Antifouling and antibacterial active carbon material and preparation method thereof

Abstract

The application provides a scale and bacteria inhibition active carbon material and a preparation method thereof, and belongs to the technical field of water treatment materials, and comprises the following preparation steps: adding active carbon particles into a nitric acid solution for oxidation, washing, drying, dispersing in a phosphate buffer solution, adding a PEI aqueous solution, EDC and N-hydroxysuccinimide, stirring and reacting, washing, drying, and obtaining an AC-PEI material; dissolving polysuccinimide in DMF, adding a silver nitrate solution and uniformly mixing, placing into the AC-PEI material for impregnation, taking out, spraying a glutaraldehyde solution and a tannin acid solution, heating and reacting, washing, drying, crushing, and obtaining composite material particles; mixing the composite material particles, reinforcing fibers and a binder, extruding, drying, and obtaining the scale and bacteria inhibition active carbon material. The product obtained by the application can combine scale inhibition, bacteria inhibition and adsorption materials, and can also play a long-term scale and bacteria inhibition effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment materials, in particular to a scale inhibition and bacteriostasis activated carbon material and a preparation method thereof. BACKGROUND

[0002] At present, there are various water treatment materials, but most of them have single function. For example, scale inhibitors generally only play a basic scale inhibition function. In the water treatment process, especially for long-acting scale inhibitors, the use cycle is relatively long, and bacteria are easy to breed in the long-term soaking in water. Therefore, long-acting scale inhibitors not only require long-term stable scale inhibition performance, but also require long-lasting bacteriostasis performance to avoid the breeding of bacteria during long-term use, which affects the water quality and safety.

[0003] In order to make the scale inhibition material play the scale inhibition performance and have long-term bacteriostasis performance, bacteriostatic agents need to be added. Nano-silver or silver compound bactericides have high bactericidal efficiency, are not easy to produce drug resistance, and have broad-spectrum antibacterial effect, so they are good bacteriostatic agents. However, the release of silver ions in general silver ion bactericides is too fast, and it is difficult to maintain long-term bacteriostasis effect. Nano-silver or silver compounds are easy to aggregate and affect the overall material performance, and are also easy to fall off. Therefore, how to obtain long-term stable scale inhibition and bacteriostasis material is a big problem in the field of water treatment materials.

[0004] For example, a silver-loaded slow-release material for drinking water sterilization and a preparation method thereof disclosed in publication No. 119330474A disclose the following preparation method: activated carbon balls are added to a silver nitrate solution and stirred to obtain an adsorbed silver activated carbon dispersion liquid, a chloride solution is added to the adsorbed silver activated carbon dispersion liquid, and stirring reaction is continued, followed by solid-liquid separation and deionized water washing to obtain the silver-loaded slow-release material. The silver-loaded slow-release material obtained by the method uses a deposition method to deposit and adsorb silver in the form of a compound on the surface of porous activated carbon, which can make the dispersion degree of silver higher and achieve long-term slow-release bacteriostasis effect. However, silver chloride compounds are easy to decompose under light, and cannot be used for a long time under light. In addition, tap water generally contains chlorine, and chloride is easy to be affected by the chlorine ion concentration in water, so the bacteriostasis effect is unstable.

[0005] In addition, activated carbon is a good adsorption material in water treatment, which is widely available and low in price, and can effectively purify water quality. If scale inhibition, bacteriostasis and adsorption materials can be combined and long-term scale inhibition and bacteriostasis performance can be achieved, it will be a new water treatment material with market application prospect. SUMMARY

[0006] Therefore, the present application provides a scale inhibition and bacteriostasis activated carbon material and a preparation method thereof, which can combine scale inhibition, bacteriostasis and adsorption materials, and also achieve long-term scale inhibition and bacteriostasis effect.

[0007] To achieve the above object, the specific scheme of the present application is as follows: a preparation method of scale and bacteria inhibition active carbon material, comprising the following preparation steps:

[0008] S1. The activated carbon particles are added into nitric acid solution for oxidation, washed, dried, and dispersed in a phosphate buffer solution, PEI aqueous solution, EDC and N-hydroxysuccinimide are added, stirred and reacted, washed, and dried to obtain AC-PEI material;

[0009] S2. The poly succinimide is dissolved in DMF, and silver nitrate solution is added and uniformly mixed, and then immersed into the AC-PEI material, taken out, sprayed with glutaraldehyde solution and tannic acid solution, and heated in a closed environment for reaction, washed, vacuum dried, and crushed to obtain composite material particles;

[0010] S3. The composite material particles and reinforcing fibers are premixed, a binder is added, and then transferred into an extruder for extrusion and drying to obtain scale and bacteria inhibition active carbon material.

