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

Abstract

The invention relates to the technical field of water treatment, in particular to a water purifying agent based on a bionic adsorption principle and a preparation process thereof, and the water purifying agent is obtained by a composite framework of an inner layer, a middle layer and an outer layer; the inner layer is a polydopamine nanofiber network; the middle layer is a spider silk protein-paraffin composite layer; the outer layer is of a spider silk protein-polydopamine macroporous skeleton structure; a multi-layer composite structure is constructed, a spider silk protein-polydopamine macroporous skeleton is used as an outer layer, a spider silk protein-paraffin composite layer is used as a middle layer, and a polydopamine nanofiber network is used as an inner layer, so that gradient capture of micro-scale to nano-scale pollutants is realized; and through bionic tough skeleton design, a dynamic aperture regulation and control mechanism, a graded adsorption synergistic effect and a bionic adhesion enhancement technology, the limitation of a traditional adsorbent is broken through.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and specifically, to a water purifying agent based on the principle of bionic adsorption and its preparation process. Background Art

[0002] With the acceleration of the industrialization and urbanization processes, the problem of water body pollution has become increasingly serious. The main pollutants include heavy metal ions (such as lead, cadmium, mercury), organic pollutants (such as pesticides, dyes), microorganisms (such as bacteria, viruses), and microplastics, etc. Traditional water purification technologies (such as coagulation, sedimentation, filtration, disinfection) have problems such as 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 purifying agents. The principle of bionic adsorption mimics the adsorption process in living organisms and improves the adsorption efficiency by designing materials with specific microstructures and functional groups.

[0003] However, under dynamic filtration conditions, the framework of existing adsorbents is prone to particle breakage due to insufficient mechanical strength, increasing the risk of system blockage. At the same time, in dynamic filtration or long-term operation of conventional adsorbents designed based on bionic structures, pollutants are likely to deposit in the pores of the water purifying agent, resulting in gradual blockage of the pores. In view of this, we propose a water purifying agent based on the principle of bionic adsorption and its preparation process. Summary of the Invention

[0004] The purpose of the present invention is to provide a water purifying agent based on the principle of bionic adsorption and its preparation process to solve the problems raised in the above background art.

[0005] To achieve the above purpose, the present invention provides a water purifying agent based on the principle of bionic adsorption, which includes the following components: the water purifying agent is obtained by compounding an inner layer, a middle layer, and an outer layer;

[0006] Among them, the inner layer is a polydopamine nanofiber network;

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

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

[0009] Through the multi-layer composite structure, the adsorption efficiency is effectively improved. The specific structure of the water purifying agent is as follows: the outer layer is a macroporous framework constructed by silk fibroin / polydopamine to pre-filter suspended solids, the middle layer is a silk fibroin - paraffin (C18 - C22 short-chain alkane paraffin) composite layer for intercepting colloidal pollutants, and the inner layer is a polydopamine nanofiber network for chelating heavy metal ions and small molecule organic substances;

[0010] Among them, spider silk protein is a very special fibrous protein. The β-sheets composed of alanine, the A-helices rich in proline, and their closely packed secondary structures make it a molecular spring structure in a semi-crystalline state, which determines its high strength and great toughness. Therefore, spider silk protein is used as the adsorbent skeleton structure. However, high strength alone is not enough, and a certain degree of toughness is also required to maintain the integrity of the adsorbent particle structure. Therefore, polydopamine is added to endow flexibility to keep the particles intact in high-speed water flow; the surface of polydopamine is rich in phenolic hydroxyl groups and amino groups, which can efficiently capture heavy metal ions through chelation, can adsorb heavy metals in water to achieve purification; in addition, it can act as an "adhesive" to composite the structure together;

[0011] Paraffin is a phase change material, and its volume will change during the phase change process. When it melts and expands, it squeezes the protein network, resulting in a reduction in pore size. When it solidifies and shrinks, it releases stress and the pore size recovers. Therefore, it can act as a "micro-valve" to slightly adjust the pore size. Although the pore size change rate is small, when the pollutants are adsorbed and blocked, paraffin solidifies and shrinks to release stress, and the pore size recovers to actively "eject" the adsorbed pollutants, reducing pore blockage and improving the anti-blocking ability;

[0012] By constructing the above multi-layer composite structure and utilizing the synergistic effect between layers, it is possible to adsorb pollutants in a hierarchical manner according to environmental temperature changes and different water environments, improving the adsorption efficiency.

