Method for recycling precious metal through photocatalysis

Abstract

The invention belongs to the field of photocatalyst and precious metal recovery, and particularly relates to a method for recovering precious metal through photocatalysis. Comprising the following steps: under an illumination condition, in an oxygen-containing environment, in a first solvent added with polyoxometallate and a noble metal-containing material, catalyzing the dissolution of noble metal in the noble metal-containing material by the polyoxometallate to generate a noble metal organic or inorganic coordination compound, so as to obtain a first reaction solution; and polyoxometallate obtained after liquid removal of the first reaction liquid and a precious metal organic or inorganic coordination compound are placed in water containing an electron sacrificial agent, and reduced and recycled precious metal is obtained under the illumination condition. According to the method, polyoxometallate is adopted as the catalyst, the method can be carried out under the illumination condition, no toxic solvent is needed, heavy metal pollution and secondary ecological risks are avoided from the source, the precious metal recovery rate is high, economical efficiency and environmental friendliness are high, and the application prospect is wide.

Description

Technical Field

[0001] The invention belongs to the field of photocatalyst and precious metal recovery, and in particular relates to a method for recovering precious metals through photocatalysis. Background Art

[0002] Precious metals (gold, silver, platinum, palladium, etc.) play an irreplaceable role in the fields of electronics, chemical industry, medicine, energy and environmental protection due to their high conductivity, corrosion resistance and catalytic activity. However, precious metal resources are scarce and unevenly distributed, and traditional mining and recovery technologies have significant defects. The pyrometallurgical method has the problems of high energy consumption, complex equipment, and easy generation of large amounts of waste gas pollution. Hydrometallurgy relies on highly corrosive or toxic reagents such as cyanide and aqua regia, which can easily cause secondary pollution and threaten ecological safety; the recovery efficiency of low-concentration precious metal ions is low (usually less than 60%), and the selectivity for complex systems (such as multi-metal coexistence solutions) is poor, making it difficult to meet industrial needs. Patent CN107586966A discloses a highly efficient dissolution process for insoluble precious metals. This technology uses aqua regia or acidic sodium chlorate as a strong oxidizing medium, combined with microwave radiation technology to achieve rapid dissolution of precious metals such as iridium and rhodium. However, this process has significant flaws: its activation process needs to be carried out under high temperature conditions of 1200-1400℃, which places strict requirements on the equipment material; at the same time, the aqua regia system used is highly corrosive, which not only causes serious corrosion to production equipment, but also poses a major environmental safety hazard.

[0003] Photocatalytic technology, a green solution, reduces precious metal ions through the redox reaction of photogenerated electron-hole pairs, offering advantages such as mild reaction conditions and environmental friendliness. Polyoxometalates (POMs) are highly promising photocatalysts due to their unique multi-nuclear cluster structure, tunable redox capacity, and ability to generate photogenerated free radicals. Summary of the Invention

[0004] To overcome the defects of the prior art, the present invention provides a method for recovering precious metals under mild and environmentally friendly conditions. The method uses polyoxometalates as catalysts and can be carried out under light conditions.

[0005] The technical solution of the present invention is:

[0006] Application of polyoxometalates in photocatalytic recovery of precious metals.

[0007] A method for photocatalytic recovery of precious metals, comprising the following steps:

[0008] (1) Under light conditions and in an oxygen-containing environment, a polyoxometalate and a first solvent containing a precious metal material are added, wherein the polyoxometalate catalyzes the dissolution of the precious metal in the precious metal material to form an organic or inorganic coordination compound of the precious metal, thereby obtaining a first reaction solution;

[0009] (2) The polyoxometalate obtained by removing the liquid from the first reaction solution and the organic or inorganic coordination compound of the noble metal are placed in water containing an electron sacrificial agent, and the noble metal is reduced and recovered under light conditions and in an environment isolated from air.

[0010] The polyoxometalates of the present invention include but are not limited to any one or any combination of the following:

[0011] a. Any one or any combination of Keggin type, Dawson type, Silverton type, Anderson type, Waugh type, Standberg type, Weakly type, and Finke type;

[0012] isopoly or heteropoly compounds of ba;

[0013] Derivatives of ca or b.

[0014] The polyoxometalates described in the present invention refer to some early transition metals (such as Mo, W, V, Nb, Ta, etc.) with MO X (M refers to the early transition metal, X refers to the number of oxygen atoms) is a class of inorganic metal oxygen cluster compounds with special properties and structures formed by unit condensation.

[0015] The isopoly compound described in the present invention refers to an isopoly acid anion formed by condensation of the same type of oxygen-containing acid radicals, thereby forming an isopoly compound.

[0016] The heteropoly compound described in the present invention refers to a heteropoly anion formed by condensation of different oxygen-containing acid radicals, thereby forming a heteropoly compound.

[0017] The derivatives described in the present invention include but are not limited to organic-inorganic hybrid derivatives, loaded derivatives, doped derivatives, etc. Organic-inorganic hybrid derivatives refer to organic-inorganic hybrid materials formed by introducing organic groups into the structure of polyoxometalates; this hybridization can be achieved through covalent bonds, coordination bonds, or electrostatic interactions. Loaded derivatives refer to polyoxometalates loaded on various carriers, such as activated carbon, molecular sieves, silica, etc.; the purpose of loading is to improve the stability, dispersibility and contact area of polyoxometalates with the substrate, thereby improving their catalytic performance or other functions. Doped derivatives refer to the electronic structure and performance of polyoxometalates altered by doping other metal ions or non-metal ions into their structure; doped ions can replace part of the original metal ions or fill in the lattice gaps of the polyoxometalates.

[0018] In step (1), in the first solvent, the mass ratio of the precious metal-containing material to the polyoxometalate is 1:0.01-5, preferably 1:0.5-1.5, and more preferably 1:1; the concentration of the polyoxometalate is 0.05-1000 mg / mL, preferably 0.1-100 mg / mL, preferably 0.5-10 mg / mL, and more preferably 1-5 mg / mL. The first solvent is a mixed solvent of a nitrile compound and an organic chloride, a nitrogen-containing organic solvent, or a halogen-containing salt aqueous solution.

[0019] In the mixed solvent of the nitrile compound and the organic chloride, the volume ratio of the nitrile compound to the organic chloride is 40-60:1, preferably 50:1; the nitrile compound includes any one or any combination of acrylonitrile, acetonitrile, benzyl cyanide, cyanoacetic acid, malononitrile, benzyl cyanide, cyclohexyl isocyanide or melamine, preferably acetonitrile; the organic chloride includes any one or any combination of dichloromethane, chloroform, dichloroethylene, trichloroethane, trichloroethanol, 1-chlorotoluene or tetrachloromethane, preferably dichloromethane.

[0020] The nitrogen-containing organic solvent includes any one or any combination of N,N-dimethylformamide, N-methyl-2-pyrrolidone, hexamethylphosphoramide, dimethyl sulfoxide, and tetrahydrofuran, preferably N,N-dimethylformamide.

