Adsorption method for directionally trapping palladium by activated carbon in strong-acidity high-chlorine medium

Abstract

The invention discloses an adsorption method for directionally trapping palladium by activated carbon in a strong-acidity high-chlorine medium, and relates to the technical field of additive manufacturing, the method comprises the following specific steps: firstly, carrying out oxidation pretreatment on original activated carbon to obtain oxidized activated carbon; then preparing a pH / Cl double-response intelligent adsorbent and three functional systems; adjusting the acidity of the palladium-containing strong acid solution to obtain a to-be-adsorbed solution; corresponding adsorbents are added in proportion, and intelligent directional adsorption and enhanced separation are achieved in different modes; finally, the adsorbent is desorbed and regenerated with a specific solution, and cyclic utilization is achieved. By preparing the multifunctional intelligent adsorbent and constructing a differentiated functional system, palladium in a strongly acidic high-chlorine medium is directionally and efficiently captured, and the bottleneck of the traditional technology is broken through; an efficient desorption regeneration process is also constructed, so that the adsorbent is recycled, and the cost is reduced; the technology gives consideration to resource recovery and environmental protection, promotes upgrading of the precious metal recovery industry, and has remarkable economic and environmental benefits.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, specifically to an adsorption method for the directional capture of palladium by activated carbon in a strongly acidic, high-chlorine medium. Background Technology

[0002] In industrial production processes, large amounts of palladium-containing waste liquid are generated in fields such as electronics manufacturing, chemical catalysis, and metallurgy. This type of waste liquid is often in a strongly acidic, high-chlorine environment. As a scarce and valuable precious metal, the efficient recovery of palladium can not only reduce resource waste but also lower industrial production costs, which is of great economic significance. Currently, the field of precious metal recovery mostly uses adsorption methods to separate the target metal. This method has become one of the mainstream technologies for treating palladium-containing waste liquid due to its advantages such as simple operation, low energy consumption, and wide applicability. However, the composition of the strongly acidic, high-chlorine medium system is complex, with multiple coexisting metal ions. Moreover, the acidic environment places higher demands on the stability and selectivity of the adsorbent. Traditional adsorption technologies still face technical challenges in adapting to this special medium and improving the accuracy of palladium capture. There is an urgent need to develop technical solutions that can adapt to the complex strongly acidic environment and have efficient directional adsorption capabilities.

[0003] Traditional adsorption technologies for palladium recovery in strongly acidic, high-chlorine media have significant limitations. Firstly, traditional adsorbents often have a single structure, a limited number of surface active sites, and poor environmental adaptability. Under strongly acidic conditions, they are prone to structural instability and adsorption capacity decay. Furthermore, they struggle to accurately identify palladium ions and are susceptible to interference from coexisting metal ions, resulting in low selectivity and purity of palladium capture. Secondly, the separation process in traditional technologies is cumbersome, often requiring complex filtration or centrifugation equipment, leading to low separation efficiency. Moreover, the adsorbent regeneration process is often imperfect, resulting in either incomplete desorption or damage to the adsorbent structure, leading to short adsorbent lifespan and low recycling efficiency. This not only increases recovery costs but may also generate secondary pollutants during regeneration, failing to meet the demands of green and environmentally friendly industrial development and hindering the practical application requirements for large-scale industrial palladium recovery. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an adsorption method for the directional capture of palladium using activated carbon in strongly acidic, high-chlorine media. This method first pre-treats activated carbon with nitric acid oxidation to enhance its surface functional groups; then, a pH / Cl⁻ dual-response smart adsorbent is prepared, modified with polyacrylic acid, and a chlorine source is introduced to further functionalize it into a magnetic, bioenzymatic, or electric field adsorption system, achieving highly selective adsorption of palladium. During adsorption, the acidity of the palladium-containing solution is adjusted, and the appropriate adsorbent is added to complete directional capture and enhanced separation under specific conditions. After adsorption, the adsorbent can be regenerated by desorption with thiourea-hydrochloric acid solution for recycling. This invention has advantages such as high adsorption efficiency, good selectivity, and strong renewability, and is suitable for palladium recovery in complex acidic environments.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: an adsorption method for the directional capture of palladium by activated carbon in a strongly acidic, high-chlorine medium, the specific steps of which are as follows: S100, Pretreatment of activated carbon oxidation: Select raw activated carbon, place it in a 10%-20% nitric acid solution, reflux and stir at 80-95℃ for 4-6 hours, cool and filter, wash with deionized water until the pH of the filtrate is neutral, and dry at 105-110℃ for 8-12 hours to obtain oxidized activated carbon. Preparation of S200, pH / Cl⁻ dual-response smart adsorbent: Oxidized activated carbon was dispersed in a 5%-10% (w / w) polyacrylic acid solution, and the crosslinking agent N,N'-methylenebisacrylamide was added. The mixture was reacted at 50-60℃ for 2-3 hours, followed by ultrasonic dispersion with a chlorine source for 30 minutes, and then vacuum dried at 60-70℃ for 4-6 hours to obtain basic smart activated carbon. Based on the basic smart activated carbon, three types of functional adsorption systems were prepared: a magnetic system was prepared by co-precipitation loading. Nanoparticles and bio-enzyme systems are cross-linked and immobilized with glutaraldehyde, and an electric field system is mixed with polytetrafluoroethylene to form a three-electrode device. S300, acidity adjustment of the adsorption solution: Take a strong acidic solution containing palladium, adjust the acidity to 3-6 mol / L with hydrochloric acid, control the initial palladium concentration to be 10-200 mg / L, and the concentration of coexisting metal ions to be 50-500 mg / L, stir evenly to obtain the adsorption solution; S400, intelligent directional adsorption and enhanced separation: Add the corresponding functional adsorbent to the solution to be adsorbed at a ratio of 0.5-2 g / L. After adsorption by stirring at 30-50℃ for 2-6 hours in the magnetic system, separation is achieved by using an external magnetic field of 0.1-0.5T. After adsorption by stirring at 30-45℃ for 2-5 hours in the biological enzyme system, separation is achieved by filtration. After adsorption by stirring at 30-50℃ for 1-2 hours in the electric field system with an electric field of 1-5V / cm, the electrode is removed and washed. S500, Adsorbent Regeneration Cycle: The adsorbent after adsorbing palladium is placed in a 5%-10% thiourea-hydrochloric acid mixed solution, stirred and desorbed at 40-60℃ for 1-3 hours, washed until neutral after desorption, and dried at 90-100℃ to obtain the regenerated adsorbent.