[0013] On the other hand, the present invention provides a preparation process of a water purifying agent based on the bionic adsorption principle for a water purifying agent based on the bionic adsorption principle described in any one of the above, including the following steps:

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

[0015] S1.2. Mix molten short-chain alkane paraffin with a composite emulsifier and homogenize at a high speed of 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 a choline chloride / urea solvent, where the molar ratio of the choline chloride / urea solvent is 1:2, stir at 55 - 60 °C for 5 - 6 h to obtain a 12 - 14% (w / v) spider silk protein solution, and add the nano-paraffin emulsion and ultrasonically emulsify for 20 - 30 min to obtain an intermediate layer solution;

[0016] S1.3. Apply the intermediate layer solution onto the inner layer surface by the dip-coating and spin-coating method, then keep it in an oven at 45 - 50 °C for 1.5 - 2 h, transfer it to an environment at 20 - 25 °C and keep it for 8 - 12 h, then spray a dopamine hydrochloride solution with a mass fraction of 0.5 - 0.8%, and perform oxidative polymerization for 12 - 16 h to obtain the inner layer-intermediate layer composite;

[0017] S1.4. Dissolve silk fibroin in a choline chloride / urea solvent to obtain a 10 - 12 wt% silk fibroin solution, add a 2 - 4 wt% polydopamine solution, mix and stir for 3 - 4 h, then add NaCl and ultrasonically disperse for 20 - 30 min, form it by the freeze-casting method, set the program to obtain a porous block, finally put the porous block into a mold, keep the pressure at 3 - 5 MPa for 30 min for shaping, and soak it in 0.5 - 1 wt% genipin for cross-linking for 4 - 6 h, and rinse it with phosphate buffer solution until the pH is 7.2 - 7.4 to obtain the silk fibroin-polydopamine macroporous framework structure, that is, the outer layer;

[0018] Among them, at a flow rate of 10 mL / min, use 100 mL of PBS (pH 7.4) to continuously rinse the silk fibroin-polydopamine macroporous framework structure for 30 - 45 min, repeat 6 - 8 times, and change fresh PBS each time to remove the residual genipin, collect the final rinse solution, and detect the genipin residue by high performance liquid chromatography (HPLC) to ensure ≤0.1 ppm;

[0019] S1.5. Immerse the outer layer in a dopamine hydrochloride solution with a pH of 8.5 - 9 and a mass fraction of 0.5 - 0.8% for oxidative polymerization for 12 - 16 h, place it in a hot press, and press and shape it according to a gradient program to make the outer layer combine with the inner layer-intermediate layer composite to obtain a composite structure. Finally, immerse the composite structure in a 1.0 - 1.2% genipin solution for cross-linking for 6 - 8 h, wash and dry it to obtain the water purifying agent.

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

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

[0022] Preferably, in S1.2, the mass ratio of the 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 in a mass ratio of 1 to 2:1, and the mass ratio of the short-chain alkane paraffin to the spider silk protein is 1:3.2 to 4.5.

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

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

[0025] Preferably, in S1.4, the specific parameters of the program are: pre-freezing: rapid freezing in liquid nitrogen at -80°C for 4 h, primary drying: maintaining at -50°C and 10 Pa for 24 h, and analytical drying: maintaining at 25°C and 1 Pa for 6 h.

[0026] Preferably, in S1.5, the specific parameters of the gradient program pressure shaping are: the first stage: 35°C, 0.5 MPa, 2 h, the second stage: 25°C, 1 MPa, 2 h, and the third stage: 10°C, 2 MPa, 2 h.

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

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

[0029] In the water purifying agent based on the bionic adsorption principle and its preparation process, a composite structure of spider silk protein and polydopamine is adopted, combining the high strength of spider silk protein and the flexible adhesion of polydopamine, so that the water purifying agent maintains structural integrity under the impact of dynamic water flow. By utilizing the phase change characteristics of short-chain alkane paraffin, the self-adaptive adjustment of pore size is realized. When the pollutants are adsorbed to saturation, the blockage is actively "ejected" to improve the anti-blocking ability. Through the macroporous framework structure of spider silk protein-polydopamine, the spider silk protein-paraffin composite layer and the polydopamine nanofiber network, the gradient capture of pollutants from the micron scale to the nanoscale is realized. And polydopamine, as a "molecular adhesive", chelates heavy metal ions synchronously to achieve the double improvement of structural strengthening and functionalization. Furthermore, in terms of the mechanical strength, adsorption capacity and anti-blocking ability of the water purifying agent, through the bionic tough framework design, dynamic pore size regulation mechanism, hierarchical adsorption synergistic effect and bionic adhesion enhancement technology, the limitations of traditional adsorbents are broken through, meeting the high-efficiency purification requirements under complex water quality conditions. Specific embodiments

[0030] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] A water purifying agent based on the principle of bionic adsorption of the present invention is obtained by compounding an inner layer, an intermediate layer and an outer layer; the inner layer is a polydopamine nanofiber network; the intermediate layer is a silk fibroin - paraffin composite layer; the outer layer is a silk fibroin - polydopamine macroporous framework structure; the silk fibroin is 250 - 350 kDa, and the short - chain alkane paraffin is a mixture of C18 - C22 with a melting point of 35 - 45 °C;

[0032] Example 1: A water purifying agent based on the principle of bionic adsorption and its preparation process, including the following steps:

[0033] S1.1. Dissolve dopamine hydrochloride in Tris - HCl buffer with a pH of 8.5 to obtain a 15 wt% dopamine hydrochloride solution. Under magnetic stirring at 800 rpm, oxidatively polymerize at room temperature for 24 h with a dissolved oxygen concentration of 8 ppm to obtain a polydopamine solution. Mix the polydopamine solution with polyvinyl alcohol, where the volume ratio of the polydopamine solution to 8% (by mass) polyvinyl alcohol is 3:1. Prepare a fiber structure by electrospinning. Set the electrospinning parameters: voltage 20 kV, receiving distance 15 cm, flow rate 0.5 mL / h, environmental humidity 35%, and vacuum dry at 60 °C for 12 h to obtain a polydopamine nanofiber network, that is, the inner layer with a thickness of 0.5 mm.