[0011] By using nitric acid to oxidize the activated carbon particles, a large number of oxygen-containing functional groups carboxyl groups (-COOH) are generated, then under the catalysis of EDC and NHS, the carboxyl groups in the activated carbon are activated to form ester intermediates, which react with the primary amine groups (-NH2) on the PEI molecular chain to form stable amide bonds (-CO-NH-), thereby obtaining PEI functionalized activated carbon material with a surface rich in amino groups, i.e. AC-PEI material. Then crosslinking reaction is carried out under the action of crosslinking promoter glutaraldehyde, wherein the Schiff base reaction occurs between glutaraldehyde and PEI (branched polyethyleneimine) to form C=N bonds, and PEI is a branched polymer, which forms a three-dimensional crosslinked gel network between PSI and PEI itself inside the pores of the activated carbon, wherein the imide ring of PSI is partially ring-opened for self-polymerization under the alkaline conditions provided by PEI, and the carboxyl groups generated by ring-opening can also react with the remaining amine groups of PEI, thereby generating PASP (polyaspartic acid) while covalently integrating the molecular chain of PASP into the PEI crosslinked network. At the same time, tannic acid (TA) as a green reducing agent reduces Ag + to Ag nanoparticles, so that the silver nanoparticles are "wrapped" in the three-dimensional crosslinked gel network just formed, and the phenolic hydroxyl groups of tannic acid itself can also react with PEI or glutaraldehyde to further enhance the stability of the crosslinked network.

[0012] By covalently fixing the PASP molecular chain on the gel network, the scale inhibition functional group carboxyl group is exposed in water, and when Ca 2+ , Mg 2+When approaching, PASP inhibits the formation of scale through threshold effect and lattice distortion, and the PASP molecules cannot freely diffuse, avoiding burst release, and can only be very slowly hydrolyzed through the three-dimensional cross-linked gel network, slowly releasing the short peptide chains of PASP, so as to maintain long-term scale inhibition effect and realize long-acting scale inhibition even in dynamic water flow. At the same time, Ag + is reduced into Ag nanoparticles and is firmly wrapped and dispersed in the gel network, avoiding agglomeration and direct exposure to light, and is more stable, while the release process of Ag + is limited by the swelling and grid of the gel network, which can avoid burst release, so that Ag + can be slowly and smoothly released, while PEI in the activated carbon itself also has bacteriostatic property, which can produce synergistic effect with Ag + to improve the antibacterial effect.

[0013] The present scheme synchronously completes cross-linking, scale inhibitor fixation and bacteriostatic material formation through one-step method, constructs a "three-dimensional interpenetrating gel network" in activated carbon, controls diffusion and avoids burst release by using the gel network, and solves the problems of long-acting release of PASP and slow release of Ag + , realizes the integration and long-acting of scale inhibition and bacteriostatic function, and the activated carbon not only acts as a carrier but also can play its own adsorption and water purification role, further improving the water treatment effect and making the application more extensive. At the same time, the safety of the present scheme is high, glutaraldehyde can react completely with PEI to form C=N covalent bond, avoiding free aldehyde residue, and even if there is a small amount of unreacted substance, it will be removed after subsequent washing and heat treatment, while other reactants and products such as PEI, PASP and tannic acid are environmentally friendly substances, and the final material is solid phase, and the three-dimensional covalent cross-linked network structure provides high stability, effectively avoiding the shedding of organic layers such as PASP, tannic acid and PEI, ensuring the purity and safety of water quality.

[0014] Preferably, the tannic acid solution further adds sodium lignosulfonate, and is prepared by dissolving tannic acid and sodium lignosulfonate in a phosphate buffer solution.

[0015] The addition of sodium lignosulfonate cooperates with tannic acid to quickly reduce Ag +The silver nanocrystal core is reduced, and then the SLS macromolecular chains are quickly wrapped thereon, thereby avoiding the agglomeration of silver nanoparticles, stabilizing the crystal core by using the three-dimensional crosslinked gel network structure, limiting the excessive growth of the crystal core, and thus forming smaller, more uniform and more stable Ag nanoparticles, which can exert a more long-acting and stable antibacterial effect. In addition, the wrapping of SLS can further protect the Ag nanoparticle core from erosion by complex components in water and photooxidation, and the antibacterial performance of the material in long-term use is more slowly attenuated. Furthermore, the phenolic hydroxyl groups of TA and SLS can be oxidized into quinones, which can react with the amino groups of PEI through Michael addition or Schiff base reaction, and in addition, the introduction of the negatively charged sulfonic acid group can produce strong electrostatic interaction with the positively charged ammonium group of PEI, and the long-chain molecules of SLS can intertwine with the PEI network, so that the three kinds of forces interact to further ensure the stability of the organic layer and the silver nanoparticles, which are not easy to fall off. All the components (PEI, PASP, TA, SLS) are biomass sources or green chemicals, which fully meet the safety requirements of drinking water treatment materials.

[0016] Preferably, the binder is a composite binder obtained by mixing polyvinyl alcohol and hydroxypropyl methyl cellulose.

[0017] By using polyvinyl alcohol (PVA) and hydroxypropyl methyl cellulose (HPMC) to form a composite binder, polyvinyl alcohol has good film-forming property and can form a strong bonding bridge between activated carbon particles, while hydroxypropyl methyl cellulose can improve the plasticity of the material during extrusion, reduce the extrusion pressure, prevent cracking, and act as a pore-forming agent to form microchannels in the final product after drying, which is beneficial to the penetration of water and the release of functional substances.

[0018] Preferably, the composite binder is obtained by heating deionized water to 70-80℃, then adding polyvinyl alcohol and hydroxypropyl methyl cellulose, and stirring and mixing.

[0019] Preferably, the PEI aqueous solution is prepared by dissolving branched polyethyleneimine in deionized water, and the molecular weight Mw of the branched polyethyleneimine is 1000-5000.

[0020] By using branched PEI with a moderate molecular weight, sufficient reaction sites and chain flexibility can be provided, and the blocking of some activated carbon pores caused by excessively large molecules can be avoided.

