Core-shell adsorption material for recycling noble metal in acid wastewater and production process thereof
By preparing core-shell structured adsorbent materials and using cobalt ferrite and polyvinylidene fluoride combined with surface functionalization modification, adsorbent materials with good acid resistance are formed, solving the problem of efficient recovery of precious metals such as palladium in strongly acidic solutions and achieving efficient and environmentally friendly recovery results.
Patent Information
- Application Number
- CN202512018200.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-30
- Publication Date
- 2026-03-17
AI Technical Summary
Existing technologies struggle to efficiently recover precious metals such as palladium from strongly acidic solutions. Traditional methods are costly and cause environmental pollution, and traditional adsorption materials are unstable under strongly acidic conditions.
The core-shell structured adsorbent uses cobalt ferrite (CoFe2O4) as the core and polyvinylidene fluoride (PVDF) as the shell. A three-dimensional network structure is formed through surface functionalization modification. Coordinating groups such as amino and carboxyl groups are introduced and cross-linked with carboxymethyl chitosan to form an adsorbent with good acid resistance.
This invention enables the efficient recovery of precious metals such as palladium in strongly acidic solutions. The material exhibits excellent acid resistance and adsorption capacity, making it suitable for various wastewater environments, reducing recycling costs and minimizing environmental pollution.
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Abstract
Description
Technical Field
[0001] This application relates to the field of precious metal adsorption and separation technology, and in particular to core-shell adsorption materials and their production process for the recovery of precious metals from acidic wastewater. Background Technology
[0002] The platinum group metals (PGMs) consist of six metallic elements: palladium (Pd), platinum (Pt), iridium (Ir), osmium (Os), rhodium (Rh), and ruthenium (Ru). These elements share similar physical and chemical properties, exhibiting excellent catalytic, high-temperature resistance, and corrosion resistance. PGMs are renowned for their scarcity and wide industrial applications; many countries consider them important strategic resources, earning them the title of "vitamins of modern industry." Palladium, one of the PGMs, is widely used in petrochemical catalysts, automotive exhaust purification catalysts, medical device alloys, electronic components, and jewelry manufacturing. Palladium is extremely rare on Earth, being one of the rarest elements in the Earth's crust.
[0003] Social production and daily life generate a large amount of palladium-containing waste, such as electronic waste and deactivated catalysts from industrial production. Palladium and its compounds are highly toxic and carcinogenic, causing significant harm to the ecological environment and accumulating through the food chain, ultimately endangering human health. From this perspective, the recovery of palladium from secondary resources is of great importance. Hydrometallurgy is widely used for the secondary resource recovery of palladium, involving dissolving palladium in waste in strong acids such as hydrochloric acid, nitric acid, and sulfuric acid, followed by concentration, separation, and purification to obtain the final product, elemental palladium. However, traditional methods using NaS to precipitate palladium from strongly acidic solutions with palladium as the main metal element are complex and costly in the subsequent treatment of sulfur-containing wastewater, and the precipitation process also introduces sulfur dioxide (S). 2- Hydrolysis produces a large amount of toxic H2S gas. In recent years, adsorption has become a research hotspot due to its green and efficient characteristics, especially suitable for the recovery of palladium from acidic wastewater with low pH. However, the technical challenge in its application is to improve the acid resistance of the adsorbent material while maintaining a high adsorption capacity.
[0004] Therefore, there is an urgent need to develop a green and environmentally friendly adsorbent material with good acid resistance, which can still maintain good adsorption performance in strongly acidic solutions and efficiently recover precious metals from acidic wastewater. Summary of the Invention
[0005] In order to provide a green and environmentally friendly chitosan adsorbent material with good acid resistance, which can still maintain good adsorption performance in strongly acidic solutions and efficiently recover palladium from acidic wastewater, this application provides a core-shell adsorbent material for precious metal recovery from acidic wastewater and its production process.