[0034] S1.2. Mix molten short - chain alkane paraffin with a Span 80 / Tween 80 (mass ratio 1:1) composite emulsifier with a mass ratio of 1:3, and homogenize at 15000 rpm for 10 min to form a nano - paraffin emulsion with a particle size of 50 nm. Dissolve silk fibroin in a choline chloride / urea solvent, stir at 60 °C for 6 h, where the molar ratio of the choline chloride / urea solvent is 1:2, to obtain a 12% (w / v) silk fibroin solution, and add the nano - paraffin emulsion, where the mass ratio of the short - chain alkane paraffin to silk fibroin is 1:3.2, and ultrasonically emulsify for 30 min to obtain an intermediate layer solution.

[0035] S1.3. Coat the intermediate layer solution on the surface of the inner layer by the dip - spin coating method, with a dipping speed of 5 mm / s and spin - coating parameters of 2000 rpm × 30 s. Then keep it in an oven at 45 °C for 2 h, transfer it to an environment at 25 °C and keep it for 12 h, and then spray 0.5% dopamine hydrochloride for oxidative polymerization for 12 h to obtain an inner layer - intermediate layer composite with a thickness of 0.8 mm.

[0036] S1.4. Dissolve the spider silk protein in a choline chloride / urea solvent to obtain a 12 wt% spider silk protein solution. Add a 3 wt% polydopamine solution and mix and stir for 3 - 4 h, where the ratio of spider silk protein to polydopamine is 3.8:1 (w / w). Then add 60 wt% NaCl (particle size 100 μm) and ultrasonically disperse for 30 min. Form it by the freeze-casting method. Set the program: pre-freezing: rapid freezing in liquid nitrogen at -80 °C for 4 h, primary drying: maintain at -50 °C and 10 Pa for 24 h, secondary drying: maintain at 25 °C and 1 Pa for 6 h to obtain a porous block. Finally, put the porous block into a mold, keep the pressure at 5 MPa for 30 min for shaping, and soak it in 0.5 wt% genipin for crosslinking for 4 h, and rinse it with phosphate buffer solution until the pH is 7.4 to obtain a spider silk protein-polydopamine macroporous framework structure, that is, the 1.3 mm thick outer layer;

[0037] S1.5. Immerse the outer layer in a 0.5% by mass dopamine hydrochloride solution with a pH of 8.5 for oxidative polymerization for 12 h. Place it in a hot press and press and shape it according to a gradient program. The first stage: 35 °C, 0.5 MPa, 2 h, the second stage: 25 °C, 1 MPa, 2 h, the third stage: 10 °C, 2 MPa, 2 h to make the outer layer combine with the inner layer-middle layer composite to obtain a composite structure. Finally, immerse the composite structure in a 1.0% genipin solution for crosslinking for 6 h, wash and dry it to obtain the water purifier.

[0038] Example 2: A water purifier based on the principle of bionic adsorption and its preparation process, including the following steps:

[0039] S1.1. Dissolve dopamine hydrochloride in a Tris-HCl buffer solution with a pH of 8.5 to obtain a 15 wt% dopamine hydrochloride solution. Under magnetic stirring at 800 rpm, oxidatively polymerize at room temperature for 24 h, and the dissolved oxygen concentration is 8 ppm to obtain a polydopamine solution. Mix the polydopamine solution with polyvinyl alcohol. The volume ratio of the polydopamine solution to 8% by mass polyvinyl alcohol is 3:1. Prepare a fiber structure by electrospinning. Set the electrospinning parameters: voltage 20 kV, receiving distance 15 cm, flow rate 0.5 mL / h, environmental humidity 35%, and vacuum dry at 60 °C for 12 h to obtain a polydopamine nanofiber network, that is, the 0.5 mm thick inner layer;

[0040] S1.2. Mix the molten short-chain alkane paraffin with a composite emulsifier of Span 80 / Tween 80 (mass ratio 1:1) at a mass ratio of 1:3, and homogenize at a high speed of 15,000 rpm for 10 min to form a nano-paraffin emulsion with a particle size of 50 nm. Dissolve the spider silk protein in a choline chloride / urea solvent, and stir at 60 °C for 6 h, where the molar ratio of the choline chloride / urea solvent is 1:2, to obtain a 12% (w / v) spider silk protein solution. Then add the nano-paraffin emulsion, where the mass ratio of the short-chain alkane paraffin to the spider silk protein is 1:3.8, and perform ultrasonic emulsification for 30 min to obtain an intermediate layer solution;