[0021] Preferably, in step S1, 20-40 mesh coconut shell activated carbon particles are added to a 30 wt% nitric acid solution, refluxed and stirred at 70-80°C for 2-3 hours for oxidation, washed with deionized water until the filtrate is neutral, dried at 75-85°C, dispersed in a phosphate buffer solution with pH=6, added with PEI aqueous solution, EDC and N-hydroxysuccinimide, stirred at room temperature for 12 hours, washed with deionized water, and dried at 60°C to obtain the AC-PEI material.

[0022] Preferably, in step S2, the AC-PEI material is placed in an ultrasonic-assisted immersion at 40°C for 2 hours, taken out, and then transferred to a reactor, sprayed with 25 wt% glutaraldehyde solution and tannin acid solution, reacted at 50°C for 6 hours in a closed environment, washed with deionized water, vacuum dried at 60°C for 24 hours, and crushed to 80-150 mesh to obtain composite particles; the glutaraldehyde solution is diluted with a phosphate buffer solution with pH=7.4 to a concentration of 25 wt%.

[0023] Preferably, in step S3, the composite particles and reinforcing fibers are added to a mixer, pre-mixed for 5 min, then mixed with a binder, transferred to a twin-screw extruder, rotated at 15-30 rpm, and the die head temperature is 40°C, then extruded, and finally dried in stages, dried at 40°C for 2 hours, dried at 80°C for 1 hour, and heat treated at 120°C for 30 min to obtain the finished product; the reinforcing fibers are food-grade wood fibers or mineral fibers with a length of 200-400 μm.

[0024] By adding food-grade wood fibers or mineral fibers for pre-mixing, then using a binder for bonding, and finally extruding, the reinforcing fibers play a role similar to "reinforcing steel" in the material, improving the bonding force and strength of the material, effectively preventing cracking during extrusion and drying, improving the strength and overall stability of the finished product, and making it more resistant to water flow erosion. By using stepwise drying, most of the free water is removed slowly at 40°C for 2 hours to prevent cracking caused by rapid drying, then further dried at 80°C for 1 hour, and finally heat treated at 120°C for 30 min for crosslinking and curing, forming crystals between polyvinyl alcohol molecular chains and physical crosslinking with organic substances such as hydroxypropyl methyl cellulose, improving strength and water resistance, and the finished product is not easily dissolved and softened in water flow.

[0025] The application further provides the anti-bacterium and scale inhibition active carbon material prepared by the preparation method.

[0026] The AC-PEI material comprises the following raw materials in parts by mass: 24-28 parts of activated carbon particles, 300 parts of 30wt% nitric acid solution, 7-8 parts of branched polyethyleneimine, 3.5-5.5 parts of EDC, 1.5-2 parts of N-hydroxysuccinimide, and the AC-PEI material.

[0027] Preferably, 0.8-1.2 parts of sodium lignosulfonate are further included; and the binder comprises 0.8-1.2 parts of polyvinyl alcohol and 0.5-0.7 parts of hydroxypropyl methyl cellulose.

[0028] By adopting the above-mentioned reasonable and optimized proportion, the bacteriostatic and scale inhibition performance of the material is improved in a smaller amount, and the overall strength and stability of the material are maintained; meanwhile, the overall material is environmentally friendly and safe, the low amount of glutaraldehyde used can be completely reacted to form a C=N covalent bond, avoiding free aldehyde residues, even if there is a small amount of unreacted material, it will be removed after subsequent washing and heat treatment, and other reactants and products such as PEI, PASP and tannic acid are environmentally friendly and safe, which can meet the requirements of higher standard water treatment processes.

[0029] The above technical solutions of the application at least have the following beneficial effects:

[0030] (1) The application adopts nitric acid to oxidize activated carbon particles, then introduces PEI to obtain PEI functionalized activated carbon material AC-PEI material rich in amino groups on the surface, and then performs crosslinking reaction under the action of crosslinking promoter glutaraldehyde, to form a three-dimensional crosslinked gel network between PEI and PSI and PEI itself in the pores of the activated carbon, wherein under the action of PEI, the imide ring of PSI will be partially ring-opened for self-polymerization, and can also react with the remaining amine groups of PEI, so as to generate PASP while covalently integrating the molecular chain of PASP into the PEI crosslinked network, and tannic acid as a green reducing agent reduces Ag + into Ag nanoparticles, so that the silver nanoparticles are "wrapped" in the three-dimensional crosslinked gel network formed in situ.

[0031] (2) This invention covalently fixes the PASP molecular chain onto a gel network, exposing its scale-inhibiting functional group (carboxyl group) to water. Through a three-dimensional cross-linked gel network, it hydrolyzes very slowly, gradually releasing short peptide chains of PASP. This maintains a long-term scale-inhibiting effect even in dynamic water flow, achieving long-lasting scale inhibition. Furthermore, it utilizes Ag... + The Ag nanoparticles are reduced to Ag nanoparticles and firmly encapsulated and dispersed in the gel network, avoiding aggregation and direct exposure to light, thus becoming more stable. + The release of Ag is restricted by the swelling and mesh of the gel network, which prevents burst release. + It can release slowly and steadily, while simultaneously addressing the issues of long-acting release of PASP and Ag. + The slow-release function has been improved, achieving the integration and long-lasting effect of scale inhibition and antibacterial function.

