spider silk protein-polydopamine macroporous framework was continuously rinsed with 100 mL PBS (pH 7.4) at a flow rate of 10 mL / min for 30-45 min, repeated 6-8 times, with fresh PBS replaced each time to remove residual genipin. The final rinsing solution was collected, and the residual genipin was detected by high performance liquid chromatography (HPLC) to ensure that it was ≤0.1 ppm.

[0019] S1.5. Immerse the outer layer in a solution of dopamine hydrochloride at pH 8.5-9 and a mass fraction of 0.5-0.8% for oxidative polymerization for 12-16 hours. Place the solution in a hot press and pressurize it according to a gradient program to bond the outer layer with the inner-middle layer composite to obtain a composite structure. Finally, immerse the composite structure in a 1.0-1.2% genipin solution for crosslinking for 6-8 hours, clean and dry it to obtain a water purification agent.

[0020] Preferably, in step S1.1, the volume ratio of polydopamine solution to polyvinyl alcohol is 2-3:1, and the mass fraction of polyvinyl alcohol is 8-12%. The electrospinning parameters are: voltage 18-25kV, receiving distance 15-20cm, flow rate 0.5-0.8mL / h, and ambient humidity 30-40%.

[0021] Preferably, in S1.2, the spider silk protein is 250-350 kDa, and the short-chain alkane paraffin is a C18-C22 mixture with a melting point of 35-45°C.

[0022] Preferably, in step S1.2, the mass ratio of molten short-chain alkane paraffin to the composite emulsifier is 1:3 to 5, and the composite emulsifier is obtained by mixing Span 80 and Tween 80 at a mass ratio of 1 to 2:1, and the short-chain alkane paraffin is mixed with spider silk protein at a mass ratio of 1:3.2 to 4.5.

[0023] Preferably, in step S1.3, the immersion speed is set to 3-5 mm / s, and the spin coating parameters are 2000 rpm × 30 s.

[0024] Preferably, in S1.4, the ratio of spider silk protein to polydopamine is 3.8-4.5:1 (w / w), the particle size of NaCl is 100-150 μm, and the amount added is 60-65 wt%.

[0025] Preferably, in step S1.4, the specific parameters of the program are set as follows: pre-freezing: rapid freezing with liquid nitrogen at -80℃ for 4 hours; primary drying: maintaining at -50℃ and 10Pa for 24 hours; and desorption drying: maintaining at 25℃ and 1Pa for 6 hours.

[0026] Preferably, the specific parameters for gradient program pressure setting in S1.5 are: first stage: 35℃, 0.5MPa, 2h; second stage: 25℃, 1MPa, 2h; third stage: 10℃, 2MPa, 2h.

[0027] Preferably, the inner layer has a thickness of 0.3-0.5 mm, the middle layer has a thickness of 0.8-1.0 mm, and the outer layer has a thickness of 1.2-1.5 mm.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] This biomimetic adsorption-based water purifier and its preparation process utilize a composite structure of spider silk protein and polydopamine. The high strength of spider silk protein combined with the flexible adhesive properties of polydopamine allows the purifier to maintain structural integrity under dynamic water flow impact. Utilizing the phase change characteristics of short-chain alkane paraffin, the pore size is adaptively adjusted. When pollutant adsorption is saturated, it actively "expels" blockages, improving anti-clogging ability. Through the spider silk protein-polydopamine macroporous framework structure, the spider silk protein-paraffin composite layer, and the polydopamine nanofiber network, it achieves gradient capture of micron- to nano-sized pollutants. Polydopamine, acting as a "molecular binder," simultaneously chelates heavy metal ions, achieving a dual enhancement of structural reinforcement and functionalization. Therefore, in terms of mechanical strength, adsorption capacity, and anti-clogging ability, through biomimetic strong framework design, dynamic pore size control mechanism, hierarchical adsorption synergistic effect, and biomimetic adhesive enhancement technology, it overcomes the limitations of traditional adsorbents and is suitable for high-efficiency purification needs under complex water quality conditions. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] This invention discloses a water purifier based on the principle of biomimetic adsorption. The water purifier is composed of an inner layer, a middle layer, and an outer layer composite framework. The inner layer is a polydopamine nanofiber network; the middle layer is a spider silk protein-paraffin composite layer; and the outer layer is a spider silk protein-polydopamine macroporous framework structure. The spider silk protein has a value of 250-350 kDa, and the short-chain alkane paraffin is a C18-C22 mixture with a melting point of 35-45°C.