[0006] The production process of the core-shell adsorbent material for precious metal recovery from acidic wastewater provided in this application adopts the following technical solution: The production process of core-shell adsorbent materials for precious metal recovery from acidic wastewater includes the following steps: S1. Cobalt ferrite is added to anhydrous ethanol and ultrasonically dispersed until uniform, thus obtaining a cobalt ferrite dispersion. S2. Add polyvinylidene fluoride powder to N,N-dimethylformamide and stir until completely dissolved to obtain a polyvinylidene fluoride solution; S3. Add the cobalt ferrite dispersion to the polyvinylidene fluoride solution, stir evenly, then add the fluorinated emulsifier and stir evenly at room temperature; then after magnetic separation treatment, wash the precipitate with anhydrous ethanol and water alternately, then vacuum dry and grind in an agate mortar to obtain cobalt ferrite@polyvinylidene fluoride core-shell material; S4. Cobalt ferrite@polyvinylidene fluoride core-shell material is added to sodium hydroxide solution for reaction. After the reaction is completed, it is magnetically separated, washed with water until neutral, and vacuum dried to obtain surface-activated cobalt ferrite@polyvinylidene fluoride core-shell material. S5. Add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide to the MES buffer solution, stir until completely dissolved, then add the surface-activated cobalt ferrite@polyvinylidene fluoride core-shell material, adjust the pH, and then add polyethyleneimine to react; after the reaction is completed, after magnetic separation, wash with sodium chloride solution and water alternately, and vacuum dry to obtain polyethyleneimine-modified cobalt ferrite@polyvinylidene fluoride core-shell material; S6. Dissolve carboxymethyl chitosan in water, filter to remove bacteria to obtain a carboxymethyl chitosan solution, and adjust the pH of the solution to 7.0–7.5; then add polyethyleneimine-modified cobalt ferrite@polyvinylidene fluoride core-shell material, stir evenly, and then add glutaraldehyde to carry out cross-linking reaction. After the reaction is completed, after magnetic separation, the reaction is quenched with glycine, washed with water until neutral, and vacuum dried to obtain the core-shell adsorbent material for the recovery of precious metals from acidic wastewater.
[0007] Preferably, the cobalt ferrite is CoFe2O4, and the particle size of the CoFe2O4 is 20-50 nm; the number average molecular weight of the polyvinylidene fluoride is 50-100 kDa.
[0008] Preferably, the mass ratio of cobalt ferrite to polyvinylidene fluoride powder is 1.8-2.5:1; the mass ratio of cobalt ferrite to anhydrous ethanol is 1:18-22; and the mass ratio of polyvinylidene fluoride powder, fluorinated emulsifier and N,N-dimethylformamide is 1:0.015-0.025:18-20.
[0009] Preferably, the concentration of the sodium hydroxide solution in S4 is 0.5-1 mol / L; the reaction temperature is 60-70℃; and the reaction time is 0.5-1.5 h.
[0010] Preferably, the mass ratio of the surface-activated cobalt ferrite@polyvinylidene fluoride core-shell material, polyethyleneimine, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide in S5 is 1:0.17-0.2:0.08-0.09:0.05-0.06.
[0011] Preferably, the pH of the MES buffer in S5 is 5-6; and the number-average molecular weight of the polyethyleneimine is 6-10 kDa.
[0012] Preferably, the reaction temperature in S5 is 40-50°C and the reaction time is 8-10 hours.
[0013] Preferably, the degree of substitution of the carboxymethyl chitosan is 0.6-0.8.
[0014] Preferably, the mass ratio of the polyethyleneimine-modified cobalt ferrite@polyvinylidene fluoride core-shell material, carboxymethyl chitosan, water, and glutaraldehyde in S6 is 1:0.08-0.1:8-10:0.1-0.2.
