Multifunctional composite water purifying agent and preparation method thereof

Abstract

The application belongs to the technical field of water treatment agents, and particularly relates to a multifunctional composite water purifying agent and a preparation method thereof, which comprises the following raw materials in parts by weight: multifunctional water purifying powder 90-100 parts, bentonite 8-10 parts, sodium carboxymethyl cellulose 0.5-1.5 parts, sodium percarbonate 0.5-1 part and sodium citrate 0.5-1 part; the multifunctional water purifying powder comprises core layer material and shell layer slurry; the multifunctional water purifying agent of the application takes the multifunctional water purifying powder with a core-shell structure as a core, cooperates with bentonite, sodium carboxymethyl cellulose, sodium percarbonate and sodium citrate, realizes efficient and synchronous removal of heavy metals, organic matters, colority and microorganisms, and has the advantages of wide spectrum, stability and easy recovery.

Description

Technical Field

[0001] This invention relates to the field of water treatment agent technology, specifically to a multifunctional composite water purification agent and its preparation method. Background Technology

[0002] Existing water pollution generally exhibits characteristics of complex pollution, with increasingly diverse pollutant types, often simultaneously including heavy metal ions such as copper, lead, and chromium, organic pollutants, suspended solids, color, and pathogenic microorganisms. Traditional water treatment technologies, such as coagulation sedimentation, activated carbon adsorption, chemical oxidation, or biodegradation, are often designed for single types of pollutants, making it difficult to achieve simultaneous and efficient removal of multiple pollutants. Furthermore, they suffer from problems such as large reagent dosages, high sludge production, difficulties in regeneration, or secondary pollution.

[0003] Patent application number CN202211537266.0 provides a water purification agent for treating chemical organic wastewater and its preparation method. The water purification agent for treating chemical organic wastewater has the following raw material composition by weight: 2-3 parts sodium silicate, 3-4 parts zinc sulfate, 8-11 parts polyaluminum ferric dicarboxylate, 2-5 parts polyacrylamide, 6-10 parts magnesium aluminum chloride polysilicate, 14-17 parts modified sepiolite powder, 16-20 parts chitosan / β-cyclodextrin complex, 2-4 parts dibutyl dithiophosphate, and 1-3 parts diphenylmethylene sorbitol. The water purification agent for treating chemical organic wastewater described in this invention can effectively remove COD, color, and metal salts from chemical organic wastewater. Patent application CN202110138084.5 discloses a water purification agent for electroplating wastewater and its preparation method. The raw materials for the water purification agent for electroplating wastewater are as follows: sodium citrate, hydroxyapatite, aluminum sulfate, polyaluminum ferric chloride, polyaluminum chloride, sodium polyacrylate, polydimethylsiloxane diquaternary ammonium salt, sodium N,N-piperazine dithiocarbamate, and sodium diethylthiocarbamate trihydrate. The preparation process of the water purification agent described in this invention is simple, and the prepared water purification agent has a good and stable removal effect on heavy metal ions in electroplating wastewater. However, the above two prior art technologies are only simple compound systems of water treatment agents, focusing only on the removal of suspended solids and some colloids through coagulation and sedimentation. When dealing with the complex pollutants in modern chemical wastewater, especially when it contains high-valence heavy metals, recalcitrant organic matter, and microorganisms, they exhibit fundamental defects such as single function, incomplete mechanism, and poor synergy. They are difficult to achieve ideal results in simultaneously removing heavy metals, degrading organic matter, and effectively inhibiting bacteria.

[0004] Therefore, there is an urgent need to develop a water purification agent that can simultaneously and efficiently remove multiple pollutants from complex polluted water bodies in order to meet increasingly stringent water purification requirements. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a multifunctional composite water purifier and its preparation method. By constructing a core-shell synergistic multifunctional water purifier powder and compounding it with auxiliary components such as bentonite, sodium carboxymethyl cellulose, sodium percarbonate, and sodium citrate, a water purifier capable of synergistically removing lead, chromium, and copper heavy metal ions, degrading organic pollutants, decolorizing, and inhibiting microorganisms is obtained.

[0006] The technical solution of the present invention to solve the above problems is as follows:

[0007] A multifunctional composite water purification agent comprises the following raw materials in parts by weight: 90-100 parts of multifunctional water purification powder, 8-10 parts of bentonite, 0.5-1.5 parts of sodium carboxymethyl cellulose, 0.5-1 parts of sodium percarbonate, and 0.5-1 parts of sodium citrate; wherein the multifunctional water purification powder comprises a core material and a shell slurry.

[0008] The preparation method of the core layer material is as follows:

[0009] Step S1: Immerse the pretreated coconut shell carbonized material in the mixed impregnation solution at 55-65℃ for 8-9 hours. After impregnation, filter under reduced pressure. Pre-dry the filter cake at 75-85℃ for 4-5 hours. Then, under a nitrogen atmosphere, heat to 540-560℃ and hold for 1-2 hours. Then switch to a hydrogen sulfide / nitrogen mixed gas and heat to 640-660℃ and hold for 1-2 hours. After the reaction is completed, switch to pure nitrogen and cool to room temperature to obtain sulfur-doped biochar support.

[0010] Step S2: Disperse the sulfur-doped biochar support in a mixed solvent, add ferrous sulfate, and sonicate under an inert atmosphere for 60-70 min. Then, add sodium borohydride solution under an ice bath and inert atmosphere, and stir at room temperature for 2-2.5 h. After the reaction is completed, the oxidation-promoted core layer material is obtained after post-treatment.

[0011] Step S3: Disperse the oxidation-promoting core layer material in anhydrous ethanol, add γ-aminopropyltriethoxysilane, and react at 55-65℃ for 4-5 hours under an inert atmosphere. After the reaction is completed, the silanized core layer material is obtained through post-treatment.

[0012] Step S4: Graphene oxide and silanized core material are ultrasonically dispersed in deionized water, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is added, and the mixture is stirred at room temperature for 12-13 hours. After the reaction is completed, the core material is obtained through post-treatment.

