Porous composite material for adsorbing nickel ions in electroplating wastewater tail water and preparation method of porous composite material
By subjecting porous diatomaceous earth to acid washing and alkaline etching treatment and silane coupling agent modification, and loading modified organic chelates, a porous composite material with a hierarchical pore structure was prepared, which solved the problem of insufficient adsorption performance in the existing technology and achieved efficient and stable adsorption of heavy metal ions.
Patent Information
- Application Number
- CN202511867005.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-11
- Publication Date
- 2026-02-17
AI Technical Summary
Existing porous composite materials have unsatisfactory adsorption capacity and selectivity for Cu2+, Ni2+ and Cr3+ in electroplating wastewater tailings, and the modification process is complex, costly, and the materials have poor stability, making them difficult to apply in engineering.
Using porous diatomaceous earth as a substrate, the pores are enlarged through acid washing and alkaline etching. Modified organic chelates are then loaded after the silane coupling agent is introduced to form a hierarchical porous structure and high-density chelation sites. The porous composite material is prepared by utilizing the stable chemical bonding between the silane coupling agent and the modified polyethyleneimine.
It improves the adsorption capacity and selectivity for Cu2+, Ni2+ and Cr3+, enhances the stability and cycle durability of the material, avoids pore blockage, and reduces the complexity and cost of the modification steps.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of wastewater treatment technology, specifically to a porous composite material for nickel ion adsorption in electroplating wastewater effluent and its preparation method. Background Technology
[0002] Currently, for the deep removal of heavy metal ions such as nickel from electroplating wastewater, adsorption methods are widely studied due to their simple process, good selectivity, and suitability for treating low-concentration wastewater. Commonly used porous adsorption materials include activated carbon, porous silica gel, zeolite, ion exchange resins, biochar, and some metal-organic frameworks (MOFs).
[0003] In order to improve its Cu 2+ Ni 2+ and Cr 3+ To assess the adsorption capacity and selectivity of metal ions, researchers typically modify them by introducing nitrogen-, sulfur-, or oxygen-containing functional groups through chemical grafting or surface grafting copolymerization, or by using methods such as metal oxides, hydroxide loading, layered bimetallic hydroxide (LDH) composites, polymer coating, and plasma treatment to construct composite adsorption materials with synergistic effects of porous structures and functional groups for the deep purification of electroplating wastewater tailwater.
[0004] Currently, although commonly used porous adsorbent materials have high specific surface areas, their effective chelation or coordination site density is limited, which is not ideal for low concentrations of Cu. 2+ Ni 2+ and Cr 3+ The adsorption capacity and selectivity are still not ideal. On the other hand, some materials modified by heavy metal oxides, polymer coating or thick inorganic particle loading are prone to clogging the pores and reducing the mass transfer rate, resulting in slower adsorption kinetics. After recycling, the structure is prone to collapse, the mechanical stability is poor, and the adsorption performance decays significantly. In addition, the complex modification steps, high raw material costs and difficulty in separating and recycling powder materials also limit the engineering promotion and application of porous composite adsorption materials in the field of deep treatment of electroplating wastewater tailwater.
[0005] To address this technical deficiency, a solution is proposed. Summary of the Invention
[0006] The purpose of this invention is to provide a porous composite material for adsorbing nickel ions in electroplating wastewater and its preparation method, in order to solve the technical problem that the adsorption performance of porous composite materials for adsorption in electroplating wastewater needs to be further improved.
[0007] The objective of this invention can be achieved through the following technical solution: a method for preparing a porous composite material for nickel ion adsorption in electroplating wastewater, comprising the following steps:
[0008] S1. Place γ-glycidyl etheroxypropyltrimethoxysilane, deionized water and ethanol in a reaction vessel and stir. Add glacial acetic acid aqueous solution to adjust the pH of the system to 4-5. Stir at room temperature for 15-30 min. Add porous diatomaceous earth. Heat the reaction vessel to 60-80℃ and keep it at that temperature for 2-4 h. Post-treatment yields silane-modified porous diatomaceous earth.
[0009] The reaction principle for preparing silane-modified porous diatomaceous earth is as follows:
[0010] During the reaction, γ-glycidoxypropyltrimethoxysilane undergoes hydrolysis under weakly acidic conditions, and the trimethoxysilane group is transformed into an active silanol structure, enabling the silane molecule to react with inorganic surfaces. When porous diatomaceous earth is added to the system, the abundant Si-OH groups on its surface undergo a condensation reaction with the silanol groups generated by the hydrolysis of silane, forming stable Si-O-Si covalent bonds. This allows the silane molecules to be firmly bonded to the surface of the diatomaceous earth, resulting in epoxy-modified silane-modified porous diatomaceous earth.