[0032] (3) The components used in this invention are highly safe. Glutaraldehyde can react completely with PEI, avoiding the residue of free aldehydes. Other reactants and products, such as PEI, PASP, and tannic acid, are all environmentally friendly substances. The three-dimensional covalent network formed provides extremely high stability, effectively preventing the shedding of organic layers such as PASP, tannic acid and PEI, and ensuring the purity and safety of the water. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are some embodiments of the present invention, and all other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0034] Example 1

[0035] 24 parts of activated carbon granules were added to 300 parts of a 30wt% nitric acid solution, refluxed and stirred at 70℃ for 2 hours, and repeatedly washed with deionized water until the filtrate was neutral. The filtrate was then dried at 75℃ to obtain oxidized activated carbon. A PEI aqueous solution was prepared by dissolving 7 parts of branched polyethyleneimine (PEI, Mw=1000) in 200 parts of deionized water. The oxidized activated carbon was dispersed in 1000 parts of a phosphate buffer solution with pH=6. The prepared PEI aqueous solution was slowly added, along with 3.5 parts of the catalyst 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and 1.5 parts of N-hydroxysuccinimide (NHS). The mixture was gently stirred at room temperature for 12 hours. After the reaction was complete, the mixture was thoroughly washed with deionized water to remove physically adsorbed PEI, and dried at 60℃ to obtain the PEI-functionalized activated carbon material AC-PEI material.

[0036] A silver nitrate solution was prepared by dissolving 1 part of AgNO3 in 50 parts of water; a tannic acid solution was prepared by dissolving 0.5 parts of tannic acid in 30 parts of a phosphate buffer solution (pH = 7.4), heating slightly and stirring to ensure complete dissolution. A solution of 3 parts of poly succinimide (PSI) in 100 parts of N, N-dimethylformamide (DMF) was prepared, and the silver nitrate solution was added and mixed well. The solution was then immersed in 20 parts of the AC-PEI material, and ultrasonic-assisted immersion was performed at 40°C for 2 hours to ensure that the PSI and Ag + The solution was then removed, and the excess liquid was drained. The material was quickly transferred to a reactor, and a 25 wt% glutaraldehyde (GA) solution diluted with a phosphate buffer solution (pH = 7.4) and the prepared tannic acid solution were sprayed simultaneously into the reactor using a high-efficiency atomizing spraying device under dynamic tumbling at 50°C for 6 hours in a closed environment. After the reaction was completed, the material was washed with a large amount of deionized water until the washing liquid was clear and odorless, thereby removing the unreacted GA, TA and solvent. The material was then dried at 60°C under vacuum for 24 hours, crushed to 80-150 mesh, and the resulting composite material particles were obtained.

[0037] A composite binder solution was prepared by heating 20 parts of deionized water to 70-80°C, adding 0.8 parts of a binder polyvinyl alcohol (PVA) and 0.5 parts of hydroxypropyl methyl cellulose (HPMC), and stirring to mix well. The composite material particles and 0.5 parts of food-grade wood fibers (400 μm in length) were then added to a mixer and pre-mixed for 5 minutes. The composite binder solution was then slowly added and mixed. The mixture was then transferred to a twin-screw extruder, and extrusion was performed at a rotation speed of 15 rpm and a die head temperature of 40°C. The extruded material was then dried in stages at 40°C for 2 hours, at 80°C for 1 hour, and at 120°C for 30 minutes, thereby obtaining the scale-inhibiting and bacteriostatic activated carbon material.

[0038] Example 2

[0039] A solution of 8 parts of branched polyethyleneimine (PEI, Mw = 5000) in 200 parts of deionized water was prepared. The oxidized activated carbon was dispersed in 1000 parts of a phosphate buffer solution (pH = 6), and the prepared PEI solution was slowly added. Then, 5.5 parts of a catalyst 1-ethyl- (3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and 2 parts of N-hydroxysuccinimide (NHS) were added. The mixture was gently stirred at room temperature for 12 hours. After the reaction was completed, the mixture was washed with deionized water to remove the physically adsorbed PEI, and the mixture was dried at 60°C, thereby obtaining the PEI-functionalized activated carbon material AC-PEI material.

[0040] A silver nitrate solution was prepared by dissolving 1.5 parts of AgNO3 in 50 parts of water; a tannic acid solution was prepared by dissolving 0.2 parts of tannic acid (TA) and 1.2 parts of sodium lignosulfonate in 40 parts of phosphate buffer solution (pH = 7.4) with slight heating and stirring to ensure complete dissolution; a poly succinimide (PSI) solution was prepared by dissolving 4 parts of PSI in 100 parts of N, N-dimethylformamide (DMF), and then adding the silver nitrate solution and mixing well; the AC-PEI material was immersed in the PSI solution, and ultrasonic-assisted immersion was performed at 40°C for 2 hours to ensure that the PSI and Ag + The AC-PEI material was removed, and the excess liquid was drained, and then the material was quickly transferred to a reactor, and a 25wt% glutaraldehyde (GA) solution diluted with 1.5 parts of phosphate buffer solution (pH = 7.4) and the prepared tannic acid solution were sprayed simultaneously under dynamic tumbling using a high-efficiency atomizing spraying device, and the reaction was performed at 50°C for 6 hours in a sealed environment; after the reaction was completed, the material was washed with a large amount of deionized water until the washing liquid was clear and odorless, thereby completely removing unreacted GA, TA, and solvent; the material was vacuum dried at 60°C for 24 hours, and then ground to 80-150 mesh to obtain composite material particles.

