An imprint resin, a method for preparing the same, and use thereof in platinum recovery

Abstract

The application discloses imprint resin, a preparation method thereof and application of the imprint resin in platinum recovery. The preparation method of the imprint resin comprises the following steps: S1, performing a nucleophilic substitution reaction on chloromethyl polystyrene resin and N-(2-mercaptoethyl) acrylamide in a solvent, and collecting the resin after the reaction is completed; S2, adding a chloroplatinic acid solution to the resin obtained in the step S1, and performing a coordination reaction; S3, adding a crosslinking agent and an initiator to the system obtained in the step S2, and performing a polymerization reaction, and collecting the resin after the reaction is completed; and S4, adding an eluent to the resin obtained in the step S3, and performing desorption of chloroplatinic acid root ions, so as to obtain the imprint resin. The imprint resin has high selectivity, high adsorption capacity and good regeneration performance on chloroplatinic acid root ions, and is suitable for efficient recovery and resource utilization of platinum.

Description

Technical Field

[0001] This invention belongs to the field of secondary resource recycling and adsorbent preparation technology, and particularly relates to an imprinted resin, its preparation method, and its application in platinum recovery. Background Technology

[0002] Platinum group metals (PGMs) are widely used in many important industrial fields due to their unique physicochemical properties, such as automotive exhaust purification catalysts, petrochemical catalysts, precision electronic components, biopharmaceuticals, environmental protection materials, and jewelry. Among these, platinum, with its excellent catalytic activity, chemical stability, and corrosion resistance, plays a crucial role in automotive exhaust purification catalysts, serving as a key material for achieving clean emissions and reducing pollution. However, PGM resources are extremely scarce, with low crustal abundance and highly uneven distribution of primary deposits. Constrained by geopolitical factors and mining conditions, their production is difficult to increase significantly. With the acceleration of global industrialization, the demand for PGMs continues to grow, leading to an increasingly severe imbalance between resource supply and demand. Therefore, how to efficiently and economically recycle platinum resources from platinum-containing materials after reuse has become a research hotspot in the fields of resource recycling and green chemistry.

[0003] Common methods for recovering platinum group metals (PGMs) include pyrometallurgy, hydrometallurgy, and adsorption separation. Pyrometallurgy primarily uses high-temperature smelting or roasting to enrich and recover metals, suitable for treating solid waste with high metal content. However, this method suffers from high equipment investment, high energy consumption, and severe secondary pollution, hindering green and sustainable development. Hydrometallurgy utilizes acids, alkalis, or complexing agents to dissolve and transfer metals to the liquid phase, followed by separation and purification through reduction, extraction, precipitation, or ion exchange. This method has certain advantages in treating low-grade PGM-containing waste, especially for precious metal recovery, but its separation selectivity is low, and it suffers from high reagent consumption, complex processes, and limited separation efficiency. Adsorption separation technology, as an environmentally friendly separation method, shows great potential in the field of precious metal recovery. This technology mainly relies on the physical adsorption or chemical coordination between the adsorbent and the target metal ions to achieve selective enrichment, offering significant advantages such as simple process, mild operation, high recovery efficiency, and reusability. Especially in low-concentration precious metal solutions, traditional separation methods often fail to achieve effective extraction, while adsorption materials can achieve efficient enrichment of precious metals in a short time. Therefore, they are widely used in scenarios such as leachate from spent catalysts and waste electronic waste treatment liquids.

[0004] To further improve the selectivity and specificity of adsorbent materials for target metal ions, researchers have gradually introduced ion imprinting technology to construct materials with recognition capabilities. Ion imprinting involves introducing template ions during polymerization, enabling functional monomers to form stable coordination structures with them. Subsequently, under the action of a crosslinking agent, polymerization forms a three-dimensional network structure. After polymerization, by eluting the template molecules, a series of "imprinted cavities" with spatial structures highly matched to the chemical environment are formed within the material. These imprinted cavities can specifically recognize and bind to corresponding target metal ions in subsequent applications, thereby achieving selective adsorption and separation. Compared with traditional adsorbents, ion-imprinted materials possess higher recognition accuracy and stronger anti-interference capabilities, making them particularly suitable for the extraction of target ions in complex systems. Simultaneously, imprinted materials exhibit good structural stability and regeneration performance, maintaining good adsorption capacity and selectivity through multiple adsorption-desorption cycles. By introducing rationally designed functional monomers, selecting appropriate template ions and crosslinking agent systems, and combining them with structurally controllable polymer supports, imprinted adsorbent materials with excellent recognition capabilities and adsorption performance can be constructed. This not only significantly improves recovery efficiency but also provides a new technical path and theoretical support for the recycling of precious metal resources. Therefore, developing an imprinting resin with high selectivity, high adsorption capacity and good regeneration performance for chloroplatinate ions is of great significance for the efficient recovery and resource utilization of platinum. Summary of the Invention

[0005] The purpose of this invention is to provide an imprinted resin, its preparation method, and its application in platinum recovery. This imprinted resin has a cavity structure that specifically recognizes chloroplatinate ions, enabling efficient and environmentally friendly recovery of platinum, and exhibits excellent selectivity, high adsorption capacity, and good chemical stability.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing an imprinting resin, comprising the following steps:

[0008] S1. Chloromethyl polystyrene resin and N-(2-mercaptoethyl)acrylamide are subjected to a nucleophilic substitution reaction in a solvent;

[0009] S2. Add chloroplatinic acid solution to the system obtained in step S1, and carry out a coordination reaction at 40-80℃;

[0010] S3. Add crosslinking agent ethylene glycol dimethacrylate and initiator to the system obtained in step S2, and carry out polymerization reaction at 40-80°C. After the reaction is complete, collect the resin.

[0011] S4. Add an eluent to the resin obtained in step S3 to desorb chloroplatinate ions and obtain the imprinted resin.