[0015] In summary, this application includes at least one of the following beneficial technical effects: 1. This application utilizes a core-shell structure design combined with multi-step surface functionalization modification to prepare an acid-resistant noble metal adsorbent material. The material uses magnetic cobalt ferrite (CoFe2O4) as the core for rapid magnetic separation and recovery, and polyvinylidene fluoride (PVDF) as the shell to provide chemical stability. After alkali activation to introduce active groups, amino groups are introduced by grafting polyethyleneimine (PEI, molecular weight 6-10 kDa) into a carbodiimide / NHS system. This is then cross-linked with carboxymethyl chitosan (degree of substitution 0.6-0.8) to form a three-dimensional network structure. The final material surface is rich in amino and carboxyl groups, enabling efficient adsorption of noble metals from acidic wastewater. It exhibits high acid resistance and is suitable for various wastewater environments. Detailed Implementation
[0016] The present application will be further described in detail below with reference to the embodiments.
[0017] The chemical reagents used in the preparation examples, embodiments, and comparative examples provided in this invention are all commercially available products.
[0018] Example 1 S1. Add 20g of cobalt ferrite CoFe2O4 with a particle size of 20nm to 360g of anhydrous ethanol, and then ultrasonically disperse it at 21kHz for 30min to obtain a cobalt ferrite dispersion. S2. Add 36g of polyvinylidene fluoride powder (number average molecular weight of 50kDa) to 648g of N,N-dimethylformamide and stir at 60℃ for 2h to obtain a polyvinylidene fluoride solution. S3. Add the cobalt ferrite dispersion to the polyvinylidene fluoride solution, stir until homogeneous, then add 0.54g of fluorinated emulsifier Zonyl FS-300, and stir until homogeneous at room temperature; subsequently, after magnetic separation treatment, wash the precipitate three times alternately with anhydrous ethanol and deionized water, then vacuum dry at 80℃ for 6h, grind in an agate mortar, and pass through a 150μm sieve to obtain cobalt ferrite@polyvinylidene fluoride core-shell material; S4. The cobalt ferrite@polyvinylidene fluoride core-shell material obtained in S3 was added to a 0.5 mol / L sodium hydroxide solution and reacted at 60 °C for 0.5 h. After the reaction was completed, it was magnetically separated and washed with water until neutral. After vacuum drying at 60 °C for 4 h, the surface-activated cobalt ferrite@polyvinylidene fluoride core-shell material was obtained. S5. Add 1.6g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 1g of N-hydroxysuccinimide to 400g of MES buffer solution with pH 5. Stir until completely dissolved, then add 20g of the surface-activated cobalt ferrite@polyvinylidene fluoride core-shell material prepared in S4. Adjust the pH to 5 with 0.1mol / L hydrochloric acid solution, then add 3.4g of polyethyleneimine (number average molecular weight of 6kDa). Stir and react at 40℃ in the dark for 8h. After the reaction is completed, after magnetic separation, wash three times alternately with sodium chloride solution and deionized water, and then vacuum dry at 60℃ for 4h to obtain the polyethyleneimine-modified cobalt ferrite@polyvinylidene fluoride core-shell material. S6. Dissolve 1.6g of carboxymethyl chitosan (degree of substitution 0.6) in 160g of deionized water, filter to remove bacteria to obtain a carboxymethyl chitosan solution, and adjust the pH of the solution to 7.0; then add 20g of polyethyleneimine-modified cobalt ferrite@polyvinylidene fluoride core-shell material prepared in S5, stir evenly, and then add 2g of glutaraldehyde to carry out cross-linking reaction at 40℃ for 6h. After the reaction is completed, after magnetic separation, the reaction is quenched with 0.1mol / L glycine, washed with deionized water until neutral, and vacuum dried at 60℃ for 10h to obtain the core-shell adsorbent material for precious metal recovery from acidic wastewater.