[0006] Furthermore, in S100, during the activated carbon oxidation pretreatment, the original activated carbon is coconut shell activated carbon, walnut shell activated carbon, or coal-based activated carbon, with a specific surface area of ​​800-1500 m² / g and a particle size of 80-120 mesh; filtration is performed using a vacuum filtration device with a filter membrane pore size of 0.45 μm; drying is performed using a forced-air drying oven, with ventilation every 2 hours for 10 minutes each time.

[0007] Furthermore, in the preparation of the S200, pH / Cl⁻ dual-response smart adsorbent, the molecular weight of polyacrylic acid is 50,000-100,000 Da, the liquid-solid ratio of oxidizing activated carbon to polyacrylic acid solution is 20 mL / g, the amount of crosslinking agent N,N'-methylenebisacrylamide added is 5%-10% of the mass of oxidizing activated carbon, and the stirring rate during the reaction is 300 r / min.

[0008] Furthermore, in the preparation of the S200, pH / Cl⁻ dual-response smart adsorbent, the chlorine source is CuCl, AgCl, or NaCl, and the amount added is 0.2-0.5g; the ultrasonic dispersion power is 80-120W, and the frequency is 40kHz; the heating rate of vacuum drying is 5℃ / min, and the vacuum degree is maintained at -0.08 to -0.1MPa.

[0009] Furthermore, in the preparation of the S200, pH / Cl⁻ dual-response smart adsorbent, the preparation process of the magnetic functional adsorbent is as follows: 1g of basic smart activated carbon is dispersed in 80mL of deionized water, and then... and The molar ratio of the two components was 2:1. The mixture was stirred at 40°C for 30 min under nitrogen protection. 2 mol / L NaOH solution was added dropwise at a rate of 1 mL / min to adjust the pH to 9-10. Stirring continued for 1.5 h. The mixture was then filtered, washed until neutral, and dried at 70°C. The load is 5%-15wt%.

[0010] Furthermore, in the preparation of the S200, pH / Cl⁻ dual-response smart adsorbent, the preparation process of the bio-enzyme functional adsorbent is as follows: 1g of basic smart activated carbon is immersed in 50mL of 0.1mol / L phosphate buffer solution with pH 6.0-7.0, 0.1-0.5mg / mL of cysteine ​​protease or glutathione reductase solution is added, and the mixture is incubated at 30℃ with constant temperature shaking for 1-2h at a shaking rate of 150r / min. 0.5%-1% glutaraldehyde solution is added dropwise for cross-linking for 0.5-1h. After washing 3-5 times with phosphate buffer solution, the mixture is vacuum dried at 40-60℃, and the enzyme fixation amount is 0.1-0.5mg / g.