[0012] Based on the above technical solutions, this invention employs a surface imprinting synthesis method to prepare imprinted resin. Using chloromethyl polystyrene resin as a substrate, N-(2-mercaptoethyl)acrylamide is grafted onto the resin surface via a nucleophilic substitution reaction, introducing a thiol structure with specific coordination ability to chloroplatinate ions. Subsequently, in the presence of the template ion chloroplatinate, a crosslinking agent, ethylene glycol dimethacrylate, and an initiator, azobisisobutyronitrile, are introduced for surface polymerization, forming imprinted cavities with spatial matching and chemoselectivity. Finally, the template ions are eluted with a mixture of thiourea and hydrochloric acid to obtain the target imprinted resin. The imprinted resin of this invention possesses a cavity structure that specifically recognizes the template ion, enabling it to specifically recognize and bind to chloroplatinate ions, thereby achieving selective adsorption and separation of chloroplatinate ions. This allows for efficient and environmentally friendly recovery of platinum, exhibiting excellent selectivity, high adsorption capacity, and good chemical stability.

[0013] According to an embodiment of the present invention, in step S1, the present invention utilizes the –CH2Cl active group on the surface of chloromethyl polystyrene resin to achieve covalent grafting of functional monomers through a nucleophilic substitution reaction, introducing a thiol structure with coordination selectivity to chloroplatinate ions into the functional monomers. Optionally, the ratio of the chloromethyl polystyrene resin to the N-(2-mercaptoethyl)acrylamide is 1g:(1-5)mmol, preferably 1g:(3-5)mmol, more preferably 1g:(3-4)mmol, 1g:3mmol, or 1g:4mmol. The inventors have found that when this ratio is too high or too low, it will lead to a decrease in platinum adsorption rate. This is because when the amount of N-(2-mercaptoethyl)acrylamide monomer is too high, the polymer network becomes dense, some functional groups are embedded or aggregated, resulting in a decrease in the accessibility of effective sites, limited mass transfer, and a decrease in adsorption capacity. Optionally, the solvent is anhydrous dimethylformamide (DMF). As an example, the ratio of the chloromethyl polystyrene resin to the solvent is 1g:20mL. As an example, the method further includes, before the nucleophilic substitution reaction, soaking the chloromethyl polystyrene resin in the solvent to allow for sufficient swelling, such as soaking at room temperature for 2 hours. It is understood that after the reaction in step S1, the method also includes separating and collecting the product, and sequentially washing and drying the product.

[0014] According to an embodiment of the present invention, the nucleophilic substitution reaction is carried out under an inert gas atmosphere, such as nitrogen. The temperature of the nucleophilic substitution reaction is 40–80°C, such as 40°C, 50°C, 60°C, 70°C, or 80°C, and the time is 4–8 h, such as 4 h, 5 h, 6 h, 7 h, or 8 h.

[0015] According to an embodiment of the present invention, the Pt concentration of the chloroplatinic acid solution is 500 ppm. The pH value of the chloroplatinic acid solution is 1 to 3, such as 1, 1.5, 2, 2.5, or 3. Under pH conditions of 1 to 3, platinum ions exist as stable PtCl6. 2- The form exists and can form stable coordination complexes with functional monomers. Functional monomers are easily oxidized or hydrolyzed under excessively high pH conditions, leading to platinum ion hydrolysis or the formation of colloidal platinum oxides. At excessively low pH, functional monomers are over-protonated, losing their coordination ability, thus interfering with polymerization and template elution. Optionally, the ratio of the chloromethyl polystyrene resin to the chloroplatinic acid solution is 1 g: (10-100) mL, including but not limited to 1 g: 50 mL. Too small a ratio results in insufficient imprinted sites, while too large a ratio leads to excessive cost and waste. The concentration unit ppm (parts per million) is expressed as the mass of the solute as a percentage of the total solution mass, also known as parts per million concentration.

[0016] According to an embodiment of the present invention, the temperature of the coordination reaction is 40-80°C, such as 40°C, 50°C, 60°C, 70°C or 80°C, and the time is 1-5 hours, such as 2 hours.

[0017] According to an embodiment of the present invention, in step S3, the present invention forms a specific recognition cavity with coordination matching and electrostatic attraction for the target ion through template-induced and crosslinking polymerization. Optionally, the crosslinking agent is ethylene glycol dimethacrylate (DVB). The molar ratio of N-(2-mercaptoethyl)acrylamide to the crosslinking agent is 1:(1-5), including but not limited to 1:1 and 1:3. Optionally, the initiator is azobisisobutyronitrile (AIBN); the molar ratio of N-(2-mercaptoethyl)acrylamide to the initiator is 1:(1-5), including but not limited to 1:1 and 1:3.

[0018] According to embodiments of the present invention, the polymerization reaction is carried out under an inert gas protection environment, such as nitrogen; the polymerization reaction temperature is 40–80°C, such as 40°C, 50°C, 60°C, 70°C, or 80°C, and the time is 4–24 h, such as 4 h, 6 h, 8 h, 12 h, or 24 h. It is understood that the method further includes, after the reaction in step S1, separating and collecting the product, and washing the product, such as by repeatedly washing with DMF, anhydrous ethanol, and deionized water until the filtrate has no obvious organic monomer odor.

[0019] According to an embodiment of the present invention, the eluent is composed of hydrochloric acid, thiourea and water; as an example, the concentration of hydrochloric acid in the eluent is 0.5 mol / L; the concentration of thiourea in the eluent is 0.5 mol / L; and the ratio of chloromethyl polystyrene resin to the eluent is 1 g: 200 mL.

[0020] According to an embodiment of the present invention, in the desorption step, the desorption temperature is 15–30°C, and the desorption time is 24 h. It is understood that the method further includes drying the resin after the desorption step, such as vacuum drying at 50°C for 24 h.

[0021] In a second aspect, the present invention provides an imprinting resin prepared by the method described in any of the preceding claims.

[0022] Thirdly, the present invention provides the application of the imprinted resin in the adsorption of chloroplatinate ions for the recovery of platinum.

