Preparation method and application of pyridine / amidoxime composite adsorbent
By introducing pyridyl axime monomers onto the surface of graphene oxide, an acid-resistant composite adsorbent was constructed, which solved the problem of low adsorption capacity of axime-based materials in strong acid environments and achieved efficient recovery of gold and palladium.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANCHANG HANGKONG UNIVERSITY
- Filing Date
- 2026-05-22
- Publication Date
- 2026-07-21
AI Technical Summary
Existing amylopyram adsorbents have low adsorption capacity and poor selectivity for precious metals in strong acid environments, making it difficult to efficiently recover gold and palladium from waste circuit boards.
By introducing pyridyl axime monomers onto the surface of graphene oxide, and utilizing the electron-donating ability of pyridine nitrogen atoms and the cross-linking effect of dopamine, an acid-resistant composite adsorbent was constructed to enhance the capture performance of gold and palladium.
It maintains structural stability in strongly acidic media, significantly improves the adsorption capacity and selectivity for gold and palladium, simplifies the recovery process, and reduces operating costs.
Smart Images
Figure CN122424784A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing a methylamine oxime composite adsorbent and its application. Background Technology
[0002] With the rapid iteration of the electronics and information industry, electronic waste from urban mines, especially waste printed circuit boards (W-PCBs), has seen an average annual compound growth rate of 3-5%, making it one of the fastest-growing solid wastes globally. W-PCBs possess both environmental and resource attributes. On the one hand, as solid waste, improper disposal can severely damage the ecological environment; on the other hand, W-PCBs contain a considerable amount of valuable metals, making them highly valuable for recycling. However, due to the lack of green, sustainable, and effective technologies, currently less than 20% of W-PCBs worldwide are recycled, resulting in resource waste. Gold and palladium are the two most valuable metals in W-PCBs; it is estimated that their content in electronic waste is far higher than in natural ores. Efficiently recovering gold and palladium from W-PCBs can not only solve the problem of electronic waste pollution but also alleviate the scarcity of precious metal resources.
[0003] Existing precious metal recovery processes in W-PCBs include three main stages: physical pretreatment, hydrometallurgical leaching, and metal enrichment and separation. Currently, the mainstream hydrometallurgical recovery route requires metal leaching in a strongly acidic medium, followed by selective separation and extraction of the target precious metal from the acidic leachate. However, these leachates are often highly acidic and contain coexisting Fe... 3+ Cu 2+ The presence of various impurity ions significantly increases the difficulty of subsequent separation and enrichment of precious metals. Traditional techniques such as precipitation, solvent extraction, and membrane separation, while capable of recovering precious metals, generally suffer from insufficient selectivity and lengthy processes in practical applications. In contrast, adsorption methods, with their advantages of simple operation, excellent selectivity, low energy consumption, and minimal secondary pollution, are gradually becoming an ideal alternative for the efficient recovery of precious metals from complex acidic leaching systems. Amine oxime-based adsorbents, with their abundant amino and hydroxyl functional groups, possess both strong reducing power and multidentate coordination characteristics, meeting the core requirements for precious metal recovery from strongly acidic leachates. However, amine oxime-based adsorbents still face the core challenge of significant degradation of their precious metal adsorption capacity in strongly acidic environments. This phenomenon stems from the simultaneous weakening of the reducing and coordination properties of amine oxime groups in strongly acidic media. Protonation of amino / hydroxyl groups in strongly acidic environments leads to a decrease in lone pair electron density, weakening electron supply capacity and triggering H+ ionization. + Competitive occupation of chelating sites leads to varying degrees of decline in the capture performance of gold and palladium ions. Therefore, how to simultaneously enhance the intrinsic reducing activity and coordination ability of the amylopyrime group through molecular design has become the key to breaking through the limits of noble metal recovery under strong acid conditions.
