Efficient nitrile-alkali-containing solvent for selectively dissolving precious metal and method for selectively dissolving precious metal by using nitrile-alkali-containing solvent

Abstract

The invention belongs to the technical field of metal recovery, and particularly relates to a nitrile-alkali-containing solvent for efficiently and selectively dissolving precious metal and a method for selectively dissolving precious metal by using the nitrile-alkali-containing solvent. The nitrile-alkali-containing solvent comprises a nitrile compound and an inorganic strong alkali solution with the pH of 8-14. The method comprises the following steps: putting a material containing noble metal into a nitrile-alkali-containing solvent system formed by mixing a nitrile compound and an inorganic strong alkali solution with the pH value of 8-14, and selectively dissolving the noble metal by light irradiation under the action of oxygen and a photocatalyst. The method selectively recovers precious metals under mild and environment-friendly conditions, does not dissolve non-precious metals, is low in equipment and environment requirements, simplifies purification post-treatment, is low in energy and cost consumption, and is suitable for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of metal recycling technology, specifically relating to a highly efficient nitrile-alkali solvent for selectively dissolving precious metals and a method for selectively dissolving precious metals. Background Technology

[0002] Precious metals comprise eight elements: gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), iridium (Ir), and osmium (Os). Among them, platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), iridium (Ir), and osmium (Os) belong to the platinum group elements, which are chemically more stable. With technological advancements, precious metals are widely used as important raw materials in various fields such as new energy and high-end materials, leading to increasing demand. This has also resulted in a significant increase in precious metal waste, making recycling technology crucial for resource reuse and environmental protection. To reduce costs, non-precious metals constitute a large proportion of secondary precious metal resources such as electronic waste and spent catalysts. Traditional precious metal recycling methods, such as pyrometallurgical and hydrometallurgical processes, cannot directly and selectively recover precious metals and often require complex post-processing, resulting in high costs due to the consumption of large amounts of reagents and energy. Therefore, developing low-cost recycling strategies for the direct and selective recovery of precious metals has attracted increasing attention.

[0003] Pyrometallurgical recycling typically uses temperatures exceeding 2000°C to melt waste containing precious metals, and then separates the precious metals from other non-precious metals through processes such as smelting and reduction. While this method has relatively high recycling efficiency, it consumes a large amount of energy, and the harmful gases produced during the high-temperature smelting process cause environmental pollution.

[0004] Wet recycling primarily relies on dissolving precious metals by introducing chlorine gas into a chemical solution at high temperatures, followed by recovery through chemical precipitation, electrolysis, and other methods. While wet recycling processes are relatively complex and reduce energy consumption to some extent, they offer no selectivity for precious metal recovery and also involve the use of toxic chemical reagents and the treatment of waste liquids and gases.

[0005] With the increasing demands for environmental protection policies and improved precious metal recycling efficiency, several new precious metal recycling technologies have been reported in recent years. For example, bioleaching technology utilizes the metabolic products of specific microorganisms to dissolve precious metals, achieving low-energy consumption and low-pollution recycling; electrochemical recycling technology extracts precious metals from waste through electrochemical reactions, while also being simple to operate and environmentally friendly.

[0006] Photocatalytic green recycling technology is also gaining attention. This technology utilizes photocatalysts to generate active oxygen species under light, dissolving precious metals from waste. Compared with traditional methods, photocatalytic recycling technology is more environmentally friendly, simple to operate, allows for solvent recovery, and can significantly improve the recovery efficiency of precious metals.

[0007] CN 111809063A discloses a photocatalytic metal dissolution method, using a mixed solution of a cyanide compound and an organochlorine, adding a photocatalyst, introducing oxygen-containing gas or adding a substance that can generate oxygen, and dissolving the metal by irradiation with light for a certain period of time. This method has good solubility for noble metals platinum, silver, gold, rhodium, palladium, and non-noble metals nickel, iron, and copper. CN112553465A discloses a photocatalytic selective metal dissolving agent and method, using a cyanide compound solution containing a photocatalyst, selectively dissolving various metals in a metallic material by irradiation with light for a certain period of time. This method can effectively dissolve noble metals gold and silver and non-noble metal copper, but does not dissolve noble metals palladium, platinum, ruthenium, rhodium, iridium, and non-noble metals aluminum, iron, cobalt, nickel, and zinc. CN113088689A discloses a method for photocatalytic selective dissolution of noble metals in aqueous solution, using an aqueous solution containing a halogen salt, adding a photocatalyst, introducing oxygen or adding a substance that can generate oxygen, and dissolving the metal by irradiation with light for a certain period of time. This method has good solubility for gold, palladium, and osmium. CN 115449630A discloses a method for selective metal leaching using a photocatalytic nitrile-amine solution system. The method employs a mixed solution containing nitrile and amine components, adds a photocatalyst, and introduces oxygen or adds a substance capable of generating oxygen, followed by light irradiation to dissolve the metal. This method exhibits excellent solubility for noble metals such as gold, silver, palladium, and platinum, and non-noble metals such as copper, iron, nickel, zinc, and aluminum, but does not dissolve noble metals such as ruthenium, rhodium, iridium, and osmium.