[0021] The concentration of the halogen salt in the halogen-containing salt aqueous solution is 1-50 g / L, preferably 10-30 g / L, and more preferably 10-15 g / L. The halogen salt comprises any one or any combination of ammonium iodide, potassium iodide, sodium iodide, lithium iodide, ammonium bromide, potassium bromide, sodium bromide, lithium bromide, and ammonium chloride, preferably ammonium iodide or ammonium chloride.

[0022] In step (1), the oxygen-containing environment includes, but is not limited to, air, oxygen, or a substance capable of generating oxygen, so that the oxygen content of the first solvent is 1% to 100%. The substance capable of generating oxygen includes any one or any combination of ozone, hydrogen peroxide, tert-butyl hydroperoxide, or sodium peroxide.

[0023] In step (1), the wavelength of the irradiation light is 150-1500 nm, covering deep ultraviolet light, ultraviolet light, visible light and near infrared light; the irradiation time is 0.01-3600 h, and the light power density is 0.01-2000 mW / cm 2 .

[0024] In step (2), the concentration of the electron sacrificial agent is 0.01-100 mg / mL, preferably 1-10 mg / mL; the electron sacrificial agent includes any one or any combination of methanol, ethanol, isopropanol, formic acid, benzyl alcohol, butanol, ethylene glycol or 1-pentanol, preferably methanol.

[0025] In step (2), the wavelength of the irradiation light is 150-1500 nm, covering deep ultraviolet light, ultraviolet light, visible light and near infrared light; the irradiation time is 0.01-3600 h, and the light power density is 0.01-2000 mW / cm 2 .

[0026] Step (2), isolating the air includes evacuating the air or replacing the air with an inert gas, etc. The inert gas includes but is not limited to any one or any combination of helium, neon, argon, krypton, xenon, radon, and nitrogen, preferably any one or any combination of nitrogen and argon.

[0027] The precious metal-containing materials described in the present invention include but are not limited to electronic waste, precious metal slag and other precious metal-containing materials.

[0028] Furthermore, the hydrothermal preparation of the polyoxometalate of the present invention includes: dissolving a metal salt and an acidifying agent in deionized water in a certain proportion, and reacting them at a specific temperature to prepare the polyoxometalate.

[0029] The metal salt includes but is not limited to any one or any combination of molybdate, tungstate, vanadate, metavanadate, etc., such as any one or any combination of sodium molybdate, sodium tungstate, sodium vanadate, ammonium molybdate, and sodium metavanadate.

[0030] The acidifying agent includes but is not limited to any one or any combination of hydrochloric acid, sulfuric acid, acetic acid, phosphoric acid, etc.

[0031] The addition ratio of metal ions to acidifiers in the metal salt is 0 <m 金属离子 / m 酸化剂 <1.

[0032] The reaction temperature is 90°C-200°C, and the reaction time is 12-72h.

[0033] Compared with the existing technology, the advantages of the present invention are:

[0034] (1) The present invention is based on photocatalytic technology and does not require the use of toxic solvents and strong acids and bases, thus avoiding heavy metal pollution and secondary ecological risks at the source;

[0035] (2) The present invention utilizes the tunable redox potential of POMs, combined with specific ligand design, to achieve directional reduction of target precious metals in multi-metal coexisting solutions, solving the problem of low recovery rate of traditional methods; it is suitable for the efficient recovery of precious metal-containing materials such as electronic waste and precious metal slag, and has significant advantages in the field of precious metal resource utilization;

[0036] The dissolution and reduction process is mild, energy consumption is low, POMs are recyclable, and costs are controllable. With the increasing scarcity of precious metal resources and rising environmental protection requirements, this technology has broad application prospects in the field of resource recycling and is of great significance to promoting green metallurgy and sustainable development.

[0037] (3) The present invention provides an efficient and environmentally friendly precious metal recovery and resource utilization solution, which is highly economical and environmentally friendly. The present invention has broad application prospects in the fields of precious metal recovery, photocatalytic materials and resource utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Flow chart for dissolving and reducing platinum.

[0039] Figure 2 The X-ray diffraction of TBADT (TBADT), the X-ray diffraction of the mixture of platinum ions and TBADT after dissolution (TBADT / Pt x+ ), X-ray diffraction of reduced platinum (Pt), comparison of X-ray diffraction standard card of platinum (Pt PDF#87-0640) and X-ray diffraction standard card of ammonium hexachloroplatinate ((NH4)2PtCl6 PDF#74-0490).

[0040] Figure 3 This is a diagram showing the dissolution effects of NaDT, TBADT and PW as photocatalysts on gold, platinum, palladium, rhodium, ruthenium and iridium.

[0041] Figure 4 The figure shows the reduction effect of NaDT, TBADT and PW as photocatalysts on dissolved gold, platinum, palladium, rhodium, ruthenium and iridium ions. DETAILED DESCRIPTION

[0042] The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings. It should be understood that these embodiments are only used to explain the present invention, and the protection scope of the present invention is not limited to these embodiments.

[0043] Preparation method of polyoxometalate:

[0044] 1. Synthesis of sodium decaptungstate (NaDT, isopolyacid compound) Experimental steps: Mix boiling sodium tungstate solution (50g Na2WO4 dissolved in 300mL ultrapure water) with 1.0M boiling hydrochloric acid (300mL) in a beaker and reflux for 20s to form a green solution. Then add 150g solid sodium chloride and stir until the solution boils again and maintain for 20s, then quickly place in an ice water bath. The suspension solution is stored in a freezer (-18°C) overnight. The next day, filter the NaCl and crude Na4W 10 O 32The suspension was then dissolved in 150 mL of acetonitrile. The acetonitrile solution was refluxed at 79°C for 5 minutes, cooled to ambient temperature, and filtered to remove insoluble NaCl. The acetonitrile solution was gently evaporated in a hot water bath (79°C) to obtain a yellow-green catalyst.

[0045] 2. Synthesis of Tetra-N-butylammonium Decatungstate (TBADT, isopolyacid compound) Experimental steps: Dissolve 32g of sodium tungstate in 200mL of boiling water. While stirring rapidly, quickly (10s) add 6.7mL of boiling 3mol / L HCl solution to acidify the solution. The resulting white precipitate will immediately disappear. After boiling for 1-2 minutes, add 12.8g of tetrabutylammonium bromide aqueous solution and filter. Wash the hot solution with 80mL of boiling water 3-6 times, 60mL of ethanol 2-3 times, and 100mL of ether twice to wash the white solid. Air dry for 1 hour. The crude product is recrystallized from 20mL of hot DMF (80°C). After 1 day, yellow prismatic crystals are obtained and separated by filtration.