[0041] Deionized water (20 parts) was heated to 80°C, 1.2 parts of a binder polyvinyl alcohol (PVA) and 0.7 parts of hydroxypropyl methyl cellulose (HPMC) were added, and stirring was performed until the mixture was uniform to obtain a composite binder solution; the composite material particles and 0.7 parts of food-grade mineral fiber (length 200 μm) were pre-mixed in a mixer for 5 minutes, and the composite binder solution was slowly added and mixed; the mixture was transferred to a twin-screw extruder, the rotation speed was 30 rpm, and the die head temperature was 40°C; the mixture was extruded, and then stepwise drying was performed, i.e., drying at 40°C for 2 hours, drying at 80°C for 1 hour, and holding at 120°C for 30 minutes, thereby obtaining a scale and bacteria inhibition activated carbon material.

[0042] Example 3

[0043] The 25 parts of activated carbon particles were added into 300 parts of nitric acid solution with a concentration of 30 wt%, and refluxed and stirred at 75°C for 2.5 hours. The activated carbon was repeatedly washed with deionized water until the filtrate was neutral, and dried at 80°C to obtain oxidized activated carbon. A PEI aqueous solution was prepared by dissolving 7.5 parts of branched polyethyleneimine (PEI, Mw=3000) in 200 parts of deionized water. The oxidized activated carbon was dispersed in 1000 parts of phosphate buffer solution with pH=6, and the prepared PEI aqueous solution was slowly added. Then, 4.5 parts of catalyst 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and 1.8 parts of N-hydroxysuccinimide (NHS) were added. The reaction was carried out at room temperature for 12 hours under gentle stirring. After the reaction was completed, the activated carbon was washed with deionized water to remove the physically adsorbed PEI, and dried at 60°C to obtain the PEI functionalized activated carbon material AC-PEI material.

[0044] A silver nitrate solution was prepared by dissolving 1.4 parts of AgNO3 in 50 parts of water. A tannic acid solution was prepared by dissolving 0.3 parts of tannic acid (TA) and 0.8 parts of sodium lignosulfonate in 40 parts of phosphate buffer solution (pH=7.4) and heating and stirring to completely dissolve. A polysuccinimide (PSI) solution was prepared by dissolving 3.5 parts of PSI in 100 parts of N,N-dimethylformamide (DMF). The PSI solution was mixed with the silver nitrate solution, and then immersed in 24 parts of the AC-PEI material. The AC-PEI material was ultrasonically assisted for 2 hours at 40°C to ensure that the PSI and Ag + The AC-PEI material was taken out, drained of excess liquid, and quickly transferred to a reactor. A high-efficiency atomizing spraying device was used to spray 1.3 parts of 25 wt% glutaraldehyde (GA) solution diluted with phosphate buffer solution (pH=7.4) and the prepared tannic acid solution into the reactor under dynamic tumbling. The reaction was carried out at 50°C for 6 hours in a sealed environment. After the reaction was completed, the activated carbon was washed with a large amount of deionized water until the washing liquid was clear and odorless, so that the unreacted GA, TA and solvent were completely removed. The activated carbon was vacuum dried at 60°C for 24 hours, crushed to 80-150 mesh, and obtained as a composite material particle.

[0045] The 20 parts of deionized water were heated to 75°C, and 1 part of binder polyvinyl alcohol (PVA) and 0.6 parts of hydroxypropyl methyl cellulose (HPMC) were added and stirred to obtain a composite binder solution. The composite material particles and 0.6 parts of food-grade mineral fiber (length 300 μm) were pre-mixed in a mixer for 5 minutes, and the composite binder solution was slowly added and mixed. The mixture was transferred to a twin-screw extruder at a speed of 25 rpm, and the die head temperature was 40°C. The mixture was extruded, and then subjected to stepwise drying at 40°C for 2 hours, 80°C for 1 hour, and 120°C for 30 minutes to obtain the scale and bacteria inhibition activated carbon material.

[0046] Example 4

[0047] The 26 parts of activated carbon particles were added to 300 parts of nitric acid solution with a concentration of 30 wt%, refluxed and stirred at 75°C for 2.5 hours, repeatedly washed with deionized water until the filtrate was neutral, and dried at 80°C to obtain oxidized activated carbon. A PEI aqueous solution was prepared by dissolving 7.6 parts of branched polyethyleneimine (PEI, Mw=3500) in 200 parts of deionized water, the oxidized activated carbon was dispersed in 1000 parts of phosphate buffer solution with pH=6, the prepared PEI aqueous solution was slowly added, and 5 parts of catalyst 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and 1.8 parts of N-hydroxysuccinimide (NHS) were added, and the reaction was carried out at room temperature for 12 hours with gentle stirring. After the reaction was completed, the PEI was removed by washing with deionized water to remove the physically adsorbed PEI, and the AC-PEI material was obtained by drying at 60°C.