[0008] The methods described above offer some improvements in energy and environmental protection for metal dissolution, but several problems remain. In industrial processes, raw materials for precious metal recovery, such as electronic waste and spent precious metal catalysts, as well as ores used for precious metal smelting, often contain a much higher content of non-precious metals than precious metals. The methods described lack selectivity in dissolving both precious and non-precious metals, resulting in simultaneous dissolution during the reaction. This not only leads to significant solvent consumption but also increases the difficulty of subsequent separation and purification of precious metals. Ammonia water is easily decomposed, volatile, and toxic, posing a threat to the environment. Prolonged reaction times exacerbate energy consumption. Using synthetic catalysts involves complex procedures and is significantly more expensive than using common commercial photocatalysts, resulting in a lower cost advantage compared to other methods in industrial applications. While cyanide compound solutions can achieve the sequential dissolution of gold, silver, and copper under photocatalysis, this method lacks selectivity for other precious metals and cannot inhibit the dissolution of non-precious metals. Therefore, it is necessary to develop photocatalytic recovery strategies that selectively dissolve precious metals while inhibiting the dissolution of non-precious metals. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention provides a highly efficient nitrile-alkali solvent for selectively dissolving precious metals and a method for doing so. This method enables photocatalytic selective recovery of precious metals under mild and environmentally friendly conditions, without dissolving non-precious metals. The reaction conditions are mild and easily controllable, with low requirements for equipment and environment, simplified post-purification processing, and low energy and cost consumption, making it suitable for industrial applications.

[0010] The technical solution of the present invention is a highly efficient selective solvent for dissolving precious metals containing nitrile-alkali, comprising a nitrile compound and an inorganic strong alkali solution with pH=8-14, wherein the volume ratio of the nitrile compound to the inorganic strong alkali solution with pH=8-14 is 1:0.01-19, preferably 1:0.1-10, more preferably 1:0.15-3, and even more preferably 1:0.3-3.

[0011] The nitrile compound comprises any one or a combination of nitrile compounds such as acetonitrile, propionitrile, butyronitrile, succinic anion, phenylacetonitrile, acrylonitrile, p-methylbenzonitrile, cyanoacetic acid, malononitrile, benzyl cyanide, dicyandiamide, or melamine, preferably any one or a combination of acetonitrile, propionitrile, butyronitrile, succinic anion, phenylacetonitrile, acrylonitrile, and p-methylbenzonitrile, more preferably acetonitrile, propionitrile, butyronitrile, succinic anion, phenylacetonitrile, acrylonitrile, and p-methylbenzonitrile. The nitrile compound may be adjusted according to actual dissolution requirements and is not limited to the examples.

[0012] The inorganic strong base solution with pH = 8-14 is preferably an inorganic strong base solution with pH = 11-14, more preferably a pH = 12-14, and even more preferably a pH = 12-13. The inorganic strong base solution with pH = 8-14 contains any one or a combination of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, beryllium hydroxide, magnesium hydroxide, strontium hydroxide, or a complex base, preferably any one or a combination of sodium hydroxide and potassium hydroxide. The strong base solution can be adjusted according to actual dissolution requirements and is not limited to the examples.

[0013] The precious metals mentioned are gold, silver, and platinum group metals, such as gold, silver, palladium, platinum, ruthenium, rhodium, and iridium shown in the examples. The precious metals dissolved in the nitrile-alkali solvent provided by the present invention are not limited to gold, silver, or a few platinum group metals such as palladium and platinum; rather, they exhibit good solubility for gold, silver, and almost all platinum group metals, as shown in the examples.

[0014] When precious metals and non-precious metals are present in the same environment, the nitrile-alkali solvent provided by the present invention only dissolves precious metals and is insoluble or almost insoluble in non-precious metals, thus truly achieving selective dissolution of precious metals. The precious metals are extracted and purified at the same time. The dissolution speed is fast, the dissolution rate is high, the steps are simplified, the operation is simple, and the reaction is mild and friendly.

[0015] A highly efficient method for selectively dissolving precious metals includes the following steps: placing a material containing precious metals in a nitrile-alkali solvent system formed by mixing a nitrile compound with an inorganic strong alkali solution with pH = 8-14, and selectively dissolving the precious metals by light irradiation under the action of oxygen and a photocatalyst.

[0016] In the process of selectively dissolving precious metals by light irradiation, heating and / or ultrasonic and / or microwave treatments are also performed to improve the activity of free radicals in the solution and increase the solubility of the precious metals. As shown in this invention, heating during the selective dissolution of precious metals by light irradiation results in a higher solubility of the precious metals. The heating temperature is 10-80℃, preferably 50-70℃, and more preferably 60-70℃. The auxiliary means used in the selective dissolution of precious metals by light irradiation can be adjusted and applied according to actual conditions and are not limited to the examples provided.

[0017] In the nitrile-alkali solvent system, the volume ratio of the nitrile compound to the inorganic strong alkali solution with pH = 8-14 is 1:0.01-19, preferably 1:0.1-10, more preferably 1:0.15-3, and even more preferably 1:0.3-3.