[0011] Furthermore, in the preparation of the S200, pH / Cl⁻ dual-response smart adsorbent, the preparation process of the electric field functional adsorption system is as follows: 1g of basic smart activated carbon and 0.11g of polytetrafluoroethylene are mixed evenly at a mass ratio of 9:1, and pressed into a sheet electrode with a diameter of 10-20mm and a thickness of 1-2mm under a pressure of 10-15MPa. The electrode porosity is ≥70%. The sheet electrode is used as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode to construct a three-electrode device.

[0012] Furthermore, in the S300 process, during the acidity adjustment of the adsorption solution, the acidity is adjusted by diluting 12 mol / L concentrated hydrochloric acid to 5 mol / L before use. During the adjustment process, the stirring rate is 300-400 r / min. After adjustment, the solution is allowed to stand for 10-15 minutes before the acidity is measured. The coexisting metal ions are... , , , ,in Concentration of 200-300 mg / L Concentration of 150-200 mg / L Concentration of 100-150 mg / L The concentration is 50-100 mg / L.

[0013] Furthermore, in the S400, during intelligent directional adsorption and enhanced separation, the stirring rate of the magnetic system adsorption is 200-300 r / min, the distance between the magnetic field and the outer wall of the container is 5 mm, and the separation time is 20-30 s; the biological enzyme system filtration uses a 0.22 μm filter membrane, the filtration pressure is -0.08 MPa, and the filter membrane is rinsed with 5 mL of deionized water after filtration; during the electric field system adsorption, the stirring rate is 100-200 r / min, the electric field voltage fluctuation is ≤ ±0.1 V, the electrode is washed by soaking in 0.1 mol / L hydrochloric acid for 5 min and then rinsing, and then washed 3 times with deionized water, with each washing volume being 30 mL.

[0014] Furthermore, in the S500 adsorbent regeneration cycle, the thiourea-hydrochloric acid mixed solution is prepared by dissolving 5%-10% thiourea in 1-3 mol / L hydrochloric acid, with a liquid-solid ratio of 10:1-30:1; the stirring rate during desorption is 200-300 r / min; the magnetic system adsorbent is washed using ultrasonic washing at a power of 80W, with each wash lasting 5 minutes, for a total of 4 washes; the bio-enzyme system adsorbent is additionally soaked in neutral phosphate buffer for 30 minutes before washing.

[0015] Compared with existing technologies, this method for the directional capture of palladium by activated carbon in a strongly acidic, high-chlorine medium has the following advantages: I. This invention optimizes the adsorption substrate structure through activated carbon oxidation pretreatment and prepares a multifunctional intelligent adsorbent by combining a pH / Cl⁻ dual-response mechanism. It constructs three differentiated functional adsorption systems—magnetic, bioenzymatic, and electric field-based—to achieve directional and efficient palladium capture in strongly acidic, high-chlorine media. Oxidation pretreatment increases the number and reactivity of active sites on the activated carbon surface, while the dual-response mechanism endows the adsorbent with sensitive adaptability to the media environment. The three functional systems, relying on magnetic separation characteristics, biological specific recognition, and electric field enhancement effects respectively, precisely improve adsorption selectivity and separation efficiency, effectively avoiding interference from coexisting metal ions, ensuring high purity and high recovery rate of palladium capture. This breakthrough overcomes the bottleneck of poor selectivity and difficult separation in traditional adsorption technologies in complex, strongly acidic media, providing a novel technical solution for the directional separation of precious metals in strongly acidic systems.

[0016] II. This invention achieves stable recycling of adsorbents through the construction of an efficient desorption and regeneration process, significantly reducing the cost of precious metal recovery. After adsorption, the adsorbent undergoes desorption treatment with a specific mixed solution, rapidly restoring its adsorption performance. The regeneration process is gentle and does not damage the adsorbent structure, extending its lifespan. The entire process is simple and controllable, requiring no stringent reaction conditions, reducing secondary pollution, and balancing resource recovery efficiency with environmental protection needs. This technology is not only applicable to the resource-based treatment of palladium-containing industrial wastewater but also provides practical support for the green and low-cost development of precious metal adsorption and separation technology, promoting technological upgrading in the precious metal recycling industry and possessing significant economic and environmental benefits.