[0032] Example 1: A water purification agent based on the principle of biomimetic adsorption and its preparation process, comprising the following steps:

[0033] S1.1. Dopamine hydrochloride was dissolved in Tris-HCl buffer at pH 8.5 to obtain a 15wt% dopamine hydrochloride solution. The solution was then subjected to oxidative polymerization at room temperature for 24 hours with magnetic stirring at 800 rpm and a dissolved oxygen concentration of 8 ppm to obtain a polydopamine solution. The polydopamine solution was mixed with polyvinyl alcohol, wherein the volume ratio of polydopamine solution to 8% polyvinyl alcohol was 3:1. The fiber structure was prepared by electrospinning. The electrospinning parameters were set as follows: voltage 20 kV, receiving distance 15 cm, flow rate 0.5 mL / h, ambient humidity 35%, and vacuum drying at 60℃ for 12 hours to obtain a polydopamine nanofiber network, i.e., an inner layer with a thickness of 0.5 mm.

[0034] S1.2. Molten short-chain alkane paraffin wax is mixed with a composite emulsifier of Span 80 / Tween 80 (mass ratio 1:1) at a mass ratio of 1:3. The mixture is homogenized at 15000 rpm for 10 min to form a nano-paraffin emulsion with a particle size of 50 nm. Spider silk protein is dissolved in choline chloride / urea solvent and stirred at 60 °C for 6 h. The molar ratio of choline chloride / urea solvent is 1:2 to obtain a 12% (w / v) spider silk protein solution. The nano-paraffin emulsion is then added to the solution, where the mass ratio of short-chain alkane paraffin wax to spider silk protein is 1:3.2. The mixture is ultrasonically emulsified for 30 min to obtain an intermediate layer solution.

[0035] S1.3. The intermediate layer solution was coated onto the inner layer surface using the dip-spray method. The dip speed was 5 mm / s and the spin coating parameters were 2000 rpm × 30 s. Then, it was kept in an oven at 45℃ for 2 h, then transferred to an environment at 25℃ for 12 h, and then 0.5% dopamine hydrochloride was sprayed and oxidized for 12 h to obtain an inner layer-intermediate layer composite with a thickness of 0.8 mm.

[0036] S1.4. Spider silk protein was dissolved in choline chloride / urea solvent to obtain a 12wt% spider silk protein solution. 3wt% polydopamine solution was added and mixed and stirred for 3-4 hours, where the spider silk protein:polydopamine = 3.8:1 (w / w). Then, 60wt% NaCl (particle size 100μm) was added and ultrasonically dispersed for 30 minutes. The mixture was then shaped by cryogenic casting. The program was set as follows: pre-freezing: rapid freezing with liquid nitrogen at -80℃ for 4 hours; primary drying: holding at -50℃ and 10Pa for 24 hours; analytical drying: holding at 25℃ and 1Pa for 6 hours to obtain a porous block. Finally, the porous block was placed into a mold and held under 5MPa pressure for 30 minutes to fix the shape. It was then immersed in 0.5wt% genipin for crosslinking for 4 hours and washed with phosphate buffer until the pH reached 7.4 to obtain a spider silk protein-polydopamine macroporous framework structure, i.e., an outer layer with a thickness of 1.3mm.

[0037] S1.5. The outer layer is immersed in a solution of 0.5% dopamine hydrochloride at pH 8.5 for oxidative polymerization for 12 hours. It is then placed in a hot press and subjected to pressure setting according to a gradient program: first stage: 35℃, 0.5MPa, 2 hours; second stage: 25℃, 1MPa, 2 hours; third stage: 10℃, 2MPa, 2 hours. This process allows the outer layer to bond with the inner-middle layer complex, resulting in a composite structure. Finally, the composite structure is immersed in a 1.0% genipin solution for crosslinking for 6 hours, then washed and dried to obtain the water purification agent.

[0038] Example 2: A water purification agent based on the principle of biomimetic adsorption and its preparation process, comprising the following steps:

[0039] S1.1. Dopamine hydrochloride was dissolved in Tris-HCl buffer at pH 8.5 to obtain a 15wt% dopamine hydrochloride solution. The solution was then subjected to oxidative polymerization at room temperature for 24 hours with magnetic stirring at 800 rpm and a dissolved oxygen concentration of 8 ppm to obtain a polydopamine solution. The polydopamine solution was mixed with polyvinyl alcohol, wherein the volume ratio of polydopamine solution to 8% polyvinyl alcohol was 3:1. The fiber structure was prepared by electrospinning. The electrospinning parameters were set as follows: voltage 20 kV, receiving distance 15 cm, flow rate 0.5 mL / h, ambient humidity 35%, and vacuum drying at 60℃ for 12 hours to obtain a polydopamine nanofiber network, i.e., an inner layer with a thickness of 0.5 mm.