[0048] A silver nitrate solution was prepared by dissolving 1.4 parts of AgNO3 in 50 parts of water; a tannic acid solution was prepared by dissolving 0.3 parts of tannic acid (TA) and 1 part of sodium lignosulfonate together in 40 parts of phosphate buffer solution (pH=7.4), and completely dissolving them by slight heating and stirring. A polysuccinimide (PSI) solution was prepared by dissolving 3.5 parts of PSI in 100 parts of N,N-dimethylformamide (DMF), and then immersing 25 parts of the AC-PEI material in the solution after adding the silver nitrate solution and uniformly mixing, and ultrasonic-assisted impregnation was carried out at 40°C for 2 hours to ensure that the PSI and Ag + The AC-PEI material was taken out, drained of excess liquid, and quickly transferred to a reactor, and a high-efficiency atomizing spraying device was used to spray 1.3 parts of a 25 wt% glutaraldehyde (GA) solution diluted with a phosphate buffer solution (pH=7.4) and the prepared tannic acid solution into the reactor at the same time under dynamic tumbling, and the reaction was carried out at 50°C for 6 hours in a sealed environment. After the reaction was completed, the unreacted GA, TA, and solvent were removed by washing with a large amount of deionized water until the washing liquid was clear and odorless, and the composite material particles were obtained by vacuum drying at 60°C for 24 hours and crushing to 80-150 mesh.

[0049] The 26 parts of activated carbon particles were added to 300 parts of nitric acid solution with a concentration of 30 wt%, refluxed and stirred at 75°C for 2.5 hours, repeatedly washed with deionized water until the filtrate was neutral, and dried at 80°C to obtain oxidized activated carbon. A PEI aqueous solution was prepared by dissolving 7.6 parts of branched polyethyleneimine (PEI, Mw=3500) in 200 parts of deionized water, the oxidized activated carbon was dispersed in 1000 parts of phosphate buffer solution with pH=6, the prepared PEI aqueous solution was slowly added, and 5 parts of catalyst 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and 1.8 parts of N-hydroxysuccinimide (NHS) were added, and the reaction was carried out at room temperature for 12 hours with gentle stirring. After the reaction was completed, the PEI was removed by washing with deionized water to remove the physically adsorbed PEI, and the AC-PEI material was obtained by drying at 60°C.

[0050] Example 5

[0051] The 25 parts of activated carbon particles were added to 300 parts of nitric acid solution with a concentration of 30 wt%, and refluxed and stirred at 75°C for 2.5 hours. The activated carbon was repeatedly washed with deionized water until the filtrate was neutral, and dried at 80°C to obtain oxidized activated carbon. A PEI aqueous solution was prepared by dissolving 7.5 parts of branched polyethyleneimine (PEI, Mw=3000) in 200 parts of deionized water. The oxidized activated carbon was dispersed in 1000 parts of phosphate buffer solution with pH=6, and the prepared PEI aqueous solution was slowly added. Then, 4.5 parts of catalyst 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and 1.6 parts of N-hydroxysuccinimide (NHS) were added. The reaction was carried out at room temperature for 12 hours with gentle stirring. After the reaction was completed, the activated carbon was washed with deionized water to remove the physically adsorbed PEI, and dried at 60°C to obtain a PEI functionalized activated carbon material AC-PEI material.

[0052] A silver nitrate solution was prepared by dissolving 1.3 parts of AgNO3 in 50 parts of water. A tannic acid solution was prepared by dissolving 0.18 parts of tannic acid (TA) and 0.8 parts of sodium lignosulfonate in 40 parts of phosphate buffer solution (pH=7.4) with slight heating and stirring to completely dissolve them. A polysuccinimide (PSI) solution was prepared by dissolving 3.5 parts of PSI in 100 parts of N,N-dimethylformamide (DMF). After the silver nitrate solution was added and mixed uniformly, the AC-PEI material was immersed in the PSI solution, and ultrasonic-assisted impregnation was carried out at 40°C for 2 hours to ensure that the PSI and Ag + The AC-PEI material was taken out, drained of excess liquid, and quickly transferred to a reactor. A high-efficiency atomizing spraying device was used to spray the prepared tannic acid solution and 1.2 parts of 25 wt% glutaraldehyde (GA) solution diluted with phosphate buffer solution (pH=7.4) into the reactor under dynamic tumbling. The reaction was carried out at 50°C for 6 hours in a sealed environment. After the reaction was completed, the activated carbon was washed with a large amount of deionized water until the washing liquid was clear and odorless, so that the unreacted GA, TA, and solvent were completely removed. The activated carbon was vacuum dried at 60°C for 24 hours, and crushed to 80-150 mesh to obtain composite particles.

[0053] The 20 parts of deionized water were heated to 75℃, 1 part of the binder polyvinyl alcohol (PVA) and 0.6 parts of hydroxypropyl methyl cellulose (HPMC) were added, stirred and mixed uniformly to obtain a composite binder solution, the composite material particles and 0.6 parts of food-grade mineral fiber (length 300 μm) were added to a mixer and pre-mixed for 5 minutes, then the composite binder solution was slowly added and mixed, and then transferred to a twin-screw extruder at a speed of 25 rpm, and the die head temperature was 40℃. The extrusion was carried out, and then the stepwise drying was carried out, i.e. drying at 40℃ for 2 hours, drying at 80℃ for 1 hour, and keeping at 120℃ for 30 minutes, to obtain the scale and bacteria inhibition activated carbon material.

[0054] The present application also provides comparative examples and conducts relevant comparative tests

[0055] Comparative Example 1

[0056] Compared with Example 4, the AC-PEI material was not prepared, and the activated carbon particles were directly used instead of the AC-PEI material, and the other preparation steps were the same, to obtain the scale and bacteria inhibition activated carbon material.