[0011] S2. Place silane-modified porous diatomaceous earth and deionized water in a reaction vessel, add polyoxyethylene nonylphenol ether, and stir at room temperature for 0.5-1 h to obtain diatomaceous earth slurry.
[0012] S3. Place the diatomaceous earth slurry and the modified organic chelate in a reactor, add ammonia to adjust the pH to 9-10, heat the reactor to 80-90℃, keep the reaction at this temperature for 4-6 hours, and then process to obtain the porous composite material.
[0013] The reaction principle for preparing porous composite materials is as follows:
[0014] During the reaction, after the addition of polyoxyethylene nonylphenol ether, the nonionic surfactant adsorbs onto the silane-modified organic diatomaceous earth surface through its hydrophobic chain, while its hydrophilic polyoxyethylene segments extend into the aqueous phase, forming a uniform hydration layer on the surface of the diatomaceous earth particles. This process significantly improves the wettability, dispersibility, and stability of the diatomaceous earth particles in the aqueous phase, inhibits particle aggregation, and forms a stable diatomaceous earth slurry. Furthermore, after the addition of the modified organic chelate, under alkaline conditions adjusted by ammonia, the nucleophilic groups such as amine groups in its molecules can undergo ring-opening reactions on the epoxy groups on the silane layer, thereby achieving covalent grafting between the organic chelate and the diatomaceous earth carrier. At the same time, the thiol, carboxyl, and amino groups in the chelate molecules remain in an open form on the material surface or inside the pores, so that the final composite material has a porous structure, high specific surface area, and high density of metal ion chelation sites, resulting in a porous composite material.
[0015] Further, in step S1, the ratio of γ-glycidoxypropyltrimethoxysilane, deionized water, ethanol and porous diatomaceous earth is 1-2g:6-8mL:80-100mL:8-10g, and the concentration of glacial acetic acid aqueous solution is 0.5-1.0mol / L. The post-treatment step includes: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed 2-4 times with deionized water and ethanol, transferred to an oven at 50-60℃, and dried to constant weight to obtain silane-modified porous diatomaceous earth.
[0016] Further, in step S2, the ratio of silane-modified porous diatomaceous earth, deionized water, and polyoxyethylene nonylphenol ether is 4-6g:100-120mL:0.5-1g; in step S3, the weight ratio of diatomaceous earth slurry to modified organic chelate is 40-60:25-28, and the concentration of ammonia water is 3-5wt%. The post-treatment steps include: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed 2-4 times with deionized water and ethanol, transferred to an oven at 50-60℃, and dried to constant weight to obtain a porous composite material.
[0017] Furthermore, the porous diatomaceous earth is prepared by the following steps:
[0018] A1. Place diatomaceous earth and hydrochloric acid aqueous solution in a reaction vessel and stir. Heat the reaction vessel to 60-80℃ and keep it at this temperature while stirring for 0.5-1.5 hours. The acid-treated diatomaceous earth is then obtained through post-treatment.
[0019] A2. Place acid-treated diatomaceous earth and sodium hydroxide aqueous solution in a reaction vessel and stir. Heat the reaction vessel to 75-95℃ and keep it at this temperature for 0.5-1.5 hours. Post-treatment yields porous diatomaceous earth.
[0020] The preparation reaction principle of porous diatomaceous earth is as follows:
[0021] During the reaction, naturally occurring impurities in diatomaceous earth, such as metal oxides or carbonates like iron, aluminum, calcium, and magnesium, are easily dissolved, replaced, or complexed in hydrochloric acid aqueous solution and effectively removed. Acid treatment not only reduces the inorganic impurity content of diatomaceous earth and improves the purity of the framework, but also removes some inorganic deposits that block the pores, gradually revealing the inherent microporous and mesoporous structures of diatomaceous earth, making the surface structure more porous and improving the material's affinity for subsequent modification reactions. Furthermore, in step A2, after introducing sodium hydroxide aqueous solution, its strong alkalinity can selectively corrode the Si-O-Si bonds in the amorphous and some weakly structured regions on the surface of diatomaceous earth. That is, the silicate framework is partially dissolved through alkaline etching to generate soluble silicates, thereby forming more micropores and mesoporous structures on the basis of the original pores, significantly increasing the overall specific surface area and porosity of the material, resulting in porous diatomaceous earth.