[0004] Pyridine heterocycles, due to their unique p-π conjugated electron system, are ideal regulatory units for optimizing electron transport behavior. Their core function stems from the directional regulation of the electron cloud density of the pyridine N atom and its strong metallic coordination energy. On the one hand, sp... 2 The lone pairs of electrons in the hybrid orbitals that do not participate in conjugation induce a redistribution of electron density in the ring structure through a strong electron-withdrawing effect, forming a π-electron-deficient aromatic system. The spatial orientation (ortho / para) of the pyridine group directly determines its orbital overlap efficiency with the substituent group. The para configuration, due to the linear extension of the conjugated chain, exhibits a more significant electron delocalization effect, effectively enhancing the electron-donating ability of the para-substituent group. As a Lewis base site, the pyridine N atom can provide highly active coordinating lone pairs of electrons to form stable coordination bonds with noble metal ions. Therefore, by controlling the electron-donating and chelating coordination abilities of the material through the spatial position (ortho / para) of the pyridine N atom and the metallo-oxime group, the metallo-oxime adsorbent material's ability to reduce Au(III) and coordinate Pd(II) can be enhanced, thereby improving its capture performance of noble metal ions in strongly acidic media. Summary of the Invention
[0005] This invention aims to address the technical problems of poor structural stability, low adsorption capacity, and poor selectivity of current amylopectin-based adsorbents in strong acid systems. It provides a method for preparing a pyridine / amylopectin composite adsorbent and its application. This material can maintain excellent structural stability and selective adsorption performance in complex waste circuit board acid leaching solutions, achieving efficient recovery of gold and palladium.
[0006] The preparation method of the pyridine / gammoxime composite adsorbent of the present invention is carried out according to the following steps:
[0007] 1. Add graphene oxide (GO) to Tris buffer solution, and then sonicate to disperse GO evenly. After sonication, place the reaction system on a magnetic stirrer and add dopamine and pyridylamine oxime monomers under constant stirring.
[0008] 2. Adjust the pH of the system to 8.5±0.1 using acid-base reagents; continue stirring at a constant speed at room temperature; after the reaction is complete, collect the precipitate by centrifugation, wash it once with DMF, then wash it with deionized water until neutral, and then freeze-dry it to obtain the pyridine / mercaptooxime composite adsorbent.
[0009] The pyridine / mercaptooxime composite adsorbent prepared in this invention is used to capture gold and palladium ions in acid leaching solutions.
[0010] The design principle of this invention is as follows: This invention uses the hierarchical porous structure of graphene oxide as a three-dimensional supporting framework, and utilizes the cross-linking effect during dopamine polymerization to achieve the dispersion and fixation of two pyridylamine oxime monomers (2-pyridylamine oxime and 4-pyridylamine oxime) between graphene oxide layers. In a weakly alkaline buffer environment (pH 8.5 ± 0.1), dopamine molecules form a strongly adherent polydopamine thin layer on the graphene oxide surface through dissolved oxygen-driven oxidative polymerization. During this process, polydopamine fixes the pyridylamine oxime monomers in situ on the graphene oxide surface through electrostatic interactions, hydrogen bonds, and π-π stacking. Furthermore, the catechol groups in polydopamine transfer electrons to the graphene oxide sheets, reducing them to reduced graphene oxide. The aromatic rings of the two pyridyl axime monomers can also achieve directional π-π stacking with the reduced graphene oxide substrate. This strong intermolecular force drives the axime monomers to uniformly insert into the reduced graphene oxide layers, effectively suppressing the aggregation phenomenon between the reduced graphene oxide layers. Thanks to the protective effect of the polydopamine layer and the π-π interaction between the pyridyl axime monomers and the reduced graphene oxide layers, the structure of this composite adsorbent can effectively resist strong acid erosion and maintain structural stability in a strongly acidic environment.
[0011] This invention successfully constructed two composite adsorbents with excellent acid resistance by simultaneously introducing pyridine-amine oxime monomers at different sites onto the surface of dopamine-assisted graphene oxide. Under strong acid conditions, the two adsorbents exhibit highly efficient and selective adsorption performance for gold and palladium ions, respectively. The adsorbents prepared in this invention can be applied to the gradient recovery of gold and palladium from waste circuit board acid leaching solutions, electroplating waste liquids, and mining and metallurgical leaching solutions.
[0012] Compared to existing adsorbents, the advantages of this invention are as follows:
[0013] (1) Excellent acid resistance: The aromatic heterocycles and conjugated structure in the pyridyl amylopyridine monomer of the present invention endow the adsorbent material with high chemical stability; at the same time, the three-dimensional cross-linked network formed between graphene oxide, polydopamine and pyridyl amylopyridine monomer further enhances the acid resistance of the adsorbent material.