[0018] The nitrile compound comprises any one or a combination of nitrile compounds such as acetonitrile, propionitrile, butyronitrile, succinic anion, phenylacetonitrile, acrylonitrile, p-methylbenzonitrile, cyanoacetic acid, malononitrile, benzyl cyanide, dicyandiamide, or melamine, preferably any one or a combination of acetonitrile, propionitrile, butyronitrile, succinic anion, phenylacetonitrile, acrylonitrile, and p-methylbenzonitrile, more preferably acetonitrile, propionitrile, butyronitrile, succinic anion, phenylacetonitrile, acrylonitrile, and p-methylbenzonitrile. The nitrile compound may be adjusted according to actual dissolution requirements and is not limited to the examples.

[0019] The inorganic strong base solution with pH = 8-14 is preferably an inorganic strong base solution with pH = 11-14, more preferably a pH = 12-14, and even more preferably a pH = 12-13. The inorganic strong base solution with pH = 8-14 contains any one or a combination of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, beryllium hydroxide, magnesium hydroxide, strontium hydroxide, or a complex base, preferably any one or a combination of sodium hydroxide and potassium hydroxide. The strong base solution can be adjusted according to actual dissolution requirements and is not limited to the examples.

[0020] The precious metals are gold, silver, and platinum group metals, such as gold, silver, palladium, platinum, ruthenium, rhodium, and iridium as shown in the examples.

[0021] The photocatalysts include organic photocatalysts, metal oxide photocatalysts, metal sulfide photocatalysts, graphitic carbon nitride compounds g-C3N4, Bi-based photocatalysts, nanomaterial photocatalysts, and photocatalysts formed by their respective modifications, surface modifications, and mutual composites.

[0022] The organic photocatalyst includes any one or a combination of carbon nitride, porphyrin, or biomimetic enzymes, where porphyrin includes any one or a combination of protoporphyrin, iron porphyrin, magnesium porphyrin, or zinc porphyrin. The metal oxide photocatalyst includes any one or a combination of titanium dioxide, steel oxide, zinc oxide, or tungsten oxide. The metal sulfide photocatalyst includes molybdenum disulfide and / or cadmium sulfide, etc. The Bi-based photocatalyst includes any one or a combination of bismuth oxyhalides BiOX (X = Cl, Br, I), BiVO4, Bi2WO6, and Bi2MoO6, such as layered bismuth oxybromine materials and oxygen-deficient bismuth oxybromine materials. The nanomaterial photocatalyst includes any one or more of metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and two-dimensional materials such as MXene.

[0023] The aforementioned organic photocatalysts, metal oxide photocatalysts, metal sulfide photocatalysts, graphitic carbon nitride compounds (g-C3N4), Bi-based photocatalysts, and nanomaterial photocatalysts can be modified and surface-modified to generate photocatalysts with improved performance. These photocatalysts can also be combined with other subcategories to form high-performance photocatalysts. Furthermore, they can be combined with other types of photocatalysts to generate improved photocatalysts. Specifically, organic photocatalysts can be modified, surface-modified, and combined to form photocatalysts, such as porphyrin self-assembled materials and biomimetic catalytic enzyme materials. Photocatalysts formed by modifying and surface-modifying metal oxide photocatalysts include, but are not limited to, titanium dioxide materials containing oxygen vacancies, hydroxyl-modified titanium dioxide materials, two-dimensional titanium dioxide materials, nitrogen-doped titanium dioxide materials, and phosphorus-doped indium oxide materials. Photocatalysts can also be formed by combining metal oxide photocatalysts with organic photocatalysts, such as porphyrin-sensitized titanium dioxide. Furthermore, photocatalysts formed by modifying and surface-modifying metal oxide photocatalysts can be combined with metal-organic framework materials to form photocatalysts, such as titanium dioxide composites with amino-modified metal-organic compounds. Additionally, photocatalysts can be formed by modifying and surface-modifying metal sulfide photocatalysts with metal oxide photocatalysts, such as molybdenum disulfide-supported titanium dioxide, cadmium sulfide composite materials, cadmium sulfide quantum dot materials, and in-situ tungsten oxide sulfide composite materials. Finally, photocatalysts can be formed by modifying and surface-modifying graphitic carbon nitride compounds (g-C3N4), such as nitrogen-deficient carbon nitride composite materials and carbon-modified carbon nitride materials, where the carbon materials include carbon dots, graphene, or carbon nanotubes.

[0024] Preferably, the photocatalyst comprises titanium dioxide or titanium dioxide-modified or surface-modified photocatalysts, or a composite photocatalyst formed by titanium dioxide and organic photocatalysts, metal sulfide photocatalysts, graphitic carbon nitride compounds g-C3N4, Bi-based photocatalysts, or nanomaterial photocatalysts. More preferably, it is titanium dioxide or titanium dioxide-modified or surface-modified photocatalysts. The selection of the photocatalyst is based on the actual dissolution conditions and is not limited to the photocatalysts shown in the examples.

[0025] The oxygen is oxygen from the air, and / or pure oxygen introduced, and / or oxygen produced by a substance capable of producing oxygen, such that the oxygen capacity in the nitrile-alkali solvent system is 1% to 100%, preferably 20% to 100%. Specifically, the oxygen-producing substance added to the nitrile-alkali solvent system includes any one or a combination of ozone, hydrogen peroxide, sodium peroxide, sodium persulfate, or potassium peroxide, preferably ozone.