[0022] Further, the ratio of diatomaceous earth to hydrochloric acid aqueous solution is 2-4g:40-60mL, and the concentration of hydrochloric acid aqueous solution is 10-15wt%. The post-treatment steps include: after the reaction is completed, wait for the reaction to cool to room temperature, filter, wash the filter cake with deionized water and ethanol 2-4 times, transfer it to an oven at 50-60℃, and dry it to constant weight to obtain acid-treated diatomaceous earth; in step A2, the ratio of acid-treated diatomaceous earth to sodium hydroxide aqueous solution is 4-6g:80-100mL, and the concentration of sodium hydroxide aqueous solution is 3-5wt%. The post-treatment steps include: after the reaction is completed, wait for the reaction to cool to room temperature, filter, wash the filter cake with deionized water and ethanol 2-4 times, transfer it to an oven at 50-60℃, dry it to constant weight, grind it through a 200-mesh sieve to obtain porous diatomaceous earth.
[0023] Furthermore, the modified organic chelate is prepared by the following steps:
[0024] B1. Place polyethyleneimine and deionized water in a reaction vessel under nitrogen atmosphere and stir. Heat the reaction vessel to 40-50℃, add succinic anhydride, add ammonia to adjust the pH to 8-9, keep the reaction at the temperature for 2-4 hours, and then process to obtain carboxylated polyethyleneimine precursor.
[0025] The reaction principle for preparing carboxylated polyethyleneimine precursor is as follows:
[0026] During the reaction, the primary and secondary amino groups on the polyethyleneimine molecular chain exhibit strong nucleophilicity under weakly alkaline conditions. When succinic anhydride is added, its cyclic anhydride structure is attacked by the nucleophilic amino groups, resulting in a ring-opening acylation reaction. An amide bond is formed at one end, and a carboxyl group is exposed at the other end. This converts some of the amino groups in polyethyleneimine into amide structures and introduces carboxyl sites on the molecular chain that can be further reacted, thus obtaining a carboxylated polyethyleneimine precursor.
[0027] B2. The carboxylated polyethyleneimine precursor and deionized water were placed in a reaction vessel and stirred. Glacial acetic acid was added to adjust the pH to 4-5. 1-Ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide were added. The mixture was stirred at room temperature for 0.5-1 h. Thiolactic acid and iminodiacetic acid were added. The reaction vessel was heated to 50-60℃ and kept at that temperature for 2-4 h. The modified organic chelate was obtained after post-treatment.
[0028] The reaction principle for the preparation of modified organic chelates is as follows:
[0029] During the reaction, the carboxyl groups of the carboxylated polyethyleneimine precursor are activated in situ with a water-soluble carbodiimide condensing agent under acidic conditions, generating a highly reactive intermediate. With the auxiliary stabilizing effect of N-hydroxysuccinimide, the activated carboxyl groups are further transformed into the more stable NHS-ester structure, which is more easily attacked by nucleophiles. The carboxyl groups in the thiolactic acid and iminodiacetic acid molecules undergo amidation with the remaining amino groups in the carboxylated polyethyleneimine precursor to generate amide bonds. Furthermore, the amino groups in iminodiacetic acid can nucleophilically attack the activated carboxyl groups to form new amide bonds. The mercapto-containing structure and the multi-carboxyl coordination structure are covalently grafted onto the polyethyleneimine backbone, ultimately yielding a modified organic chelate containing amino, mercapto, and carboxyl groups that can coordinate with transition metal ions.
[0030] Further, in step B1, the ratio of polyethyleneimine, deionized water and succinic anhydride is 1-2g:10-12mL:0.2-0.4g, the concentration of ammonia is 1-3wt%, and the post-processing step includes: after the reaction is completed, the reaction system is heated to 90-100℃, and the solvent is removed by vacuum distillation to obtain the carboxylated polyethyleneimine precursor;
[0031] Further, in step B2, the ratio of the carboxylated polyethyleneimine precursor, deionized water, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, thiolactic acid, and iminodiacetic acid is 1-2g:20-25mL:0.20-0.40g:0.10-0.30g:0.20-0.50g:0.10-0.30g. The post-treatment step includes: after the reaction is completed, heating the reaction system to 90-100℃, removing the solvent by vacuum distillation, and obtaining the modified organic chelate.
[0032] The present invention also proposes a porous composite material for nickel ion adsorption in electroplating wastewater tailwater, which is prepared by the above-mentioned preparation method of the porous composite material for nickel ion adsorption in electroplating wastewater tailwater.