[0040] S1.2. Molten short-chain alkane paraffin wax is mixed with a composite emulsifier of Span 80 / Tween 80 (mass ratio 1:1) at a mass ratio of 1:3. The mixture is homogenized at 15000 rpm for 10 min to form a nano-paraffin emulsion with a particle size of 50 nm. Spider silk protein is dissolved in choline chloride / urea solvent and stirred at 60 °C for 6 h. The molar ratio of choline chloride / urea solvent is 1:2 to obtain a 12% (w / v) spider silk protein solution. The nano-paraffin emulsion is then added, with the mass ratio of short-chain alkane paraffin wax to spider silk protein being 1:3.8. The mixture is ultrasonically emulsified for 30 min to obtain an intermediate layer solution.

[0041] S1.3. The intermediate layer solution was coated onto the inner layer surface using the dip-spray method. The dip speed was 5 mm / s and the spin coating parameters were 2000 rpm × 30 s. Then, it was kept in an oven at 45℃ for 2 h, then transferred to an environment at 25℃ for 12 h, and then 0.5% dopamine hydrochloride was sprayed and oxidized for 12 h to obtain an inner layer-intermediate layer composite with a thickness of 0.8 mm.

[0042] S1.4. Spider silk protein was dissolved in choline chloride / urea solvent to obtain a 12wt% spider silk protein solution. 3wt% polydopamine solution was added and mixed and stirred for 3-4 hours, where the spider silk protein:polydopamine = 3.8:1 (w / w). Then, 60wt% NaCl (particle size 100μm) was added and ultrasonically dispersed for 30 minutes. The mixture was then shaped by cryogenic casting. The program was set as follows: pre-freezing: rapid freezing with liquid nitrogen at -80℃ for 4 hours; primary drying: holding at -50℃ and 10Pa for 24 hours; analytical drying: holding at 25℃ and 1Pa for 6 hours to obtain a porous block. Finally, the porous block was placed into a mold and held under 5MPa pressure for 30 minutes to fix the shape. It was then immersed in 0.5wt% genipin for crosslinking for 4 hours and washed with phosphate buffer until the pH reached 7.4 to obtain a spider silk protein-polydopamine macroporous framework structure, i.e., an outer layer with a thickness of 1.3mm.

[0043] S1.5. The outer layer is immersed in a solution of 0.5% dopamine hydrochloride at pH 8.5 for oxidative polymerization for 12 hours. It is then placed in a hot press and subjected to pressure setting according to a gradient program: first stage: 35℃, 0.5MPa, 2 hours; second stage: 25℃, 1MPa, 2 hours; third stage: 10℃, 2MPa, 2 hours. This process allows the outer layer to bond with the inner-middle layer complex, resulting in a composite structure. Finally, the composite structure is immersed in a 1.0% genipin solution for crosslinking for 6 hours, then washed and dried to obtain the water purification agent.

[0044] Example 3: A water purification agent based on the principle of biomimetic adsorption and its preparation process, comprising the following steps:

[0045] S1.1. Dopamine hydrochloride was dissolved in Tris-HCl buffer at pH 8.5 to obtain a 15wt% dopamine hydrochloride solution. The solution was then subjected to oxidative polymerization at room temperature for 24 hours with magnetic stirring at 800 rpm and a dissolved oxygen concentration of 8 ppm to obtain a polydopamine solution. The polydopamine solution was mixed with polyvinyl alcohol, wherein the volume ratio of polydopamine solution to 8% polyvinyl alcohol was 3:1. The fiber structure was prepared by electrospinning. The electrospinning parameters were set as follows: voltage 20 kV, receiving distance 15 cm, flow rate 0.5 mL / h, ambient humidity 35%, and vacuum drying at 60℃ for 12 hours to obtain a polydopamine nanofiber network, i.e., an inner layer with a thickness of 0.5 mm.

[0046] S1.2 The molten short-chain alkane paraffin wax was mixed with a composite emulsifier of Span 80 / Tween 80 (mass ratio 1:1) at a mass ratio of 1:3. The mixture was homogenized at 15000 rpm for 10 min to form a nano-paraffin emulsion with a particle size of 50 nm. Spider silk protein was dissolved in a choline chloride / urea solvent and stirred at 60 °C for 6 h. The molar ratio of choline chloride / urea solvent was 1:2 to obtain a 12% (w / v) spider silk protein solution. The nano-paraffin emulsion was then added, with the mass ratio of short-chain alkane paraffin wax to spider silk protein being 1:4.5. The mixture was ultrasonically emulsified for 30 min to obtain an intermediate layer solution.