[0013] Further, in step S1, the mass ratio of the pretreated coconut shell carbonized material to the mixed impregnation solution is 17:95-105. The mixed impregnation solution contains ferric chloride and sodium thiosulfate in a mass ratio of 8.7-9.1:3, the solvent is deionized water, and the concentration of ferric chloride is 0.5-0.7 mol / L.

[0014] Further, in step S2, the mass ratio of the sulfur-doped biochar carrier, mixed solvent, ferrous sulfate, and sodium borohydride solution is 44:105-115:2-2.5:27.4-27.8. The mixed solvent is composed of anhydrous ethanol and deionized water in a volume ratio of 1:2.5-3.5, and the sodium borohydride solution is composed of sodium borohydride and 0.1 mol / L NaOH solution in a mass ratio of 5-5.4:50.

[0015] Further, in step S3, the mass ratio of the oxidation-promoting core layer material, anhydrous ethanol, and γ-aminopropyltriethoxysilane is 60-60.5:1200:1.5-2.

[0016] Further, in step S4, the mass ratio of graphene oxide, silanized core material, deionized water, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is 0.8-1:61-61.5:900:0.2-0.3.

[0017] Furthermore, the preparation method of the shell slurry is as follows:

[0018] Step a: Dissolve chitosan in acetic acid solution, add 3-chloro-2-hydroxypropyltrimethylammonium chloride, react at 55-65℃ for 6-7 hours to obtain intermediate solution;

[0019] Step b: Adjust the pH of the intermediate solution to 5.9-6.1, add N,N'-diisopropylcarbodiimide and guanidinoacetic acid, and react at room temperature for 12-13 h. After the reaction is completed, the modified chitosan quaternary ammonium salt is obtained through post-treatment.

[0020] Step c: Add titanium dioxide and modified chitosan quaternary ammonium salt to deionized water and ultrasonically disperse for 30-40 minutes to obtain shell slurry.

[0021] Further, the mass ratio of chitosan, acetic acid solution, and 3-chloro-2-hydroxypropyltrimethylammonium chloride in step a is 4.3:425-435:3-4.

[0022] Further, in step b, the mass ratio of the intermediate solution, N,N'-diisopropylcarbodiimide, and guanidinoacetic acid is 435-440:5-5.5:4.

[0023] Further, in step c, the mass ratio of titanium dioxide, modified chitosan quaternary ammonium salt, and deionized water is 25:5-5.3:295-305.

[0024] The preparation method of the above-mentioned multifunctional composite water purification agent includes the following steps:

[0025] (1) Add the core material to the shell slurry and stir at 25-35℃ for 6-7h. After the reaction is completed, after post-treatment, mix with the auxiliary functional solution at a solid-liquid mass ratio of 1:2.5-3.5 and stir at room temperature for 2-3h. Then, after post-treatment, obtain multifunctional water purification powder. The auxiliary functional solution is composed of 3,3'-dithiodipropionic acid, 2-aminoethylphosphonic acid, polyaspartic acid and deionized water in a mass ratio of 1:0.5:0.5:66.

[0026] (2) Mix the multifunctional water purification powder, bentonite, sodium carboxymethyl cellulose, sodium percarbonate and sodium citrate evenly to obtain the final product.

[0027] The present invention has the following beneficial effects:

[0028] The multifunctional composite water purifier provided by this invention constructs a multifunctional water purifier powder with a core-shell structure and scientifically combines it with bentonite, sodium carboxymethyl cellulose, sodium percarbonate, and sodium citrate to form a highly synergistic and functionally complementary material system, significantly improving the simultaneous removal capacity of various pollutants such as heavy metal ions, organic pollutants, color, and microorganisms. The multifunctional water purifier powder comprises a core material and a shell slurry. The core material uses sulfur-doped biochar as a framework, loaded with nano-zero-valent iron, aminosilane, and graphene oxide, possessing strong reducing properties, high specific surface area, abundant functional groups, and magnetic separation characteristics, primarily achieving efficient adsorption, reduction, and fixation of heavy metals such as copper, lead, and chromium. The shell slurry is composed of quaternized chitosan and nano-titanium dioxide, endowing the multifunctional water purifier powder with cationic adsorption capacity, broad-spectrum antibacterial properties, and photocatalytic oxidation activity, effectively capturing anionic pollutants, inhibiting bacterial growth, and degrading organic matter. The core-shell structure, through spatially ordered integration, enables the synergistic action of multiple mechanisms, including adsorption, reduction, catalysis, and antibacterial activity. This avoids interference between functional components and promotes the transfer or in-situ degradation of pollutants from the shell layer to the core layer after enrichment. Furthermore, bentonite provides additional adsorption sites and enhances particle shapeability, sodium carboxymethyl cellulose improves dispersion stability, sodium percarbonate generates reactive oxygen species to enhance oxidation under the activation of ferrous ions in the core layer, and sodium citrate regulates the form of metal ions and prevents precipitation from clogging active sites through complexation. In this composite water purifier system, the components support each other and are functionally coupled, forming an organic whole. This results in a water purifier exhibiting highly efficient, broad-spectrum, and long-lasting comprehensive performance in heavy metal removal, COD degradation, decolorization, and antibacterial activity, significantly outperforming single-functional materials or simple physical mixtures, demonstrating excellent overall integrity. Attached Figure Description

[0029] Figure 1 The graph shows the removal rates of copper, chromium, and lead ions in the water purification agents prepared in Examples 1-4 and Comparative Examples 1-4.