[0046] 3. Synthesis of phosphotungstic acid (PW, Keggin type) Experimental steps: Dissolve 100g Na2WO4·2H2O in 100L water, heat to boiling until the solution is clear, add 10mL 85% phosphoric acid and then add 80mL concentrated HCl solution dropwise. The addition speed should not be too fast. Cool to obtain a crystalline product, but it contains a small amount of tungstic acid. After 4h, filter under reduced pressure until it is as dry as possible, redissolve the product in 120mL water, place the solution in a separatory funnel, add 70mL ether, and then add 40mL concentrated HCl solution, shaking while adding. After a few minutes, the mixture will separate into layers. Transfer the polyacid ether compound at the bottom to another separatory funnel, add 120mL water, shake, add 30mL ether and 40mL concentrated HCl solution, shake, let it stand for a while, and the solution will separate into three layers. The upper transparent solution is excess ether, the middle layer is the impurity NaCl and the aqueous solution of tungstic acid, and the lower colorless viscous liquid is H3[PW 12 O 40 ] ether complex. The bottom ether complex was transferred to another beaker, 10 mL of water was added, and the mixture was separated into two layers. Bubbles were generated when heated in a water bath, and a pungent odor was emitted. At the same time, the bottom solution gradually decreased until it disappeared, and there was H3[α-PW 12 O 40 ]Crystals are produced.

[0047] Example 1

[0048] Dissolving precious metals: 50 mg of material containing 1% gold was dispersed in 50 mL of a mixture of acetonitrile and dichloromethane (volume ratio 50:1). Then 50 mg of NaDT was added and irradiated with UV light in air for 12 hours. The gold dissolution rate was 100% ( Figure 3 ).

[0049] Reduction of precious metals: After the solvent was removed, the mixture of NaDT and gold ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, and the mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The gold reduction rate was 100% ( Figure 4 ).

[0050] Example 2

[0051] Dissolving precious metals: 50 mg of material containing 1% gold was dispersed in 50 mL of a mixture of acetonitrile and dichloromethane at a volume ratio of 50:1. Then 50 mg of tetra-N-butylammonium decatungstate (TBADT) was added and irradiated with UV light in air for 12 hours. The gold dissolution rate was 100% ( Figure 3 ).

[0052] Reduction of precious metals: After the solvent was removed, the mixture of TBADT and gold ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, and the mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The gold reduction rate was 100% ( Figure 4 ).

[0053] Example 3

[0054] Dissolving precious metals: 50 mg of material containing 1% gold was dispersed in 50 mL of a mixture of acetonitrile and dichloromethane with a volume ratio of 50:1. Then 50 mg of phosphotungstic acid (PW) was added and irradiated with ultraviolet light in air for 12 hours. The gold dissolution rate was 100% ( Figure 3 ).

[0055] Reduction of precious metals: After the solvent was removed, the mixture of PW and gold ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, and the mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The gold reduction rate was 100% ( Figure 4 ).

[0056] Example 4

[0057] Dissolving precious metals: 50 mg of material containing 1% platinum was dispersed in 50 mL of a mixture of acetonitrile and dichloromethane with a volume ratio of 50:1. Then 50 mg of NaDT was added and irradiated with UV light in air for 12 hours. The gold dissolution rate was 100% ( Figure 3 ).

[0058] Reduction of precious metals: After the solvent was removed, the mixture of NaDT and platinum ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, and the mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of platinum was 100% ( Figure 4 ).

[0059] Example 5

[0060] Dissolving precious metals: 50 mg of material containing 1% platinum was dispersed in 50 mL of a mixture of acetonitrile and dichloromethane with a volume ratio of 50:1. Then 50 mg of tetra-N-butylammonium decatungstate (TBADT) was added and irradiated with ultraviolet light in air for 12 hours. The dissolution rate of platinum was 100% ( Figure 1 、 3 ).

[0061] Reduction of precious metals: After the solvent is removed, the mixture of TBADT and platinum ions ( Figure 2 ) was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, the solution was isolated from air, and irradiated with ultraviolet light for 12 hours. The reduction rate of platinum was 100% ( Figure 4 ).

[0062] Example 6

[0063] Dissolving precious metals: 50 mg of material containing 1% platinum was dispersed in 50 mL of a mixed solution of acetonitrile and dichloromethane with a volume ratio of 50:1. Then 50 mg of phosphotungstic acid (PW) was added and irradiated with ultraviolet light in air for 12 hours. The dissolution rate of platinum was 100% ( Figure 3 ).

[0064] Reduction of precious metals: After the solvent was removed, the mixture of PW and platinum ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, and the mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of platinum was 100% ( Figure 4 ).

[0065] Example 7

[0066] Dissolving precious metals: 50 mg of material containing 1% palladium was dispersed in 50 mL of a mixture of acetonitrile and dichloromethane with a volume ratio of 50:1. Then 50 mg of NaDT was added and irradiated with ultraviolet light in air for 12 hours. The dissolution rate of palladium was 100% ( Figure 3 ).

[0067] Reduction of precious metals: After the solvent was removed, the mixture of NaDT and palladium ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, and the mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The palladium reduction rate was 100% ( Figure 4 ).

[0068] Example 8

[0069] Dissolving precious metals: 50 mg of material containing 1% palladium was dispersed in 50 mL of a mixed solution of acetonitrile and dichloromethane with a volume ratio of 50:1. Then 50 mg of tetra-N-butylammonium decatungstate (TBADT) was added and irradiated with ultraviolet light in air for 12 hours. The dissolution rate of palladium was 100% ( Figure 3 ).

[0070] Reduction of precious metals: After the solvent was removed, the mixture of TBADT and palladium ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, and the mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The palladium reduction rate was 100% ( Figure 4 ).

[0071] Example 9

[0072] Dissolving precious metals: 50 mg of material containing 1% palladium was dispersed in 50 mL of a mixed solution of acetonitrile and dichloromethane with a volume ratio of 50:1. Then 50 mg of phosphotungstic acid (PW) was added and irradiated with ultraviolet light in air for 12 hours. The dissolution rate of palladium was 100% ( Figure 3 ).

[0073] Reduction of precious metals: After the solvent was removed, the mixture of PW and palladium ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, and the mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The palladium reduction rate was 100% ( Figure 4 ).

[0074] Example 10

[0075] Dissolving precious metals: 50 mg of material containing 1% rhodium was dispersed in 50 mL of a mixed solution of acetonitrile and dichloromethane with a volume ratio of 50:1. Then 50 mg of sodium decatungstate (NaDT) was added and irradiated with ultraviolet light in air for 12 hours. The dissolution rate of rhodium was 81% ( Figure 3 ).

[0076] Reduction of precious metals: After the solvent was removed, the mixture of NaDT and rhodium ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, and the mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of rhodium was 99% ( Figure 4 ).

[0077] Example 11

[0078] Dissolving precious metals: 50 mg of material containing 1% rhodium was dispersed in 50 mL of a mixed solution of acetonitrile and dichloromethane with a volume ratio of 50:1. Then 50 mg of tetra-N-butylammonium decatungstate (TBADT) was added and irradiated with ultraviolet light in air for 12 hours. The dissolution rate of rhodium was 78% ( Figure 3).

[0079] Reduction of precious metals: After the solvent was removed, the mixture of TBADT and rhodium ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, and the mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of rhodium was 99% ( Figure 4 ).

[0080] Example 12

[0081] Dissolving precious metals: 50 mg of material containing 1% rhodium was dispersed in 50 mL of a mixed solution of acetonitrile and dichloromethane with a volume ratio of 50:1. Then 50 mg of phosphotungstic acid (PW) was added and irradiated with ultraviolet light in air for 12 hours. The dissolution rate of rhodium was 62% ( Figure 3 ).