[0019] Example 2 S1. Add 20g of cobalt ferrite CoFe2O4 with a particle size of 35nm to 400g of anhydrous ethanol, and then ultrasonically disperse it at 21.5kHz for 35min to obtain a cobalt ferrite dispersion. S2. Add 42g of polyvinylidene fluoride powder (number average molecular weight of 70kDa) to 798g of N,N-dimethylformamide and stir at 65℃ for 2.5h to obtain a polyvinylidene fluoride solution. S3. Add the cobalt ferrite dispersion to the polyvinylidene fluoride solution, stir evenly, then add 0.84g of fluorinated emulsifier Zonyl FS-300, and stir evenly at room temperature; then after magnetic separation treatment, wash the precipitate with anhydrous ethanol and deionized water four times alternately, then vacuum dry at 75℃ for 8h, grind in an agate mortar and pass through a 150μm sieve to obtain cobalt ferrite@polyvinylidene fluoride core-shell material; S4. The cobalt ferrite@polyvinylidene fluoride core-shell material obtained in S3 was added to a 0.75 mol / L sodium hydroxide solution and reacted at 65 °C for 1 h. After the reaction was completed, it was magnetically separated and washed with water until neutral. After vacuum drying at 65 °C for 4 h, the surface-activated cobalt ferrite@polyvinylidene fluoride core-shell material was obtained. S5. Add 17g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 1.1g of N-hydroxysuccinimide to 420g of MES buffer solution with pH 5.5. Stir until completely dissolved, then add 20g of the surface-activated cobalt ferrite@polyvinylidene fluoride core-shell material prepared in S4. Adjust the pH to 5.5 with 0.1mol / L hydrochloric acid solution, and then add 3.7g of polyethyleneimine (number average molecular weight of 8kDa). Stir and react at 45℃ in the dark for 9h. After the reaction is completed, after magnetic separation, wash 4 times alternately with sodium chloride solution and deionized water, and then vacuum dry at 65℃ for 5h to obtain the polyethyleneimine-modified cobalt ferrite@polyvinylidene fluoride core-shell material. S6. Dissolve 1.8g of carboxymethyl chitosan (degree of substitution 0.7) in 180g of deionized water, filter to remove bacteria to obtain a carboxymethyl chitosan solution, and adjust the pH of the solution to 7.0; then add 20g of polyethyleneimine-modified cobalt ferrite@polyvinylidene fluoride core-shell material prepared in S5, stir evenly, and then add 3g of glutaraldehyde to carry out cross-linking reaction at 45℃ for 7h. After the reaction is completed, after magnetic separation, the reaction is quenched with 0.1mol / L glycine, washed with deionized water until neutral, and vacuum dried at 65℃ for 12h to obtain the core-shell adsorbent material for precious metal recovery from acidic wastewater.
[0020] Example 3 S1. Add 20g of cobalt ferrite CoFe2O4 with a particle size of 50nm to 440g of anhydrous ethanol, and then ultrasonically disperse it at 22kHz for 40min to obtain a cobalt ferrite dispersion. S2. Add 50g of polyvinylidene fluoride powder (number average molecular weight of 100kDa) to 1000g of N,N-dimethylformamide and stir at 70℃ for 3h to obtain a polyvinylidene fluoride solution. S3. Add the cobalt ferrite dispersion to the polyvinylidene fluoride solution, stir evenly, then add 1.25g of fluorinated emulsifier Zonyl FS-300, and stir evenly at room temperature; then after magnetic separation treatment, wash the precipitate with anhydrous ethanol and deionized water five times alternately, then vacuum dry at 70℃ for 10h, grind in an agate mortar and pass through a 150μm sieve to obtain cobalt ferrite@polyvinylidene fluoride core-shell material; S4. The cobalt ferrite@polyvinylidene fluoride core-shell material obtained in S3 was added to a 1 mol / L sodium hydroxide solution and reacted at 70°C for 1.5 h. After the reaction was completed, it was magnetically separated and washed with water until