[0033] The present invention has the following beneficial effects:
[0034] 1. This invention uses porous diatomaceous earth as the inorganic support for a composite material. Diatomaceous earth itself is composed of a natural siliceous bio-framework, possessing a high specific surface area and a natural hierarchical porous structure. After acid washing and alkali etching treatment, impurities are removed, the framework becomes more porous, surface pores increase, and the proportion of mesopores rises, providing more effective loading sites for organic chelates. This porous structure not only improves the adsorption capacity of the composite material but also accelerates the mass transfer rate of metal ions, making the adsorption process more rapid and complete, thus improving the adsorption capacity of Cu. 2+ Ni 2+ and Cr 3+The synergistic adsorption efficiency is improved. Secondly, the introduction of silane coupling agent generates active silane groups on the surface of diatomaceous earth, which can achieve stable chemical bonding with organic chelates such as modified polyethyleneimine, avoiding the detachment of the load during adsorption and regeneration, and improving the stability and cycle durability of the composite material.
[0035] 2. The modified organic chelate of this invention is derived from carboxylated polyethyleneimine and further grafted with polydentate ligands such as thiolactic acid and iminodiacetic acid, enriching the material surface with various high-affinity chelating groups such as carboxyl, amino, and thiohydroxy groups. These functional groups can bind with Cu 2+ Ni 2+ and Cr 3+ The modified organic chelate forms a stable chelate complex, thereby significantly improving the adsorption capacity and selectivity of the material for heavy metals. Secondly, due to its flexible organic segments and dense functional group arrangement, the modified organic chelate can form a uniform functionalized coating inside the hierarchical pores of diatomaceous earth. This increases the effective adsorption sites without clogging the pores, achieving a synergistic effect of high specific surface area and high functional group density. In addition, the organic component is grafted or composited more firmly through a silane coupling agent, giving the material better structural stability and anti-leakage ability in repeated adsorption-desorption cycles, thereby improving cycle durability. Detailed Implementation
[0036] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0037] The polyoxyethylene nonylphenol ether used in this invention is purchased from polyoxyethylene nonylphenol ether, the product name is emulsifier NP-10, the model is YN-NP-10, and the molecular weight is 616.82.
[0038] The diatomaceous earth used in this invention was purchased from Lingshou County Lingchuang Mineral Products Processing Co., Ltd., with a particle size of 325 mesh, a moisture content of 0.1%, and a pH of 8.
[0039] Example 1
[0040] This embodiment provides a method for preparing a modified organic chelate, comprising the following steps:
[0041] Step I: Preparation of carboxylated polyethyleneimine precursor
[0042] Weigh 10g of polyethyleneimine and 100mL of deionized water and place them in a reaction vessel under nitrogen atmosphere protection and stir. Heat the reaction vessel to 40℃, add 2g of succinic anhydride, add 1wt% ammonia water to adjust the pH to 8, and keep the reaction at this temperature for 2h. After the reaction is complete, heat the reaction system to 90℃ and remove the solvent by vacuum distillation to obtain the carboxylated polyethyleneimine precursor.
[0043] Step II: Preparation of modified organic chelates
[0044] Weigh 10g of carboxylated polyethyleneimine precursor and 200mL of deionized water and place them in a reaction vessel. Stir, add glacial acetic acid to adjust the pH to 4, add 2g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 1g of N-hydroxysuccinimide, stir at room temperature for 0.5h, add 2g of thiolactic acid and 1g of iminodiacetic acid, heat the reaction vessel to 50℃ and keep it at that temperature for 2h. After the reaction is complete, heat the reaction system to 90℃ and remove the solvent by vacuum distillation to obtain the modified organic chelate.
[0045] Example 2
[0046] This embodiment provides a method for preparing a modified organic chelate, comprising the following steps:
[0047] Step I: Preparation of carboxylated polyethyleneimine precursor
[0048] Weigh 15g of polyethyleneimine and 110mL of deionized water and place them in a reaction vessel under nitrogen atmosphere protection and stir. Heat the reaction vessel to 45℃, add 3g of succinic anhydride, add 2wt% ammonia water to adjust the pH to 8.5, and keep the reaction at this temperature for 3h. After the reaction is complete, heat the reaction system to 95℃ and remove the solvent by vacuum distillation to obtain the carboxylated polyethyleneimine precursor.
[0049] Step II: Preparation of modified organic chelates
[0050] Weigh 15g of carboxylated polyethyleneimine precursor and 225mL of deionized water and place them in a reaction vessel. Stir, add glacial acetic acid to adjust the pH to 4.5, add 3g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 2g of N-hydroxysuccinimide, stir at room temperature for 1h, add 3.5g of thiolactic acid and 2g of iminodiacetic acid, heat the reaction vessel to 55℃ and keep it at that temperature for 3h. After the reaction is complete, heat the reaction system to 95℃ and remove the solvent by vacuum distillation to obtain the modified organic chelate.