[0041] S1.3. Coat the intermediate layer solution on the inner layer surface by the dip-coating and spin-coating method, with a dipping speed of 5 mm / s and spin-coating parameters of 2000 rpm × 30 s. Then keep it in an oven at 45 °C for 2 h, transfer it to an environment at 25 °C and keep it for 12 h, and then spray 0.5% dopamine hydrochloride for oxidative polymerization for 12 h to obtain an inner layer - intermediate layer composite with a thickness of 0.8 mm;

[0042] S1.4. Dissolve the spider silk protein in a choline chloride / urea solvent to obtain a 12 wt% spider silk protein solution, add a 3 wt% polydopamine solution, and mix and stir for 3 - 4 h, where the ratio of spider silk protein to polydopamine is 3.8:1 (w / w). Then add 60 wt% NaCl (particle size 100 μm) and perform ultrasonic dispersion for 30 min. Shape it by the freeze-casting method, set the program: pre-freezing: rapid freezing in liquid nitrogen at -80 °C for 4 h, primary drying: keep at -50 °C and 10 Pa for 24 h, secondary drying: keep at 25 °C and 1 Pa for 6 h to obtain a porous block. Finally, put the porous block into a mold, keep it under pressure at 5 MPa for 30 min for shaping, and soak it in 0.5 wt% genipin for crosslinking for 4 h, and rinse it with phosphate buffer solution until the pH is 7.4 to obtain a spider silk protein - polydopamine macroporous framework structure, that is, the outer layer with a thickness of 1.3 mm;

[0043] S1.5. Immerse the outer layer in a dopamine hydrochloride solution with a pH of 8.5 and a mass fraction of 0.5% for oxidative polymerization for 12 h, place it in a hot press, and press and shape it according to a gradient program: the first stage: 35 °C, 0.5 MPa, 2 h, the second stage: 25 °C, 1 MPa, 2 h, the third stage: 10 °C, 2 MPa, 2 h, to combine the outer layer with the inner layer - intermediate layer composite to obtain a composite structure. Finally, immerse the composite structure in a 1.0% genipin solution for crosslinking for 6 h, wash and dry it to obtain a water purifying agent.

[0044] Example 3: A water purifying agent based on the principle of bionic adsorption and its preparation process, including the following steps:

[0045] S1.1. Dissolve dopamine hydrochloride in Tris-HCl buffer with a pH of 8.5 to obtain a 15 wt% dopamine hydrochloride solution. Under magnetic stirring at 800 rpm, oxidatively polymerize at room temperature for 24 h with a dissolved oxygen concentration of 8 ppm to obtain a polydopamine solution. Mix the polydopamine solution with polyvinyl alcohol. Among them, the volume ratio of the polydopamine solution to 8% (mass fraction) polyvinyl alcohol is 3:1. Prepare a fibrous structure by electrospinning. Set the electrospinning parameters: voltage 20 kV, receiving distance 15 cm, flow rate 0.5 mL / h, environmental humidity 35%, and vacuum dry at 60 °C for 12 h to obtain a polydopamine nanofiber network, which is the inner layer with a thickness of 0.5 mm;

[0046] S1.2. Mix molten short-chain alkane paraffin with a composite emulsifier of Span 80 / Tween 80 (mass ratio 1:1) at a mass ratio of 1:3. Homogenize at high speed of 15000 rpm for 10 min to form a nano paraffin emulsion with a particle size of 50 nm. Dissolve silk fibroin in a choline chloride / urea solvent and stir at 60 °C for 6 h, where the molar ratio of the choline chloride / urea solvent is 1:2, to obtain a 12% (w / v) silk fibroin solution. Add the nano paraffin emulsion. Among them, the mass ratio of short-chain alkane paraffin to silk fibroin is 1:4.5. Ultrasonic emulsify for 30 min to obtain an intermediate layer solution;

[0047] S1.3. Coating the intermediate layer solution on the surface of the inner layer by the dip-coating and spin-coating method, with a dipping speed of 5 mm / s and spin-coating parameters of 2000 rpm × 30 s. Then keep it in an oven at 45 °C for 2 h, transfer it to an environment at 25 °C and keep it for 12 h, and then spray 0.5% dopamine hydrochloride for oxidative polymerization for 12 h to obtain an inner layer - intermediate layer composite with a thickness of 0.8 mm;

[0048] S1.4. Dissolve silk fibroin in a choline chloride / urea solvent to obtain a 12 wt% silk fibroin solution. Add a 3 wt% polydopamine solution and mix and stir for 3 - 4 h. Among them, silk fibroin: polydopamine = 3.8:1 (w / w). Then add 60 wt% NaCl (particle size 100 μm) and ultrasonic disperse for 30 min. Mold it by the freeze-casting method. Set the program: pre-freezing: rapid freezing in liquid nitrogen at -80 °C for 4 h, primary drying: keep at -50 °C and 10 Pa for 24 h, analytical drying: keep at 25 °C and 1 Pa for 6 h to obtain a porous block. Finally, put the porous block into a mold and keep it under pressure of 5 MPa for 30 min for shaping, and soak it in 0.5 wt% genipin for crosslinking for 4 h, and rinse it with phosphate buffer solution until the pH is 7.4 to obtain a silk fibroin - polydopamine macroporous framework structure, which is the outer layer with a thickness of 1.3 mm;