[0047] S1.3. The intermediate layer solution was coated onto the inner layer surface using the dip-spray method. The dip speed was 5 mm / s and the spin coating parameters were 2000 rpm × 30 s. Then, it was kept in an oven at 45℃ for 2 h, then transferred to an environment at 25℃ for 12 h, and then 0.5% dopamine hydrochloride was sprayed and oxidized for 12 h to obtain an inner layer-intermediate layer composite with a thickness of 0.8 mm.

[0048] S1.4. Spider silk protein was dissolved in choline chloride / urea solvent to obtain a 12wt% spider silk protein solution. 3wt% polydopamine solution was added and mixed and stirred for 3-4 hours, where the spider silk protein:polydopamine = 3.8:1 (w / w). Then, 60wt% NaCl (particle size 100μm) was added and ultrasonically dispersed for 30 minutes. The mixture was then shaped by cryogenic casting. The program was set as follows: pre-freezing: rapid freezing with liquid nitrogen at -80℃ for 4 hours; primary drying: holding at -50℃ and 10Pa for 24 hours; analytical drying: holding at 25℃ and 1Pa for 6 hours to obtain a porous block. Finally, the porous block was placed into a mold and held under 5MPa pressure for 30 minutes to fix the shape. It was then immersed in 0.5wt% genipin for crosslinking for 4 hours and washed with phosphate buffer until the pH reached 7.4 to obtain a spider silk protein-polydopamine macroporous framework structure, i.e., an outer layer with a thickness of 1.3mm.

[0049] S1.5. The outer layer is immersed in a solution of 0.5% dopamine hydrochloride at pH 8.5 for oxidative polymerization for 12 hours. It is then placed in a hot press and subjected to pressure setting according to a gradient program: first stage: 35℃, 0.5MPa, 2 hours; second stage: 25℃, 1MPa, 2 hours; third stage: 10℃, 2MPa, 2 hours. This process allows the outer layer to bond with the inner-middle layer complex, resulting in a composite structure. Finally, the composite structure is immersed in a 1.0% genipin solution for crosslinking for 6 hours, then washed and dried to obtain the water purification agent.

[0050] Example 4: A water purification agent based on the principle of biomimetic adsorption and its preparation process, comprising the following steps:

[0051] S1.1. Dopamine hydrochloride was dissolved in Tris-HCl buffer at pH 8.5 to obtain a 15wt% dopamine hydrochloride solution. The solution was then subjected to oxidative polymerization at room temperature for 24 hours with magnetic stirring at 800 rpm and a dissolved oxygen concentration of 8 ppm to obtain a polydopamine solution. The polydopamine solution was mixed with polyvinyl alcohol, wherein the volume ratio of polydopamine solution to 8% polyvinyl alcohol was 3:1. The fiber structure was prepared by electrospinning. The electrospinning parameters were set as follows: voltage 20 kV, receiving distance 15 cm, flow rate 0.5 mL / h, ambient humidity 35%, and vacuum drying at 60℃ for 12 hours to obtain a polydopamine nanofiber network, i.e., an inner layer with a thickness of 0.5 mm.

[0052] S1.2. Molten short-chain alkane paraffin wax is mixed with a composite emulsifier of Span 80 / Tween 80 (mass ratio 1:1) at a mass ratio of 1:3. The mixture is homogenized at 15000 rpm for 10 min to form a nano-paraffin emulsion with a particle size of 50 nm. Spider silk protein is dissolved in choline chloride / urea solvent and stirred at 60 °C for 6 h. The molar ratio of choline chloride / urea solvent is 1:2 to obtain a 12% (w / v) spider silk protein solution. The nano-paraffin emulsion is then added, with the mass ratio of short-chain alkane paraffin wax to spider silk protein being 1:3.8. The mixture is ultrasonically emulsified for 30 min to obtain an intermediate layer solution.

[0053] S1.3. The intermediate layer solution was coated onto the inner layer surface using the dip-spray method. The dip speed was 5 mm / s and the spin coating parameters were 2000 rpm × 30 s. Then, it was kept in an oven at 45℃ for 2 h, then transferred to an environment at 25℃ for 12 h, and then 0.5% dopamine hydrochloride was sprayed and oxidized for 12 h to obtain an inner layer-intermediate layer composite with a thickness of 0.8 mm.