[0017] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0019] Figure 1 This is a flowchart of an adsorption method for the directional capture of palladium by activated carbon in a strongly acidic, high-chlorine medium. Detailed Implementation

[0020] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below. Example 1:

[0021] A magnetic system is used to directionally capture palladium in a strongly acidic, high-chlorine medium.

[0022] S100, activated carbon oxidation pretreatment: Coconut shell activated carbon with a specific surface area of ​​1200 m² / g and a particle size of 100 mesh was selected as the initial activated carbon. It was placed in a 15% nitric acid solution and refluxed at 90℃ for 5 hours. The oxidation effect of the nitric acid solution introduced more oxygen-containing functional groups onto the surface of the activated carbon, creating conditions for subsequent bonding with polyacrylic acid. After cooling to room temperature, the activated carbon was filtered using a vacuum filtration device with a filter membrane pore size of 0.45 μm. The filter residue was repeatedly washed with deionized water until the pH of the filtrate was neutral to completely remove residual nitric acid and avoid interference from acidic impurities in subsequent reactions. The washed activated carbon was placed in a forced-air drying oven and dried at 108℃ for 10 hours. Ventilation was carried out every 2 hours for 10 minutes each time to ensure thorough drying and improve the uniformity of dispersion in the polyacrylic acid solution, resulting in oxidized activated carbon. Figure 1 As shown.

[0023] Preparation of S200, a pH / Cl⁻ dual-response smart adsorbent: Oxidized activated carbon was dispersed in an 8% (w / w) polyacrylic acid solution with a molecular weight of 80,000 Da. The liquid-to-solid ratio of oxidized activated carbon to polyacrylic acid solution was 20 mL / g. Polyacrylic acid imparts pH-responsive properties to the adsorbent, aiding in subsequent selective recognition of palladium. 8% (w / w) of the crosslinking agent N,N'-methylenebisacrylamide was added, and the mixture was reacted at 55°C with a stirring rate of 300 r / min for 2.5 h. This crosslinking enhances the binding stability between polyacrylic acid and oxidized activated carbon, preventing detachment during subsequent use. Subsequently, 0.3 g of chlorine source CuCl was added, and the mixture was ultrasonically dispersed for 30 min at a power of 100 W and a frequency of 40 kHz to ensure uniform dispersion of the chlorine source in the system, providing Cl⁻ response sites for the adsorbent. The temperature was then increased to 65°C at a rate of 5°C / min, and vacuum dried at -0.09 MPa for 5 h to remove moisture, yielding a structurally stable basic intelligent activated carbon.

[0024] Disperse 1g of basic smart activated carbon in 80mL of deionized water, add and (The molar ratio of the two is 2:1), and the mixture is stirred at 40°C for 30 minutes under nitrogen protection. Nitrogen can prevent Fe²⁺ from being oxidized, ensuring... and The ratio is stable; adjust the pH to 9.5 by adding 2 mol / L NaOH solution dropwise at a rate of 1 mL / min, so that... and Coprecipitation occurs under suitable alkaline conditions. Nanoparticles, continue stirring for 1.5 hours to ensure... The mixture is fully loaded onto the surface of basic smart activated carbon. After filtration and washing until neutral to remove unreacted salt impurities, it is dried at 70°C to obtain... A magnetic functional adsorbent with a loading of 10 wt%. The loading can make the adsorbent magnetic, which facilitates rapid separation in the future.

[0025] S300, acidity adjustment of the adsorption solution: A strongly acidic solution containing palladium was diluted to 5 mol / L with 12 mol / L concentrated hydrochloric acid, and the acidity was adjusted to 4 mol / L. A strongly acidic environment helps maintain the stable form of palladium in the solution. During the adjustment process, the stirring rate was 350 r / min to ensure uniform acidity. After adjustment, the solution was allowed to stand for 12 minutes, and the acidity was then measured to avoid fluctuations in acidity affecting subsequent adsorption. The initial palladium concentration in the solution was controlled at 100 mg / L, and the concentrations of coexisting metal ions were as follows: 250mg / L 180mg / L 120mg / L 80 mg / L was used to simulate the scenario of interfering ions in a real palladium-containing solution. The solution was stirred evenly to obtain the adsorption solution, ensuring that subsequent adsorption experiments were closer to actual application conditions.

[0026] S400, intelligent directional adsorption and enhanced separation: The prepared magnetic functional adsorbent was added to the absorbent solution at a ratio of 1 g / L. This ratio ensures adsorption efficiency while avoiding adsorbent waste. Adsorption was carried out at 40℃ with a stirring rate of 250 r / min for 4 hours. The suitable temperature and stirring rate promote sufficient contact between the adsorbent and the absorbent solution, improving the palladium collection efficiency. After adsorption, an external magnetic field of 0.3 T was applied close to the outer wall of the container and maintained for 25 seconds to achieve separation of the adsorbent from the solution. The rapid separation was achieved using magnetic attraction, eliminating the need for complex centrifugation or filtration, thus saving separation time.