[0049] S1.5. Immerse the outer layer in a dopamine hydrochloride solution with a pH of 8.5 and a mass fraction of 0.5% for 12 h of oxidative polymerization. Place it in a hot press and apply pressure for shaping according to a gradient program. The first stage: 35°C, 0.5 MPa, 2 h; the second stage: 25°C, 1 MPa, 2 h; the third stage: 10°C, 2 MPa, 2 h, to bond the outer layer with the inner layer - intermediate layer composite to obtain a composite structure. Finally, immerse the composite structure in a 1.0% genipin solution for crosslinking for 6 h, wash and dry to obtain the water purifier.

[0050] Example 4: A water purifier based on the principle of bionic adsorption and its preparation process, including the following steps:

[0051] S1.1. Dissolve dopamine hydrochloride in a Tris-HCl buffer solution with a pH of 8.5 to obtain a 15 wt% dopamine hydrochloride solution. Under magnetic stirring at 800 rpm, perform oxidative polymerization at room temperature for 24 h with a dissolved oxygen concentration of 8 ppm to obtain a polydopamine solution. Mix the polydopamine solution with polyvinyl alcohol, where the volume ratio of the polydopamine solution to polyvinyl alcohol with a mass fraction of 8% is 3:1. Prepare a fibrous structure by electrospinning. Set the electrospinning parameters: voltage 20 kV, receiving distance 15 cm, flow rate 0.5 mL / h, environmental humidity 35%, and vacuum dry at 60°C for 12 h to obtain a polydopamine nanofiber network, which is the inner layer with a thickness of 0.5 mm.

[0052] S1.2. Mix molten short-chain alkane paraffin with a composite emulsifier of Span 80 / Tween 80 (mass ratio 1:1) at a mass ratio of 1:3 and homogenize at a high speed of 15000 rpm for 10 min to form a nano paraffin emulsion with a particle size of 50 nm. Dissolve silk fibroin in a choline chloride / urea solvent and stir at 60°C for 6 h, where the molar ratio of the choline chloride / urea solvent is 1:2, to obtain a 12% (w / v) silk fibroin solution, and add the nano paraffin emulsion, where the mass ratio of the short-chain alkane paraffin to silk fibroin is 1:3.8, and perform ultrasonic emulsification for 30 min to obtain the intermediate layer solution.

[0053] S1.3. Use the dip-coating - spin-coating method to coat the intermediate layer solution on the surface of the inner layer at an immersion speed of 5 mm / s and spin-coating parameters of 2000 rpm × 30 s. Then keep it in an oven at 45°C for 2 h, transfer it to an environment at 25°C and keep it for 12 h, and then spray 0.5% dopamine hydrochloride for 12 h of oxidative polymerization to obtain an inner layer - intermediate layer composite with a thickness of 0.8 mm.

[0054] S1.4. Dissolve the spider silk protein in the choline chloride / urea solvent to obtain a 12 wt% spider silk protein solution. Add a 3 wt% polydopamine solution and mix and stir for 3 - 4 h, where the ratio of spider silk protein to polydopamine is 4.3:1 (w / w). Then add 60 wt% NaCl (particle size 100 μm) and ultrasonically disperse for 30 min. Form it by the freeze-casting method. Set the program: pre-freezing: rapidly freeze in liquid nitrogen at -80 °C for 4 h, primary drying: maintain at -50 °C and 10 Pa for 24 h, secondary drying: maintain at 25 °C and 1 Pa for 6 h to obtain a porous block. Finally, place the porous block into a mold, hold the pressure at 5 MPa for 30 min for shaping, and soak it in 0.5 wt% genipin for crosslinking for 4 h. Rinse it with phosphate buffer solution until the pH is 7.4 to obtain a spider silk protein-polydopamine macroporous framework structure, that is, the outer layer with a thickness of 1.3 mm;

[0055] S1.5. Immerse the outer layer in a 0.5% by mass dopamine hydrochloride solution with a pH of 8.5 for oxidative polymerization for 12 h. Place it in a hot press and press and shape it according to a gradient program. The first stage: 35 °C, 0.5 MPa, 2 h, the second stage: 25 °C, 1 MPa, 2 h, the third stage: 10 °C, 2 MPa, 2 h to make the outer layer combine with the inner layer-middle layer composite to obtain a composite structure. Finally, immerse the composite structure in a 1.0% genipin solution for crosslinking for 6 h, wash and dry it to obtain a water purifying agent.