[0054] S1.4. Spider silk protein was dissolved in choline chloride / urea solvent to obtain a 12wt% spider silk protein solution. 3wt% polydopamine solution was added and mixed and stirred for 3-4 hours, where the ratio of spider silk protein to polydopamine was 4.3:1 (w / w). Then, 60wt% NaCl (particle size 100μm) was added and ultrasonically dispersed for 30 minutes. The mixture was then shaped by cryogenic casting. The program was set as follows: pre-freezing: rapid freezing with liquid nitrogen at -80℃ for 4 hours; primary drying: holding at -50℃ and 10Pa for 24 hours; and analytical drying: holding at 25℃ and 1Pa for 6 hours to obtain a porous block. Finally, the porous block was placed into a mold and held under 5MPa pressure for 30 minutes to solidify. It was then immersed in 0.5wt% genipin for crosslinking for 4 hours and washed with phosphate buffer until the pH reached 7.4 to obtain a spider silk protein-polydopamine macroporous framework structure, i.e., an outer layer with a thickness of 1.3mm.

[0055] S1.5. The outer layer is immersed in a solution of 0.5% dopamine hydrochloride at pH 8.5 for oxidative polymerization for 12 hours. It is then placed in a hot press and subjected to pressure setting according to a gradient program: first stage: 35℃, 0.5MPa, 2 hours; second stage: 25℃, 1MPa, 2 hours; third stage: 10℃, 2MPa, 2 hours. This process allows the outer layer to bond with the inner-middle layer complex, resulting in a composite structure. Finally, the composite structure is immersed in a 1.0% genipin solution for crosslinking for 6 hours, then washed and dried to obtain the water purification agent.

[0056] Example 5: A water purification agent based on the principle of biomimetic adsorption and its preparation process, comprising the following steps:

[0057] S1.1. Dopamine hydrochloride was dissolved in Tris-HCl buffer at pH 8.5 to obtain a 15wt% dopamine hydrochloride solution. The solution was then subjected to oxidative polymerization at room temperature for 24 hours with magnetic stirring at 800 rpm and a dissolved oxygen concentration of 8 ppm to obtain a polydopamine solution. The polydopamine solution was mixed with polyvinyl alcohol, wherein the volume ratio of polydopamine solution to 8% polyvinyl alcohol was 3:1. The fiber structure was prepared by electrospinning. The electrospinning parameters were set as follows: voltage 20 kV, receiving distance 15 cm, flow rate 0.5 mL / h, ambient humidity 35%, and vacuum drying at 60℃ for 12 hours to obtain a polydopamine nanofiber network, i.e., an inner layer with a thickness of 0.5 mm.

[0058] S1.2. Molten short-chain alkane paraffin wax is mixed with a composite emulsifier of Span 80 / Tween 80 (mass ratio 1:1) at a mass ratio of 1:3. The mixture is homogenized at 15000 rpm for 10 min to form a nano-paraffin emulsion with a particle size of 50 nm. Spider silk protein is dissolved in choline chloride / urea solvent and stirred at 60 °C for 6 h. The molar ratio of choline chloride / urea solvent is 1:2 to obtain a 12% (w / v) spider silk protein solution. The nano-paraffin emulsion is then added, with the mass ratio of short-chain alkane paraffin wax to spider silk protein being 1:3.8. The mixture is ultrasonically emulsified for 30 min to obtain an intermediate layer solution.

[0059] S1.3. The intermediate layer solution was coated onto the inner layer surface using the dip-spray method. The dip speed was 5 mm / s and the spin coating parameters were 2000 rpm × 30 s. Then, it was kept in an oven at 45℃ for 2 h, then transferred to an environment at 25℃ for 12 h, and then 0.5% dopamine hydrochloride was sprayed and oxidized for 12 h to obtain an inner layer-intermediate layer composite with a thickness of 0.8 mm.

[0060] S1.4. Spider silk protein was dissolved in choline chloride / urea solvent to obtain a 12wt% spider silk protein solution. 3wt% polydopamine solution was added and mixed and stirred for 3-4 hours, where the ratio of spider silk protein to polydopamine was 4.5:1 (w / w). Then, 60wt% NaCl (particle size 100μm) was added and ultrasonically dispersed for 30 minutes. The mixture was then shaped by cryogenic casting. The program was set as follows: pre-freezing: rapid freezing with liquid nitrogen at -80℃ for 4 hours; primary drying: holding at -50℃ and 10Pa for 24 hours; and analytical drying: holding at 25℃ and 1Pa for 6 hours to obtain a porous block. Finally, the porous block was placed into a mold and held under 5MPa pressure for 30 minutes to fix the shape. It was then immersed in 0.5wt% genipin for crosslinking for 4 hours and washed with phosphate buffer until the pH reached 7.4 to obtain a spider silk protein-polydopamine macroporous framework structure, i.e., an outer layer with a thickness of 1.3mm.