[0014] (2) Outstanding adsorption performance: The abundant amylopectin groups in the adsorbent material endow it with excellent noble metal capture performance; in addition, the pyridine nitrogen atoms in the structure of the adsorbent material can regulate the redox ability of the amylopectin groups on the one hand, and can directly participate in the capture of noble metal ions as adsorption sites on the other hand, thereby significantly improving the adsorption performance of the adsorbent material for noble metal ions.
[0015] (3) The present invention uses a water-DMF mixed solvent system and is synthesized in one pot at room temperature. It does not require high temperature and high pressure, has no harmful by-products, and is easy to operate. Attached Figure Description
[0016] Figure 1 SEM images and corresponding EDS elemental distribution maps of the two pyridine-amine oxime composite adsorbents, o-AO / rGO and p-AO / rGO, prepared in Experiment 1 and Experiment 2, respectively.
[0017] Figure 2 Comparison of hydrophilicity and hydrophobicity tests between o-AO / rGO and p-AO / rGO prepared for Experiment 1 and Experiment 2, respectively, and the original GO;
[0018] Figure 3 The adsorption performance of the two composite adsorbents, p-AO / rGO and o-AO / rGO, for gold ions and palladium ions under strong acid conditions was demonstrated in Experiment 3.
[0019] Figure 4 The adsorption performance of o-AO / rGO and p-AO / rGO composite adsorbents for gold and palladium ions in a multi-metal ion coexistence system was demonstrated in Experiment 4.
[0020] Figure 5 The graph shows the performance of o-AO / rGO and p-AO / rGO in recovering gold and palladium in the acid leaching process of actual waste circuit boards in Experiment 5. Detailed Implementation
[0021] Specific Implementation Method 1: This implementation method is a preparation method of a pyridine / gammoxime composite adsorbent, specifically carried out according to the following steps:
[0022] 1. Add graphene oxide to Tris buffer solution, and then sonicate to disperse GO evenly. After sonication, place the reaction system on a magnetic stirrer and add dopamine and pyridylamine oxime monomer under constant stirring.
[0023] 2. Adjust the pH of the system to 8.5±0.1 using acid-base reagents; continue stirring at a constant speed at room temperature; after the reaction is complete, collect the precipitate by centrifugation, wash it once with DMF, then wash it with deionized water until neutral, and then freeze-dry it to obtain the pyridine / mercaptooxime composite adsorbent.
[0024] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the preparation method of the Tris buffer solution in step one is as follows: 0.1211 g of tris(hydroxymethyl)aminomethane (Tris) is placed in a 100 mL volumetric flask, dissolved in a mixed solvent of water and DMF, and diluted to the mark to prepare a 10 mM Tris buffer solution; the volume ratio of water and DMF in the mixed solvent is 1:1. Everything else is the same as in Specific Implementation Method One.
[0025] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 2 in that the mass ratio of graphene oxide to Tris buffer solution in step one is 2 mg:1 mL. Everything else is the same as in Specific Implementation Method 2.
[0026] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the pyridylamine oxime monomer mentioned in step one is 2-pyridylamine oxime or 4-pyridylamine oxime. Everything else is the same as in Specific Implementation Methods One to Three.
[0027] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method Four in that the mass ratio of dopamine to pyridylamine oxime monomer in step one is 1:(0.5~4). Everything else is the same as in Specific Implementation Method Four.
[0028] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method Five in that the mass ratio of graphene oxide to pyridylamine oxime monomer in step one is 1:(0.5~4). Everything else is the same as in Specific Implementation Method Five.
[0029] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method Six in that the constant speed stirring speed mentioned in step one is 300 rpm. Everything else is the same as in Specific Implementation Method Six.
[0030] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Seven in that the acid and base reagents mentioned in step two are 0.1M NaOH solution and 0.1M HCl solution. Everything else is the same as in Specific Implementation Method Seven.
[0031] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Eight in that, in step two, constant-speed stirring is continued at room temperature for 2 to 5 hours. Everything else is the same as in Specific Implementation Method Eight.
[0032] Specific Implementation Method 10: This implementation method is the application of the pyridine / mercaptooxime composite adsorbent prepared in Specific Implementation Method 1, specifically used to capture gold ions and palladium ions in acid leaching solution.