[0056] Example 5: A water purifying agent based on the principle of bionic adsorption and its preparation process, including the following steps:

[0057] S1.1. Dissolve dopamine hydrochloride in a Tris-HCl buffer solution with a pH of 8.5 to obtain a 15 wt% dopamine hydrochloride solution. Under magnetic stirring at 800 rpm, oxidatively polymerize at room temperature for 24 h with a dissolved oxygen concentration of 8 ppm to obtain a polydopamine solution. Mix the polydopamine solution with polyvinyl alcohol, where the volume ratio of the polydopamine solution to 8% by mass polyvinyl alcohol is 3:1. Prepare a fiber structure by electrospinning. Set the electrospinning parameters: voltage 20 kV, receiving distance 15 cm, flow rate 0.5 mL / h, environmental humidity 35%, and vacuum dry at 60 °C for 12 h to obtain a polydopamine nanofiber network, that is, the inner layer with a thickness of 0.5 mm;

[0058] S1.2. Mix the molten short-chain alkane paraffin with a composite emulsifier of Span 80 / Tween 80 (mass ratio 1:1) at a mass ratio of 1:3, and homogenize at a high speed of 15000 rpm for 10 min to form a nano-paraffin emulsion with a particle size of 50 nm. Dissolve the spider silk protein in a choline chloride / urea solvent, stir at 60 °C for 6 h, where the molar ratio of the choline chloride / urea solvent is 1:2, to obtain a 12% (w / v) spider silk protein solution, and add the nano-paraffin emulsion. Among them, the mass ratio of the short-chain alkane paraffin to the spider silk protein is 1:3.8, and ultrasonic emulsification is carried out for 30 min to obtain an intermediate layer solution;

[0059] S1.3. Coating the intermediate layer solution on the inner layer surface by the dip-coating and spin-coating method, with a dipping speed of 5 mm / s and spin-coating parameters of 2000 rpm × 30 s, then maintaining in an oven at 45 °C for 2 h, transferring to an environment at 25 °C and maintaining for 12 h, and then spraying 0.5% dopamine hydrochloride for oxidative polymerization for 12 h to obtain an inner layer - intermediate layer composite with a thickness of 0.8 mm;

[0060] S1.4. Dissolve the spider silk protein in a choline chloride / urea solvent to obtain a 12 wt% spider silk protein solution, add a 3 wt% polydopamine solution, and mix and stir for 3 - 4 h. Among them, the ratio of spider silk protein to polydopamine is 4.5:1 (w / w), then add 60 wt% NaCl (particle size 100 μm) and ultrasonically disperse for 30 min, and form a shape by the freeze-casting method. Set the program: pre-freezing: rapid freezing in liquid nitrogen at -80 °C for 4 h, primary drying: maintaining at -50 °C and 10 Pa for 24 h, analytical drying: maintaining at 25 °C and 1 Pa for 6 h to obtain a porous block. Finally, put the porous block into a mold, keep the pressure at 5 MPa for 30 min for shaping, and soak in 0.5 wt% genipin for crosslinking for 4 h, and rinse with phosphate buffer solution until the pH is 7.4 to obtain a spider silk protein - polydopamine macroporous framework structure, that is, the outer layer with a thickness of 1.3 mm;

[0061] S1.5. Immerse the outer layer in a dopamine hydrochloride solution with a pH of 8.5 and a mass fraction of 0.5% for oxidative polymerization for 12 h, place it in a hot press, and press and shape according to a gradient program. The first stage: 35 °C, 0.5 MPa, 2 h, the second stage: 25 °C, 1 MPa, 2 h, the third stage: 10 °C, 2 MPa, 2 h to make the outer layer combine with the inner layer - intermediate layer composite to obtain a composite structure. Finally, immerse the composite structure in a 1.0% genipin solution for crosslinking for 6 h, wash and dry to obtain a water purifier.

[0062] Comparative Example 1: Using the method of Example 4, the intermediate layer is only composed of spider silk protein and is not compounded with short-chain alkane paraffin.

[0063] Comparative Example 2: Using the method of Example 4, the outer layer is only composed of spider silk protein and is not compounded with 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 layer and the outer layer.

[0065] A water purifying agent based on the principle of bionic adsorption prepared by adopting a multi-layer composite structure in the present invention, wherein, the inspection items and inspection standards of the performance indexes of the water purifying agent are as follows:

[0066] Prepare a 100 mg / L Cu 2+ solution, weigh 0.1 g of the water purifying agent and add it to 50 mL of the solution, oscillate at a constant temperature of 25 °C (150 rpm) for 24 h until the adsorption equilibrium is reached, centrifuge to take the supernatant, and measure the residual Cu 2+ concentration, calculate the adsorption capacity, q e =(C 0 -C e )V / m, C 0 Initial concentration, C e Equilibrium concentration, V Solution volume, m Adsorbent mass; Prepare 100 mg / L colloidal silica (pH = 7), weigh 0.1 g of the water purifying agent and add it to 50 mL of the solution, oscillate at a constant temperature of 25 °C (150 rpm) for 24 h until the adsorption equilibrium is reached, centrifuge (10000 rpm, 10 min) to separate the adsorbent, take the supernatant to measure the residual colloidal concentration, and calculate the adsorption capacity to characterize the adsorption capacity of the adsorbent;

[0067] Load the water purifying agent into a dynamic filtration column (flow rate 10 mL / min), pass through simulated sewage containing kaolin (1 g / L), and test the interception rate after running for 12 h with a turbidimeter. Interception rate (%) = effluent turbidity / influent turbidity × 100%;