[0023] Fourthly, the present invention provides a method for recovering platinum using the aforementioned imprinting resin, comprising the following steps:

[0024] (1) The imprinted resin is added to a solution containing chloroplatinate ions, and the resin adsorbed by shaking is obtained by separation.

[0025] (2) Add an eluent to the resin that adsorbs platinum, shake to desorb, and separate to obtain the regenerated imprinted resin and the platinum-containing solution.

[0026] According to an embodiment of the present invention, the platinum concentration in the solution containing chloroplatinate ions is 100 to 500 ppm; the concentration unit ppm (parts per million) is the concentration expressed as the mass of the solute as a percentage of the total mass of the solution, also known as the parts per million concentration.

[0027] According to an embodiment of the present invention, the method includes, before the oscillation adsorption, adjusting the pH of the solution containing chloroplatinate ions to 1-3, such as 1, 1.5, 2, 2.5, or 3. Under acidic conditions of pH 1-3, platinum ions exist primarily in the stable chloride complex anion form, maintaining good solubility and chemical stability. When the pH increases, PtCl6... 2- It is prone to stepwise hydrolysis. Conversely, under excessively low pH conditions, the system becomes too acidic, resulting in an overly corrosive reaction environment that is detrimental to subsequent polymerization and the maintenance of template interactions.

[0028] According to an embodiment of the present invention, the ratio of the imprinting resin to the solution containing chloroplatinate ions is 0.1 g: 50 mL.

[0029] According to embodiments of the present invention, to achieve sufficient adsorption, in the oscillation adsorption step, the oscillation temperature is 25℃~65℃, such as 25℃, 35℃, 45℃, 55℃, 65℃; the rotation speed is 150~200 r / min, such as 150 r / min, 160 r / min, 180 r / min, 200 r / min, 220 r / min; and the oscillation time is 12~48h, such as 24h. The inventors have found that moderately increasing the oscillation temperature can improve the adsorption rate and adsorption amount, but excessively high temperatures weaken the coordination bond between Pt ions and functional groups, causing the adsorption equilibrium to shift towards desorption, resulting in a decrease in adsorption rate and an increase in desorption rate. The oscillation temperature is preferably 35~55℃, more preferably 45℃.

[0030] According to an embodiment of the present invention, the eluent is composed of hydrochloric acid, thiourea and water; the concentration of hydrochloric acid in the eluent is 0.5 mol / L; the concentration of thiourea in the eluent is 0.5 mol / L.

[0031] According to an embodiment of the present invention, the ratio of the imprinting resin to the eluent is 0.1 g: 50 mL.

[0032] According to an embodiment of the present invention, in order to achieve sufficient desorption, in the oscillation desorption step, the oscillation temperature is 25℃~65℃, such as 25℃, 35℃, 45℃, 55℃, 65℃, the rotation speed is 150~200 r / min, such as 160 r / min, 180 r / min, 200 r / min, 220 r / min, and the oscillation time is 12~48h, such as 24h.

[0033] The present invention has the following beneficial effects:

[0034] (1) This invention uses chloromethyl polystyrene resin as a substrate. Chloromethyl polystyrene resin has a regular network structure and surface chloromethyl groups, which facilitates controlled grafting reactions with nucleophilic functional monomers. Its chlorine content can be accurately determined by elemental analysis or titration, which is beneficial for evaluating grafting efficiency. At the same time, its degree of crosslinking is adjustable and its structure is stable, making it suitable for studying the effect of crosslinking on adsorption performance.

[0035] (2) This invention uses N-(2-mercaptoethyl)acrylamide as a functional monomer. A thiol structure with coordination selectivity to chloroplatinate ions is introduced through this functional monomer. Further, through template-induced and cross-linking polymerization, a recognition cavity with both coordination matching and electrostatic attraction for the target ion is formed. The covalently grafted structure in the imprinted resin of this invention exhibits good acid and alkali resistance, and the imprinted sites are stable, maintaining high adsorption performance even after elution and regeneration.

[0036] (3) The base resin used in the imprinting resin prepared by the method of the present invention has a wide range of sources, mild reaction conditions, strong stability, and good acid resistance. It can be applied to metal hydrometallurgy and gold-containing industrial waste liquid systems, and can also be used for the separation and recovery of precious metals in complex fuel cell systems, providing a new solution for the resource utilization of fuel cell waste liquid.

[0037] (4) The imprinted resin of the present invention exhibits an adsorption rate of 94.37% and a desorption rate of 90.11% for Pt in a chloroplatinic acid solution of 500 ppm and a solid-liquid ratio of 0.1 g: 50 mL, and the adsorption rate remains at 78.34% after five cycles. In a mixed solution of Pt, Ni, and Co of 500 ppm, the adsorption amounts for Ni and Co are only 3.82 and 4.27 mg / g, respectively, demonstrating excellent selectivity and cycling stability. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the preparation method of N-(2-mercaptoethyl)acrylamide modified imprinting resin.

[0039] Figure 2 The effect of changing the number of functional monomers on the adsorption performance of the synthesized imprinted resin under the synthesis method of Example 3.

[0040] Figure 3 The effect of changing the adsorption temperature on the adsorption performance of the synthesized imprinted resin under the synthesis method of Example 3. Detailed Implementation

[0041] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0042] Unless otherwise specified, the methods used in the following embodiments are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.

[0043] The chloromethyl polystyrene resins used in the following examples were all purchased from Maclean's Reagents, product code 014531569, with product specifications of 1.0–1.24 mmol / g, 100–200 mesh, and 1% DVB.