[0026] The light irradiation encompasses deep ultraviolet, ultraviolet, visible, and near-infrared light, with wavelengths ranging from 150 to 1500 nm, and is achieved using ultraviolet lamps or xenon lamps (full-band light). The light intensity of the irradiation is greater than 1 mW / cm². 2 The light irradiation time is 0.1-24 hours. The light irradiation intensity and time may be adjusted according to the reagent solubility and are not limited to the ranges shown in the examples.

[0027] The content of the photocatalyst in the nitrile-alkali solvent system is 0.1-100 mg / mL. As shown in this invention, the content of the photocatalyst in the nitrile-alkali solvent system is 1-10 mg / mL. The concentration of the photocatalyst in the nitrile-alkali solvent system is determined comprehensively based on the noble metal content in the noble metal-containing material and the size of the solvent system, and is not limited to the range shown in the examples.

[0028] The mass ratio of the precious metal-containing material to the photocatalyst is 1-10:1. This mass ratio is determined by a combination of the precious metal content and the size of the solvent system, and is not limited to the range shown in the examples.

[0029] The selective dissolution method for precious metals provided by the present invention achieves selective dissolution of gold, silver and all platinum group metals, extracts all kinds of precious metals, including gold, silver and platinum group metals, from the material to be recovered, avoids interference from non-selective dissolution of non-precious metals, realizes the extraction and purification of precious metals in one step, simplifies the recovery steps, reduces reaction requirements, improves the efficiency and quality of precious metal leaching and extraction, and is simple, easy to control, mild and friendly.

[0030] Beneficial effects:

[0031] 1. This invention provides a novel and highly efficient photocatalytic selective dissolution method for noble metals. Due to the differences in reaction mechanisms and reaction products between non-noble metals and noble metals in the same system, the dissolution of non-noble metals and their oxides can be suppressed under the condition of introducing an inorganic base without affecting the dissolution of noble metals, thereby achieving selective dissolution of noble metals.

[0032] 2. The method provided by this invention can rapidly dissolve precious metals on precious metal-containing materials that are subject to interference from non-precious metals, without introducing highly toxic cyanides, inorganic halide salts, or organic halide compounds. The entire process has advantages such as being mild, energy-saving, green, environmentally friendly, low-cost, and easy to operate. The solvent can also be reused, making it suitable for large-scale industrial selective dissolution treatment of precious metals.

[0033] 3. This invention can achieve efficient and rapid dissolution of platinum group metals that cannot be dissolved quickly by existing technologies, without dissolving non-precious metals and their oxides.

[0034] 4. The photocatalytic noble metal dissolution method of the present invention is simple and highly scalable. External conditions (such as heating, adding ultrasound, introducing oxygen, introducing ozone, microwave radiation, etc.) can be added according to actual needs to achieve efficient dissolution of noble metals in industrial samples (waste automotive three-way catalysts, waste noble metal catalysts, etc.) or natural samples (including noble metal ores, etc.). Attached Figure Description

[0035] Figure 1 Selective leaching curves of precious metals on discarded computer chips (CPUs).

[0036] Figure 2 Selective dissolution curves of silver, copper, and nickel in a mixture of titanium dioxide materials containing 1% silver (Ag / TiO2), titanium dioxide materials containing 1% copper (Cu / TiO2), and titanium dioxide materials containing 1% nickel.

[0037] Figure 3 This is a comparison chart of palladium dissolution rates under different volume ratios of acetonitrile-alkali solutions.

[0038] Figure 4 The selective leaching curves of palladium, copper, zinc and nickel in titanium dioxide materials (containing palladium, copper, zinc and nickel) are shown.

[0039] Figure 5 This is a comparison chart of palladium dissolution rates under alkaline solution conditions with different pH values.

[0040] Figure 6 This is a comparison chart of palladium dissolution rates under different light intensities.

[0041] Figure 7 Selective leaching curves of platinum, copper, zinc and nickel in carbon materials (containing platinum, copper, zinc and nickel).

[0042] Figure 8 This is a comparison chart of gold dissolution rates under different temperature conditions.

[0043] Figure 9 This is a comparison chart of palladium dissolution rates under different temperature conditions.

[0044] Figure 10 This is a comparison chart of platinum dissolution rates under different temperature conditions. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Modifications or equivalent substitutions made by those skilled in the art based on their understanding of the technical solutions of this invention, without departing from the spirit and scope of the invention, should all be covered within the protection scope of this invention.

[0046] All raw materials used in the following specific embodiments were purchased from the market or synthesized in the laboratory. Unless otherwise specified, the reaction temperature was 25°C. The solubility D of the precious metal was calculated using the following formula: D=(c*V) / m*100%

[0047] Where m is the mass of the noble metal before the reaction, V is the volume of the leaching solution, and c is the concentration of the noble metal in the leaching solution, which is detected by ICP-OES or ICP-MS.

[0048] Example 1

[0049] 50 mg of carbon material containing 1% gold (Au / C), 50 mg of carbon material containing 1% copper (Cu / C), and 50 mg of carbon material containing 1% nickel (Ni / C) were mixed and dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH 12 (volume ratio of acetonitrile:alkaline solution = 3:1). Then, 50 mg of commercial titanium dioxide catalyst was added. After irradiation with ultraviolet light in air containing 20% ​​oxygen for 1 h, the solubility of Au exceeded 98%, while the solubility of Cu and Ni was less than 0.5%.