[0068] Place 100 water purifying agents in a simulated dynamic water flow (flow rate 1 m / s, containing 10% suspended matter) and circulate and impact for 10 h, screen and break the particles with a particle size < 0.5 mm, and calculate the breakage rate: Breakage rate (%) = mass of broken particles / initial total mass × 100%, which is used to characterize the mechanical strength of the water purifying agent;

[0069] Prepare simulated sewage containing typical pollutants (0.1 g / L microplastic particles, 50 mg / L humic acid, 1 mg / L nano-clay), pass through a constant pressure filtration system (0.1 MPa), operate at 25 °C, record the pure water flux, which is the initial flux measurement (J 0 ), heat up to 45 °C, inject the pollutant solution, test the flux J 5 after the 5th cycle, compare the flux decay trend, flux decay rate = (J 0 -J 5 ) / J 0 × 100%, calculate and use it to characterize the anti-blocking ability of the water purifying agent.

[0070] Through the above criteria, the water purifying agents prepared in the above Examples 1-5 and Comparative Examples 1-3 were tested, and the obtained data 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 show that compared with Comparative Examples 1-3, Examples 1-5 can fully show the effects of the multi-layer composite structure on the mechanical strength, adsorption capacity, and anti-clogging ability of the water purifying agent.

[0074] Since the water purifying agent prepared by the present invention using a multi-layer composite structure has improved mechanical strength, adsorption capacity, and anti-clogging ability, the performance of the water purifying agent is effectively improved through the multi-layer composite structure, as follows:

[0075] It can be seen from Examples 1-3 that as the mass ratio of the short-chain alkane paraffin to the spider silk protein in the middle layer changes continuously, the mechanical strength and anti-clogging ability of the water purifying agent change continuously. 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 bond effect is enhanced. Therefore, the mechanical strength of the water purifying agent is enhanced, while the dynamic regulation of the pore size by short-chain alkane paraffin also decreases due to the decrease in its content, resulting in a decrease in the anti-clogging ability.

[0076] It can be seen from Examples 3-5 that as the mass ratio of the outer-layer spider silk protein to the polydopamine changes continuously, the mechanical strength, adsorption capacity, and anti-clogging ability of the water purifying agent change continuously. The outer-layer spider silk protein provides a rigid skeleton, and the flexible chain segments of polydopamine buffer stress through hydrogen bonds. When the proportion of polydopamine increases, the rigid network is diluted and the mechanical strength decreases slightly. However, the density of phenolic hydroxyl groups and amino groups of polydopamine increases, so the chelating ability for Cu 2 w is enhanced and the adsorption capacity increases.

[0077] According to the above test experiments, a water purifying agent based on the principle of bionic adsorption prepared according to Example 4 has the optimal performance. Therefore, Example 4 is taken as the optimal example;

[0078] It can be seen by comparing Example 4 with Comparative Examples 1-3:

[0079] In Comparative Example 1, the middle layer is only composed of spider silk protein without composite short-chain alkane paraffin. The anti-clogging ability of the water purifying agent is worse. Without short-chain alkane paraffin, the function of dynamically regulating the pore size is lacking, and it is difficult to remove the deposited pollutants and cannot rely on physical ejection, resulting in low anti-clogging ability.

[0080] In Comparative Example 2, the outer layer is only composed of silk fibroin and not compounded with polydopamine. The mechanical strength and adsorption capacity of the water purifier are poorer. Since the brittleness of silk fibroin is not compensated by the flexible segments of polydopamine, the structure is prone to collapse under the impact of dynamic water flow, resulting in a decrease in mechanical strength. Moreover, due to the lack of chelating sites of polydopamine, the adsorption capacity of the water purifier decreases.

[0081] In Comparative Example 3, only the polydopamine nanofiber network of the inner layer is prepared, without binding the middle layer and the outer layer. The mechanical strength, adsorption capacity and anti-clogging ability of the water purifier are poorer. Since the hierarchical adsorption structure is lacking and the molecular size cannot be distinguished, non-specific adsorption occurs, resulting in a reduction in the adsorption effect. Moreover, the single-layer polydopamine nanofiber network also lacks the ability of rigid structure and pore size regulation, resulting in poorer performance of the mechanical strength, adsorption capacity and anti-clogging ability of the water purifier.

[0082] In summary, through the silk fibroin-polydopamine macroporous framework structure, the silk fibroin-paraffin composite layer and the polydopamine nanofiber network, the gradient capture of pollutants from the micron scale to the nanoscale is achieved. And through the bionic tough framework design, the dynamic pore size regulation mechanism, the hierarchical adsorption synergistic effect and the bionic adhesion enhancement technology, the limitations of traditional adsorbents are broken through, meeting the high-efficiency purification requirements under complex water quality conditions.

[0083] The above shows and describes 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 by the above embodiments. The above embodiments and the descriptions in the specification are only preferred examples of the present invention and do not limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A water purifier based on the bionic adsorption principle, characterized in that: The water purifier is obtained by a composite structure of an inner layer, a middle layer and an outer layer; Among them, 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 skeleton structure.