[0082] Reduction of precious metals: After the solvent is removed, the mixture of PW and rhodium ions is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, the mixture is isolated from air, and irradiated with ultraviolet light for 12 hours. The reduction rate of rhodium is 99% ( Figure 4 ).

[0083] Example 13

[0084] Dissolving precious metals: 50 mg of material containing 1% ruthenium was dispersed in 50 mL of a mixture of acetonitrile and dichloromethane (volume ratio 50:1). Then 50 mg of NaDT was added and irradiated with UV light in air for 12 hours. The dissolution rate of ruthenium was 48% ( Figure 3 ).

[0085] Reduction of precious metals: After the solvent is removed, a mixture of sodium decatungstate (NaDT) and ruthenium ions is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, the mixture is isolated from air, and irradiated with ultraviolet light for 12 hours. The reduction rate of ruthenium is 99% ( Figure 4 ).

[0086] Example 14

[0087] Dissolving precious metals: 50 mg of material containing 1% ruthenium was dispersed in 50 mL of a mixture of acetonitrile and dichloromethane (50:1 by volume). 50 mg of tetra-N-butylammonium decatungstate (TBADT) was then added and the mixture was irradiated with UV light in air for 12 hours. The dissolution rate of ruthenium was 42% ( Figure 3 ).

[0088] Reduction of precious metals: After the solvent was removed, the mixture of TBADT and ruthenium ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, and the mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of ruthenium was 99% ( Figure 4 ).

[0089] Example 15

[0090] Dissolving precious metals: 50 mg of material containing 1% ruthenium was dispersed in 50 mL of a mixture of acetonitrile and dichloromethane with a volume ratio of 50:1. Then 50 mg of phosphotungstic acid (PW) was added and irradiated with ultraviolet light in air for 12 hours. The dissolution rate of ruthenium was 23% ( Figure 3 ).

[0091] Reduction of precious metals: After the solvent was removed, the mixture of PW and ruthenium ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, and the mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of ruthenium was 99% ( Figure 4 ).

[0092] Example 16

[0093] Dissolving precious metals: 50 mg of material containing 1% iridium was dispersed in 50 mL of a mixture of acetonitrile and dichloromethane with a volume ratio of 50:1. Then 50 mg of sodium decatungstate (NaDT) was added and irradiated with ultraviolet light in air for 12 hours. The dissolution rate of iridium was 9% ( Figure 3 ).

[0094] Reduction of precious metals: After the solvent is removed, sodium decatungstate (NaDT) and a mixture containing iridium ions are dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, the mixture is isolated from air, and irradiated with ultraviolet light for 12 hours. The reduction rate of iridium is 99% ( Figure 4 ).

[0095] Example 17

[0096] Dissolving precious metals: 50 mg of material containing 1% iridium was dispersed in 50 mL of a mixture of acetonitrile and dichloromethane at a volume ratio of 50:1. Then 50 mg of tetra-N-butylammonium decatungstate (TBADT) was added and the mixture was irradiated with ultraviolet light in air for 12 hours. The dissolution rate of iridium was 6% ( Figure 3 ).

[0097] Reduction of precious metals: After the solvent was removed, the mixture of TBADT and iridium ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, and the mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of iridium was 99% ( Figure 4 ).

[0098] Example 18

[0099] Dissolving precious metals: 50 mg of material containing 1% iridium was dispersed in 50 mL of a mixed solution of acetonitrile and dichloromethane with a volume ratio of 50:1. Then 50 mg of phosphotungstic acid (PW) was added and irradiated with ultraviolet light in air for 12 hours. The dissolution rate of iridium was 2% ( Figure 3 ).

[0100] Reduction of precious metals: After the solvent was removed, the mixture of PW and iridium ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, and the mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of iridium was 99% ( Figure 4 ).

[0101] Example 19

[0102] Precious metal dissolution procedure: Disperse 50 mg of a material containing 1% gold in 50 mL of N,N-dimethylformamide (DMF) solution. Then, add 50 mg of sodium decatungstate (NaDT). Irradiate with UV light in air for 12 hours. The gold dissolution rate is 100%.

[0103] Precious metal reduction step: After the solvent is removed, the mixture of NaDT and gold ions is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, and the mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The gold reduction rate is 100%.

[0104] Example 20

[0105] Precious metal dissolution procedure: Disperse 50 mg of a material containing 1% gold in 50 mL of N,N-dimethylformamide (DMF). Then, add 50 mg of tetra-N-butylammonium decatungstate (TBADT). Irradiate with UV light in air for 12 hours. The gold dissolution rate is 100%.

[0106] Precious metal reduction step: After the solvent is removed, the mixture of TBADT and gold ions is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, the mixture is isolated from air, and irradiated with ultraviolet light for 12 hours. The gold reduction rate is 100%.

[0107] Example 21

[0108] Precious metal dissolution procedure: Disperse 50 mg of a material containing 1% gold in 50 mL of N,N-dimethylformamide (DMF) solution. Add 50 mg of phosphotungstic acid (PW) and irradiate with UV light in air for 12 hours. The gold dissolution rate is 100%.

[0109] Reduction of precious metals: After the solvent was removed, the mixture of PW and gold ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, the mixture was isolated from air, and irradiated with ultraviolet light for 12 hours. The gold reduction rate was 100%.

[0110] Example 22

[0111] Precious metal dissolution step: Disperse 50 mg of a material containing 1% platinum in 50 mL of N,N-dimethylformamide (DMF) solution. Then, add 50 mg of sodium decatungstate (NaDT). Irradiate with UV light in air for 12 hours. The gold dissolution rate is 100%.

[0112] Precious metal reduction step: After the solvent is removed, the mixture of NaDT and platinum ions is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of platinum is 100%.

[0113] Example 23

[0114] Precious metal dissolution step: Disperse 50 mg of a material containing 1% platinum in 50 mL of N,N-dimethylformamide (DMF). Then, add 50 mg of tetra-N-butylammonium decatungstate (TBADT). Irradiate with UV light in air for 12 hours. The platinum dissolution rate is 100%.

[0115] Reduction of precious metals: After the solvent was removed, the mixture of TBADT and platinum ions was dispersed in 50 mL of water, to which 5 mg / mL of methanol was added as an electron sacrificial agent. The mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of platinum was 100%.

[0116] Example 24

[0117] Precious metal dissolution step: Disperse 50 mg of a material containing 1% platinum in 50 mL of N,N-dimethylformamide (DMF) solution. Then, add 50 mg of phosphotungstic acid (PW). Irradiate with UV light in air for 12 hours. The platinum dissolution rate is 100%.

[0118] Precious metal reduction step: After the solvent is removed, the mixture of PW and platinum ions is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, and the mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of platinum is 100%.

[0119] Example 25

[0120] Dissolving precious metals: Disperse 50 mg of a material containing 1% palladium in 50 mL of N,N-dimethylformamide (DMF). Add 50 mg of sodium decatungstate (NaDT) and irradiate with UV light in air for 12 hours. The palladium dissolution rate is 100%.