[0030] Figure 2The graph shows the COD removal rate results of the water purification agents prepared in Examples 1-4 and Comparative Examples 1-4. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] The raw materials used in the following examples are all commercially available products. Bentonite with 96% effective ingredient content, 300 mesh particle size, and 75% whiteness, produced by Sishui Shengxin Refractory Materials Co., Ltd.; Sodium carboxymethyl cellulose with 99.7% effective ingredient content, viscosity 3100 mPa·s, conforming to standard GB1886.232-2016, produced by Shandong Pingju Biotechnology Co., Ltd.; Coconut shell carbonized material with moisture ≤10wt%, ash content ≤10wt%, and methylene blue value (ml / 0.1g) 8-12, produced by Henan Xiangzhiyuan Water Treatment Materials Co., Ltd.; Ferrous sulfate (ferrous sulfate heptahydrate) with 96% effective ingredient content, produced by Shanghai Yantai E-commerce Co., Ltd.; Graphene oxide with 99% effective ingredient content, produced by Hubei Langbowan Biomedical Co., Ltd.; Chitosan with 99% purity and 90% deacetylation degree, produced by Hubei Watson Chemical Technology Co., Ltd.; Guanidoacetic acid with 98% effective ingredient content, produced by Wuhan Huajiu Pharmaceutical Technology Co., Ltd.; Titanium dioxide (P25 type) with 98% effective ingredient content, produced by Shanghai Zhenlishi Network Technology Co., Ltd.; Polyaspartic acid with 40% effective ingredient content and pH value 9-11, produced by Shandong Wanhua Tianhe New Materials Co., Ltd. Example 1

[0033] A multifunctional composite water purification agent comprises the following raw materials in parts by weight: 90 parts multifunctional water purification powder, 8 parts bentonite, 0.5 parts sodium carboxymethyl cellulose, 0.5 parts sodium percarbonate, and 0.5 parts sodium citrate; the multifunctional water purification powder comprises a core material and a shell slurry.

[0034] The preparation method of the core layer material is as follows:

[0035] Step S1: At 60℃, the pretreated coconut shell carbonized material is impregnated in a mixed impregnation solution at 200 rpm for 8.5 h with stirring. After impregnation, the mixture is filtered under reduced pressure. The filter cake is pre-dried at 80℃ for 4.5 h, then heated to 550℃ at 10℃ / min and held for 1.5 h under a nitrogen atmosphere with a flow rate of 1.5 L / min. Subsequently, the temperature is switched to a hydrogen sulfide / nitrogen mixture containing 5% hydrogen sulfide, with a total flow rate of 1.0 L / min, and heated to 650℃ at 10℃ / min and held for 1.5 h. The reaction is then completed. The mixture was replaced with pure nitrogen and allowed to cool naturally to room temperature to obtain a sulfur-doped biochar carrier. The pretreatment process for the coconut shell carbonized material was as follows: the coconut shell carbonized material was crushed and passed through a 40-mesh sieve, washed three times with deionized water, and then dried at 80°C for 12 hours to obtain the pretreated coconut shell carbonized material. The mass ratio of the pretreated coconut shell carbonized material to the mixed impregnation solution was 17:100. The mixed impregnation solution contained ferric chloride and sodium thiosulfate in a mass ratio of 8.9:3. The solvent was deionized water, and the concentration of ferric chloride was 0.6 mol / L.

[0036] Step S2: The sulfur-doped biochar support is dispersed in a mixed solvent, ferrous sulfate is added, and the mixture is ultrasonically treated for 65 min at a power of 300 W and a frequency of 40 kHz under a nitrogen atmosphere with a flow rate of 0.5 L / min. Then, sodium borohydride solution is added dropwise at a rate of 3 mL / min under an ice bath and a nitrogen atmosphere while stirring. After the addition is complete, the mixture is stirred and reacted at room temperature for 2.3 h. After the reaction is completed, magnetic separation is performed using a permanent magnet, followed by washing with deoxygenated deionized water and anhydrous ethanol in sequence, and then vacuum drying at 60 °C for 12 h to obtain the oxidation-promoting core layer material. The mass ratio of sulfur-doped biochar support, mixed solvent, ferrous sulfate, and sodium borohydride solution is 44:110:2.2:27.6. The mixed solvent is composed of anhydrous ethanol and deionized water in a volume ratio of 1:3, and the sodium borohydride solution is composed of sodium borohydride and 0.1 mol / L NaOH solution in a mass ratio of 5.2:50.

[0037] Step S3: Disperse the oxidation-promoting core layer material in anhydrous ethanol, add γ-aminopropyltriethoxysilane, and reflux at 60°C for 4.5 h under a nitrogen atmosphere. After the reaction is completed, the product is magnetically separated, washed three times with anhydrous ethanol, and dried at 60°C to constant weight to obtain the silanized core layer material. The mass ratio of the oxidation-promoting core layer material, anhydrous ethanol, and γ-aminopropyltriethoxysilane is 60.3:1200:1.8.

[0038] Step S4: Graphene oxide and silanized core material are ultrasonically dispersed in deionized water at a power of 300W and a frequency of 40kHz. 1-Ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is added, and the mixture is stirred at room temperature for 12.5h. After the reaction is completed, the product is magnetically separated, washed three times with anhydrous ethanol, and dried at 60℃ to constant weight to obtain the core material. The mass ratio of graphene oxide, silanized core material, deionized water, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is 0.9:61.3:900:0.25.

[0039] The preparation method of the shell slurry is as follows:

[0040] Step a: Dissolve chitosan in 1 wt% acetic acid solution, add 3-chloro-2-hydroxypropyltrimethylammonium chloride, react at 60℃ for 6.5 h to obtain an intermediate solution, wherein the mass ratio of chitosan, acetic acid solution, and 3-chloro-2-hydroxypropyltrimethylammonium chloride is 4.3:430:3.5;

[0041] Step b: Adjust the pH of the intermediate solution to 5.9-6.1 with 0.5M NaOH solution, add N,N'-diisopropylcarbodiimide and guanidinoacetic acid, and react at room temperature for 12.5 h. After the reaction is complete, transfer the product to a dialysis bag with a molecular weight cutoff of 50,000 Daltons, dialyze with deionized water for 48 h, changing the water every 8 h, and then freeze-dry to constant weight to obtain modified chitosan quaternary ammonium salt. The mass ratio of intermediate solution, N,N'-diisopropylcarbodiimide and guanidinoacetic acid is 438:5.2:4.

[0042] Step c: Add titanium dioxide and modified chitosan quaternary ammonium salt to deionized water and ultrasonically disperse for 35 minutes at a power of 400W and a frequency of 40kHz to obtain a shell slurry, wherein the mass ratio of titanium dioxide, modified chitosan quaternary ammonium salt and deionized water is 25:5.1:300.