[0027] S500, Adsorbent Regeneration Cycle: The magnetic functional adsorbent, after adsorbing palladium, was placed in an 8% (w / w) mixed solution of thiourea and 2 mol / L hydrochloric acid, with a liquid-to-solid ratio of 20:1. Thiourea forms a stable complex with palladium, and hydrochloric acid provides an acidic environment to promote the desorption of palladium from the adsorbent surface. This liquid-to-solid ratio ensures sufficient desorbent and adequate contact with the adsorbent. Desorption was carried out at 50°C with a stirring rate of 250 r / min for 2 h. The appropriate temperature and stirring rate accelerated the desorption reaction. After desorption, the adsorbent was ultrasonically washed with an 80W ultrasonic cleaner for 5 min each time, for a total of 4 washes. The ultrasonic action thoroughly removed the residual thiourea-palladium complex and impurities from the adsorbent surface until the washing solution was neutral. The washed adsorbent was dried at 95°C to remove moisture, yielding a regenerated adsorbent that can be used again to capture palladium, thus achieving adsorbent recycling.

[0028] In summary, this embodiment achieves the directional capture of palladium in a strongly acidic, high-chlorine medium based on a magnetic system, strictly adhering to the parameters in the documentation throughout the process. First, 1200 m² / g, 100-mesh coconut shell activated carbon was used as raw material, oxidized by reflux with 15% nitric acid at 90°C, followed by neutral washing and drying at 108°C to obtain oxidized activated carbon. Then, a basic adsorbent was prepared by grafting polyacrylic acid and introducing Cl⁻ sites with CuCl, and Fe₃O₄ was loaded to obtain a magnetic adsorbent. After adjusting the adsorption solution to an acidity of 4 mol / L and a palladium concentration of 100 mg / L, the adsorbent was added at 1 g / L and adsorbed at 40°C. Separation was then performed under a 0.3T magnetic field for 25 s. Regeneration was achieved by desorption with 8% thiourea-2 mol / L hydrochloric acid, ultrasonic washing, and drying at 95°C. The entire process balanced the directional capture and rapid separation of palladium with the recycling of the adsorbent. Example 2:

[0029] A bio-enzyme system was used to directionally capture palladium in a strongly acidic, high-chlorine medium.

[0030] S100, activated carbon oxidation pretreatment: Coal-based activated carbon with a specific surface area of ​​1000 m² / g and a particle size of 90 mesh was selected as the initial activated carbon. It was placed in a 12% (w / w) nitric acid solution and refluxed at 85°C for 4.5 h. The oxidizing properties of nitric acid were utilized to construct more oxygen-containing active sites on the surface of the coal-based activated carbon, enhancing its subsequent interaction with polyacrylic acid. After cooling to room temperature, the activated carbon was filtered using a vacuum filtration device with a pore size of 0.45 μm. The filtrate was washed with deionized water until the pH was neutral to remove residual nitric acid and impurities from the activated carbon surface, preventing adverse effects on subsequent adsorbent preparation. The activated carbon was then placed in a forced-air drying oven and dried at 106°C for 9 h. Ventilation was carried out every 2 h for 10 min each time to ensure thorough drying and improve its dispersion in solution, resulting in oxidized activated carbon.

[0031] Preparation of S200, a pH / Cl⁻ dual-response smart adsorbent: Oxidized activated carbon was dispersed in a 6% (w / w) polyacrylic acid solution with a molecular weight of 60,000 Da. The liquid-to-solid ratio of oxidized activated carbon to polyacrylic acid solution was 20 mL / g. The introduction of polyacrylic acid enables the adsorbent to have pH responsiveness, facilitating subsequent adjustment of palladium adsorption performance based on solution pH changes. 6% (w / w) of the crosslinking agent N,N'-methylenebisacrylamide was added to the oxidized activated carbon, and the mixture was reacted at 52°C with a stirring rate of 300 r / min for 2.2 h. This crosslinking reaction allows the polyacrylic acid and oxidized activated carbon to form a stable structure, reducing dissolution and loss during use. 0.4 g of chlorine source NaCl was added, and the mixture was ultrasonically dispersed for 30 min at a power of 90 W and a frequency of 40 kHz to ensure uniform dispersion of NaCl within the system, providing Cl⁻ responsive sites for the adsorbent. The temperature was then increased to 62°C at a rate of 5°C / min, and vacuum dried at -0.085 MPa for 4.5 h to remove moisture, yielding the basic intelligent activated carbon.