[0044] In the examples below, N-(2-mercaptoethyl)acrylamide was prepared by the applicant using conventional methods and an optimized synthetic process. This compound was obtained under specific reaction conditions and purification steps to ensure its purity and structure met the requirements of subsequent reactions. The specific steps are as follows: In a fume hood, 17 mmol of mercaptoethylamine was dissolved in 50 mL of anhydrous acetonitrile, placed in an ice bath (0 °C), and nitrogen was introduced to maintain an inert atmosphere. 34 mmol of triethylamine was slowly added, and stirring was continued for 20 min. Subsequently, 17 mmol of acryloyl chloride was dissolved in 20 mL of anhydrous acetonitrile and slowly added dropwise to the reaction system under ice bath conditions, while maintaining stirring. After the addition was complete, stirring was continued at 0 °C for 4 h, followed by reaction at room temperature for 12 h. After the reaction was completed, the generated triethylamine salt was removed by filtration, the filtrate was collected, and the organic phase was extracted with 30 mL of chloroform. Then, the mixture was stirred with 10 wt% sodium bicarbonate solution for 30 min each time, and washed three times with sodium bicarbonate solution after extraction. The organic layer was dried with anhydrous sodium sulfate for 30 min and then filtered. The filtrate was slowly purged with nitrogen at 35 °C or allowed to evaporate to remove the solvent, yielding a pale yellow to colorless oily substance. The product was sealed and stored at -20 °C, protected from light.

[0045] The chloroplatinic acid solution in the following examples was prepared from H2PtCl6 hydrate, and the pH value was adjusted with HCl solution and NaOH solution.

[0046] The formula for calculating the adsorption rate of Pt is:

[0047]

[0048] in, E a Indicates adsorption rate. c 0 indicates the concentration of Pt in the original solution. c This indicates the concentration of Pt in the solution after adsorption.

[0049] The formula for calculating the desorption rate of Pt is:

[0050]

[0051] in, Ed Indicates the desorption rate. c d This indicates the Pt concentration in the solution after desorption. c 0 indicates the concentration of Pt in the original solution. c This indicates the concentration of Pt in the solution after adsorption.

[0052] Example 1: Preparation of platinum-imprinted resin and recovery of platinum from chloroplatinic acid solution using this resin.

[0053] I. Preparation of Platinum Imprinted Resin

[0054] according to Figure 1 The flowchart shown illustrates the preparation of the imprinted resin, with the specific steps as follows:

[0055] (1) Weigh 1.00 g of chloromethyl polystyrene resin into a 100 mL volumetric flask, attach a condenser, add 20 mL of anhydrous dimethylformamide, and soak at room temperature for 2 h to allow it to swell fully. Then add 1 mmol of N-(2-mercaptoethyl)acrylamide, introduce N2 to isolate it from air, place it in a constant temperature water bath and stir, control the temperature at 40 ℃, and react for 4 h.

[0056] (2) Add 50 mL of chloroplatinic acid solution (Pt concentration of 500 ppm, pH≈1), and adsorb at 40 °C with magnetic stirring for 2 h to allow template ions to coordinate with the thiol groups on the functional monomers to form a prepolymer complex.

[0057] (3) Add 1 mmol of ethylene glycol dimethacrylate and 1 mmol of azobisisobutyronitrile to the above system, introduce N2, and place in a constant temperature water bath at 40 °C for polymerization reaction for 4 h. After the reaction is completed, collect the product by vacuum filtration, and wash it repeatedly with DMF, anhydrous ethanol and deionized water in sequence until the filtrate has no obvious organic monomer odor.

[0058] (4) Transfer the resin obtained in step (3) into a 500 mL flask, add 200 mL of an eluent composed of equal volumes of 1 mol / L hydrochloric acid and 1 mol / L thiourea, and magnetically stir for 24 h at room temperature to remove template ions from the resin. Finally, place the resin in a vacuum drying oven and dry at 50 °C for 24 h to obtain chloroplatinate ion-imprinted resin.

[0059] II. Recovery of Platinum from Chloroplatinic Acid Solution

[0060] Platinum in the chloroplatinic acid simulation solution was recovered using the following steps:

[0061] (1) Weigh 0.1 g of the prepared platinum imprinted resin and add it to 50 mL of chloroplatinic acid solution with a concentration of 500 ppm (pH≈1.0). The temperature is controlled at 25 °C and the rotation speed is 150 r / min in a constant temperature shaker for 24 h.

[0062] (2) After adsorption, solid-liquid separation is performed by vacuum filtration, the saturated resin is collected, and the filtrate is used to determine the remaining Pt concentration by ICP-OES.

[0063] (3) The saturated resin was transferred into 50 mL of elution buffer (a mixture of equal volumes of 1 mol / L hydrochloric acid and 1 mol / L thiourea) and desorbed for 24 h at 25 °C and 180 r / min.

[0064] (4) Wash the desorbed resin with deionized water and dry it. Repeat the adsorption-desorption operation 5 times.

[0065] The results showed that the Pt adsorption rate in the solution was 85.04%, and the desorption rate was 90.21%. After five cycles, the Pt adsorption rate decreased from 85.04% to 74.15%, with a performance degradation rate of 12.81%, but it still exhibited high cycling stability.

[0066] Selectivity test: 0.1 g of the prepared platinum-imprinted resin was added to 50 mL of a mixed solution of Pt, Ni, and Co (chloroplatinic acid, nickel chloride, and cobalt chloride), with a concentration of 500 ppm for each metal ion, pH=1, temperature controlled at 25 ℃, rotation speed at 150 r / min, and adsorption time at 24 h. ICP test results showed that the resin adsorbed 103.14 mg / g of Pt, 4.71 mg / g of Ni, and 4.63 mg / g of Co. This demonstrates that the resin of this invention exhibits high adsorption capacity for chloroplatinic acid ions and excellent selectivity.

[0067] Example 2

[0068] The difference from Example 1 is that the amounts of N-(2-mercaptoethyl)acrylamide, ethylene glycol dimethacrylate, and azobisisobutyronitrile were adjusted, as well as the reaction temperature and time; and the adsorption and desorption conditions were adjusted.

[0069] I. Preparation of Platinum Imprinted Resin

[0070] (1) Weigh 1.00 g of chloromethyl polystyrene resin into a 100 mL volumetric flask, attach a condenser, add 20 mL of anhydrous dimethylformamide, and soak at room temperature for 2 h to allow it to swell fully. Then add 2 mmol of N-(2-mercaptoethyl)acrylamide, introduce N2 to isolate it from air, place it in a constant temperature water bath and stir, control the temperature at 50 ℃, and react for 5 h.