[0043] The preparation method of the above-mentioned multifunctional composite water purification agent includes the following steps:

[0044] (1) The core material was added to the shell slurry, and the mass ratio of the core material to the shell slurry was 31:165. The mixture was stirred at 25°C for 6 hours. After the reaction was completed, the mixture was magnetically separated, washed three times with deionized water, dried at 80°C for 12 hours, and then mixed with the auxiliary functional solution at a solid-liquid mass ratio of 1:2.5. The mixture was stirred at room temperature for 2 hours and then spray-dried: the inlet air temperature was 180°C, the outlet air temperature was 85°C, and the atomizer speed was 20000 rpm to obtain a multifunctional water purification powder. The auxiliary functional solution was composed of 3,3'-dithiodipropionic acid, 2-aminoethylphosphonic acid, polyaspartic acid, and deionized water in a mass ratio of 1:0.5:0.5:66.

[0045] (2) Mix the multifunctional water purification powder, bentonite, sodium carboxymethyl cellulose, sodium percarbonate and sodium citrate evenly at 30 rpm to obtain the final product. Example 2

[0046] A multifunctional composite water purification agent comprises the following raw materials in parts by weight: 95 parts multifunctional water purification powder, 9 parts bentonite, 1 part sodium carboxymethyl cellulose, 0.8 parts sodium percarbonate, and 0.7 parts sodium citrate; the multifunctional water purification powder comprises a core material and a shell slurry.

[0047] The preparation methods for the core material and the shell slurry are the same as in Example 1.

[0048] The preparation method of the above-mentioned multifunctional composite water purification agent includes the following steps:

[0049] (1) The core material was added to the shell slurry, and the mass ratio of the core material to the shell slurry was 31:165. The mixture was stirred at 30°C for 6.5 h. After the reaction was completed, the mixture was magnetically separated, washed three times with deionized water, dried at 80°C for 12 h, and then mixed with the auxiliary functional solution at a solid-liquid mass ratio of 1:3. The mixture was stirred at room temperature for 2.5 h and then spray dried: the inlet air temperature was 180°C, the outlet air temperature was 85°C, and the atomizer speed was 20000 rpm to obtain a multifunctional water purification powder. The auxiliary functional solution was composed of 3,3'-dithiodipropionic acid, 2-aminoethylphosphonic acid, polyaspartic acid, and deionized water in a mass ratio of 1:0.5:0.5:66.

[0050] (2) Mix the multifunctional water purification powder, bentonite, sodium carboxymethyl cellulose, sodium percarbonate and sodium citrate evenly at 30 rpm to obtain the final product. Example 3

[0051] A multifunctional composite water purification agent comprises the following raw materials in parts by weight: 100 parts of multifunctional water purification powder, 10 parts of bentonite, 1.5 parts of sodium carboxymethyl cellulose, 1 part of sodium percarbonate, and 1 part of sodium citrate; wherein the multifunctional water purification powder comprises a core material and a shell slurry.

[0052] The preparation methods for the core material and the shell slurry are the same as in Example 1.

[0053] The preparation method of the above-mentioned multifunctional composite water purification agent includes the following steps:

[0054] (1) The core material was added to the shell slurry at a mass ratio of 31:165. The mixture was stirred at 35°C for 7 hours. After the reaction was completed, the mixture was magnetically separated, washed three times with deionized water, dried at 80°C for 12 hours, and then mixed with the auxiliary functional solution at a solid-liquid mass ratio of 1:3.5. The mixture was stirred at room temperature for 3 hours and then spray-dried: the inlet air temperature was 180°C, the outlet air temperature was 85°C, and the atomizer speed was 20000 rpm to obtain a multifunctional water purification powder. The auxiliary functional solution was composed of 3,3'-dithiodipropionic acid, 2-aminoethylphosphonic acid, polyaspartic acid, and deionized water at a mass ratio of 1:0.5:0.5:66.

[0055] (2) Mix the multifunctional water purification powder, bentonite, sodium carboxymethyl cellulose, sodium percarbonate and sodium citrate evenly at 30 rpm to obtain the final product. Example 4

[0056] A multifunctional composite water purification agent comprises the following raw materials in parts by weight: 100 parts of multifunctional water purification powder, 10 parts of bentonite, 1.5 parts of sodium carboxymethyl cellulose, 1 part of sodium percarbonate, and 1 part of sodium citrate; wherein the multifunctional water purification powder comprises a core material and a shell slurry.

[0057] The preparation method of the core layer material is as follows:

[0058] Step S1: At 65℃, the pretreated coconut shell carbonized material is impregnated in a mixed impregnation solution at 200 rpm for 9 hours. After impregnation, the mixture is filtered under reduced pressure. The filter cake is pre-dried at 85℃ for 5 hours, and then heated to 560℃ at 10℃ / min and held for 2 hours under a nitrogen atmosphere at a flow rate of 1.5 L / min. Subsequently, the temperature is switched to a hydrogen sulfide / nitrogen mixture containing 5% hydrogen sulfide at a total flow rate of 1.0 L / min and heated to 660℃ at 10℃ / min and held for 2 hours. After the reaction is completed, pure nitrogen is switched to the solution. The mixture was allowed to cool naturally to room temperature to obtain a sulfur-doped biochar carrier. The pretreatment process of the coconut shell carbonized material was as follows: the coconut shell carbonized material was crushed to 40 mesh and sieved, washed three times with deionized water, and then dried at 80℃ for 12 hours to obtain the pretreated coconut shell carbonized material. The mass ratio of the pretreated coconut shell carbonized material to the mixed impregnation solution was 17:105. The mixed impregnation solution contained ferric chloride and sodium thiosulfate in a mass ratio of 9.1:3. The solvent was deionized water, and the concentration of ferric chloride was 0.7 mol / L.