[0121] Reduction of precious metals: After the solvent is removed, the mixture of NaDT and palladium ions is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The palladium reduction rate is 100%.

[0122] Example 26

[0123] Dissolving precious metals: Disperse 50 mg of a 1% palladium-containing material in 50 mL of N,N-dimethylformamide (DMF). Add 50 mg of tetra-N-butylammonium decatungstate (TBADT). Irradiate with UV light in air for 12 hours. The palladium dissolution rate is 100%.

[0124] Reduction of precious metals: After the solvent was removed, the mixture of TBADT and palladium ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, the mixture was isolated from air, and irradiated with ultraviolet light for 12 hours. The palladium reduction rate was 100%.

[0125] Example 27

[0126] Dissolving precious metals: Disperse 50 mg of a material containing 1% palladium in 50 mL of N,N-dimethylformamide (DMF). Add 50 mg of phosphotungstic acid (PW) and irradiate with UV light in air for 12 hours. The palladium dissolution rate is 100%.

[0127] Reduction of precious metals: After the solvent is removed, the mixture of PW and palladium ions is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, the mixture is isolated from air, and irradiated with ultraviolet light for 12 hours. The palladium reduction rate is 100%.

[0128] Example 28

[0129] Dissolving precious metals: Disperse 50 mg of a 1% rhodium-containing material in 50 mL of N,N-dimethylformamide (DMF). Add 50 mg of sodium decatungstate (NaDT). Irradiate with UV light in air for 12 hours. The rhodium dissolution rate reaches 77%.

[0130] Reduction of precious metals: After removing the solvent, the mixture of NaDT and rhodium ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, the mixture was isolated from air, and irradiated with ultraviolet light for 12 hours. The rhodium reduction rate was 99%.

[0131] Example 29

[0132] Dissolving precious metals: Disperse 50 mg of a 1% rhodium-containing material in 50 mL of N,N-dimethylformamide (DMF). Add 50 mg of tetra-N-butylammonium decatungstate (TBADT). Irradiate with UV light in air for 12 hours. The rhodium dissolution rate reaches 72%.

[0133] Reduction of precious metals: After the solvent is removed, the mixture of TBADT and rhodium ions is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, the mixture is isolated from air, and irradiated with ultraviolet light for 12 hours. The rhodium reduction rate is 99%.

[0134] Example 30

[0135] Dissolving precious metals: Disperse 50 mg of a 1% rhodium-containing material in 50 mL of N,N-dimethylformamide (DMF). Add 50 mg of phosphotungstic acid (PW) and irradiate with UV light in air for 12 hours. The rhodium dissolution rate is 56%.

[0136] Reduction of precious metals: After the solvent is removed, the mixture of PW and rhodium ions is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, the mixture is isolated from air, and irradiated with ultraviolet light for 12 hours. The rhodium reduction rate is 99%.

[0137] Example 31

[0138] Dissolving precious metals: Disperse 50 mg of a material containing 1% ruthenium in 50 mL of N,N-dimethylformamide (DMF). Add 50 mg of sodium decatungstate (NaDT) and irradiate with UV light in air for 12 hours. The ruthenium dissolution rate reaches 33%.

[0139] Precious metal reduction step: After the solvent is removed, the NaDT and ruthenium ion mixture is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The ruthenium reduction rate is 99%.

[0140] Example 32

[0141] Dissolving precious metals: Disperse 50 mg of a 1% ruthenium-containing material in 50 mL of N,N-dimethylformamide (DMF). Add 50 mg of tetra-N-butylammonium decatungstate (TBADT). Irradiate with UV light in air for 12 hours. The ruthenium dissolution rate reaches 29%.

[0142] Precious metal reduction step: After the solvent is removed, the TBADT and ruthenium ion mixture is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The ruthenium reduction rate is 99%.

[0143] Example 33

[0144] Dissolving precious metals: Disperse 50 mg of a material containing 1% ruthenium in 50 mL of N,N-dimethylformamide (DMF). Add 50 mg of phosphotungstic acid (PW) and irradiate with UV light in air for 12 hours. The ruthenium dissolution rate reaches 18%.

[0145] Precious metal reduction step: After the solvent is removed, the PW and ruthenium ion mixture is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The ruthenium reduction rate is 99%.

[0146] Example 34

[0147] Dissolving precious metals: Disperse 50 mg of a material containing 1% iridium in 50 mL of N,N-dimethylformamide (DMF). Add 50 mg of sodium decatungstate (NaDT) and irradiate with UV light in air for 12 hours. The iridium dissolution rate is 2%.

[0148] Reduction of precious metals: After removing the solvent, the NaDT and iridium ion mixture were dispersed in 50 mL of water, to which 5 mg / mL of methanol was added as an electron sacrificial agent. The mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The iridium reduction rate was 99%.

[0149] Example 35

[0150] Dissolving precious metals: Disperse 50 mg of a material containing 1% iridium in 50 mL of N,N-dimethylformamide (DMF). Add 50 mg of tetra-N-butylammonium decatungstate (TBADT) and irradiate with UV light in air for 12 hours. The iridium dissolution rate is 1%.

[0151] Reduction of precious metals: After the solvent was removed, TBADT and the mixture containing iridium ions were dispersed in 50 mL of water, to which 5 mg / mL of methanol was added as an electron sacrificial agent. The mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of iridium was 99%.

[0152] Example 36

[0153] Dissolving precious metals: Disperse 50 mg of a material containing 1% iridium in 50 mL of N,N-dimethylformamide (DMF). Add 50 mg of phosphotungstic acid (PW) and irradiate with UV light in air for 12 hours. The iridium dissolution rate is 1%.

[0154] Reduction of precious metals: After the solvent was removed, the PW and iridium ion mixture was dispersed in 50 mL of water, to which 5 mg / mL of methanol was added as an electron sacrificial agent. The mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The iridium reduction rate was 99%.

[0155] Example 37

[0156] Precious metal dissolution procedure: Disperse 50 mg of a material containing 1% gold in 50 mL of a 10 g / L aqueous ammonium iodide solution. Then, add 50 mg of sodium decatungstate (NaDT). Irradiate the mixture with UV light in air for 12 hours. The gold dissolution rate is 100%.

[0157] Precious metal reduction step: After the solvent is removed, the mixture of NaDT and gold ions is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, and the mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The gold reduction rate is 100%.

[0158] Example 38

[0159] Precious metal dissolution procedure: Disperse 50 mg of a material containing 1% gold in 50 mL of a 10 g / L aqueous ammonium iodide solution. Then, add 50 mg of tetra-N-butylammonium decatungstate (TBADT). Irradiate with UV light in air for 12 hours. The gold dissolution rate is 100%.

[0160] Precious metal reduction step: After the solvent is removed, the mixture of TBADT and gold ions is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, the mixture is isolated from air, and irradiated with ultraviolet light for 12 hours. The gold reduction rate is 100%.