[0061] S1.5. The outer layer is immersed in a solution of 0.5% dopamine hydrochloride at pH 8.5 for oxidative polymerization for 12 hours. It is then placed in a hot press and subjected to pressure setting according to a gradient program: first stage: 35℃, 0.5MPa, 2 hours; second stage: 25℃, 1MPa, 2 hours; third stage: 10℃, 2MPa, 2 hours. This process allows the outer layer to bond with the inner-middle layer complex, resulting in a composite structure. Finally, the composite structure is immersed in a 1.0% genipin solution for crosslinking for 6 hours, then washed and dried to obtain the water purification agent.

[0062] Comparative Example 1: The method of Example 4 was used, with the intermediate layer consisting only of spider silk protein and without compounding short-chain alkane paraffin.

[0063] Comparative Example 2: The method of Example 4 was used, with the outer layer consisting only of spider silk protein and without polydopamine.

[0064] Comparative Example 3: Using the method of Example 4, only the inner layer of polydopamine nanofiber network was prepared, without combining the middle and outer layers.

[0065] This invention discloses a water purification agent based on the biomimetic adsorption principle, prepared using a multi-layer composite framework. The performance indicators and testing standards for this water purification agent are as follows:

[0066] Prepare 100mg / LCu 2+ Weigh 0.1g of water purification agent and add it to 50mL of solution. Incubate at 25℃ with shaking (150rpm) for 24 hours until adsorption equilibrium is reached. Centrifuge and collect the supernatant. Determine the residual Cu. 2+ Concentration, calculate adsorption capacity, q e =(C0-C e V / m, initial concentration of C0, C e Equilibrium concentration, V solution volume, m adsorbent mass; prepare 100 mg / L colloidal silica (pH = 7), weigh 0.1 g water purification agent and add to 50 mL solution, constant temperature shaking (150 rpm) at 25℃ for 24 h until adsorption equilibrium is reached, centrifuge (10000 rpm, 10 min) to separate the adsorbent, take the supernatant to determine the residual colloid concentration, calculate the adsorption capacity, which is used to characterize the adsorption capacity of the adsorbent;

[0067] The water purification agent was loaded into a dynamic filter column (flow rate 10 mL / min), and simulated wastewater containing kaolin (1 g / L) was introduced. The retention rate after 12 hours of operation was tested with a turbidity meter. Retention rate (%) = effluent turbidity / influent turbidity × 100%.

[0068] 100 water purification agent granules were placed in simulated dynamic water flow (flow velocity 1m / s, containing 10% suspended solids) for 10 hours for circulation and impact. The crushed particles were screened (particle size <0.5mm), and the breakage rate was calculated: Breakage rate (%) = mass of crushed particles / initial total mass × 100%, which is used to characterize the mechanical strength of the water purification agent.

[0069] Simulated wastewater containing typical pollutants (0.1 g / L microplastic particles, 50 mg / L humic acid, and 1 mg / L nano-clay) was prepared and filtered through a constant pressure filtration system (0.1 MPa) at 25°C. The pure water flux was recorded as the initial flux determination (J0). The temperature was raised to 45°C, and the pollutant solution was injected. The flux J5 was tested after the 5th cycle. The flux decay trend was compared, and the flux decay rate was calculated as (J0-J5) / J0×100%. The anti-clogging ability of the water purification agent was then calculated.

[0070] The water purification agents prepared in Examples 1-5 and Comparative Examples 1-3 were tested according to the above standards, and the data obtained are shown in Table 1:

[0071] Table 1 Performance data of Examples 1-5 and Comparative Examples 1-3

[0072]

[0073] The above data fully demonstrates that, compared to Comparative Examples 1-3, Examples 1-5 clearly show the effect of the multi-layer composite structure on the mechanical strength, adsorption capacity, and anti-clogging ability of the water purification agent.