[0059] Step S2: The sulfur-doped biochar support is dispersed in a mixed solvent, ferrous sulfate is added, and the mixture is ultrasonically treated for 70 min at a power of 300 W and a frequency of 40 kHz under a nitrogen atmosphere with a flow rate of 0.5 L / min. Then, under an ice bath and nitrogen atmosphere, sodium borohydride solution is added dropwise at a rate of 3 mL / min while stirring. After the addition is complete, the mixture is stirred and reacted at room temperature for 2.5 h. After the reaction is completed, magnetic separation is performed using a permanent magnet, followed by washing with deoxygenated deionized water and anhydrous ethanol in sequence, and then vacuum drying at 60 °C for 12 h to obtain the oxidation-promoting core layer material. The mass ratio of sulfur-doped biochar support, mixed solvent, ferrous sulfate, and sodium borohydride solution is 44:115:2.5:27.8. The mixed solvent is composed of anhydrous ethanol and deionized water with a volume ratio of 1:3.5, and the sodium borohydride solution is composed of sodium borohydride and 0.1 mol / L NaOH solution with a mass ratio of 5.4:50.

[0060] Step S3: Disperse the oxidation-promoting core layer material in anhydrous ethanol, add γ-aminopropyltriethoxysilane, and reflux at 65°C for 5 hours under a nitrogen atmosphere. After the reaction is completed, the product is magnetically separated, washed three times with anhydrous ethanol, and dried at 60°C to constant weight to obtain the silanized core layer material. The mass ratio of the oxidation-promoting core layer material, anhydrous ethanol, and γ-aminopropyltriethoxysilane is 60.5:1200:2.

[0061] Step S4: Graphene oxide and silanized core material are ultrasonically dispersed in deionized water at a power of 300W and a frequency of 40kHz. 1-Ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is added, and the mixture is stirred at room temperature for 13 hours. After the reaction is completed, the product is magnetically separated, washed three times with anhydrous ethanol, and dried at 60°C to constant weight to obtain the core material. The mass ratio of graphene oxide, silanized core material, deionized water, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is 1:61.5:900:0.3.

[0062] The preparation method of the shell slurry is as follows:

[0063] Step a: Dissolve chitosan in 1 wt% acetic acid solution, add 3-chloro-2-hydroxypropyltrimethylammonium chloride, react at 65℃ for 7 h to obtain an intermediate solution, wherein the mass ratio of chitosan, acetic acid solution and 3-chloro-2-hydroxypropyltrimethylammonium chloride is 4.3:435:4;

[0064] Step b: Adjust the pH of the intermediate solution to 5.9-6.1 with 0.5M NaOH solution, add N,N'-diisopropylcarbodiimide and guanidinoacetic acid, and react at room temperature for 13 h. After the reaction is complete, transfer the product to a dialysis bag with a molecular weight cutoff of 50,000 Daltons, dialyze with deionized water for 48 h, changing the water every 8 h, and then freeze-dry to constant weight to obtain modified chitosan quaternary ammonium salt. The mass ratio of intermediate solution, N,N'-diisopropylcarbodiimide and guanidinoacetic acid is 440:5.5:4.

[0065] Step c: Add titanium dioxide and modified chitosan quaternary ammonium salt to deionized water and ultrasonically disperse for 40 minutes at a power of 400W and a frequency of 40kHz to obtain a shell slurry, wherein the mass ratio of titanium dioxide, modified chitosan quaternary ammonium salt and deionized water is 25:5.3:305.

[0066] The preparation method of the above-mentioned multifunctional composite water purification agent includes the following steps:

[0067] (1) The core material was added to the shell slurry at a mass ratio of 31:165. The mixture was stirred at 35°C for 7 hours. After the reaction was completed, the mixture was magnetically separated, washed three times with deionized water, dried at 80°C for 12 hours, and then mixed with the auxiliary functional solution at a solid-liquid mass ratio of 1:3.5. The mixture was stirred at room temperature for 3 hours and then spray-dried: the inlet air temperature was 180°C, the outlet air temperature was 85°C, and the atomizer speed was 20000 rpm to obtain a multifunctional water purification powder. The auxiliary functional solution was composed of 3,3'-dithiodipropionic acid, 2-aminoethylphosphonic acid, polyaspartic acid, and deionized water at a mass ratio of 1:0.5:0.5:66.

[0068] (2) Mix the multifunctional water purification powder, bentonite, sodium carboxymethyl cellulose, sodium percarbonate and sodium citrate evenly at 30 rpm to obtain the final product. Comparative Example 1

[0069] A multifunctional composite water purification agent comprises the following raw materials in parts by weight: 50 parts of multifunctional water purification powder, 10 parts of bentonite, 1.5 parts of sodium carboxymethyl cellulose, 1 part of sodium percarbonate, and 1 part of sodium citrate; wherein the multifunctional water purification powder comprises a core material and a shell slurry.

[0070] The preparation method of the core layer material is as follows:

[0071] Step S1: At room temperature, the pretreated coconut shell carbonized material is stirred and impregnated in the mixed impregnation solution at 200 rpm for 9 hours. After impregnation, the material is filtered under reduced pressure. The filter cake is pre-dried at 85℃ for 5 hours. Then, under a nitrogen atmosphere with a flow rate of 1.5 L / min, the temperature is increased to 560℃ at 10℃ / min and held for 2 hours. Then, the temperature is increased to 660℃ at 10℃ / min and held for 2 hours. The material is then allowed to cool naturally to room temperature to obtain a sulfur-doped biochar carrier. The pretreatment process of the coconut shell carbonized material is to crush the coconut shell carbonized material to a 40-mesh sieve, wash it three times with deionized water, and dry it at 80℃ for 12 hours to obtain the pretreated coconut shell carbonized material. The mass ratio of the pretreated coconut shell carbonized material to the mixed impregnation solution is 17:105. The mixed impregnation solution contains ferric chloride and sodium thiosulfate in a mass ratio of 1:1. The solvent is deionized water, and the concentration of ferric chloride is 0.7 mol / L.

[0072] Step S2: The sulfur-doped biochar support is dispersed in a mixed solvent, ferrous sulfate is added, and the mixture is ultrasonically treated for 70 min at a power of 300 W and a frequency of 40 kHz under a nitrogen atmosphere with a flow rate of 0.5 L / min. Then, sodium borohydride solution is added under an ice bath and a nitrogen atmosphere. After the addition is complete, the mixture is stirred at room temperature for 1 h. After the reaction is completed, magnetic separation is performed using a permanent magnet. The mixture is then washed sequentially with deoxygenated deionized water and anhydrous ethanol, and then vacuum dried at 60 °C for 12 h to obtain the oxidation-promoting core layer material. The mass ratio of sulfur-doped biochar support, mixed solvent, ferrous sulfate, and sodium borohydride solution is 44:115:1:20. The mixed solvent is composed of anhydrous ethanol and deionized water with a volume ratio of 1:3.5, and the sodium borohydride solution is composed of sodium borohydride and 0.1 mol / L NaOH solution with a mass ratio of 5.4:50.