neutral. After vacuum drying at 70°C for 6 h, the surface-activated cobalt ferrite@polyvinylidene fluoride core-shell material was obtained. S5. Add 1.8g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 1.2g of N-hydroxysuccinimide to 440g of MES buffer solution with pH 6. Stir until completely dissolved, then add 20g of the surface-activated cobalt ferrite@polyvinylidene fluoride core-shell material prepared in S4. Adjust the pH to 6 with 0.1mol / L hydrochloric acid solution, then add 4g of polyethyleneimine (number average molecular weight of 6kDa). Stir the reaction at 50℃ in the dark for 10h. After the reaction is completed, after magnetic separation, wash 5 times alternately with sodium chloride solution and deionized water, and then vacuum dry at 70℃ for 6h to obtain polyethyleneimine-modified cobalt ferrite@polyvinylidene fluoride core-shell material. S6. Dissolve 2g of carboxymethyl chitosan (degree of substitution 0.8) in 200g of deionized water, filter to remove bacteria to obtain a carboxymethyl chitosan solution, and adjust the pH of the solution to 7.5; then add 20g of polyethyleneimine-modified cobalt ferrite@polyvinylidene fluoride core-shell material prepared in S5, stir evenly, and then add 4g of glutaraldehyde to carry out cross-linking reaction at 50℃ for 8h. After the reaction is completed, after magnetic separation, the reaction is quenched with 0.1mol / L glycine, washed with deionized water until neutral, and vacuum dried at 70℃ for 14h to obtain the core-shell adsorbent material for precious metal recovery from acidic wastewater.
[0021] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 did not use carboxymethyl chitosan for treatment. The specific operation is as follows: S1. Add 20g of cobalt ferrite CoFe2O4 with a particle size of 20nm to 360g of anhydrous ethanol, and then ultrasonically disperse it at 21kHz for 30min to obtain a cobalt ferrite dispersion. S2. Add 36g of polyvinylidene fluoride powder (number average molecular weight of 50kDa) to 648g of N,N-dimethylformamide and stir at 60℃ for 2h to obtain a polyvinylidene fluoride solution. S3. Add the cobalt ferrite dispersion to the polyvinylidene fluoride solution, stir until homogeneous, then add 0.54g of fluorinated emulsifier Zonyl FS-300, and stir until homogeneous at room temperature; subsequently, after magnetic separation treatment, wash the precipitate three times alternately with anhydrous ethanol and deionized water, then vacuum dry at 80℃ for 6h, grind in an agate mortar, and pass through a 150μm sieve to obtain cobalt ferrite@polyvinylidene fluoride core-shell material; S4. The cobalt ferrite@polyvinylidene fluoride core-shell material obtained in S3 was added to a 0.5 mol / L sodium hydroxide solution and reacted at 60 °C for 0.5 h. After the reaction was completed, it was magnetically separated and washed with water until neutral. After vacuum drying at 60 °C for 4 h, the surface-activated cobalt ferrite@polyvinylidene fluoride core-shell material was obtained. S5. Add 1.6g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 1g of N-hydroxysuccinimide to 400g of MES buffer solution with pH 5. Stir until completely dissolved, then add 20g of the surface-activated cobalt ferrite@polyvinylidene fluoride core-shell material prepared in S4. Adjust the pH to 5 with 0.1mol / L hydrochloric acid solution, and then add 3.4g of polyethyleneimine (number average molecular weight of 6kDa). Stir and react in the dark at 40℃ for 8h. After the reaction is completed, after magnetic separation, wash three times alternately with sodium chloride solution and deionized water, and then vacuum dry at 60℃ for 4h to obtain the polyethyleneimine-modified cobalt ferrite@polyvinylidene fluoride core-shell material, which is the core-shell adsorbent material for the recovery of precious metals from acidic wastewater.