[0051] Example 3
[0052] This embodiment provides a method for preparing a modified organic chelate, comprising the following steps:
[0053] Step I: Preparation of carboxylated polyethyleneimine precursor
[0054] Weigh 20g of polyethyleneimine and 120mL of deionized water and place them in a reaction vessel under nitrogen atmosphere protection and stir. Heat the reaction vessel to 50℃, add 4g of succinic anhydride, add 3wt% ammonia water to adjust the pH to 9, and keep the reaction at this temperature for 4h. After the reaction is complete, heat the reaction system to 100℃ and remove the solvent by vacuum distillation to obtain the carboxylated polyethyleneimine precursor.
[0055] Step II: Preparation of modified organic chelates
[0056] Weigh 20g of carboxylated polyethyleneimine precursor and 250mL of deionized water and place them in a reaction vessel and stir. Add glacial acetic acid to adjust the pH to 5, add 4g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 3g of N-hydroxysuccinimide, stir at room temperature for 1h, add 5g of thiolactic acid and 3g of iminodiacetic acid, heat the reaction vessel to 60℃ and keep it at that temperature for 4h. After the reaction is complete, heat the reaction system to 100℃ and remove the solvent by vacuum distillation to obtain the modified organic chelate.
[0057] Example 4
[0058] This embodiment provides a method for preparing porous diatomaceous earth, including the following steps:
[0059] Step ①: Preparation of acid-treated diatomaceous earth
[0060] Weigh 20g of diatomaceous earth and 400mL of hydrochloric acid aqueous solution and place them in a reaction vessel and stir. Heat the reaction vessel to 60℃ and keep it at that temperature for 0.5h. After the reaction is complete, wait for the reaction to cool to room temperature, filter, wash the filter cake twice with deionized water and ethanol, and then transfer it to an oven at 50℃ and dry it to constant weight to obtain acid-treated diatomaceous earth.
[0061] Step 2: Preparation of porous diatomaceous earth
[0062] Weigh out 40g of acid-treated diatomaceous earth and 800mL of sodium hydroxide aqueous solution and place them in a reaction vessel. Stir the reaction vessel and heat it to 75℃. Keep it at this temperature and stir for 0.5h. After the reaction is complete, wait for the reaction to cool to room temperature, filter the mixture, wash the filter cake twice with deionized water and ethanol, transfer it to an oven at 50℃, dry it to constant weight, grind it through a 200-mesh sieve, and obtain porous diatomaceous earth.
[0063] Example 5
[0064] This embodiment provides a method for preparing porous diatomaceous earth, including the following steps:
[0065] Step ①: Preparation of acid-treated diatomaceous earth
[0066] Weigh 30g of diatomaceous earth and 500mL of hydrochloric acid aqueous solution and place them in a reaction vessel and stir. Heat the reaction vessel to 70℃ and keep it at this temperature for 1 hour. After the reaction is complete, wait for the reaction to cool to room temperature, filter the mixture, wash the filter cake three times with deionized water and ethanol, and then transfer it to an oven at 55℃ and dry it to constant weight to obtain acid-treated diatomaceous earth.
[0067] Step 2: Preparation of porous diatomaceous earth
[0068] Weigh out 50g of acid-treated diatomaceous earth and 900mL of sodium hydroxide aqueous solution and place them in a reaction vessel. Stir the reaction vessel and heat it to 80℃. Keep it at this temperature and stir for 1 hour. After the reaction is complete, wait for the reaction to cool to room temperature, filter the mixture, wash the filter cake three times with deionized water and ethanol, transfer it to an oven at 55℃, dry it to constant weight, grind it through a 200-mesh sieve, and obtain porous diatomaceous earth.
[0069] Example 6
[0070] This embodiment provides a method for preparing porous diatomaceous earth, including the following steps:
[0071] Step ①: Preparation of acid-treated diatomaceous earth
[0072] Weigh 40g of diatomaceous earth and 600mL of hydrochloric acid aqueous solution and place them in a reaction vessel and stir. Heat the reaction vessel to 80℃ and keep it at that temperature for 1.5h. After the reaction is complete, wait for the reaction to cool to room temperature, filter, wash the filter cake four times with deionized water and ethanol, and then transfer it to an oven at 60℃ and dry it to constant weight to obtain acid-treated diatomaceous earth.