[0033] The invention was verified using the following experiments:
[0034] Experiment 1: This experiment demonstrates a method for preparing a pyridine / gammoxime composite adsorbent, specifically carried out according to the following steps:
[0035] 1. Place 0.1211 g of tris(hydroxymethyl)aminomethane (Tris) in a 100 mL volumetric flask, dissolve it in a mixed solvent of water and DMF (volume ratio 1:1), and dilute to the mark to prepare a 10 mM Tris buffer solution.
[0036] 2. Add 100 mg of graphene oxide (GO) to 50 mL of the Tris buffer solution prepared in step 1, and then sonicate for 20 min to disperse the GO evenly. After sonication, place the reaction system on a magnetic stirrer and maintain constant stirring speed (300 rpm). Then add 100 mg of dopamine (DA) and 200 mg of 2-pyridylamine oxime.
[0037] 3. Add pre-prepared 0.1M NaOH solution and 0.1M HCl solution dropwise to the reaction system and adjust the pH of the system to 8.5±0.1; continue stirring at the same constant speed for 3 hours at room temperature (25±2℃);
[0038] IV. After the reaction was completed, the precipitate was collected by centrifugation, washed three times with DMF, then washed with deionized water until neutral, and then freeze-dried for 24 hours to obtain a composite adsorbent with pyridine nitrogen atoms located in the ortho position of the amylopyridine group, named o-AO / rGO, where AO refers to amylopyridine.
[0039] Experiment 2: This experiment differs from Experiment 1 in that the 2-pyridylamine oxime in step 2 is replaced with 4-pyridylamine oxime, ultimately yielding a composite adsorbent with the pyridine nitrogen atom located at the para position of the amine oxime group, named p-AO / rGO. The rest is the same as Experiment 1.
[0040] Figure 1 SEM images and corresponding EDS elemental distribution maps of the o-AO / rGO and p-AO / rGO pyridine-amine oxime composite adsorbents prepared for Experiments 1 and 2, respectively, show that both o-AO / rGO and p-AO / rGO exhibit typical wrinkled two-dimensional topology with a continuously undulating corrugated structure on the surface. This morphology is inherited from the intrinsic characteristics of graphene oxide. The flexible graphene oxide sheets undergo random cross-linking through spontaneous curling and non-covalent interactions, ultimately self-assembling to form a porous three-dimensional network. Notably, compared to the original graphene oxide, the wrinkled structure of the composite material is significantly denser, a phenomenon mainly attributed to the cross-linking effect of polydopamine. Polydopamine molecular chains undergo in-situ polymerization within the graphene oxide layers, forming a continuous polymer film uniformly coating the graphene surface, successfully anchoring the pyridine-amine oxime monomers within the graphene oxide interlayers. No obvious particles formed by the self-aggregation / deposition of polydopamine or pyridylamine oxime monomers were observed on the surface of the composite material, indicating that the synthesis process achieved uniform composite formation of pyridylamine oxime monomers and graphene oxide. Elemental spatial distribution analysis using EDS showed that the carbon skeleton (C), nitrogen species (N), and oxygen-containing groups (O) exhibited highly uniform dispersion characteristics in both o-AO / rGO and p-AO / rGO composite materials, corroborating the in-situ anchoring of pyridylamine oxime monomers between graphene oxide layers.
[0041] Figure 2 The figures show a comparison of the hydrophilicity and hydrophobicity of o-AO / rGO and p-AO / rGO prepared in Experiments 1 and 2, respectively, with that of the original GO. The original GO, rich in strongly hydrophilic functional groups such as hydroxyl (-OH) and carboxyl (-COOH), exhibits a low contact angle of 38.41°, confirming its hydrophilic properties. Although the polydopamine crosslinking process leads to partial reduction of graphene oxide (rGO), weakening some surface hydrophilicity, it also introduces dual hydrophilic groups. The polydopamine phenolic hydroxyl groups and the amylopectin groups (containing highly electronegative N / O atoms) synergistically compensate for this hydrophilic loss, resulting in both composite materials exhibiting superior hydrophilic properties compared to the original graphene oxide. Notably, in the para-configuration p-AO / rGO, the pyridine nitrogen (strongly polar center) and the amylopectin groups (polydentate ligands) are linearly enantiomeric, and the polar superposition produces a molecular-level synergistic hydrophilic effect, significantly reducing the contact angle to 25.25°. The ortho configuration o-AO / rGO, due to the ability of pyridine nitrogen to form stable OH···N intramolecular hydrogen bonds with the amylopyroxime group, results in spatial shielding of the polar group, increasing the contact angle to 30.34°.