[0050] Example 2

[0051] 50 mg of titanium dioxide material containing 1% gold (Au / TiO2), 50 mg of titanium dioxide material containing 1% copper (Cu / TiO2), and 50 mg of titanium dioxide material containing 1% nickel (Ni / TiO2) were mixed and dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with KOH) at pH 12 (volume ratio of acetonitrile:alkaline solution = 7:1). Then, 50 mg of commercial titanium dioxide catalyst was added, and the mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 1 h. The solubility of Au exceeded 98%, while the solubility of Cu and Ni was less than 0.5%.

[0052] Example 3

[0053] 50 mg of silica material containing 1% gold (Au / SiO2), 50 mg of silica material containing 1% copper (Cu / SiO2), and 50 mg of silica material containing 1% nickel (Ni / SiO2) were mixed and dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH 12 (volume ratio of acetonitrile:alkaline solution = 3:1). Then, 50 mg of commercial titanium dioxide catalyst was added. After irradiation with ultraviolet light in air containing 20% ​​oxygen for 1 h, the solubility of Au exceeded 98%, while the solubility of Cu and Ni was less than 0.5%.

[0054] Example 4

[0055] 50 mg of silica material containing 1% gold (Au / SiO2), 50 mg of silica material containing 1% copper (Cu / SiO2), and 50 mg of silica material containing 1% nickel (Ni / SiO2) were mixed and dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution at pH 12 (prepared by a molar ratio of NaOH:KOH = 1:1) (volume ratio of acetonitrile:alkaline solution = 3:1). Then, 50 mg of commercial titanium dioxide catalyst was added. After irradiation with ultraviolet light and microwave radiation at 200 W for 20 min in air containing 20% ​​oxygen, the solubility of Au exceeded 98%, while the solubility of Cu and Ni was less than 0.5%.

[0056] Example 5

[0057] 50 mg of silica material containing 1% gold (Au / SiO2), 50 mg of silica material containing 1% copper (Cu / SiO2), and 50 mg of silica material containing 1% nickel (Ni / SiO2) were mixed and dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH 12 (volume ratio of acetonitrile:alkaline solution = 3:1). Then, 50 mg of commercial titanium dioxide catalyst was added, and the mixture was irradiated with a xenon lamp (full-band light) for 40 min in an ozone atmosphere with a gas concentration of 1 ppm. The solubility of gold exceeded 98%, while the solubility of Cu and Ni was less than 0.5%.

[0058] Example 6

[0059] Five pieces of discarded computer chip material (CPU) totaling 10g, containing gold and other non-precious metals such as copper, zinc, nickel, iron, and tin, were placed in a 100mL mixture of acetonitrile and a pH 14 alkaline solution (prepared with NaOH) (acetonitrile:alkaline solution = 3:1 by volume). Then, 1g of commercial titanium dioxide catalyst was added. The mixture was irradiated for 8 hours in air containing 20% ​​oxygen using a xenon lamp (full-spectrum light). The solubility rates of each metal were as follows: Figure 1 As shown, the solubility of Au exceeds 98%, while the solubility of non-precious metals such as copper, zinc, nickel, iron, and tin (Cu, Zn, Ni, Fe, Sn) is less than 0.5%.

[0060] Example 7

[0061] 50 mg of titanium dioxide material containing 1% silver (Ag / TiO2), 50 mg of titanium dioxide material containing 1% copper (Cu / TiO2), and 50 mg of titanium dioxide material containing 1% nickel (Ni / TiO2) were mixed and dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with KOH at pH 12) (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added, and the mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 30 min. The solubility of each metal was as follows. Figure 2 As shown, the solubility of Ag exceeds 98%, while the solubility of Cu and Ni is less than 0.5%.

[0062] Example 8

[0063] 50 mg of titanium dioxide material containing 1% silver (Ag / TiO2), 50 mg of titanium dioxide material containing 1% copper (Cu / TiO2), and 50 mg of titanium dioxide material containing 1% nickel (Ni / TiO2) were mixed and dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH 12 (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added. After irradiation with ultraviolet light and microwave radiation at 200 W for 15 min in air containing 20% ​​oxygen, the solubility of Ag exceeded 98%, while the solubility of Cu and Ni was less than 0.5%.

[0064] Example 9

[0065] 50 mg of titanium dioxide material containing 1% silver (Ag / TiO2), 50 mg of titanium dioxide material containing 1% copper (Cu / TiO2), and 50 mg of titanium dioxide material containing 1% nickel (Ni / TiO2) were mixed and dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH 12 (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added, and the mixture was irradiated with a xenon lamp (full-band light) for 20 min in an ozone atmosphere with a gas concentration of 1 ppm. The solubility of Ag exceeded 98%, while the solubility of Cu and Ni was less than 0.5%.

[0066] Example 10

[0067] A solar panel (containing silver, aluminum, copper, zinc, tin, etc.) was added to a mixed solution of 100 mL of acetonitrile and an alkaline solution (prepared with NaOH) at pH 13 (volume ratio of acetonitrile:alkaline solution = 3:1). Then, 200 mg of commercial titanium dioxide catalyst was added. After irradiating with ultraviolet light in air containing 20% ​​oxygen for 4 hours, the solubility of Ag exceeded 98%, while the solubility of other metals was less than 0.5%.