[0071] (2) Add 50 mL of chloroplatinic acid solution (Pt concentration of 500 ppm, pH≈1.5), and adsorb at 50 °C with magnetic stirring for 2 h to allow the template ions to coordinate with the thiol groups on the functional monomers to form a prepolymer complex.

[0072] (3) Add 2 mmol of ethylene glycol dimethacrylate and 2 mmol of azobisisobutyronitrile to the above system, introduce N2, and place in a constant temperature water bath at 50 °C for polymerization reaction for 6 h. After the reaction is completed, collect the product by vacuum filtration, and wash it repeatedly with DMF, anhydrous ethanol and deionized water in sequence until the filtrate has no obvious organic monomer odor.

[0073] (4) Transfer the resin obtained in step (3) into a 500 mL flask, add 200 mL of an eluent composed of equal volumes of 1 mol / L hydrochloric acid and 1 mol / L thiourea, and magnetically stir for 24 h at room temperature to remove template ions from the resin. Finally, place the resin in a vacuum drying oven and dry at 50 °C for 24 h to obtain chloroplatinate ion-imprinted resin.

[0074] II. Recovery of Platinum from Chloroplatinic Acid Solution

[0075] (1) Weigh 0.1 g of the prepared platinum imprinted resin and add it to 50 mL of chloroplatinic acid solution with a concentration of 500 ppm (pH≈1.5). Control the temperature at 35 ℃ and the rotation speed at 160 r / min in a constant temperature shaker for 24 h.

[0076] (2) After adsorption, solid-liquid separation is performed by vacuum filtration, the saturated resin is collected, and the filtrate is used to determine the remaining Pt concentration by ICP-OES.

[0077] (3) The saturated resin was transferred into 50 mL of elution buffer (a mixture of equal volumes of 1 mol / L hydrochloric acid and 1 mol / L thiourea) and desorbed at 35 °C and 160 r / min for 24 h.

[0078] (4) Wash the desorbed resin with deionized water and dry it. Repeat the adsorption-desorption operation 5 times.

[0079] The results showed that the Pt adsorption rate in the solution was 90.13%, and the desorption rate was 89.69%. After five cycles, the Pt adsorption rate decreased from 90.13% to 77.47%, with a performance degradation rate of 14.05%, but it still exhibited high cycling stability.

[0080] Selectivity test: 0.1 g of the prepared platinum-imprinted resin was added to 50 mL of a mixed solution of Pt, Ni, and Co (chloroplatinic acid, nickel chloride, and cobalt chloride), with a concentration of 500 ppm for each metal ion, a solution pH of 1.5, a controlled temperature of 35 ℃, a rotation speed of 160 r / min, and an adsorption time of 24 h. ICP test results showed that the resin adsorbed 108.62 mg / g of Pt, 4.37 mg / g of Ni, and 4.64 mg / g of Co. This demonstrates that the resin of this invention exhibits high adsorption capacity for chloroplatinic acid ions and excellent selectivity.

[0081] Example 3

[0082] The difference from Example 1 is that the amounts of N-(2-mercaptoethyl)acrylamide, ethylene glycol dimethacrylate, and azobisisobutyronitrile were adjusted, as well as the reaction temperature and time; and the adsorption and desorption conditions were adjusted.

[0083] I. Preparation of Platinum Imprinted Resin

[0084] (1) Weigh 1.00 g of chloromethyl polystyrene resin into a 100 mL volumetric flask, attach a condenser, add 20 mL of anhydrous dimethylformamide, and soak at room temperature for 2 h to allow it to swell fully. Then add 3 mmol of N-(2-mercaptoethyl)acrylamide, introduce N2 to isolate it from air, place it in a constant temperature water bath and stir, control the temperature at 60 ℃, and react for 6 h.

[0085] (2) Add 50 mL of chloroplatinic acid solution (Pt concentration is 500 ppm, pH≈2), and adsorb at 60 °C with magnetic stirring for 2 h to allow template ions to coordinate with the thiol groups on the functional monomers to form a prepolymer complex.

[0086] (3) Add 3 mmol of ethylene glycol dimethacrylate and 3 mmol of azobisisobutyronitrile to the above system, introduce N2, and place in a constant temperature water bath at 60 °C for polymerization reaction for 8 h. After the reaction is completed, collect the product by vacuum filtration, and wash it repeatedly with DMF, anhydrous ethanol and deionized water in sequence until the filtrate has no obvious organic monomer odor.

[0087] (4) Transfer the resin obtained in step (3) into a 500 mL flask, add 200 mL of an eluent composed of equal volumes of 1 mol / L hydrochloric acid and 1 mol / L thiourea, and magnetically stir for 24 h at room temperature to remove template ions from the resin. Finally, place the resin in a vacuum drying oven and dry at 50 °C for 24 h to obtain chloroplatinate ion-imprinted resin.

[0088] II. Recovery of Platinum from Chloroplatinic Acid Solution

[0089] (1) Weigh 0.1 g of the prepared platinum imprinted resin and add it to 50 mL of chloroplatinic acid solution with a concentration of 500 ppm (pH≈2.0). The temperature is controlled at 45 °C and the rotation speed is 180 r / min in a constant temperature shaker for 24 h.

[0090] (2) After adsorption, solid-liquid separation is performed by vacuum filtration, the saturated resin is collected, and the filtrate is used to determine the remaining Pt concentration by ICP-OES.

[0091] (3) The saturated resin was transferred into 50 mL of elution buffer (a mixture of equal volumes of 1 mol / L hydrochloric acid and 1 mol / L thiourea) and desorbed at 45 °C and 180 r / min for 24 h.

[0092] (4) Wash the desorbed resin with deionized water and dry it. Repeat the adsorption-desorption operation 5 times.

[0093] The results showed that the Pt adsorption rate in the solution was 94.37%, and the desorption rate was 90.11%. After five cycles, the Pt adsorption rate decreased from 94.37% to 78.34%, with a performance degradation rate of 16.99%, but it still exhibited high cycling stability.