2. A process for preparing a water purifier based on the bionic adsorption principle, used for preparing the water purifier based on the bionic adsorption principle as claimed in claim 1, characterized in that: The steps include: S1.1, dissolving dopamine hydrochloride in a Tris-HCl buffer solution with a pH of 8.5-9 to obtain a 10-15wt% dopamine hydrochloride solution, subjecting the mixture to oxidative polymerization at room temperature for 24-48h under magnetic stirring at 800-1000rpm, with a dissolved oxygen concentration of 8-10ppm, to obtain a polydopamine solution, mixing the polydopamine solution with polyvinyl alcohol, preparing a fiber structure by electrospinning, setting electrospinning parameters, and vacuum drying at 60-80°C for 10-12h to obtain a polydopamine nanofiber network, i.e., an inner layer; S1.2, mixing molten short-chain alkane paraffin with a composite emulsifier, homogenizing at 15000-16000 rpm for 5-10 min to form a nano paraffin emulsion with a particle size of 50-200 nm, dissolving spider silk protein in a choline chloride / urea solvent, wherein the molar ratio of choline chloride / urea solvent is 1:2, stirring at 55-60° C. for 5-6 h to obtain a 12-14% (w / v) spider silk protein solution, and adding the nano paraffin emulsion, ultrasonically emulsifying for 20-30 min to obtain an intermediate layer solution; S1.3, the middle layer solution is applied to the inner layer surface by dip-spin coating, and then kept in a 45-50°C oven for 1.5-2h, transferred to a 20-25°C environment and kept for 8-12h, and then sprayed with a 0.5-0.8% mass fraction of dopamine hydrochloride solution, and oxidatively polymerized for 12-16h to obtain an inner layer-middle layer composite; S1.4, dissolving spider silk protein in choline chloride / urea solvent to obtain a 10-12wt% spider silk protein solution, adding 2-4wt% polydopamine solution, mixing and stirring for 3-4h, then adding NaCl for ultrasonic dispersion for 20-30min, forming by freeze casting, setting the program to obtain a porous block, and finally putting the porous block into a mold, holding the mold at a pressure of 3-5MPa for 30min, and immersing it in 0.5-1wt% genipin for cross-linking for 4-6h, and rinsing it with phosphate buffer to a pH of 7.2-7.4 to obtain a spider silk protein-polydopamine macroporous skeleton structure, i.e., the outer layer; S1.

5. Immerse the outer layer in dopamine hydrochloride with a pH of 8.5-9 and a mass fraction of 0.5-0.8% for oxidative polymerization for 12-16 hours, place it in a hot press, and press and shape it according to a gradient program to combine the outer layer with the inner layer-middle layer complex to obtain a composite structure. Finally, immerse the composite structure in a 1.0-1.2% genipin solution for cross-linking for 6-8 hours, wash and dry, and obtain a water purifier.

3. The preparation process of the water purifier based on the bionic adsorption principle according to claim 2 is characterized in that: In the 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 18-25 kV, receiving distance 15-20 cm, flow rate 0.5-0.8 mL / h, and ambient humidity 30-40%.

4. The preparation process of the water purifier based on the bionic adsorption principle according to claim 2 is characterized in that: In the S1.2, the spider silk protein is 250-350 kDa, the short-chain alkane paraffin is a C18-C22 mixture, and the melting point is 35-45°C.

5. The preparation process of the water purifier based on the bionic adsorption principle according to claim 2 is characterized in that: In S1.2, the mass ratio of molten short-chain alkane paraffin to the composite emulsifier is 1:3-5, and the composite emulsifier is obtained by mixing Span 80 and Tween 80 in a mass ratio of 1-2:1, and the short-chain alkane paraffin and spider silk protein are mixed in a mass ratio of 1:3.2-4.

5.

6. The preparation process of the water purifier based on the bionic adsorption principle according to claim 2 is 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.

7. The preparation process of the water purifier based on the bionic adsorption principle according to claim 2 is characterized in that: In the S1.4, spider silk protein: polydopamine = 3.8-4.5:1 (w / w), the particle size of NaCl is 100-150 μm, and the addition amount is 60-65 wt%.

8. The preparation process of the water purifier based on the bionic adsorption principle according to claim 2 is characterized in that: In the S1.4, the specific parameters of the program are set as follows: pre-freezing: -80°C liquid nitrogen rapid freezing for 4 hours, primary drying: -50°C, 10Pa for 24 hours, analytical drying: 25°C, 1Pa for 6 hours.

9. The preparation process of the water purifier based on the bionic adsorption principle according to claim 2 is characterized in that: In the S1.5, the specific parameters of the gradient program pressurization are: the first stage: 35°C, 0.5MPa, 2h, the second stage: 25°C, 1MPa, 2h, the third stage: 10°C, 2MPa, 2h.

10. The preparation process of the water purifier based on the bionic adsorption principle according to claim 2 is characterized in that: The thickness of the inner layer is 0.3-0.5 mm, the thickness of the middle layer is 0.8-1.0 mm, and the thickness of the outer layer is 1.2-1.5 mm.

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