[0068] Example 11

[0069] A solar panel (containing silver, aluminum, copper, zinc, tin, etc.) was added to a mixture of 100 mL of acetonitrile and a pH 13 alkaline solution (prepared with NaOH) (volume ratio of acetonitrile:alkaline solution = 3:1). Then, 200 mg of commercial titanium dioxide catalyst was added. The mixture was irradiated with a xenon lamp (full-band light) for 4 hours in an ozone atmosphere with a gas concentration of 1 ppm. The dissolution rate of Ag exceeded 98%, while the dissolution rate of other metals was less than 0.5%.

[0070] Example 12

[0071] 50 mg of carbon material (Pd / C) containing 5% palladium was dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with KOH) at pH 12 (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added, and the mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 1 h. The solubility of Pd exceeded 98%.

[0072] Example 13

[0073] 50 mg of titanium dioxide material (Pd / TiO2) containing 1% palladium was dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH 12. Then, 50 mg of a commercial titanium dioxide catalyst was added. The mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 1 hour. The solubility at different acetonitrile to alkaline solution ratios was as follows: Figure 3 As shown.

[0074] Example 14

[0075] 50 mg of a mixed metal titanium dioxide material (containing palladium, copper, zinc, and nickel) was dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH 12 (acetonitrile:alkaline solution = 1:1, by volume). Then, 50 mg of a commercial titanium dioxide catalyst was added, and the mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 1 hour. The dissolution curve is shown below. Figure 4 As shown, the solubility of Pd exceeds 98%, while the solubility of Cu, Zn, and Ni is less than 0.5%.

[0076] Example 15

[0077] 50 mg of a mixed metal titanium dioxide material (containing palladium, copper, zinc, and nickel) was dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with KOH) at pH 12 (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added. The mixture was irradiated with ultraviolet light and microwaved with 200 W for 25 min in air containing 20% ​​oxygen. The solubility of Pd exceeded 98%, while the solubility of Cu, Zn, and Ni was less than 0.5%.

[0078] Example 16

[0079] 50 mg of a mixed metal titanium dioxide material (containing palladium, copper, zinc, and nickel) was dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH 12 (volume ratio of acetonitrile:alkaline solution = 3:1). Then, 50 mg of a commercial titanium dioxide catalyst was added. The mixture was irradiated with a xenon lamp (full-band light) for 40 min in an ozone atmosphere with a gas concentration of 1 ppm. The solubility of Pd exceeded 98%, while the solubility of Cu, Zn, and Ni was less than 0.5%.

[0080] Example 17

[0081] 50 mg of carbon material (Pd / C) containing 5% palladium was dispersed in a 20 mL mixture of phenylacetonitrile and an alkaline solution (prepared with NaOH) at pH 12 (volume ratio of phenylacetonitrile to alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added, and the mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 1 h. The solubility of Pd exceeded 70%.

[0082] Example 18

[0083] 50 mg of carbon material (Pd / C) containing 5% palladium was dispersed in a 20 mL mixture of dicyandiamine and an alkaline solution (prepared with NaOH) at pH 12 (the dicyandiamine content was 10% of the total mass of the mixture). Then, 50 mg of commercial titanium dioxide catalyst was added, and the mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 1 h. The solubility of Pd exceeded 6%.

[0084] Example 19

[0085] 50 mg of carbon material (Pd / C) containing 5% palladium was dispersed in 20 mL of a mixed solution of propionitrile and an alkaline solution (prepared with NaOH) at pH 12 (volume ratio of propionitrile:alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added, and the mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 1 h. The solubility of Pd exceeded 80%.

[0086] Example 20

[0087] 50 mg of carbon material (Pd / C) containing 5% palladium was dispersed in 20 mL of a mixed solution of nitrile butadiene and alkaline solution (prepared with NaOH) at pH 12 (volume ratio of nitrile butadiene:alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added, and the mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 1 h. The solubility of Pd exceeded 80%.

[0088] Example 21

[0089] 50 mg of carbon material (Pd / C) containing 5% palladium was dispersed in a mixed solution of 20 mL of succinic anion and an alkaline solution (prepared with NaOH) at pH 12 (succinic anion content was 10% of the total mass of the mixed solution). Then, 50 mg of commercial titanium dioxide catalyst was added, and the mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 1 h. The solubility of Pd exceeded 60%.

[0090] Example 22

[0091] 50 mg of carbon material (Pd / C) containing 5% palladium was dispersed in 20 mL of a mixture of acrylonitrile and an alkaline solution (prepared with NaOH) at pH 12 (volume ratio of acrylonitrile:alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added, and the mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 1 h. The solubility of Pd exceeded 70%.

[0092] Example 23

[0093] 50 mg of a carbon material (Pd / C) containing 5% palladium was dispersed in 20 mL of a mixed solution of acetonitrile and alkaline solutions of different pH values ​​(prepared with NaOH) (acetonitrile:alkaline solution volume ratio = 1:1). Then, 50 mg of a commercial titanium dioxide catalyst was added, and the mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 1 hour. The solubility of Pd was as follows: Figure 5 As shown.