[0161] Example 39

[0162] Precious metal dissolution procedure: Disperse 50 mg of a material containing 1% gold in 50 mL of a 10 g / L aqueous ammonium iodide solution. Add 50 mg of phosphotungstic acid (PW) and irradiate with UV light in air for 12 hours. The gold dissolution rate is 100%.

[0163] Reduction of precious metals: After the solvent was removed, the mixture of PW and gold ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, the mixture was isolated from air, and irradiated with ultraviolet light for 12 hours. The gold reduction rate was 100%.

[0164] Example 40

[0165] Precious metal dissolution procedure: Disperse 50 mg of a material containing 1% platinum in 50 mL of a 10 g / L aqueous ammonium iodide solution. Then, add 50 mg of sodium decatungstate (NaDT). Irradiate the mixture with UV light in air for 12 hours. The gold dissolution rate is 100%.

[0166] Precious metal reduction step: After the solvent is removed, the mixture of NaDT and platinum ions is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of platinum is 100%.

[0167] Example 41

[0168] Precious metal dissolution step: Disperse 50 mg of a material containing 1% platinum in 50 mL of a 10 g / L aqueous ammonium iodide solution. Then, add 50 mg of tetra-N-butylammonium decatungstate (TBADT). Irradiate with UV light in air for 12 hours. The platinum dissolution rate reaches 100%.

[0169] Reduction of precious metals: After the solvent was removed, the mixture of TBADT and platinum ions was dispersed in 50 mL of water, to which 5 mg / mL of methanol was added as an electron sacrificial agent. The mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of platinum was 100%.

[0170] Example 42

[0171] Precious metal dissolution step: Disperse 50 mg of a material containing 1% platinum in 50 mL of a 10 g / L aqueous ammonium iodide solution. Then, add 50 mg of phosphotungstic acid (PW). Irradiate the solution with UV light in air for 12 hours. The platinum dissolution rate is 100%.

[0172] Precious metal reduction step: After the solvent is removed, the mixture of PW and platinum ions is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, and the mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of platinum is 100%.

[0173] Example 43

[0174] Precious metal dissolution step: Disperse 50 mg of a material containing 1% palladium in 50 mL of a 10 g / L aqueous ammonium iodide solution. Then, add 50 mg of sodium decatungstate (NaDT). Irradiate the mixture with ultraviolet light in air for 12 hours. The palladium dissolution rate is 100%.

[0175] Reduction of precious metals: After the solvent is removed, the mixture of NaDT and palladium ions is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The palladium reduction rate is 100%.

[0176] Example 44

[0177] Dissolving precious metals: Disperse 50 mg of a 1% palladium-containing material in 50 mL of a 10 g / L aqueous ammonium iodide solution. Add 50 mg of tetra-N-butylammonium decatungstate (TBADT) and irradiate with UV light in air for 12 hours. The palladium dissolution rate is 100%.

[0178] Reduction of precious metals: After the solvent was removed, the mixture of TBADT and palladium ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, the mixture was isolated from air, and irradiated with ultraviolet light for 12 hours. The palladium reduction rate was 100%.

[0179] Example 45

[0180] Dissolving precious metals: Disperse 50 mg of a material containing 1% palladium in 50 mL of a 10 g / L aqueous ammonium iodide solution. Add 50 mg of phosphotungstic acid (PW) and irradiate the solution with UV light in air for 12 hours. The palladium dissolution rate is 100%.

[0181] Reduction of precious metals: After the solvent is removed, the mixture of PW and palladium ions is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, the mixture is isolated from air, and irradiated with ultraviolet light for 12 hours. The palladium reduction rate is 100%.

[0182] Example 46

[0183] Dissolving precious metals: Disperse 50 mg of a material containing 1% rhodium in 50 mL of a 10 g / L aqueous ammonium iodide solution. Add 50 mg of sodium decatungstate (NaDT) and irradiate with ultraviolet light in air for 12 hours. The rhodium dissolution rate is 92%.

[0184] Reduction of precious metals: After removing the solvent, the mixture of NaDT and rhodium ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, the mixture was isolated from air, and irradiated with ultraviolet light for 12 hours. The rhodium reduction rate was 99%.

[0185] Example 47

[0186] Dissolving precious metals: Disperse 50 mg of a 1% rhodium-containing material in 50 mL of a 10 g / L aqueous ammonium iodide solution. Add 50 mg of tetra-N-butylammonium decatungstate (TBADT) and irradiate with ultraviolet light in air for 12 hours. The rhodium dissolution rate reaches 90%.

[0187] Reduction of precious metals: After the solvent is removed, the mixture of TBADT and rhodium ions is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, the mixture is isolated from air, and irradiated with ultraviolet light for 12 hours. The rhodium reduction rate is 99%.

[0188] Example 48

[0189] Dissolving precious metals: 50 mg of a material containing 1% rhodium was dispersed in 50 mL of a 10 g / L aqueous ammonium iodide solution. 50 mg of phosphotungstic acid (PW) was then added. The mixture was exposed to ultraviolet light in air for 12 hours, resulting in a rhodium dissolution rate of 86%.

[0190] Reduction of precious metals: After the solvent is removed, the mixture of PW and rhodium ions is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, the mixture is isolated from air, and irradiated with ultraviolet light for 12 hours. The rhodium reduction rate is 99%.

[0191] Example 49

[0192] Dissolving precious metals: Disperse 50 mg of a material containing 1% ruthenium in 50 mL of a 10 g / L aqueous ammonium iodide solution. Add 50 mg of sodium decatungstate (NaDT) and irradiate with ultraviolet light in air for 12 hours. The ruthenium dissolution rate reaches 78%.

[0193] Precious metal reduction step: After the solvent is removed, the NaDT and ruthenium ion mixture is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The ruthenium reduction rate is 99%.

[0194] Example 50

[0195] Precious metal dissolution step: Disperse 50 mg of a material containing 1% ruthenium in 50 mL of a 10 g / L aqueous ammonium iodide solution. Then, add 50 mg of tetra-N-butylammonium decatungstate (TBADT). Irradiate with ultraviolet light in air for 12 hours. The ruthenium dissolution rate reaches 80%.

[0196] Precious metal reduction step: After the solvent is removed, the TBADT and ruthenium ion mixture is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The ruthenium reduction rate is 99%.

[0197] Example 51

[0198] Dissolving precious metals: Disperse 50 mg of a material containing 1% ruthenium in 50 mL of a 10 g / L aqueous ammonium iodide solution. Add 50 mg of phosphotungstic acid (PW) and irradiate the solution with UV light in air for 12 hours. The ruthenium dissolution rate reaches 78%.

[0199] Precious metal reduction step: After the solvent is removed, the PW and ruthenium ion mixture is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The ruthenium reduction rate is 99%.

[0200] Example 52

[0201] Dissolving precious metals: Disperse 50 mg of a material containing 1% iridium in 50 mL of a 10 g / L aqueous solution of ammonium iodide. Add 50 mg of sodium decatungstate (NaDT) and irradiate with ultraviolet light in air for 12 hours. The iridium dissolution rate is 19%.