[0073] Step S3: Disperse the oxidation-promoting core layer material in anhydrous ethanol, add γ-aminopropyltriethoxysilane, and reflux at room temperature for 5 hours under a nitrogen atmosphere. After the reaction is completed, the product is magnetically separated, washed three times with anhydrous ethanol, and dried at 60°C to constant weight to obtain the silanized core layer material. The mass ratio of the oxidation-promoting core layer material, anhydrous ethanol, and γ-aminopropyltriethoxysilane is 60.5:1200:1.

[0074] Step S4: Graphene oxide and silanized core material are ultrasonically dispersed in deionized water at a power of 300W and a frequency of 40kHz. 1-Ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is added, and the mixture is stirred at room temperature for 2 hours. After the reaction is completed, the product is magnetically separated, washed three times with anhydrous ethanol, and dried at 60℃ to constant weight to obtain the core material. The mass ratio of graphene oxide, silanized core material, deionized water, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is 1:50:900:0.3.

[0075] The preparation method of the shell slurry is as follows:

[0076] Step a: Dissolve chitosan in 1 wt% acetic acid solution, add 3-chloro-2-hydroxypropyltrimethylammonium chloride, react at room temperature for 7 h to obtain an intermediate solution, wherein the mass ratio of chitosan, acetic acid solution, and 3-chloro-2-hydroxypropyltrimethylammonium chloride is 4.3:435:1;

[0077] Step b: Adjust the pH of the intermediate solution to 5.9-6.1 with 0.5M NaOH solution, add N,N'-diisopropylcarbodiimide and guanidinoacetic acid, and react at room temperature for 13 h. After the reaction is complete, transfer the product to a dialysis bag with a molecular weight cutoff of 50,000 Daltons, dialyze with deionized water for 48 h, changing the water every 8 h, and then freeze-dry to constant weight to obtain modified chitosan quaternary ammonium salt. The mass ratio of intermediate solution, N,N'-diisopropylcarbodiimide and guanidinoacetic acid is 440:1:1.

[0078] Step c: Add titanium dioxide and modified chitosan quaternary ammonium salt to deionized water and ultrasonically disperse for 40 minutes at a power of 400W and a frequency of 40kHz to obtain a shell slurry, wherein the mass ratio of titanium dioxide, modified chitosan quaternary ammonium salt and deionized water is 5:5:305.

[0079] The preparation method of the above-mentioned multifunctional composite water purification agent includes the following steps:

[0080] (1) The core material was added to the shell slurry. The mass ratio of the core material to the shell slurry was 31:165. The mixture was stirred at 35°C for 7 hours. After the reaction was completed, the mixture was magnetically separated, washed three times with deionized water, dried at 80°C for 12 hours, and then mixed with the auxiliary functional solution at a solid-liquid mass ratio of 1:1. The mixture was stirred at room temperature for 3 hours and then spray-dried: the inlet air temperature was 180°C, the outlet air temperature was 85°C, and the atomizer speed was 20000 rpm to obtain a multifunctional water purification powder. The auxiliary functional solution was composed of 3,3'-dithiodipropionic acid, 2-aminoethylphosphonic acid, polyaspartic acid, and deionized water in a mass ratio of 1:0.5:0.5:66.

[0081] (2) Mix the multifunctional water purification powder, bentonite, sodium carboxymethyl cellulose, sodium percarbonate and sodium citrate evenly at 30 rpm to obtain the final product. Comparative Example 2

[0082] A multifunctional composite water purifier, wherein the core material is replaced with coconut shell carbonized material, and the rest is the same as in Example 1. Comparative Example 3

[0083] A multifunctional composite water purification agent, wherein the shell layer slurry is replaced with a chitosan acetic acid solution, wherein the mass ratio of chitosan to 1 wt% acetic acid solution is 4.3:430, and the rest are the same as in Example 1. Comparative Example 4

[0084] A multifunctional composite water purifier, wherein the core material is replaced with coconut shell carbonized material, and the shell slurry is replaced with chitosan acetic acid solution, wherein the mass ratio of chitosan to 1wt% acetic acid solution is 4.3:430, and the rest are the same as in Example 1.

[0085] The prepared multifunctional composite water purification agent was added to industrial wastewater at a dosage of 0.5 g / L. The pH of the wastewater was 6.5. The initial and treated components of the wastewater were analyzed, and the removal rates of various components before and after the addition of the water purification agent were calculated, including copper ion removal rate, chromium ion removal rate, lead ion removal rate, COD removal rate, and color removal rate. The 48-hour inhibition rate of Escherichia coli was measured according to the dilution plate method in GB / T4789.2-2022. The test results are shown in Table 1. Figure 1-2 As shown.

[0086] Table 1 Performance Test Results

[0087] sample Copper ion removal rate (%) Chromium ion removal rate (%) Lead ion removal rate (%) COD removal rate (%) Color removal rate (%) Escherichia coli inhibition rate (%) after 48 hours Example 1 99.5 99.1 98.4 73.7 78.0 99.5 Example 2 99.0 99.5 98.0 73.2 78.2 99.8 Example 3 99.3 99.2 98.2 73.5 78.5 99.6 Example 4 99.1 99.6 98.0 72.8 78.4 99.6 Comparative Example 1 86.7 88.3 87.6 65.8 70.6 90.2 Comparative Example 2 78.4 75.9 80.2 69.3 76.9 97.5 Comparative Example 3 89.3 92.7 89.4 63.4 64.1 88.3 Comparative Example 4 76.5 74.1 78.7 60.5 62.0 84.8

[0088] From Table 1 and Figure 1-2 It can be seen that the comprehensive performance of the multifunctional composite water purifier prepared in Examples 1-4 is better than that of the water purifier prepared in Comparative Example 1. Its removal rates of copper, chromium and lead ions are significantly higher, and the COD removal rate and color removal rate brought about by the degradation of recalcitrant organic matter are better. It also has a more prominent 48-hour antibacterial effect on Escherichia coli. Therefore, it can be concluded that the raw material ratio and process parameters of the examples are optimal.