[0032] One g of basic smart activated carbon was immersed in 50 mL of 0.1 mol / L phosphate buffer (pH 6.5). The phosphate buffer maintains a stable pH environment and protects the activity of the subsequently added bio-enzymes. A 0.3 mg / mL cysteine ​​protease solution was added, and the mixture was incubated at 30 °C with constant shaking at 150 r / min for 1.5 h. The appropriate temperature and shaking rate allow the cysteine ​​protease to be fully adsorbed onto the surface of the basic smart activated carbon. Subsequently, a 0.8% glutaraldehyde solution was added dropwise for cross-linking for 0.8 h. The glutaraldehyde cross-linking effect firmly fixes the cysteine ​​protease onto the basic smart activated carbon, preventing the enzyme from falling off during subsequent use. The carbon was washed four times with phosphate buffer to remove unfixed enzymes and impurities. The carbon was then vacuum dried at 50 °C to obtain a bio-enzyme functional adsorbent with an enzyme fixation amount of 0.3 mg / g. The fixed bio-enzyme can enhance the selective capture ability of the adsorbent for palladium.

[0033] S300 Acidity Adjustment of Adsorption Solution A strongly acidic solution containing palladium was diluted to 5 mol / L with 12 mol / L concentrated hydrochloric acid. The acidity was then adjusted to 5 mol / L to ensure palladium exists in a suitable form, facilitating capture by the bio-enzyme adsorbent. The stirring rate was 320 r / min during the adjustment process to ensure uniform acidity distribution. After adjustment, the solution was allowed to stand for 13 minutes, and the acidity was then measured to ensure it met adsorption requirements. The initial palladium concentration in the solution was controlled at 150 mg / L, and the concentrations of coexisting metal ions were as follows: 220mg / L 160mg / L 130mg / L 70 mg / L was used to simulate the ionic composition of a real palladium-containing solution. The solution was stirred evenly to obtain the adsorption solution, making subsequent adsorption experiments more practically valuable.

[0034] S400, intelligent directional adsorption and enhanced separation: The bio-enzyme functional adsorbent was added to the absorbent solution at a ratio of 1.5 g / L. This dosage ensures effective palladium capture while controlling costs. Adsorption was performed at 35°C with a stirring rate of 200 r / min for 3 hours. The suitable temperature maintains the activity of the bio-enzyme, and stirring promotes sufficient contact between the adsorbent and the absorbent solution, increasing the palladium adsorption capacity. After adsorption, the absorbent was separated by filtration using a 0.22 μm filter membrane. The pore size of the filter membrane effectively retains the bio-enzyme functional adsorbent. The filtration pressure was -0.08 MPa, and the negative pressure was used to accelerate the filtration rate. After filtration, the filter membrane was rinsed with 5 mL of deionized water to remove any residual absorbent solution and unadsorbed palladium, preventing palladium loss.

[0035] S500, Adsorbent Regeneration Cycle: The bio-enzyme functional adsorbent, after palladium adsorption, was placed in a 6% (w / w) mixed solution of thiourea and 1.5 mol / L hydrochloric acid, with a liquid-to-solid ratio of 15:1. Thiourea can complex with the adsorbed palladium, while hydrochloric acid provides an acidic environment to facilitate palladium desorption from the adsorbent surface. This liquid-to-solid ratio ensures sufficient contact between the desorbent and adsorbent. Desorption was carried out at 45℃ with a stirring rate of 220 r / min for 1.5 h. The gentle temperature promotes the desorption reaction while minimizing damage to the bio-enzyme structure. After desorption, the adsorbent was first soaked in neutral phosphate buffer for 30 min to repair any potentially damaged bio-enzyme structure, and then washed with deionized water until neutral to remove residual desorbent and impurities. The washed adsorbent was then dried at 92℃ to remove moisture, yielding a recyclable regenerated bio-enzyme functional adsorbent, reducing the cost of subsequent palladium capture.