[0042] Experiment 3: This experiment tested the adsorption performance of the p-AO / rGO composite adsorbent prepared in Experiment 2 for gold ions and the o-AO / rGO composite adsorbent prepared in Experiment 1 for palladium ions under strongly acidic conditions (pH=0). The specific steps are as follows:
[0043] Measure 20 mL of Au respectively 3+ Aqueous solutions and Pd 2+ Add the aqueous solution to an Erlenmeyer flask, then weigh 5 mg of the o-AO / rGO prepared in Experiment 1 and 5 mg of the p-AO / rGO composite adsorbent prepared in Experiment 2 into their respective Erlenmeyer flasks (the o-AO / rGO composite adsorbent is used to adsorb Pd). 2+ p-AO / rGO composite adsorbent is used to adsorb Au. 3+ Each solution was sonicated for 30 seconds to ensure uniform dispersion, then placed in a shaker and shaken for 2 hours. After adsorption, the Au content in the solution was measured using an atomic absorption spectrophotometer. 3+ and Pd 2+ The concentrations of Au were calculated separately. 3+ and Pd 2+ The adsorption capacity;
[0044] The Au 3+ The aqueous solution was prepared from HAuCl4 and Pd 2+ The aqueous solution was prepared from Na₂PdCl₄, and the concentration of both ion solutions was 100 mg / L. -1 ;
[0045] The reaction conditions for the oscillating adsorption are 25°C and 180 rpm.
[0046] Figure 3 This study demonstrates the adsorption performance of the p-AO / rGO composite adsorbent for gold ions under strong acid conditions and the adsorption performance of the o-AO / rGO composite adsorbent for palladium ions under strong acid conditions. The results show that p-AO / rGO reaches adsorption equilibrium for gold ions within 5 minutes, while o-AO / rGO reaches adsorption equilibrium for palladium ions within 20 minutes. Both materials maintain high adsorption capacities for noble metals under strong acid conditions, fully demonstrating their potential for efficient capture of noble metals in strongly acidic environments.
[0047] Experiment 4: This experiment tests the adsorption selectivity of two composite adsorbents, o-AO / rGO and p-AO / rGO, for gold and palladium ions in various mixed ionic solutions. The specific steps are as follows:
[0048] Configure two identical copies, both containing Au. 3+ Pd 2+ Ag + Cu 2+ Co 2+ Ni 2+ Pb 2+ Fe 3+ And Al 3+ A solution of 100 mL was prepared, with each metal ion having a concentration of 0.5 mmol / L. -1 Two solutions were each added with 25 mg of o-AO / rGO prepared in Experiment 1 and 25 mg of p-AO / rGO prepared in Experiment 2. The solutions were then subjected to constant temperature shaking at 25 °C for 2 h for adsorption. After adsorption, the supernatant was separated and the residual metal concentration was measured to calculate the adsorption capacity.
[0049] Figure 4 The adsorption performance of o-AO / rGO and p-AO / rGO composite adsorbents for gold and palladium ions in a multi-metal ion coexistence system was demonstrated in Experiment 4. The results show that both composite materials exhibit excellent noble metal targeting and capture capabilities even in a highly competitive ion background. Specifically, p-AO / rGO showed an adsorption capacity of up to 457.05 mg·g for gold ions. -1 It was significantly higher than the 369.76 mg / g of o-AO / rGO. -1 The adsorption capacity of o-AO / rGO for palladium ions is 122.65 mg·g. -1 It is significantly superior to p-AO / rGO at 87.85 mg / g. -1The above data indicate that p-AO / rGO has higher selectivity for gold ions; while when gold ions in the solution are basically completely adsorbed, o-AO / rGO exhibits better adsorption selectivity for palladium ions.