[0074] Because the water purification agent prepared using the multi-layer composite framework of this invention has improved mechanical strength, adsorption capacity, and anti-clogging ability, the performance of the water purification agent is effectively enhanced through the multi-layer composite framework, as detailed below:

[0075] As can be seen from Examples 1-3, the mechanical strength and anti-clogging ability of the water purifier change continuously with the change in the mass ratio of short-chain alkane paraffin to spider silk protein in the intermediate layer. Since spider silk protein has good rigidity, it is the main load-bearing component. When the proportion of short-chain alkane paraffin decreases, the spider silk protein network becomes denser and the hydrogen bonding effect is enhanced, thus increasing the mechanical strength of the water purifier. However, the dynamic adjustment pore size of short-chain alkane paraffin also decreases due to the reduction in its content, resulting in a decrease in anti-clogging ability.

[0076] As can be seen from Examples 3-5, with the continuous change of the mass ratio of outer spider silk protein to polydopamine, the mechanical strength, adsorption capacity, and anti-clogging ability of the water purifier continuously change. The outer spider silk protein provides a rigid framework, while the flexible segments of polydopamine buffer stress through hydrogen bonds. When the proportion of polydopamine increases, the rigid network is diluted, and the mechanical strength decreases somewhat. However, the density of phenolic hydroxyl and amino groups in polydopamine increases, thus improving the performance of Cu... 2 The chelating ability of w is enhanced, and the adsorption capacity is increased.

[0077] Based on the above test experiments, it can be seen that the water purification agent based on the biomimetic adsorption principle prepared according to Example 4 has the best performance. Therefore, Example 4 is regarded as the best example.

[0078] A comparison of Example 4 with Comparative Examples 1-3 shows that:

[0079] Comparative Example 1: The intermediate layer is composed only of spider silk protein and does not contain compound short-chain alkane paraffin. The less effective the water purifier is at preventing clogging, the less effective it is at dynamically adjusting pore size. Once pollutants are deposited, they are difficult to remove and cannot be physically ejected, resulting in poor anti-clogging ability.

[0080] Comparative Example 2: The outer layer is composed only of spider silk protein and does not contain polydopamine. The worse the mechanical strength and adsorption capacity of the water purifier, the more likely it is to collapse under the impact of dynamic water flow because the brittleness of spider silk protein is not compensated by the flexible segments of polydopamine. This leads to a decrease in mechanical strength and a lack of chelating sites for polydopamine, resulting in a decrease in the adsorption capacity of the water purifier.

[0081] Comparative Example 3 only prepared the inner layer of polydopamine nanofiber network without combining the middle and outer layers. The mechanical strength, adsorption capacity and anti-clogging ability of the water purification agent were worse. Due to the lack of a hierarchical adsorption structure, it was impossible to distinguish molecular size, resulting in non-specific adsorption and thus reducing the adsorption effect. In addition, the single-layer polydopamine nanofiber network also lacked a rigid structure and the ability to adjust the pore size, which led to poor mechanical strength, adsorption capacity and anti-clogging ability of the water purification agent.

[0082] In summary, a gradient capture of pollutants ranging from micron to nanometer scale is achieved through a spider silk protein-polydopamine macroporous framework structure, a spider silk protein-paraffin composite layer, and a polydopamine nanofiber network. Furthermore, by employing a biomimetic robust framework design, a dynamic pore size control mechanism, a hierarchical adsorption synergistic effect, and biomimetic adhesion enhancement technology, the limitations of traditional adsorbents are overcome, making it suitable for high-efficiency purification needs under complex water quality conditions.

[0083] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A preparation process for a water purification agent based on the principle of biomimetic adsorption, characterized in that: The water purification agent is composed of an inner layer, a middle layer, and an outer layer composite structure; The inner layer is a polydopamine nanofiber network; The middle layer is a spider silk protein-paraffin composite layer; The outer layer is a spider silk protein-polydopamine macroporous framework structure; The preparation process of water purification agents includes the following steps: S1.

1. Dissolve dopamine hydrochloride in Tris-HCl buffer solution with pH 8.5-9 to obtain a 10-15 wt% dopamine hydrochloride solution. Perform oxidative polymerization at room temperature for 24-48 h with magnetic stirring at 800-1000 rpm and dissolved oxygen concentration of 8-10 ppm to obtain a polydopamine solution. Mix the polydopamine solution with polyvinyl alcohol and prepare fiber structure by electrospinning. Set the electrospinning parameters and vacuum dry at 60-80℃ for 10-12 h to obtain a polydopamine nanofiber network, i.e., the inner layer. S1.

2. Mix molten short-chain alkane paraffin with a composite emulsifier. Mix short-chain alkane paraffin with spider silk protein at a mass ratio of 1:3.2-4.