[0089] From Table 1 and Figure 1-2It can be seen that the removal rates of copper, chromium, and lead ions, COD, color, and E. coli inhibition rate of the multifunctional composite water purifier prepared in Comparative Example 2 are all worse than those of the water purifiers prepared in Examples 1-4. This is because the core material was replaced with coconut shell carbonized material. In step S1 of the example, sulfur was introduced into the coconut shell carbonized material skeleton through high-temperature carbonization and gas-phase sulfidation processes. This sulfur-doped biochar carrier not only retains the high specific surface area and fast mass transfer channels given by the porous structure of biomass, but more importantly, sulfur atoms are embedded in the carbon matrix in the form of CSC and Fe-S bonds, which significantly enhances the negative charge on the material surface and produces specific electrostatic adsorption and chemical complexation for cationic heavy metals such as copper and lead ions. At the same time, the electron-rich characteristics of sulfur reduce the charge transfer impedance when loading nano-zero valent iron, providing sufficient electron donor capacity for the reduction and removal of Cr(VI), thereby directly improving the overall removal efficiency of heavy metals by the water purifier. In step S2 of the embodiment, nano-zero-valent iron particles are generated in situ on the surface of sulfur-doped biochar, forming a composite structure with magnetic properties and strong reducing power. This gives the core material Fenton-like catalytic activity and electron donor capability, which can effectively reduce toxic high-valent metals such as hexavalent chromium to low-toxicity or easily precipitated forms, significantly enhancing the removal efficiency of heavy metals such as chromium, copper, and lead. At the same time, the ferrous ions slowly released by zero-valent iron in the water environment can activate sodium percarbonate in the system to generate active oxygen, promoting the oxidative degradation of organic matter, thereby improving the COD removal rate. In addition, the magnetic characteristics facilitate material recycling, ensuring the ease of operation and recyclability of the water purification agent in actual water treatment processes. In step S3 of the embodiment, the silanization treatment optimizes the surface properties and interfacial compatibility of the core layer material. Introducing amino functional groups onto the core surface not only enhances the material's dispersion stability in water but also provides active sites for the subsequent chemical bonding of the shell slurry. The amino groups can capture heavy metal ions through coordination and form amide bonds with graphene oxide, constructing a stable conductive network and promoting electron transfer, thereby improving the catalytic degradation efficiency of pollutants. This step also improves the bonding force between the core and shell layers, preventing the functional components from detaching during use and ensuring the long-term stability of the water purification agent's performance. In step S4 of the embodiment, the introduction of graphene oxide further expands the adsorption and catalytic interface of the core layer material. Graphene oxide is covalently linked to silanized core materials via amide bonds. Its layered structure not only significantly increases the specific surface area and provides more adsorption sites, but its abundant carboxyl functional groups can also attract positively charged heavy metal ion pollutants through electrostatic interactions. At the same time, the high conductivity of graphene promotes electron transport within the core material, enhances the efficiency of redox reactions, and helps to further improve the removal effect of organic pollutants and color.

[0090] From Table 1 and Figure 1-2It can be seen that the removal rates of copper, chromium, and lead ions, COD, color, and E. coli inhibition rate of the multifunctional composite water purifier prepared in Comparative Example 3 are all worse than those prepared in Examples 1-4. This is because the shell slurry was replaced with chitosan acetate solution. In step a of the example, chitosan was first modified by quaternization, and the introduction of quaternary ammonium groups endowed the material with strong positive charge and antibacterial function. This step significantly improved the E. coli inhibition rate of the water purifier and helped to enhance the removal ability of negatively charged pollutants. Specifically, the quaternary ammonium salt groups bind to the bacterial cell membrane through electrostatic attraction, destroying the membrane structure and causing cell death. At the same time, the positive charge on the surface of the material can adsorb cationic heavy metals such as copper and lead through ion exchange and complexation, providing a charge basis for subsequent functionalization. In step b of the example, N,N'-diisopropylcarbodiimide and guanidinoacetic acid were introduced to further graft guanidino group-containing functional groups onto the intermediate. Guanidinium compounds possess strong basicity, high protonation capacity, and excellent antibacterial activity. They not only enhance the material's ability to capture anionic heavy metal complexes such as chromate, thereby indirectly improving chromium ion removal efficiency, but also disrupt bacterial cell membrane integrity, significantly enhancing the long-lasting antibacterial effect against microorganisms such as Escherichia coli. Furthermore, this step improves the hydrophilicity and stability of chitosan derivatives, making them easier to disperse and fully contact with pollutants during water purification, synergistically promoting the removal of COD and color. In step c of the embodiment, modified chitosan quaternary ammonium salt is combined with titanium dioxide to form a stable shell slurry, giving the shell both photocatalytic activity and polymer adsorption function. Titanium dioxide can generate reactive oxygen species under light, effectively degrading difficult-to-treat organic pollutants and significantly improving COD and color removal capabilities. Modified chitosan, through its cationic properties, can complex or exchange with heavy metal ions such as copper and lead, enhancing the simultaneous removal of multiple heavy metals. The synergistic effect of titanium dioxide and modified chitosan enables the shell layer to not only have a broad-spectrum pollutant removal capability, but also maintain water purification efficiency under light-free conditions by relying on adsorption and antibacterial functions, thereby comprehensively improving the overall purification performance of the water purifier under complex water quality conditions.