[0050] Experiment 5: This experiment demonstrates a method for recovering gold and palladium from actual waste circuit board leaching solutions using two pyridine-amine oxime composite adsorbents. The specific experimental steps are as follows:
[0051] 200 mg of the p-AO / rGO adsorbent prepared in Experiment 2 was packed into a first fixed-pack column. The actual waste circuit board leaching solution was then pumped through the first fixed-pack column under vacuum to recover gold ions. The effluent from the outlet of the first fixed-pack column was collected. Subsequently, 200 mg of the o-AO / rGO adsorbent prepared in Experiment 1 was packed into a second fixed-pack column. The effluent from the first fixed-pack column was then pumped through the second fixed-pack column under vacuum to further recover the remaining palladium ions.
[0052] Figure 5 Figure a shows the performance of o-AO / rGO and p-AO / rGO in recovering gold and palladium from actual waste circuit board leaching solution in Experiment 5. As can be seen from Figure a, when the waste circuit board leaching solution flows through the p-AO / rGO packed column (i.e., the first fixed packed column), gold ions exhibit significant removal efficiency, with the concentration decreasing from the initial 15.24 mg / L. -1 Decreased to 0.5 mg / L -1 Below, the capture efficiency reached 96.8%, while palladium ions were essentially not adsorbed, and the residual concentration remained above 98.1% of the initial value (from 2.13 mg / L). -1 Slightly decreased to 2.09 mg / L -1 The specific enrichment of gold ions was successfully achieved. Figure b shows the treatment effect of the o-AO / rGO packed column (second fixed packed column), which shows that the palladium ion concentration in the leachate increased from 2.09 mg / L. -1 The concentration dropped sharply to below 0.04 mg / L, with a recovery rate as high as 98.5%.
Claims
1. A method for preparing a pyridine / gammoxime composite adsorbent, characterized in that... The preparation method is carried out according to the following steps:
1. Add graphene oxide to Tris buffer solution, and then sonicate to disperse GO evenly. After sonication, place the reaction system on a magnetic stirrer and add dopamine and pyridylamine oxime monomer under constant stirring.
2. Adjust the pH of the system to 8.5±0.1 using acid-base reagents; continue stirring at a constant speed at room temperature; after the reaction is complete, collect the precipitate by centrifugation, wash it once with DMF, then wash it with deionized water until neutral, and then freeze-dry it to obtain the pyridine / mercaptooxime composite adsorbent.
2. The method for preparing a pyridine / gammoxime composite adsorbent according to claim 1, characterized in that... The preparation method of the Tris buffer solution in step one is as follows: 0.1211 g of tris(hydroxymethyl)aminomethane is placed in a 100 mL volumetric flask, dissolved in a mixed solvent of water and DMF, and diluted to the mark to prepare a 10 mM Tris buffer solution; the volume ratio of water and DMF in the mixed solvent is 1:
1.
3. The method for preparing a pyridine / gammoxime composite adsorbent according to claim 1, characterized in that... The mass ratio of graphene oxide to Tris buffer solution in step one is 2 mg: 1 mL.
4. The method for preparing a pyridine / gammoxime composite adsorbent according to claim 1, characterized in that... The pyridylamine oxime monomer mentioned in step one is 2-pyridylamine oxime or 4-pyridylamine oxime.
5. The method for preparing a pyridine / gammoxime composite adsorbent according to claim 1, characterized in that... The mass ratio of dopamine to pyridylamine oxime monomer in step one is 1:(0.5~4).
6. The method for preparing a pyridine / gammoxime composite adsorbent according to claim 1, characterized in that... The mass ratio of graphene oxide to pyridylamine oxime monomer mentioned in step one is 1:(0.5~4).
7. The method for preparing a pyridine / gammoxime composite adsorbent according to claim 1, characterized in that... The constant speed stirring speed mentioned in step one is 300 rpm.
8. The method for preparing a pyridine / gammoxime composite adsorbent according to claim 1, characterized in that... The acid-base reagents mentioned in step two are 0.1M NaOH solution and 0.1M HCl solution.
9. The method for preparing a pyridine / gammoxime composite adsorbent according to claim 1, characterized in that... In step two, continue stirring at a constant speed at room temperature for 2 to 5 hours.
10. The application of the pyridine / gammoxime composite adsorbent prepared according to claim 1, characterized in that... Specifically, it is used to capture gold and palladium ions in acid leaching solutions.