[0094] Selectivity test: 0.1 g of the prepared platinum-imprinted resin was added to 50 mL of a mixed solution of Pt, Ni, and Co (chloroplatinic acid, nickel chloride, and cobalt chloride), with a concentration of 500 ppm for each metal ion, a solution pH of 2, a controlled temperature of 45 ℃, a rotation speed of 180 r / min, and an adsorption time of 24 h. ICP test results showed that the resin adsorbed 116.33 mg / g of Pt, 3.82 mg / g of Ni, and 4.27 mg / g of Co. This demonstrates that the resin of this invention exhibits high adsorption capacity for chloroplatinic acid ions and excellent selectivity.

[0095] Example 4

[0096] The difference from Example 1 is that the amounts of N-(2-mercaptoethyl)acrylamide, ethylene glycol dimethacrylate, and azobisisobutyronitrile were adjusted, as well as the reaction temperature and time; and the adsorption and desorption conditions were adjusted.

[0097] I. Preparation of Platinum Imprinted Resin

[0098] (1) Weigh 1.00 g of chloromethyl polystyrene resin into a 100 mL volumetric flask, attach a condenser, add 20 mL of anhydrous dimethylformamide, and soak at room temperature for 2 h to allow it to swell fully. Then add 4 mmol of N-(2-mercaptoethyl)acrylamide, introduce N2 to isolate it from air, place it in a constant temperature water bath and stir, control the temperature at 70 ℃, and react for 7 h.

[0099] (2) Add 50 mL of chloroplatinic acid solution (Pt concentration of 500 ppm, pH≈2.5), and adsorb at 70 °C with magnetic stirring for 2 h to allow template ions to coordinate with the thiol groups on the functional monomers to form a prepolymer complex.

[0100] (3) Add 4 mmol of ethylene glycol dimethacrylate and 4 mmol of azobisisobutyronitrile to the above system, introduce N2, and place in a constant temperature water bath at 70 °C for polymerization reaction for 12 h. After the reaction is completed, collect the product by vacuum filtration, and wash it repeatedly with DMF, anhydrous ethanol and deionized water in sequence until the filtrate has no obvious organic monomer odor.

[0101] (4) Transfer the resin obtained in step (3) into a 500 mL flask, add 200 mL of an eluent composed of equal volumes of 1 mol / L hydrochloric acid and 1 mol / L thiourea, and magnetically stir for 24 h at room temperature to remove template ions from the resin. Finally, place the resin in a vacuum drying oven and dry at 50 °C for 24 h to obtain chloroplatinate ion-imprinted resin.

[0102] II. Recovery of Platinum from Chloroplatinic Acid Solution

[0103] (1) Weigh 0.1 g of the prepared platinum imprinted resin and add it to 50 mL of chloroplatinic acid solution with a concentration of 500 ppm (pH≈2.5). Control the temperature at 55 ℃ and the rotation speed at 200 r / min in a constant temperature shaker for 24 h.

[0104] (2) After adsorption, solid-liquid separation is performed by vacuum filtration, the saturated resin is collected, and the filtrate is used to determine the remaining Pt concentration by ICP-OES.

[0105] (3) The saturated resin was transferred into 50 mL of elution buffer (a mixture of equal volumes of 1 mol / L hydrochloric acid and 1 mol / L thiourea) and desorbed at 55 °C and 200 r / min for 24 h.

[0106] (4) Wash the desorbed resin with deionized water and dry it. Repeat the adsorption-desorption operation 5 times.

[0107] The results showed that the Pt adsorption rate in the solution was 91.87%, and the desorption rate was 92.33%. After five cycles, the Pt adsorption rate decreased from 91.87% to 76.45%, with a performance degradation rate of 16.78%, but it still exhibited high cycling stability.

[0108] Selectivity test: 0.1 g of the prepared platinum-imprinted resin was added to 50 mL of a mixed solution of Pt, Ni, and Co (chloroplatinic acid, nickel chloride, and cobalt chloride), with a concentration of 500 ppm for each metal ion, a solution pH of 2.5, a controlled temperature of 55 ℃, a rotation speed of 200 r / min, and an adsorption time of 24 h. ICP test results showed that the resin adsorbed 105.34 mg / g of Pt, 4.95 mg / g of Ni, and 4.90 mg / g of Co. This demonstrates that the resin of this invention exhibits high adsorption capacity for chloroplatinic acid ions and excellent selectivity.

[0109] Example 5

[0110] The difference from Example 1 is that the amounts of N-(2-mercaptoethyl)acrylamide, ethylene glycol dimethacrylate, and azobisisobutyronitrile were adjusted, as well as the reaction temperature and time; and the adsorption and desorption conditions were adjusted.

[0111] I. Preparation of Platinum Imprinted Resin

[0112] (1) Weigh 1.00 g of chloromethyl polystyrene resin into a 100 mL volumetric flask, attach a condenser, add 20 mL of anhydrous dimethylformamide, and soak at room temperature for 2 h to allow it to swell fully. Then add 5 mmol of N-(2-mercaptoethyl)acrylamide, introduce N2 to isolate it from air, place it in a constant temperature water bath and stir, control the temperature at 80 ℃, and react for 8 h.

[0113] (2) Add 50 mL of chloroplatinic acid solution (Pt concentration of 500 ppm, pH≈3.0), and adsorb at 80 °C with magnetic stirring for 2 h to allow template ions to coordinate with the thiol groups on the functional monomers to form a prepolymer complex.

[0114] (3) Add 5 mmol of ethylene glycol dimethacrylate and 5 mmol of azobisisobutyronitrile to the above system, introduce N2, and place in an 80 ℃ constant temperature water bath for polymerization reaction for 24 h. After the reaction is completed, collect the product by vacuum filtration, and wash it repeatedly with DMF, anhydrous ethanol and deionized water in sequence until the filtrate has no obvious organic monomer odor.