5. Homogenize at 15000-16000 rpm for 5-10 min to form a nano-paraffin emulsion with a particle size of 50-200 nm. Dissolve spider silk protein in choline chloride / urea solvent, wherein the molar ratio of choline chloride / urea solvent is 1:

2. Stir at 55-60℃ for 5-6 h to obtain a spider silk protein solution with a w / v of 12-14%. Add the nano-paraffin emulsion and ultrasonically emulsify for 20-30 min to obtain an intermediate layer solution. S1.

3. The intermediate layer solution is coated onto the inner layer surface using the dip-spin coating method, and then kept in an oven at 45-50℃ for 1.5-2 hours, then transferred to an environment at 20-25℃ for 8-12 hours, and then sprayed with a 0.5-0.8% dopamine hydrochloride solution. The mixture is then oxidatively polymerized for 12-16 hours to obtain the inner layer-intermediate layer composite. S1.4 Dissolve spider silk protein in choline chloride / urea solvent to obtain a 10-12 wt% spider silk protein solution. Add 2-4 wt% polydopamine solution, with a spider silk protein:polydopamine ratio of 3.8-4.5:1 w / w. Mix and stir for 3-4 h. Then add NaCl and ultrasonically disperse for 20-30 min. Shape by freeze casting, set the program, and obtain a porous block. Finally, put the porous block into a mold, hold it under 3-5 MPa pressure for 30 min to fix it, and soak it in 0.5-1 wt% genipin for crosslinking for 4-6 h. Wash with phosphate buffer until the pH is 7.2-7.4 to obtain the spider silk protein-polydopamine macroporous framework structure, i.e., the outer layer. S1.

5. Immerse the outer layer in a solution of dopamine hydrochloride at pH 8.5-9 and a mass fraction of 0.5-0.8% for oxidative polymerization for 12-16 hours. Place the solution in a hot press and pressurize it according to a gradient program to bond the outer layer with the inner-middle layer complex to obtain a composite structure. Finally, immerse the composite structure in a 1.0-1.2% genipin solution for crosslinking for 6-8 hours, clean and dry it to obtain a water purification agent. The spider silk protein has a 250-350 kDa content, and the short-chain alkane paraffin is a C18-C22 mixture with a melting point of 35-45℃. The spider silk protein is a semi-crystalline molecular spring structure formed by β-sheets composed of alanine and A-helices rich in proline, as well as their tightly packed secondary structures.

2. The preparation process of the water purification agent based on the biomimetic adsorption principle according to claim 1, characterized in that: In step S1.1, the volume ratio of polydopamine solution to polyvinyl alcohol is 2-3:1, and the mass fraction of polyvinyl alcohol is 8-12%. The electrospinning parameters are: voltage 18-25kV, receiving distance 15-20cm, flow rate 0.5-0.8mL / h, and ambient humidity 30-40%.

3. The preparation process of the water purification agent based on the biomimetic adsorption principle according to claim 1, characterized in that: In S1.2, the mass ratio of molten short-chain alkane paraffin to composite emulsifier is 1:3 to 5, and the composite emulsifier is obtained by mixing Span 80 and Tween 80 in a mass ratio of 1 to 2:

1.

4. The preparation process of the water purification agent based on the biomimetic adsorption principle according to claim 1, characterized in that: In S1.3, the immersion speed is set to 3-5 mm / s, and the spin coating parameters are 2000 rpm × 30 s.

5. The preparation process of the water purification agent based on the biomimetic adsorption principle according to claim 1, characterized in that: In S1.4, the NaCl has a particle size of 100-150 μm and an addition amount of 60-65 wt%.

6. The preparation process of the water purification agent based on the biomimetic adsorption principle according to claim 1, characterized in that: In S1.4, the specific parameters of the program are set as follows: pre-freezing: rapid freezing with liquid nitrogen at -80℃ for 4 hours, primary drying: maintaining at -50℃ and 10Pa for 24 hours, and desorption drying: maintaining at 25℃ and 1Pa for 6 hours.

7. The preparation process of the water purification agent based on the biomimetic adsorption principle according to claim 1, characterized in that: In S1.5, the specific parameters for gradient program pressure setting are as follows: First stage: 35℃, 0.5MPa, 2h; Second stage: 25℃, 1MPa, 2h; Third stage: 10℃, 2MPa, 2h.

8. The preparation process of the water purification agent based on the biomimetic adsorption principle according to claim 1, characterized in that: The inner layer has a thickness of 0.3-0.5 mm, the middle layer has a thickness of 0.8-1.0 mm, and the outer layer has a thickness of 1.2-1.5 mm.

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