[0057] Comparative Example 2

[0058] Compared with Example 4, the tannin acid solution was not added, and the other preparation steps were the same, to obtain the scale and bacteria inhibition activated carbon material.

[0059] Comparative Example 3

[0060] Compared with Example 4, the food-grade wood fiber was not added, and the other preparation steps were the same, to obtain the scale and bacteria inhibition activated carbon material.

[0061] Scale inhibition performance test

[0062] The scale and bacteria inhibition activated carbon materials obtained in Examples 1-5 and Comparative Examples 1-3 were subjected to initial static scale inhibition performance test according to the standard GB / T 16632-2019 "Determination of scale inhibition performance of water treatment agent - calcium carbonate deposition method". The calcium ion concentration in the test water was 250 mg / L (calculated as CaCO3), and the test was carried out in a constant temperature water bath at 80℃ for 6 hours. The calcium ion concentration in the test water before and after heating was measured, the scale inhibition rate was calculated, and the results are shown in Table 1.

[0063] The scale and bacteria inhibition activated carbon materials obtained in Examples 1-5 and Comparative Examples 1-3 were subjected to long-term dynamic scale inhibition performance test, simulating dynamic flowing water, controlling the water flow speed at 1.5 m / s, and the calcium ion concentration at 200 mg / L (calculated as CaCO3), and continuously running for 30 days at room temperature (25℃). Water samples were taken and detected at 1st, 15th and 30th day, the scale inhibition rate at different time points was calculated, and the results are shown in Table 1.

[0064]

[0065] From the test results of Table 1 above, it can be clearly seen that the products obtained in Examples 1-5 have excellent scale inhibition effect in static or dynamic water and the scale inhibition effect can be maintained for a long time, and the scale inhibition rate can still be maintained at more than 85% after 30 days. Although the products obtained in Comparative Examples 1-3 have excellent scale inhibition performance in static water for a short period of time, the scale inhibition effect of the product obtained in Comparative Example 1 decreases rapidly with time and cannot maintain long-term scale inhibition performance. Although the scale inhibition effects of Comparative Examples 2 and 3 are long-lasting, the addition of tannin acid solution or the enhancement of fibers affects the enhancement of cross-linking stability or the overall strength, and the long-term scale inhibition rate of the material obtained in Example 4 is relatively decreased.

[0066] Long-term bacteriostatic performance test

[0067] The scale and bacteriostatic activated carbon materials obtained in each example and comparative example were placed in a continuous dynamic water flow with a water flow speed of 1.5 m / s, and continuously operated at room temperature (25°C) for 30 days. The sample materials were periodically taken at 1st, 15th and 30th day, and after ethanol disinfection and sterile water washing, the bacteriostatic performance test was carried out by inoculating Escherichia coli (ATCC 8739) according to the standard GB / T31402-2015, the data was summarized, the bacteriostatic rate was calculated, and the test results are shown in Table 2 below.

[0068]

[0069] From the test results of Table 2 above, it can be known that the products obtained in Examples 1-5 have excellent and stable long-term bacteriostatic performance. However, the long-term bacteriostatic effect of Example 1 decreases slightly faster than that of Examples 2-5, because sodium lignosulfonate is not added in Example 1, which affects the coating effect of nano-silver.

[0070] Although the products obtained in Comparative Examples 1-3 have excellent bacteriostatic performance at the beginning, Comparative Example 1 cannot maintain long-term bacteriostatic effect because it does not prepare AC-PEI material, and the activated carbon cannot be oxidized and grafted with PEI, so that the cross-linking network cannot be formed inside to coat the nano-silver, and the release rate of silver ions is too fast. Comparative Example 2 cannot maintain long-term and efficient bacteriostatic performance in the later period because a large amount of free silver ions are quickly dissolved out due to the fact that silver ions cannot be effectively reduced and fixed without adding tannin acid solution.

[0071] Safety test

[0072] The detection results of whether the scale inhibition and bacteriostasis active carbon materials obtained in Examples 1-5 and Comparative Examples 1-3 have heavy metal elution, release harmful organic matter, silver ion elution amount, and whether the treated water produces peculiar smell or odor according to the standard GB / T 17219-2021 "Safety Evaluation Standard for Drinking Water Transmission and Distribution Equipment and Protective Materials" are shown in Table 3.

[0073]

[0074] From the results in Table 3, it can be seen that the products obtained in Examples 1-5 do not have heavy metal elution, do not release harmful organic matter, and the treated water does not produce peculiar smell or odor, and the silver ion elution amount does not exceed the standard limit of GB / T 17219-2021 (≤0.1 mg / L), and also does not exceed the limit value of "Drinking Water Health Standards" GB 5749-2022 (≤0.05 mg / L), which can meet the high standard water quality requirements.

[0075] The product obtained in Comparative Example 1 does not prepare AC-PEI material, and the active carbon is not oxidized and grafted with PEI. Although the reaction of glutaraldehyde is not complete, it has been removed by sufficient washing, so there is no release of harmful organic matter. However, the silver nanoparticles are not firmly combined with the active carbon, lack a slow-release protective layer, and the silver is easily and quickly lost, resulting in silver ion elution amount exceeding the standard limit of GB / T 17219-2021 (≤0.1 mg / L). In Comparative Example 2, since tannic acid solution is not added, silver ions cannot be effectively reduced and fixed, resulting in rapid elution of a large amount of free silver ions. Although the ion elution amount does not exceed the standard limit of GB / T 17219-2021 (≤0.1 mg / L), it exceeds the limit value of "Drinking Water Health Standards" GB 5749-2022 (≤0.05 mg / L), and cannot meet the requirements of high standard water quality.