[0036] In summary, this embodiment utilizes a bio-enzyme system to capture palladium in a strongly acidic, high-chlorine medium. All parameters are derived from relevant documents. Using 1000 m² / g, 90-mesh coal-based activated carbon as the substrate, oxidized activated carbon was prepared by reflux oxidation with 12% nitric acid at 85°C, neutral washing, and drying at 106°C. A bio-enzyme adsorbent was obtained by grafting polyacrylic acid and introducing Cl⁻ sites with NaCl to immobilize cysteine ​​protease. After adjusting the adsorption solution to 5 mol / L acidity and 150 mg / L palladium, adsorbent was added at 1.5 g / L and adsorbed at 35°C. Separation was achieved by negative pressure filtration through a 0.22 μm filter membrane. Desorption was performed using 6% thiourea-1.5 mol / L hydrochloric acid, enzyme repair was achieved with phosphate buffer, and regeneration was completed by drying at 92°C. This process achieves selective palladium capture and adsorbent recycling, closely aligning with practical application scenarios.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for the directional capture of palladium by activated carbon in a strongly acidic, high-chlorine medium, characterized in that, The specific steps of this method are as follows: S100, Pretreatment of activated carbon oxidation: Select raw activated carbon, place it in a 10%-20% nitric acid solution, reflux and stir at 80-95℃ for 4-6 hours, cool and filter, wash with deionized water until the pH of the filtrate is neutral, and dry at 105-110℃ for 8-12 hours to obtain oxidized activated carbon. Preparation of S200, pH / Cl⁻ dual-response smart adsorbent: Disperse oxidized activated carbon in a 5%-10% (w / w) polyacrylic acid solution, add crosslinking agent N,N'-methylenebisacrylamide, react at 50-60℃ for 2-3 h, then add chlorine source and ultrasonically disperse for 30 min, and vacuum dry at 60-70℃ for 4-6 h to obtain basic smart activated carbon; Three types of functional adsorption systems were prepared based on basic smart activated carbon: a magnetic system was prepared by co-precipitation loading. Nanoparticles and bio-enzyme systems are cross-linked and immobilized with glutaraldehyde, and an electric field system is mixed with polytetrafluoroethylene to form a three-electrode device. S300, acidity adjustment of the adsorption solution: Take a strong acidic solution containing palladium, adjust the acidity to 3-6 mol / L with hydrochloric acid, control the initial palladium concentration to be 10-200 mg / L, and the concentration of coexisting metal ions to be 50-500 mg / L, stir evenly to obtain the adsorption solution; S400, intelligent directional adsorption and enhanced separation: Add the corresponding functional adsorbent to the solution to be adsorbed at a ratio of 0.5-2 g / L. After adsorption by stirring at 30-50℃ for 2-6 hours in the magnetic system, separation is achieved by using an external magnetic field of 0.1-0.5T. After adsorption by stirring at 30-45℃ for 2-5 hours in the biological enzyme system, separation is achieved by filtration. After adsorption by stirring at 30-50℃ for 1-2 hours in the electric field system with an electric field of 1-5V / cm, the electrode is removed and washed. S500, Adsorbent Regeneration Cycle: The adsorbent after adsorbing palladium is placed in a 5%-10% thiourea-hydrochloric acid mixed solution, stirred and desorbed at 40-60℃ for 1-3 hours, washed until neutral after desorption, and dried at 90-100℃ to obtain the regenerated adsorbent.

2. The adsorption method for the directional capture of palladium by activated carbon in a strongly acidic, high-chlorine medium according to claim 1, characterized in that, In the S100 activated carbon oxidation pretreatment, the original activated carbon is coconut shell activated carbon, walnut shell activated carbon or coal-based activated carbon, with a specific surface area of ​​800-1500 m² / g and a particle size of 80-120 mesh; filtration is carried out using a vacuum filtration device with a filter membrane pore size of 0.45 μm; drying is carried out using a forced-air drying oven, with ventilation every 2 hours for 10 minutes each time.

3. The adsorption method for the directional capture of palladium by activated carbon in a strongly acidic, high-chlorine medium according to claim 1, characterized in that, In the preparation of the S200, pH / Cl⁻ dual-response smart adsorbent, the molecular weight of polyacrylic acid is 50,000-100,000 Da, the liquid-solid ratio of oxidized activated carbon to polyacrylic acid solution is 20 mL / g, the amount of crosslinking agent N,N'-methylenebisacrylamide added is 5%-10% of the mass of oxidized activated carbon, and the stirring rate during the reaction is 300 r / min.

4. The adsorption method for the directional capture of palladium by activated carbon in a strongly acidic, high-chlorine medium according to claim 1, characterized in that, In the preparation of the S200, pH / Cl⁻ dual-response smart adsorbent, the chlorine source is CuCl, AgCl, or NaCl, and the amount added is 0.2-0.5g; the ultrasonic dispersion power is 80-120W, and the frequency is 40kHz; the heating rate of vacuum drying is 5℃ / min, and the vacuum degree is maintained at -0.08 to -0.1MPa.