[0115] (4) Transfer the resin obtained in step (3) into a 500 mL flask, add 200 mL of an eluent composed of equal volumes of 1 mol / L hydrochloric acid and 1 mol / L thiourea, and magnetically stir for 24 h at room temperature to remove template ions from the resin. Finally, place the resin in a vacuum drying oven and dry at 50 °C for 24 h to obtain chloroplatinate ion-imprinted resin.

[0116] II. Recovery of Platinum from Chloroplatinic Acid Solution

[0117] (1) Weigh 0.1 g of the prepared platinum imprinted resin and add it to 50 mL of chloroplatinic acid solution with a concentration of 500 ppm (pH≈3.0). The temperature is controlled at 65 °C and the rotation speed is 220 r / min in a constant temperature shaker for 24 h.

[0118] (2) After adsorption, solid-liquid separation is performed by vacuum filtration, the saturated resin is collected, and the filtrate is used to determine the remaining Pt concentration by ICP-OES.

[0119] (3) The saturated resin was transferred into 50 mL of elution buffer (a mixture of equal volumes of 1 mol / L hydrochloric acid and 1 mol / L thiourea) and desorbed at 65 °C and 220 r / min for 24 h.

[0120] (4) Wash the desorbed resin with deionized water and dry it. Repeat the adsorption-desorption operation 5 times.

[0121] The results showed that the Pt adsorption rate in the solution was 82.39%, and the desorption rate was 86.25%. After five cycles, the Pt adsorption rate decreased from 82.39% to 61.74%, with a performance degradation rate of 25.06%.

[0122] Selectivity test: 0.1 g of the prepared platinum-imprinted resin was added to 50 mL of a mixed solution of Pt, Ni, and Co (chloroplatinic acid, nickel chloride, and cobalt chloride), with a concentration of 500 ppm for each metal ion, a solution pH of 2.5, a controlled temperature of 55 ℃, a rotation speed of 200 r / min, and an adsorption time of 24 h. ICP test results showed that the resin adsorbed 105.34 mg / g of Pt, 4.67 mg / g of Ni, and 5.01 mg / g of Co. This demonstrates that the resin of this invention exhibits high adsorption capacity for chloroplatinic acid ions and excellent selectivity.

[0123] Example 6

[0124] The difference from Example 3 lies in adjusting the amount of N-(2-mercaptoethyl)acrylamide added, to 1, 2, 3, 4, and 5 mmol respectively. The difference in the recovery steps is that the selectivity under different conditions was not measured. The remaining steps are consistent with Example 3. Results are as follows: Figure 2 As shown, with increasing N-(2-mercaptoethyl)acrylamide dosage, the number of thiol coordination sites in the resin increases, promoting the complexation and adsorption of Pt ions, and the adsorption capacity gradually increases. However, when the monomer dosage is too high, the polymer network becomes dense, and some functional groups are embedded or aggregated, leading to decreased accessibility of effective sites, limited mass transfer, and a decrease in adsorption capacity. The resin achieved its highest adsorption rate of 95.01% when the functional monomer dosage was 4 mmol.

[0125] Example 7

[0126] The difference from Example 3 lies in adjusting the adsorption temperature to 25, 35, 45, 55, and 65°C. The difference in the harvesting steps is that the selectivity under different conditions was not measured. The remaining steps are the same as in Example 3. The results are as follows: Figure 3 As shown, moderate heating can enhance the diffusion rate of molecules in the solution and reduce the viscosity of the system, thereby promoting the migration of Pt ions to the adsorption sites and increasing the adsorption rate and amount. However, excessively high temperatures weaken the coordination bonds between Pt ions and functional groups, shifting the adsorption equilibrium towards desorption, resulting in a decrease in adsorption rate and an increase in desorption rate. The resin achieved its highest adsorption rate of 94.37% at 45℃.

[0127] Comparative Example 1

[0128] The difference from Example 3 is that step (2) is omitted.

[0129] I. Preparation of Non-Imprinting Resin

[0130] (1) Weigh 1.00 g of chloromethyl polystyrene resin into a 100 mL volumetric flask, attach a condenser, add 20 mL of anhydrous dimethylformamide, and soak at room temperature for 2 h to allow it to swell fully. Then add 3 mmol of N-(2-mercaptoethyl)acrylamide, introduce N2 to isolate it from air, place it in a constant temperature water bath and stir, control the temperature at 60 ℃, and react for 6 h.

[0131] (2) Add 3 mmol of ethylene glycol dimethacrylate and 3 mmol of azobisisobutyronitrile to the above system, introduce N2, and place in a constant temperature water bath at 60 °C for polymerization reaction for 8 h. After the reaction is completed, collect the product by vacuum filtration, and wash it repeatedly with DMF, anhydrous ethanol and deionized water in sequence until the filtrate has no obvious organic monomer odor.

[0132] (3) Transfer the resin obtained in step (2) into a 500 mL flask, add 200 mL of eluent composed of equal volumes of 1 mol / L hydrochloric acid and 1 mol / L thiourea, and magnetically stir for 24 h at room temperature to remove template ions from the resin. Finally, place the resin in a vacuum drying oven and dry at 50 °C for 24 h to obtain non-imprinted resin.

[0133] II. Recovery of Platinum from Chloroplatinic Acid Solution

[0134] (1) Weigh 0.1 g of the prepared non-imprinted resin and add it to 50 mL of chloroplatinic acid solution with a concentration of 500 ppm (pH≈2.0). The temperature is controlled at 45 °C and the rotation speed is 180 r / min in a constant temperature shaker for 24 h.

[0135] (2) After adsorption, solid-liquid separation is performed by vacuum filtration, the saturated resin is collected, and the filtrate is used to determine the remaining Pt concentration by ICP-OES.

[0136] (3) The saturated resin was transferred into 50 mL of elution buffer (a mixture of equal volumes of 1 mol / L hydrochloric acid and 1 mol / L thiourea) and desorbed at 45 °C and 180 r / min for 24 h.

[0137] (4) Wash the desorbed resin with deionized water and dry it. Repeat the adsorption-desorption operation 5 times.