[0094] Example 24

[0095] 1g of waste alumina catalyst (Pd / Al2O3) containing 3% palladium was ball-milled and dispersed in 200mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH=14 (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 1g of commercial titanium dioxide catalyst was added, and the mixture was irradiated with a xenon lamp (full-band light) in air containing 20% ​​oxygen for 2h. The solubility of Pd exceeded 98%, and the solubility of Al was less than 0.5%.

[0096] Example 25

[0097] 1g of waste alumina catalyst (Pd / Al2O3) containing 3% palladium was ball-milled and dispersed in a mixed solution of 200mL acetonitrile and an alkaline solution (prepared with NaOH) at pH=14 (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 1g of commercial titanium dioxide catalyst was added. The mixture was irradiated with ultraviolet light and microwaved with 200W for 1.5h in air containing 20% ​​oxygen. The dissolution rate of Pd exceeded 98%, and the dissolution rate of Al was less than 0.5%.

[0098] Example 26

[0099] 1g of waste alumina catalyst (Pd / Al2O3) containing 3% palladium was ball-milled and dispersed in 200mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH=14 (volume ratio of acetonitrile:alkaline solution = 3:1). Then, 1g of commercial titanium dioxide catalyst was added, and the mixture was irradiated with a xenon lamp (full-band light) for 1.5h in an ozone atmosphere with a gas concentration of 1ppm. The dissolution rate of Pd exceeded 98%, and the dissolution rate of Al was less than 0.5%.

[0100] Example 27

[0101] 50 mg of a carbon material (Pd / C) containing 5% palladium was dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH 13 (acetonitrile:alkaline solution = 1:1, by volume). Then, 50 mg of a commercial titanium dioxide catalyst was added. The mixture was irradiated with ultraviolet light of varying intensities in air containing 20% ​​oxygen for 1 hour. The solubility of Pd was as follows: Figure 6 As shown.

[0102] Example 28

[0103] 50 mg of carbon material (Pt / C) containing 5% platinum was dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH 12 (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added, and the mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 4 h. The solubility of Pt exceeded 70%.

[0104] Example 29

[0105] 50 mg of a mixed metal titanium dioxide material (containing platinum, copper, zinc, and nickel) was dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH 12 (volume ratio of acetonitrile to alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added. After irradiation with ultraviolet light and microwave radiation at 200 W for 3 h in air containing 20% ​​oxygen, the solubility of Pt exceeded 70%, while the solubility of Cu, Zn, and Ni was less than 0.5%.

[0106] Example 30

[0107] 50 mg of a mixed metal carbon material (containing platinum, copper, zinc, and nickel) was dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH 12 (acetonitrile:alkaline solution = 3:1, by volume). Then, 50 mg of a commercial titanium dioxide catalyst was added. The mixture was irradiated with ultraviolet light for 4 hours in an ozone atmosphere with a gas concentration of 1 ppm. The dissolution curve is shown below. Figure 7 As shown, the solubility of Pt exceeds 98%, while the solubility of Cu, Zn, and Ni is less than 0.5%.

[0108] Example 31

[0109] 50 mg of a mixed metal titanium dioxide material (containing platinum, copper, zinc, and nickel) was dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH 12 (volume ratio of acetonitrile:alkaline solution = 3:1). Then, 50 mg of a commercial titanium dioxide catalyst was added. After irradiation with ultraviolet light in an atmosphere containing 100% oxygen for 4 h, the solubility of Pt exceeded 98%, while the solubility of Cu, Zn, and Ni was less than 0.5%.

[0110] Example 32

[0111] 1g of waste alumina catalyst (Pt / Al2O3) containing 3% platinum was ball-milled and dispersed in a 200mL mixture of acetonitrile and an alkaline solution (prepared with NaOH) at pH 14 (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 1g of commercial titanium dioxide catalyst was added. The mixture was irradiated with a xenon lamp (full-band light) in air containing 20% ​​oxygen for 6 hours. The solubility of Pt exceeded 80%, and the solubility of Al was less than 0.5%.

[0112] Example 33

[0113] 1g of waste alumina catalyst (Pt / Al2O3) containing 3% platinum was ball-milled and dispersed in a mixed solution of 200mL acetonitrile and an alkaline solution (prepared with KOH) at pH=14 (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 1g of commercial titanium dioxide catalyst was added. The mixture was irradiated with ultraviolet light and microwaved with 200W for 4h in an atmosphere containing 100% oxygen. The solubility of Pt exceeded 80%, and the solubility of Al was less than 0.5%.

[0114] Example 34

[0115] 1g of waste alumina catalyst (Pt / Al2O3) containing 3% platinum was ball-milled and dispersed in a 200mL mixture of acetonitrile and an alkaline solution (prepared with NaOH) at pH 14 (volume ratio of acetonitrile:alkaline solution = 3:1). Then, 1g of commercial titanium dioxide catalyst was added, and the mixture was irradiated with a xenon lamp (full-band light) for 4h in an ozone atmosphere with a gas concentration of 1ppm. The dissolution rate of Pt exceeded 80%, and the dissolution rate of Al was less than 0.5%.