[0022] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 did not use polyethyleneimine and carboxymethyl chitosan for treatment. The specific operation is as follows: S1. Add 20g of cobalt ferrite CoFe2O4 with a particle size of 20nm to 360g of anhydrous ethanol, and then ultrasonically disperse it at 21kHz for 30min to obtain a cobalt ferrite dispersion. S2. Add 36g of polyvinylidene fluoride powder (number average molecular weight of 50kDa) to 648g of N,N-dimethylformamide and stir at 60℃ for 2h to obtain a polyvinylidene fluoride solution. S3. Add the cobalt ferrite dispersion to the polyvinylidene fluoride solution, stir evenly, then add 0.54g of fluorinated emulsifier Zonyl FS-300, and stir evenly at room temperature; then, after magnetic separation treatment, wash the precipitate three times alternately with anhydrous ethanol and deionized water, then vacuum dry at 80℃ for 6h, grind in an agate mortar, and pass through a 150μm sieve to obtain the cobalt ferrite@polyvinylidene fluoride core-shell material, which is the core-shell adsorbent material for the recovery of precious metals from acidic wastewater.
[0023] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that an equal amount of iron(III) oxide is used instead of cobalt ferrite CoFe2O4 in Comparative Example 3.
[0024] Performance testing Palladium chloride was dissolved in hydrochloric acid solution to prepare a Pd(II) concentration of 250 mg / L as the adsorption stock solution, and the pH was adjusted to 2. The core-shell adsorbent materials prepared in Examples 1-3 and Comparative Examples 1-3 of this application were measured at a dosage of 0.5 g / L. The samples were placed in an air shaker at 25°C and 140 rpm for 24 h, and the supernatant was diluted. The palladium concentration in the diluted samples was then determined using the following specific testing methods: A palladium standard solution with a concentration of 1000 mg / L and hydrochloric acid as the medium was pipetted and diluted with 0.1 mol / L dilute hydrochloric acid to obtain a series of palladium standard curve solutions with concentration gradients (1 mg / L, 2 mg / L, 5 mg / L, 8 mg / L, 10 mg / L, 15 mg / L, 20 mg / L). The samples were filtered through a 0.22 μm filter and then diluted with 0.1 M hydrochloric acid to a palladium concentration of less than 20 mg / L. This was used as the injection point for ICP-AES. The measurement wavelength for Pd was selected as 340.458 nm. Before each sample measurement, the linear correlation R² of the obtained standard curve was ensured to be greater than 0.9990, and the relative standard deviation (RSD) of each sample measurement was less than 3%. After measurement, the peak at the spectral wavelength of 340.458 nm was corrected, and the final measurement results were derived. The adsorption capacity calculation formula is as follows: ; Where: q: adsorption capacity, mg / g; C0: Palladium concentration in the adsorption solution, mg / L; C1: Palladium concentration in the supernatant after adsorption, mg / L; n: Adsorbent dosage, g / L.
[0025] The results are shown in Table 1.
[0026] The specific test results are as follows:
[0027] As can be seen from the test results in Table 1, the core-shell adsorbent material for precious metal recovery from acidic wastewater and its production process provided in this application produce a core-shell adsorbent material with excellent acid resistance and precious metal adsorption efficiency. Even in an environment with a pH of 2, it still maintains a high adsorption capacity.
[0028] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.