[0202] Reduction of precious metals: After removing the solvent, the NaDT and iridium ion mixture were dispersed in 50 mL of water, to which 5 mg / mL of methanol was added as an electron sacrificial agent. The mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The iridium reduction rate was 99%.

[0203] Example 53

[0204] Dissolving precious metals: Disperse 50 mg of a material containing 1% iridium in 50 mL of a 10 g / L aqueous ammonium iodide solution. Add 50 mg of tetra-N-butylammonium decatungstate (TBADT) and irradiate with ultraviolet light in air for 12 hours. The iridium dissolution rate is 14%.

[0205] Reduction of precious metals: After the solvent was removed, TBADT and the mixture containing iridium ions were dispersed in 50 mL of water, to which 5 mg / mL of methanol was added as an electron sacrificial agent. The mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of iridium was 99%.

[0206] Example 54

[0207] Dissolving precious metals: Disperse 50 mg of a material containing 1% iridium in 50 mL of a 10 g / L aqueous solution of ammonium iodide. Add 50 mg of phosphotungstic acid (PW) and irradiate with ultraviolet light in air for 12 hours. The iridium dissolution rate is 8%.

[0208] Reduction of precious metals: After the solvent was removed, the PW and iridium ion mixture was dispersed in 50 mL of water, to which 5 mg / mL of methanol was added as an electron sacrificial agent. The mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The iridium reduction rate was 99%.

[0209] Example 55

[0210] Precious metal dissolution procedure: Disperse 50 mg of a material containing 1% gold in 50 mL of a 10 g / L ammonium chloride solution. Then, add 50 mg of sodium decatungstate (NaDT). Irradiate the mixture with UV light in air for 12 hours. The gold dissolution rate is 45%.

[0211] Precious metal reduction step: After the solvent is removed, the mixture of NaDT and gold ions is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The gold reduction rate is 99%.

[0212] Example 56

[0213] Precious metal dissolution procedure: Disperse 50 mg of a material containing 1% gold in 50 mL of a 10 g / L aqueous ammonium chloride solution. Then, add 50 mg of tetra-N-butylammonium decatungstate (TBADT). Irradiate with UV light in air for 12 hours. The gold dissolution rate is 52%.

[0214] Precious metal reduction step: After the solvent is removed, the TBADT and gold ion mixture is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, the mixture is isolated from air, and irradiated with ultraviolet light for 12 hours. The gold reduction rate is 99%.

[0215] Example 57

[0216] Precious metal dissolution: Disperse 50 mg of a material containing 1% gold in 50 mL of a 10 g / L ammonium chloride solution. Add 50 mg of phosphotungstic acid (PW) and irradiate with UV light in air for 12 hours. The gold dissolution rate is 40%.

[0217] Precious metal reduction step: After the solvent is removed, the PW and gold ion-containing mixture is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, the mixture is isolated from air, and irradiated with ultraviolet light for 12 hours. The gold reduction rate is 99%.

[0218] Example 58

[0219] Precious metal dissolution procedure: Disperse 50 mg of a material containing 1% platinum in 50 mL of a 10 g / L ammonium chloride solution. Then, add 50 mg of sodium decatungstate (NaDT). Irradiate the mixture with UV light in air for 12 hours. The gold dissolution rate is 38%.

[0220] Precious metal reduction step: After the solvent is removed, the mixture of NaDT and platinum ions is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of platinum is 99%.

[0221] Example 59

[0222] Precious metal dissolution step: Disperse 50 mg of a material containing 1% platinum in 50 mL of a 10 g / L ammonium chloride solution. Then, add 50 mg of tetra-N-butylammonium decatungstate (TBADT). Irradiate with UV light in air for 12 hours. The platinum dissolution rate is 32%.

[0223] Precious metal reduction step: After the solvent is removed, the mixture of TBADT and platinum ions is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The platinum reduction rate is 99%.

[0224] Example 60

[0225] Precious metal dissolution step: Disperse 50 mg of a material containing 1% platinum in 50 mL of a 10 g / L ammonium chloride aqueous solution. Then, add 50 mg of phosphotungstic acid (PW). Irradiate the solution with UV light in air for 12 hours. The platinum dissolution rate is 30%.

[0226] Precious metal reduction step: After the solvent is removed, the mixture of PW and platinum ions is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of platinum is 99%.

[0227] Example 61

[0228] Dissolving precious metals: Disperse 50 mg of a material containing 1% palladium in 50 mL of a 10 g / L aqueous ammonium chloride solution. Add 50 mg of sodium decatungstate (NaDT) and irradiate with ultraviolet light in air for 12 hours. The palladium dissolution rate is 37%.

[0229] Reduction of precious metals: After the solvent is removed, the mixture of NaDT and palladium ions is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The palladium reduction rate is 99%.

[0230] Example 62

[0231] Precious metal dissolution step: Disperse 50 mg of a material containing 1% palladium in 50 mL of a 10 g / L aqueous ammonium chloride solution. Then, add 50 mg of tetra-N-butylammonium decatungstate (TBADT). Irradiate with ultraviolet light in air for 12 hours. The palladium dissolution rate is 39%.

[0232] Reduction of precious metals: After the solvent is removed, the mixture of TBADT and palladium ions is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The palladium reduction rate is 99%.

[0233] Example 63

[0234] Dissolving precious metals: Disperse 50 mg of a material containing 1% palladium in 50 mL of a 10 g / L ammonium chloride solution. Add 50 mg of phosphotungstic acid (PW) and irradiate with ultraviolet light in air for 12 hours. The palladium dissolution rate is 32%.

[0235] Reduction of precious metals: After the solvent is removed, the mixture of PW and palladium ions is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, the mixture is isolated from air, and irradiated with ultraviolet light for 12 hours. The palladium reduction rate is 99%.

[0236] Example 64

[0237] Dissolving precious metals: Disperse 50 mg of a material containing 1% rhodium in 50 mL of a 10 g / L ammonium chloride solution. Add 50 mg of sodium decatungstate (NaDT) and irradiate with ultraviolet light in air for 12 hours. The rhodium dissolution rate is 30%.

[0238] Reduction of precious metals: After removing the solvent, the mixture of NaDT and rhodium ions was dispersed in 50 mL of water, 5 mg / mL of methanol was added as an electron sacrificial agent, the mixture was isolated from air, and irradiated with ultraviolet light for 12 hours. The rhodium reduction rate was 99%.

[0239] Example 65

[0240] Precious metal dissolution step: Disperse 50 mg of a material containing 1% rhodium in 50 mL of a 10 g / L aqueous ammonium chloride solution. Then, add 50 mg of tetra-N-butylammonium decatungstate (TBADT). Irradiate with ultraviolet light in air for 12 hours. The rhodium dissolution rate is 28%.

[0241] Reduction of precious metals: After the solvent is removed, the mixture of TBADT and rhodium ions is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, the mixture is isolated from air, and irradiated with ultraviolet light for 12 hours. The rhodium reduction rate is 99%.

[0242] Example 66

[0243] Dissolving precious metals: Disperse 50 mg of a material containing 1% rhodium in 50 mL of a 10 g / L ammonium chloride solution. Add 50 mg of phosphotungstic acid (PW) and irradiate with ultraviolet light in air for 12 hours. The rhodium dissolution rate is 22%.