[0073] Step 2: Preparation of porous diatomaceous earth
[0074] Weigh out 60g of acid-treated diatomaceous earth and 1000mL of sodium hydroxide aqueous solution and place them in a reaction vessel. Stir the reaction vessel and heat it to 95℃. Keep it at this temperature and stir for 1.5h. After the reaction is complete, wait for the reaction to cool to room temperature, filter the mixture, wash the filter cake four times with deionized water and ethanol, transfer it to an oven at 60℃, dry it to constant weight, grind it through a 200-mesh sieve, and obtain porous diatomaceous earth.
[0075] Example 7
[0076] This embodiment provides a method for preparing a porous composite material for nickel ion adsorption in electroplating wastewater, including the following steps:
[0077] Step (1): Preparation of silane-modified porous diatomaceous earth
[0078] Weigh out 10g of γ-glycidoxypropyltrimethoxysilane, 60mL of deionized water and 800mL of ethanol and place them in a reaction vessel and stir. Add 0.5mol / L glacial acetic acid aqueous solution to adjust the pH of the system to 4. Stir at room temperature for 15min. Add 80g of porous diatomaceous earth prepared in Example 4. Heat the reaction vessel to 60℃ and keep it at that temperature for 2h. After the reaction is complete, let the reaction system cool to room temperature, filter it, wash the filter cake twice with deionized water and ethanol, transfer it to an oven at 50℃ and dry it to constant weight to obtain silane-modified porous diatomaceous earth.
[0079] Step 2: Preparation of diatomaceous earth slurry
[0080] Weigh 40g of silane-modified porous diatomaceous earth and 1000mL of deionized water and place them in a reaction vessel. Add 5g of polyoxyethylene nonylphenol ether and stir at room temperature for 0.5h to obtain diatomaceous earth slurry.
[0081] Step 3: Preparation of porous composite materials
[0082] Weigh 400g of diatomaceous earth slurry and 250g of the modified organic chelate prepared in Example 1 and place them in a reaction vessel. Add 3wt% ammonia water to adjust the pH to 9. Heat the reaction vessel to 80℃ and keep it at that temperature for 4 hours. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the filter cake twice with deionized water and ethanol, transfer it to an oven at 50℃, and dry it to constant weight to obtain a porous composite material.
[0083] Example 8
[0084] This embodiment provides a method for preparing a porous composite material for nickel ion adsorption in electroplating wastewater, including the following steps:
[0085] Step (1): Preparation of silane-modified porous diatomaceous earth
[0086] Weigh 15g of γ-glycidoxypropyltrimethoxysilane, 70mL of deionized water, and 900mL of ethanol and place them in a reaction vessel. Stir, add 0.75mol / L glacial acetic acid aqueous solution, adjust the pH of the system to 4.5, stir at room temperature for 22min, add 90g of porous diatomaceous earth prepared in Example 5, heat the reaction vessel to 70℃, and keep the reaction at this temperature for 3h. After the reaction is completed, wait for the reaction system to cool to room temperature, filter, wash the filter cake three times with deionized water and ethanol, transfer it to an oven at 55℃, and dry it to constant weight to obtain silane-modified porous diatomaceous earth.
[0087] Step 2: Preparation of diatomaceous earth slurry
[0088] Weigh out 50g of silane-modified porous diatomaceous earth and 1100mL of deionized water and place them in a reaction vessel. Add 7.5g of polyoxyethylene nonylphenol ether and stir at room temperature for 1h to obtain diatomaceous earth slurry.
[0089] Step 3: Preparation of porous composite materials
[0090] Weigh 500g of diatomaceous earth slurry and 260g of the modified organic chelate prepared in Example 2 and place them in a reaction vessel. Add 4wt% ammonia water to adjust the pH to 9.5. Heat the reaction vessel to 85℃ and keep it at that temperature for 5 hours. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the filter cake three times with deionized water and ethanol, transfer it to an oven at 55℃ and dry it to constant weight to obtain a porous composite material.
[0091] Example 9
[0092] This embodiment provides a method for preparing a porous composite material for nickel ion adsorption in electroplating wastewater, including the following steps:
[0093] Step (1): Preparation of silane-modified porous diatomaceous earth
[0094] Weigh 20g of γ-glycidoxypropyltrimethoxysilane, 80mL of deionized water, and 1000mL of ethanol and place them in a reaction vessel. Stir, add 1.0mol / L glacial acetic acid aqueous solution, adjust the pH of the system to 5, stir at room temperature for 30min, add 100g of porous diatomaceous earth prepared in Example 6, heat the reaction vessel to 80℃, and keep the temperature for 4h. After the reaction is completed, wait for the reaction system to cool to room temperature, filter, wash the filter cake 4 times with deionized water and ethanol, transfer it to an oven at 60℃, and dry it to constant weight to obtain silane-modified porous diatomaceous earth.