Claims
1. A process for producing a core-shell adsorbent material for the recovery of noble metals from acidic waste water, characterized in that: The method comprises the following steps: S1. The cobalt ferrite is added into anhydrous ethanol, and is uniformly dispersed by ultrasonic to obtain a cobalt ferrite dispersion liquid; S2. The polyvinylidene fluoride powder is added into N,N-dimethylformamide, and is stirred until completely dissolved to obtain a polyvinylidene fluoride solution; S3. The cobalt ferrite dispersion liquid is added into the polyvinylidene fluoride solution, and is stirred until uniform, and then a fluorinated emulsifier is added, and is stirred until uniform at room temperature; after magnetic separation, the precipitate is washed with anhydrous ethanol and water alternately, and is vacuum dried and ground by a maragaret mortar to obtain a cobalt ferrite@polyvinylidene fluoride core-shell material; S4. The cobalt ferrite@polyvinylidene fluoride core-shell material is added into a sodium hydroxide solution for reaction, and after magnetic separation, the product is washed with water until neutral, and is vacuum dried to obtain a surface-activated cobalt ferrite@polyvinylidene fluoride core-shell material; S5. 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide and N-hydroxy succinimide are added into a MES buffer solution, and are stirred until completely dissolved, and then the surface-activated cobalt ferrite@polyvinylidene fluoride core-shell material is added, and after pH adjustment, polyethyleneimine is added for reaction; after reaction, the product is washed with a sodium chloride solution and water alternately, and is vacuum dried to obtain a polyethyleneimine-modified cobalt ferrite@polyvinylidene fluoride core-shell material; S6. The carboxymethyl chitosan is dissolved in water, and is filtered to obtain a carboxymethyl chitosan solution, and the pH of the solution is adjusted to 7.0-7.5; then the polyethyleneimine-modified cobalt ferrite@polyvinylidene fluoride core-shell material is added, and is stirred until uniform, and then glutaraldehyde is added for crosslinking reaction, and after reaction, the product is quenched with glycine, and is washed with water until neutral, and is vacuum dried to obtain a core-shell adsorption material for precious metal recovery in acid wastewater.
2. The process for producing a core-shell adsorbent material for precious metal recovery from acid wastewater according to claim 1, characterized in that: The cobalt ferrite is CoFe2O4, and the particle size of the CoFe2O4 is 20-50 nm; the number average molecular weight of the polyvinylidene fluoride is 50-100 kDa.
3. The process for producing a core-shell adsorbent material for noble metal recovery from acid waste water according to claim 1, characterized in that: The mass ratio of the cobalt ferrite to the polyvinylidene fluoride powder is 1.8-2.5:1; the mass ratio of the cobalt ferrite to the anhydrous ethanol is 1:18-22; the mass ratio of the polyvinylidene fluoride powder, the fluorinated emulsifier and the N,N-dimethylformamide is 1:0.015-0.025:18-20.
4. The process for producing a core-shell adsorbent material for precious metal recovery from acid wastewater according to claim 1, characterized in that: The concentration of the sodium hydroxide solution in S4 is 0.5-1 mol / L; the reaction temperature is 60-70℃, and the reaction time is 0.5-1.5 h.
5. The process for producing a core-shell adsorbent material for precious metal recovery from acid wastewater according to claim 1, characterized in that: The pH of the MES buffer solution in S5 is 5-6; the number average molecular weight of the polyethyleneimine is 6-10 kDa.
6. The process for producing a core-shell adsorbent material for precious metal recovery from acid wastewater according to claim 1, characterized in that: The mass ratio of the surface-activated cobalt ferrite@polyvinylidene fluoride core-shell material, the polyethyleneimine, 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide and N-hydroxy succinimide in S5 is 1:0.17-0.2:0.08-0.09:0.05-0.
06.
7. The process for producing a core-shell adsorbent material for precious metal recovery from acid wastewater according to claim 1, characterized in that: The reaction temperature in S5 is 40-50℃, and the reaction time is 8-10 h.
8. The process for producing a core-shell adsorbent material for precious metal recovery from acid wastewater according to claim 1, characterized in that: The degree of substitution of the carboxymethyl chitosan is 0.6-0.
8.
9. The process for producing a core-shell adsorbent material for precious metal recovery from acid wastewater according to claim 1, characterized in that: The mass ratio of the polyethyleneimine modified cobalt ferrite@polyvinylidene fluoride core-shell material, carboxymethyl chitosan, water and glutaraldehyde in S6 is 1:0.08-0.1:8-10:0.1-0.
2.
10. A core-shell adsorbent material for recovery of noble metals from acidic waste water, characterized by: The core-shell adsorption material is prepared according to the production process of the core-shell adsorption material for recovering noble metals from acid wastewater in claims 1-9.