5. The adsorption method for the directional capture of palladium by activated carbon in a strongly acidic, high-chlorine medium according to claim 1, characterized in that, In the preparation of the S200, pH / Cl⁻ dual-response smart adsorbent, the preparation process of the magnetic functional adsorbent is as follows: 1g of basic smart activated carbon is dispersed in 80mL of deionized water, and then... and The molar ratio of the two components was 2:

1. The mixture was stirred at 40°C for 30 min under nitrogen protection. 2 mol / L NaOH solution was added dropwise at a rate of 1 mL / min to adjust the pH to 9-10. Stirring continued for 1.5 h. The mixture was then filtered, washed until neutral, and dried at 70°C. The load is 5%-15wt%.

6. The adsorption method for the directional capture of palladium by activated carbon in a strongly acidic, high-chlorine medium according to claim 1, characterized in that, In the preparation of the S200, pH / Cl⁻ dual-response smart adsorbent, the preparation process of the bio-enzyme functional adsorbent is as follows: 1g of basic smart activated carbon is immersed in 50mL of 0.1mol / L phosphate buffer solution with pH 6.0-7.0, and 0.1-0.5mg / mL of cysteine ​​protease or glutathione reductase solution is added. The mixture is incubated at 30℃ with constant temperature shaking for 1-2h at a shaking rate of 150r / min. 0.5%-1% glutaraldehyde solution is added dropwise for cross-linking for 0.5-1h. After washing 3-5 times with phosphate buffer solution, the mixture is vacuum dried at 40-60℃, and the enzyme fixation amount is 0.1-0.5mg / g.

7. The adsorption method for the directional capture of palladium by activated carbon in a strongly acidic, high-chlorine medium according to claim 1, characterized in that, In the preparation of the S200, pH / Cl⁻ dual-response smart adsorbent, the preparation process of the electric field functional adsorption system is as follows: 1g of basic smart activated carbon and 0.11g of polytetrafluoroethylene are mixed evenly at a mass ratio of 9:1, and pressed into a sheet electrode with a diameter of 10-20mm and a thickness of 1-2mm under a pressure of 10-15MPa. The electrode porosity is ≥70%. The sheet electrode is used as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode to construct a three-electrode device.

8. The adsorption method for the directional capture of palladium by activated carbon in a strongly acidic, high-chlorine medium according to claim 1, characterized in that, For the S300, during the acidity adjustment of the adsorption solution, 12 mol / L concentrated hydrochloric acid is diluted to 5 mol / L before use. During the adjustment process, the stirring rate is 300-400 r / min. After adjustment, the solution is allowed to stand for 10-15 minutes before the acidity is measured. The coexisting metal ions are... , , , ,in Concentration of 200-300 mg / L Concentration of 150-200 mg / L Concentration of 100-150 mg / L The concentration is 50-100 mg / L.

9. The adsorption method for the directional capture of palladium by activated carbon in a strongly acidic, high-chlorine medium according to claim 1, characterized in that, In the S400 intelligent directional adsorption and enhanced separation process, the stirring rate of the magnetic system adsorption is 200-300 r / min, the distance between the magnetic field and the outer wall of the container is 5 mm, and the separation time is 20-30 s. The biological enzyme system filtration uses a 0.22 μm filter membrane at a filtration pressure of -0.08 MPa, and the filter membrane is rinsed with 5 mL of deionized water after filtration. The stirring rate of the electric field system adsorption is 100-200 r / min, the electric field voltage fluctuation is ≤ ±0.1 V, and the electrode is washed by soaking in 0.1 mol / L hydrochloric acid for 5 min and then rinsing, followed by washing with deionized water 3 times, with a washing volume of 30 mL each time.

10. The adsorption method for the directional capture of palladium by activated carbon in a strongly acidic, high-chlorine medium according to claim 1, characterized in that, In the S500, during the adsorbent regeneration cycle, the thiourea-hydrochloric acid mixed solution is prepared by dissolving thiourea with a mass concentration of 5%-10% in 1-3 mol / L hydrochloric acid, with a liquid-solid ratio of 10:1-30:1; the stirring rate during desorption is 200-300 r / min; the magnetic system adsorbent is washed using ultrasonic washing at a power of 80W, with each wash lasting 5 minutes, for a total of 4 washes; The bio-enzyme system adsorbent was soaked in neutral phosphate buffer for 30 minutes before washing.

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