[0091] From Table 1 and Figure 1-2It can be seen that the multifunctional composite water purifier prepared in Comparative Example 4 had the worst removal rates of copper, chromium, and lead ions, COD, color, and E. coli inhibition rate over 48 hours. This is because the core material was replaced with coconut shell carbonized material, and the shell slurry was replaced with chitosan acetate solution. The core layer of this example is rich in sulfur doping sites, nano-zero-valent iron, and graphene oxide, possessing strong reducing properties and heavy metal chelation ability. The shell layer is composed of quaternized chitosan and titanium dioxide, possessing both cation adsorption, antibacterial, and photocatalytic oxidation functions. After the two are combined, the shell layer can pre-enrich anionic pollutants and inhibit microorganisms, guiding them to migrate to the core layer to achieve efficient reduction or fixation. At the same time, the core layer protects titanium dioxide from heavy metal poisoning and maintains its catalytic activity. The synergistic effect of the core-shell structure of the water purifier significantly improves the simultaneous removal efficiency of heavy metals such as copper, chromium, and lead, COD, color, and E. coli, enabling the water purifier to exhibit broad-spectrum, stable, and efficient comprehensive purification performance in complex water conditions.

[0092] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multifunctional composite water purifier, characterized in that, The raw materials include the following parts by weight: 90-100 parts of multifunctional water purification powder, 8-10 parts of bentonite, 0.5-1.5 parts of sodium carboxymethyl cellulose, 0.5-1 parts of sodium percarbonate, and 0.5-1 parts of sodium citrate; the multifunctional water purification powder includes a core material and a shell slurry. The preparation method of the core layer material is as follows: Step S1: Immerse the pretreated coconut shell carbonized material in a mixed impregnation solution at 55-65℃ for 8-9 hours. After impregnation, filter under reduced pressure. Pre-dry the filter cake at 75-85℃ for 4-5 hours. Then, under a nitrogen atmosphere, heat to 540-560℃ and hold for 1-2 hours. Subsequently, switch to a hydrogen sulfide / nitrogen mixture and heat to 640-660℃ and hold for 1-2 hours. After the reaction is complete, switch to pure nitrogen and cool to room temperature to obtain a sulfur-doped biochar carrier. The mixed impregnation solution contains ferric chloride and sodium thiosulfate in a mass ratio of 8.7-9.1:

3. The solvent is deionized water, and the concentration of ferric chloride is 0.5-0.7 mol / L. Step S2: Disperse the sulfur-doped biochar support in a mixed solvent, add ferrous sulfate, and sonicate under an inert atmosphere for 60-70 min. Then, under an ice bath and inert atmosphere, add sodium borohydride solution and stir at room temperature for 2-2.5 h. After the reaction is completed, the oxidation-promoting core layer material is obtained through post-treatment. The mixed solvent is composed of anhydrous ethanol and deionized water in a volume ratio of 1:2.5-3.

5. Step S3: Disperse the oxidation-promoting core layer material in anhydrous ethanol, add γ-aminopropyltriethoxysilane, and react at 55-65℃ for 4-5 hours under an inert atmosphere. After the reaction is completed, the silanized core layer material is obtained through post-treatment. Step S4: Graphene oxide and silanized core material are ultrasonically dispersed in deionized water, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is added, and the mixture is stirred at room temperature for 12-13 hours. After the reaction is completed, the core material is obtained through post-processing. The preparation method of the shell slurry is as follows: Step a: Dissolve chitosan in acetic acid solution, add 3-chloro-2-hydroxypropyltrimethylammonium chloride, react at 55-65℃ for 6-7 hours to obtain intermediate solution; Step b: Adjust the pH of the intermediate solution to 5.9-6.1, add N,N'-diisopropylcarbodiimide and guanidinoacetic acid, and react at room temperature for 12-13 h. After the reaction is completed, the modified chitosan quaternary ammonium salt is obtained through post-treatment. Step c: Add titanium dioxide and modified chitosan quaternary ammonium salt to deionized water and ultrasonically disperse for 30-40 minutes to obtain shell slurry.

2. The multifunctional composite water purifier according to claim 1, characterized in that, The mass ratio of the pretreated coconut shell carbonized material to the mixed impregnation solution in step S1 is 17:95-105.

3. The multifunctional composite water purifier according to claim 1, characterized in that, In step S2, the mass ratio of the sulfur-doped biochar carrier, mixed solvent, ferrous sulfate, and sodium borohydride solution is 44:105-115:2-2.5:27.4-27.

8. The sodium borohydride solution is composed of sodium borohydride and 0.1 mol / L NaOH solution in a mass ratio of 5-5.4:

50.

4. The multifunctional composite water purifier according to claim 1, characterized in that, The mass ratio of the oxidation-promoting core layer material, anhydrous ethanol, and γ-aminopropyltriethoxysilane in step S3 is 60-60.5:1200:1.5-2.

5. The multifunctional composite water purifier according to claim 1, characterized in that, The mass ratio of graphene oxide, silanized core material, deionized water, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride in step S4 is 0.8-1:61-61.5:900:0.2-0.

3.

6. The multifunctional composite water purifier according to claim 1, characterized in that, The mass ratio of chitosan, acetic acid solution, and 3-chloro-2-hydroxypropyltrimethylammonium chloride in step a is 4.3:425-435:3-4.

7. The multifunctional composite water purifier according to claim 1, characterized in that, The mass ratio of the intermediate solution, N,N'-diisopropylcarbodiimide, and guanidinoacetic acid in step b is 435-440:5-5.5:

4.

8. The multifunctional composite water purifier according to claim 1, characterized in that, The mass ratio of titanium dioxide, modified chitosan quaternary ammonium salt, and deionized water in step c is 25:5-5.3:295-305.

9. The method for preparing the multifunctional composite water purifier according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Add the core material to the shell slurry and stir at 25-35℃ for 6-7h. After the reaction is completed, perform magnetic separation, wash with deionized water 3 times, dry at 80℃ for 12h, and then mix with the auxiliary functional solution at a solid-liquid mass ratio of 1:2.5-3.

5. Stir at room temperature for 2-3h, and then perform spray drying: inlet air temperature 180℃, outlet air temperature 85℃, atomizer speed 20000rpm to obtain multifunctional water purification powder. The auxiliary functional solution is composed of 3,3'-dithiodipropionic acid, 2-aminoethylphosphonic acid, polyaspartic acid and deionized water in a mass ratio of 1:0.5:0.5:

66. (2) Mix the multifunctional water purification powder, bentonite, sodium carboxymethyl cellulose, sodium percarbonate and sodium citrate evenly to obtain the final product.

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