[0138] The results showed that the Pt adsorption rate in the solution was 74.11%, and the desorption rate was 93.46%. After five cycles, the Pt adsorption rate decreased from 74.11% to 66.29%, with a performance degradation rate of 10.55%.

[0139] Selectivity test: 0.1 g of the prepared non-imprinted resin was added to 50 mL of a mixed solution of Pt, Ni, and Co (chloroplatinic acid, nickel chloride, and cobalt chloride), with a concentration of 500 ppm for each metal ion, pH=2, controlled temperature at 45 ℃, rotation speed at 180 r / min, and adsorption time at 24 h. ICP test results showed that the resin adsorbed 70.83 mg / g of Pt, 4.93 mg / g of Ni, and 4.86 mg / g of Co.

[0140] The results of Example 3 and Comparative Example 1 demonstrate that introducing template ions during the polymerization process of the imprinted resin can induce functional monomers to orient themselves around it, forming specific spatial configurations through coordination, hydrogen bonding, or electrostatic interactions. After polymerization, the template ions are removed, leaving recognition sites that are highly complementary to chloroplatinate ions in shape, size, and coordination environment. These "molecularly imprinted cavities" can precisely match chloroplatinate ions, lowering the adsorption energy barrier and significantly improving binding stability, making it easier to capture and firmly adsorb chloroplatinate ions. In contrast, non-imprinted resins lack these structured sites, have disordered functional group distribution, and a lower probability of effective contact, resulting in a smaller overall adsorption capacity.

[0141] Comparative Example 2

[0142] The difference from Example 3 is that the imprinting resin used was replaced with chloromethyl polystyrene resin to recover platinum from the chloroplatinic acid solution. No recycling experiment was performed, but the remaining recovery steps were the same as in Example 3.

[0143] The results showed that the Pt adsorption rate in the solution was 4.03%, and the desorption rate was 54.69%. This indicates that the resin substrate has very low adsorption performance for platinum, and the present invention significantly increases the adsorption performance of the resin for platinum through modification.

[0144] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including modifications made using conventional techniques known in the art that depart from the scope disclosed herein.

Claims

1. A method for preparing an imprinting resin, characterized in that, Includes the following steps: S1. Chloromethyl polystyrene resin and N-(2-mercaptoethyl)acrylamide are subjected to a nucleophilic substitution reaction in a solvent; The ratio of the chloromethyl polystyrene resin to the N-(2-mercaptoethyl)acrylamide is 1 g: (1-5) mmol; The nucleophilic substitution reaction was carried out at a temperature of 40–80 °C for 4–8 h. S2. Add chloroplatinic acid solution to the system obtained in step S1, and carry out a coordination reaction at 40-80℃; The Pt concentration of the chloroplatinic acid solution is 500 ppm; The pH value of the chloroplatinic acid solution is 1 to 3; The ratio of the chloromethyl polystyrene resin to the chloroplatinic acid solution is 1g:(10-100)mL; S3. Add crosslinking agent ethylene glycol dimethacrylate and initiator to the system obtained in step S2, and carry out polymerization reaction at 40-80°C. After the reaction is complete, collect the resin. The molar ratio of N-(2-mercaptoethyl)acrylamide to the crosslinking agent is 1:(1-5); The polymerization reaction takes 4–24 hours; S4. Add an eluent to the resin obtained in step S3 to desorb chloroplatinate ions and obtain the imprinted resin.

2. The method for preparing the imprinting resin according to claim 1, characterized in that: The solvent is anhydrous dimethylformamide; The nucleophilic substitution reaction was carried out under an inert gas atmosphere.

3. The method for preparing the imprinting resin according to claim 1, characterized in that: The coordination reaction takes 1 to 5 hours.

4. The method for preparing the imprinting resin according to claim 1, characterized in that: The initiator is azobisisobutyronitrile; The molar ratio of N-(2-mercaptoethyl)acrylamide to the initiator is 1:(1-5); The polymerization reaction is carried out under the protection of an inert gas.

5. The method for preparing the imprinting resin according to claim 1, characterized in that: The eluent consists of hydrochloric acid, thiourea, and water; The concentration of hydrochloric acid in the eluent is 0.5 mol / L; The concentration of thiourea in the eluent is 0.5 mol / L; The ratio of the chloromethyl polystyrene resin to the eluent is 1g:200mL; In the desorption step, the desorption temperature is 15–30°C and the desorption time is 24 hours.

6. The imprinting resin prepared by any one of claims 1-5.

7. The application of the imprinting resin according to claim 6 in the adsorption of chloroplatinate ions for platinum recovery.

8. The method for recovering platinum using the imprinting resin according to claim 6, characterized in that, Includes the following steps: (1) The imprinted resin is added to a solution containing chloroplatinate ions, and the resin adsorbed by shaking is obtained by separation. (2) Add an eluent to the resin that adsorbs platinum, shake to desorb, and separate to obtain the regenerated imprinted resin and the platinum-containing solution.

9. The method for recovering platinum according to claim 8, characterized in that: The platinum concentration in the solution containing chloroplatinate ions is 100–500 ppm; The ratio of the imprinting resin to the solution containing chloroplatinate ions is 0.1 g: 50 mL; The method includes, before the oscillation adsorption, adjusting the pH of the solution containing chloroplatinate ions to 1-3; In the oscillation adsorption step, the oscillation temperature is 25℃~65℃, the rotation speed is 150~200 r / min, and the oscillation time is 12~48h.

10. The method for recovering platinum according to any one of claims 8-9, characterized in that: The eluent consists of hydrochloric acid, thiourea, and water; The concentration of hydrochloric acid in the eluent is 0.5 mol / L; The concentration of thiourea in the eluent is 0.5 mol / L; The ratio of the imprinting resin to the eluent is 0.1 g: 50 mL; In the oscillation desorption step, the oscillation temperature is 25℃~65℃, the rotation speed is 150~200 r / min, and the oscillation time is 12~48h.

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