[0076] The above is the preferred embodiment of the present application. For ordinary skilled persons in the technical field, some improvements and refinements made without departing from the principles of the present application should also be considered within the protection scope of the present application.

Claims

1. A method for preparing an antifouling and antibacterial active carbon material, characterized by, The preparation steps include: S1. The activated carbon particles are added into a nitric acid solution for oxidation, washed, dried, and dispersed in a phosphate buffer solution, and then PEI aqueous solution, EDC and N-hydroxysuccinimide are added for stirring reaction, washing, drying, and obtaining the AC-PEI material; S2. The poly succinimide is dissolved in DMF, and then silver nitrate solution is added and uniformly mixed, and then the AC-PEI material is immersed, taken out, and then sprayed with glutaraldehyde solution and tannic acid solution, and then heated in a closed environment, washed, vacuum dried, and crushed to obtain the composite material particles; S3. The composite material particles and the reinforcing fibers are premixed, and then the binder is added for mixing, and then transferred to an extruder for extrusion, drying, and obtaining the scale and bacteria inhibition activated carbon material; The PEI aqueous solution is prepared by dissolving branched polyethyleneimine in deionized water.

2. The method for preparing the scale and bacteria inhibiting active carbon material according to claim 1, characterized in that, The tannic acid solution further contains sodium lignosulfonate, and is prepared by dissolving tannic acid and sodium lignosulfonate in a phosphate buffer solution.

3. The method of claim 1, wherein the method is characterized by: The binder is a composite binder, which is obtained by mixing polyvinyl alcohol and hydroxypropyl methyl cellulose.

4. The method of claim 3, wherein the carbon material is prepared by the steps of: (a) mixing a carbon material with a metal salt; (b) heating the mixture to a temperature of 300-800°C; (c) cooling the mixture to room temperature; and (d) washing the mixture with water. The composite binder is obtained by heating deionized water to 70-80℃, and then adding polyvinyl alcohol and hydroxypropyl methyl cellulose for stirring and mixing.

5. The method of claim 1, wherein the method is characterized by: The branched polyethyleneimine has a molecular weight Mw=1000-5000.

6. The method of claim 1, wherein the method is characterized by: In the step S1, 20-40 mesh coconut shell activated carbon particles are added into a 30wt% nitric acid solution, and then refluxed and stirred at 70-80℃ for 2-3 hours for oxidation, and then washed with deionized water until the filtrate is neutral, and then dried at 75-85℃ to obtain the oxidized activated carbon, which is dispersed in a phosphate buffer solution with pH=6, and then PEI aqueous solution, EDC and N-hydroxysuccinimide are added for stirring reaction at room temperature for 12 hours, and then washed with deionized water and dried at 60℃ to obtain the AC-PEI material.

7. The method of claim 1, wherein the method is characterized by: In the step S2, the AC-PEI material is immersed at 40℃ for 2 hours under ultrasonic assistance, taken out, and then transferred to a reactor, and then 25wt% glutaraldehyde solution and tannic acid solution are sprayed, and then reacted in a closed environment at 50℃ for 6 hours, and then washed with deionized water and vacuum dried at 60℃ for 24 hours, and then crushed to 80-150 mesh to obtain the composite material particles; the glutaraldehyde solution is diluted with a phosphate buffer solution with pH=7.4 to a concentration of 25wt%.

8. The method of claim 1, wherein the method is characterized by: In the step S3, the composite material particles and the reinforcing fibers are added into a mixer for premixing for 5 minutes, and then the binder is added for mixing, and then transferred to a twin-screw extruder, and then extruded at a rotating speed of 15-30rpm and a die head temperature of 40℃, and then subjected to stepwise drying, and then dried at 40℃ for 2 hours, 80℃ for 1 hour, and 120℃ for 30 minutes to obtain the finished product; the reinforcing fibers are food-grade wood fibers or mineral fibers with a length of 200-400μm.

9. A scale and bacteria inhibiting activated carbon material, characterized by, A preparation method of a scale and bacteria inhibition active carbon material according to any one of claims 1-8, comprising the following raw materials in mass fraction: 20-25 parts of AC-PEI material, 3-4 parts of polysuccinimide, 100 parts of DMF, 1-1.5 parts of AgNO3, 1-1.5 parts of 25wt% glutaraldehyde solution, 0.2-0.5 parts of tannic acid, 1.3-1.9 parts of binder and 0.5-0.7 parts of reinforcing fiber; The AC-PEI material comprises the following raw materials in mass fraction: 24-28 parts of activated carbon particles, 300 parts of 30wt% nitric acid solution, 7-8 parts of branched polyethyleneimine, 3.5-5.5 parts of EDC, 1.5-2 parts of N-hydroxysuccinimide.

10. The scale and bacteria inhibiting activated carbon material of claim 9, wherein the activated carbon material is characterized by, Further comprising 0.8-1.2 parts of sodium lignosulfonate; the binder comprises 0.8-1.2 parts of polyvinyl alcohol and 0.5-0.7 parts of hydroxypropyl methyl cellulose.

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