[0095] Step 2: Preparation of diatomaceous earth slurry
[0096] Weigh out 60g of silane-modified porous diatomaceous earth and 1200mL of deionized water and place them in a reaction vessel. Add 10g of polyoxyethylene nonylphenol ether and stir at room temperature for 1h to obtain diatomaceous earth slurry.
[0097] Step 3: Preparation of porous composite materials
[0098] Weigh 600g of diatomaceous earth slurry and 280g of the modified organic chelate prepared in Example 3 and place them in a reaction vessel. Add 5wt% ammonia water to adjust the pH to 10. Heat the reaction vessel to 90℃ and keep it at that temperature for 6 hours. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the filter cake four times with deionized water and ethanol, transfer it to an oven at 60℃ and dry it to constant weight to obtain a porous composite material.
[0099] Comparative Example 1
[0100] The difference between this comparative example and Example 9 is that, in step (1) when preparing silane-modified porous diatomaceous earth, diatomaceous earth is used in an equal amount to replace porous diatomaceous earth.
[0101] Comparative Example 2
[0102] The difference between this comparative example and Example 9 is that, in step (2) when preparing the diatomaceous earth slurry, porous diatomaceous earth is used in an equal amount to replace the silane-modified porous diatomaceous earth.
[0103] Comparative Example 3
[0104] The difference between this comparative example and Example 9 is that, in step (3) when preparing the porous composite material, the modified organic chelate is replaced with an equal amount of carboxylated polyethyleneimine precursor.
[0105] Performance testing:
[0106] Weigh 0.079g of copper sulfate pentahydrate, 0.090g of nickel sulfate hexahydrate, 0.051g of chromium chloride hexahydrate and 7L of deionized water into a beaker, mix well, add 1mol / L hydrochloric acid aqueous solution to adjust the pH to 2-3, add deionized water to make up to 10L, and obtain simulated electroplating wastewater tailwater.
[0107] Referring to standard GB / T 38596-2020 "Determination of Heavy Metal Content in Wastewater from Catalyst Production", the porous composite materials prepared in Examples 7-9 and Comparative Examples 1-3 were used to investigate the effect of Cu on simulated electroplating wastewater effluent. 2+ Ni 2+ and Cr 3+ The concentration of Cu in the simulated electroplating wastewater was tested, recorded, and calculated. 2+ Ni 2+ and Cr 3+ The single adsorption capacity, removal rate, and adsorption performance decay rate after 5 cycles;
[0108] The specific surface area of the porous composite materials prepared in Examples 7-9 and Comparative Examples 1-3 was tested according to the standard GB / T 7702.20-2025 "Test methods for coal-based granular activated carbon - Part 20: Determination of pore volume and specific surface area". The specific data are shown in Table 1.
[0109] Table 1 - Performance Test Data for Each Sample
[0110]
[0111] Data Analysis:
[0112] Comparative analysis of the data in Table 1 reveals that the specific surface area of the porous composite material prepared in this invention is 84.6 m². 2 ·g -1 For Cu 2+ Ni 2+ and Cr 3+ The single adsorption capacities were 76%, 86%, and 64%, respectively. After five cycles, the adsorption capacity of Cu was [not specified]. 2+Ni 2+ and Cr 3+ The adsorption performance degradation rates were 9.3%, 8.5% and 9.6%, respectively, all of which were better than the comparative example;
[0113] This invention first subjectes diatomaceous earth to acid washing to remove impurities and alkaline etching to expand pores and increase specific surface area. Then, a silane coupling agent is used to modify the surface, introducing epoxy groups to enhance the binding stability of organic matter, resulting in silane-modified porous diatomaceous earth. Finally, a modified organic chelate containing multiple functional groups is loaded onto the modified diatomaceous earth, giving the porous composite material both a hierarchical pore structure and abundant chelation sites. This not only improves the porous composite material's ability to resist Ni in electroplating wastewater tailings... 2+ The adsorption performance of Cu was also improved. 2+ and Cr 3+ Adsorption performance.
[0114] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.