[0244] Reduction of precious metals: After the solvent is removed, the mixture of PW and rhodium ions is dispersed in 50 mL of water, 5 mg / mL of methanol is added as an electron sacrificial agent, the mixture is isolated from air, and irradiated with ultraviolet light for 12 hours. The rhodium reduction rate is 99%.

[0245] Example 67

[0246] Dissolving precious metals: Disperse 50 mg of a material containing 1% ruthenium in 50 mL of a 10 g / L aqueous ammonium chloride solution. Add 50 mg of sodium decatungstate (NaDT) and irradiate with ultraviolet light in air for 12 hours. The ruthenium dissolution rate reaches 30%.

[0247] Precious metal reduction step: After the solvent is removed, the NaDT and ruthenium ion mixture is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The ruthenium reduction rate is 99%.

[0248] Example 68

[0249] Precious metal dissolution step: Disperse 50 mg of a material containing 1% ruthenium in 50 mL of a 10 g / L aqueous ammonium chloride solution. Then, add 50 mg of tetra-N-butylammonium decatungstate (TBADT). Irradiate with ultraviolet light in air for 12 hours. The ruthenium dissolution rate is 27%.

[0250] Precious metal reduction step: After the solvent is removed, the TBADT and ruthenium ion mixture is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The ruthenium reduction rate is 99%.

[0251] Example 69

[0252] Dissolving precious metals: Disperse 50 mg of a material containing 1% ruthenium in 50 mL of a 10 g / L ammonium chloride solution. Add 50 mg of phosphotungstic acid (PW) and irradiate the solution with UV light in air for 12 hours. The ruthenium dissolution rate is 22%.

[0253] Precious metal reduction step: After the solvent is removed, the PW and ruthenium ion mixture is dispersed in 50 mL of water, to which 5 mg / mL of methanol is added as an electron sacrificial agent. The mixture is isolated from air and irradiated with ultraviolet light for 12 hours. The ruthenium reduction rate is 99%.

[0254] Example 70

[0255] Dissolving precious metals: Disperse 50 mg of a material containing 1% iridium in 50 mL of a 10 g / L ammonium chloride solution. Add 50 mg of sodium decatungstate (NaDT) and irradiate with ultraviolet light in air for 12 hours. The iridium dissolution rate is 4%.

[0256] Reduction of precious metals: After removing the solvent, the NaDT and iridium ion mixture were dispersed in 50 mL of water, to which 5 mg / mL of methanol was added as an electron sacrificial agent. The mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The iridium reduction rate was 99%.

[0257] Example 71

[0258] Dissolving precious metals: Disperse 50 mg of a material containing 1% iridium in 50 mL of a 10 g / L aqueous ammonium chloride solution. Add 50 mg of tetra-N-butylammonium decatungstate (TBADT) and irradiate with ultraviolet light in air for 12 hours. The iridium dissolution rate is 3%.

[0259] Reduction of precious metals: After the solvent was removed, TBADT and the mixture containing iridium ions were dispersed in 50 mL of water, to which 5 mg / mL of methanol was added as an electron sacrificial agent. The mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The reduction rate of iridium was 99%.

[0260] Example 72

[0261] Dissolving precious metals: Disperse 50 mg of a material containing 1% iridium in 50 mL of a 10 g / L ammonium chloride solution. Add 50 mg of phosphotungstic acid (PW) and irradiate with ultraviolet light in air for 12 hours. The iridium dissolution rate is 3%.

[0262] Reduction of precious metals: After the solvent was removed, the PW and iridium ion mixture was dispersed in 50 mL of water, to which 5 mg / mL of methanol was added as an electron sacrificial agent. The mixture was isolated from air and irradiated with ultraviolet light for 12 hours. The iridium reduction rate was 99%.

[0263] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for photocatalytic recovery of precious metals, characterized in that the steps include: (1) Under light conditions and in an oxygen-containing environment, a polyoxometalate and a first solvent containing a precious metal material are added, wherein the polyoxometalate catalyzes the dissolution of the precious metal in the precious metal material to form an organic or inorganic coordination compound of the precious metal, thereby obtaining a first reaction solution; (2) The polyoxometalate obtained by removing the liquid from the first reaction solution and the organic or inorganic coordination compound of the noble metal are placed in water containing an electron sacrificial agent, and the noble metal is reduced and recovered under light conditions and in an environment isolated from air.

2. The method according to claim 1, characterized in that The polyoxometalates include any one or any combination of the following: a. Any one or any combination of Keggin type, Dawson type, Silverton type, Anderson type, Waugh type, Standberg type, Weakly type, and Finke type; isopoly or heteropoly compounds of ba; Derivatives of ca or b.

3. The method according to claim 1, characterized in that In step (1), in the first solvent, the mass ratio of the noble metal-containing material to the polyoxometalate is 1:0.01-5, and the concentration of the polyoxometalate is 0.05-1000 mg / mL.

4. The method according to claim 1, wherein The first solvent is a mixed solvent of a nitrile compound and an organic chloride, or a nitrogen-containing organic solvent, or a halogen-containing salt aqueous solution.

5. The method according to claim 4, characterized in that In the mixed solvent of the nitrile compound and the organic chloride, the volume ratio of the nitrile compound to the organic chloride is 40-60:1, the nitrile compound includes any one or any combination of acrylonitrile, acetonitrile, benzyl cyanide, cyanoacetic acid, malononitrile, benzyl cyanide, cyclohexyl isonitrile or melamine, and the organic chloride includes any one or any combination of dichloromethane, chloroform, dichloroethylene, trichloroethane, trichloroethanol, 1-chlorotoluene or tetrachloromethane; The nitrogen-containing organic solvent includes any one or any combination of N,N-dimethylformamide, N-methyl-2-pyrrolidone, hexamethylphosphoramide, dimethyl sulfoxide, and tetrahydrofuran; The concentration of the halogen salt in the halogen-containing salt aqueous solution is 1-50 g / L, and the halogen salt includes any one or any combination of ammonium iodide, potassium iodide, sodium iodide, lithium iodide, ammonium bromide, potassium bromide, sodium bromide, lithium bromide, and ammonium chloride.

6. The method according to claim 1, characterized in that In step (1), the oxygen-containing environment includes air, oxygen or a substance capable of generating oxygen, so that the oxygen capacity in the first solvent is 1%-100%.

7. The method according to claim 1, characterized in that Step (1): the wavelength of the irradiation light is 150-1500nm, the irradiation time is 0.01-3600h, and the light power density is 0.01-2000mW / cm 2 .

8. The method according to claim 1, characterized in that In step (2), the concentration of the electron sacrificial agent is 0.01-100 mg / mL.

9. The method according to claim 1, characterized in that Step (2): the wavelength of the irradiation light is 150-1500nm, the irradiation time is 0.01-3600h, and the light power density is 0.01-2000mW / cm 2 .

10. Application of polyoxometalates in photocatalytic recovery of precious metals.

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