Claims
1. A method for preparing porous composite materials for nickel ion adsorption in electroplating wastewater tailings, characterized in that, Includes the following steps: S1. Place γ-glycidyl etheroxypropyltrimethoxysilane, deionized water and ethanol in a reaction vessel and stir. Add glacial acetic acid aqueous solution to adjust the pH of the system to 4-5. Stir at room temperature for 15-30 min. Add porous diatomaceous earth. Heat the reaction vessel to 60-80℃ and keep it at that temperature for 2-4 h. Post-treatment yields silane-modified porous diatomaceous earth. S2. Place silane-modified porous diatomaceous earth and deionized water in a reaction vessel, add polyoxyethylene nonylphenol ether, and stir at room temperature for 0.5-1 h to obtain diatomaceous earth slurry. S3. Place the diatomaceous earth slurry and the modified organic chelate in a reactor, add ammonia to adjust the pH to 9-10, heat the reactor to 80-90℃, keep the reaction at this temperature for 4-6 hours, and then process to obtain the porous composite material.
2. The method for preparing porous composite material for nickel ion adsorption in electroplating wastewater according to claim 1, characterized in that, In step S1, the ratio of γ-glycidyl etheroxypropyltrimethoxysilane, deionized water, ethanol, and porous diatomaceous earth is 1-2g:6-8mL:80-100mL:8-10g, and the concentration of the glacial acetic acid aqueous solution is 0.5-1.0mol / L; in step S2, the ratio of silane-modified porous diatomaceous earth, deionized water, and polyoxyethylene nonylphenol ether is 4-6g:100-120mL:0.5-1g; in step S3, the weight ratio of the diatomaceous earth slurry and the modified organic chelate is 40-60:25-28, and the concentration of ammonia water is 3-5wt%.
3. The method for preparing porous composite material for nickel ion adsorption in electroplating wastewater according to claim 1, characterized in that, The porous diatomaceous earth is prepared by the following steps: A1. Place diatomaceous earth and hydrochloric acid aqueous solution in a reaction vessel and stir. Heat the reaction vessel to 60-80℃ and keep it at this temperature while stirring for 0.5-1.5 hours. The acid-treated diatomaceous earth is then obtained through post-treatment. A2. Place acid-treated diatomaceous earth and sodium hydroxide aqueous solution in a reaction vessel and stir. Heat the reaction vessel to 75-95℃ and keep it at this temperature for 0.5-1.5 hours. Post-treatment yields porous diatomaceous earth.
4. The method for preparing porous composite material for nickel ion adsorption in electroplating wastewater according to claim 3, characterized in that, The ratio of diatomaceous earth to hydrochloric acid aqueous solution is 2-4g:40-60mL, and the concentration of hydrochloric acid aqueous solution is 10-15wt%; in step A2, the ratio of acid-treated diatomaceous earth to sodium hydroxide aqueous solution is 4-6g:80-100mL, and the concentration of sodium hydroxide aqueous solution is 3-5wt%.
5. The method for preparing porous composite material for nickel ion adsorption in electroplating wastewater according to claim 1, characterized in that, The modified organic chelate was prepared by the following steps: B1. Place polyethyleneimine and deionized water in a reaction vessel under nitrogen atmosphere and stir. Heat the reaction vessel to 40-50℃, add succinic anhydride, add ammonia to adjust the pH to 8-9, keep the reaction at the temperature for 2-4 hours, and then process to obtain carboxylated polyethyleneimine precursor. B2. The carboxylated polyethyleneimine precursor and deionized water were placed in a reaction vessel and stirred. Glacial acetic acid was added to adjust the pH to 4-5. 1-Ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide were added. The mixture was stirred at room temperature for 0.5-1 h. Thiolactic acid and iminodiacetic acid were added. The reaction vessel was heated to 50-60℃ and kept at that temperature for 2-4 h. The modified organic chelate was obtained after post-treatment.
6. The method for preparing porous composite material for nickel ion adsorption in electroplating wastewater according to claim 5, characterized in that, In step B1, the ratio of polyethyleneimine, deionized water and succinic anhydride is 1-2g:10-12mL:0.2-0.4g, and the concentration of ammonia is 1-3wt%.
7. The method for preparing porous composite material for nickel ion adsorption in electroplating wastewater according to claim 5, characterized in that, In step B2, the ratio of the carboxylated polyethyleneimine precursor, deionized water, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, thiolactic acid, and iminodiacetic acid is 1-2g:20-25mL:0.20-0.40g:0.10-0.30g:0.20-0.50g:0.10-0.30g.
8. A porous composite material for adsorbing nickel ions in electroplating wastewater tailings, characterized in that, The porous composite material for nickel ion adsorption in electroplating wastewater tailings is prepared by the preparation method of the porous composite material for nickel ion adsorption in electroplating wastewater tailings as described in any one of claims 1-7.