[0116] Example 35

[0117] 50 mg of carbon material containing 5% ruthenium (Ru / C) was dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution of pH 12 (prepared with NaOH) (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added, and the mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 4 h. The solubility of Ru was 25%.

[0118] Example 36

[0119] 50 mg of carbon material containing 5% ruthenium (Ru / C), 50 mg of carbon material containing 1% copper (Cu / C), and 50 mg of carbon material containing 1% nickel (Ni / C) were mixed and dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with KOH) at pH 12 (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added, and the mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 4 h. The solubility of Ru was 25%, and the solubility of Cu and Ni was less than 0.5%.

[0120] Example 37

[0121] 50 mg of carbon material containing 5% ruthenium (Ru / C) was dispersed in a mixed solution of 20 mL acetonitrile and an alkaline solution of pH 12 (prepared with NaOH) (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added. The mixture was irradiated with ultraviolet light and microwaved with 200 W for 3 h in air containing 20% ​​oxygen. The solubility of Ru was 35%.

[0122] Example 38

[0123] 50 mg of carbon material containing 5% ruthenium (Ru / C) was dispersed in a mixed solution of 20 mL acetonitrile and an alkaline solution (prepared with NaOH) at pH 12 (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added. The mixture was irradiated with ultraviolet light for 4 h in an ozone atmosphere with a gas concentration of 1 ppm. The solubility of Ru was 35%.

[0124] Example 39

[0125] 50 mg of carbon material containing 5% rhodium (Rh / C) was dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution of pH 12 (prepared with NaOH) (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added, and the mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 4 h. The solubility of Rh was 20%.

[0126] Example 40

[0127] 50 mg of carbon material containing 5% rhodium (Rh / C), 50 mg of carbon material containing 1% copper (Cu / C), and 50 mg of carbon material containing 1% nickel (Ni / C) were mixed and dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH 12 (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added, and the mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 4 h. The solubility of Rh was 20%, and the solubility of Cu and Ni was less than 0.5%.

[0128] Example 41

[0129] 50 mg of carbon material containing 5% rhodium (Rh / C) was dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution of pH 12 (prepared with NaOH) (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added. The mixture was irradiated with ultraviolet light and microwaved with 200 W for 4 h in air containing 20% ​​oxygen. The solubility of Rh was 30%.

[0130] Example 42

[0131] 50 mg of carbon material containing 5% rhodium (Rh / C) was dispersed in a 20 mL mixture of acetonitrile and an alkaline solution (prepared with NaOH) at pH 12 (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 50 mg of commercial titanium dioxide catalyst was added. The mixture was irradiated with ultraviolet light for 4 h in an ozone atmosphere with a gas concentration of 1 ppm. The solubility of Rh was 30%.

[0132] Example 43

[0133] One g of waste automotive three-way catalyst (TWC) containing platinum, palladium, and rhodium (Pt, Pd, Rh) was ball-milled and dispersed in 200 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH 14 (volume ratio of acetonitrile:alkaline solution = 1:1). Then, one g of commercial titanium dioxide catalyst was added. The mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 4 hours. The dissolution rate of Pt was 50%, the dissolution rate of Pd was over 70%, and the dissolution rate of Rh was 20%. No other non-precious metals were detected to dissolve.

[0134] Example 44

[0135] One g of waste automotive three-way catalytic converter (TWC) containing platinum, palladium, and rhodium (Pt, Pd, Rh) was ball-milled and dispersed in a 200 mL mixture of acetonitrile and an alkaline solution (prepared with NaOH) at pH 14 (acetonitrile:alkaline solution = 1:1 by volume). Then, one g of commercial titanium dioxide catalyst was added. The mixture was irradiated with ultraviolet light and microwaved with 200 W for 4 h in air containing 20% ​​oxygen. The dissolution rate of Pt was 60%, the dissolution rate of Pd was over 70%, and the dissolution rate of Rh was 20%. No other non-precious metals were detected to dissolve.

[0136] Example 45

[0137] One g of waste automotive three-way catalytic converter (TWC) containing platinum, palladium, and rhodium (Pt, Pd, Rh) was ball-milled and dispersed in a 200 mL mixture of acetonitrile and an alkaline solution (prepared with NaOH) at pH 14 (volume ratio of acetonitrile:alkaline solution = 3:1). Then, one g of commercial titanium dioxide catalyst was added. The mixture was irradiated with ultraviolet light for 4 h in an ozone atmosphere with a gas concentration of 1 ppm. The dissolution rate of Pt was 60%, the dissolution rate of Pd was over 70%, and the dissolution rate of Rh was 20%. No other non-precious metals were detected to dissolve.

[0138] Example 46

[0139] 10g of precious metal-containing ore was ball-milled and dispersed in a 200mL mixture of acetonitrile and an alkaline solution (pH=14, prepared with NaOH) (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 1g of commercial titanium dioxide catalyst was added. The mixture was irradiated with ultraviolet light in air containing 20% ​​oxygen for 4h. The dissolution rates were 70% for Au, 40% for Pt, 60% for Pd, 10% for Ru, and 5% for Ir. No other non-precious metals were detected to dissolve.

[0140] Example 47

[0141] 1g of precious metal-containing ore was ball-milled and dispersed in a 200mL mixture of acetonitrile and an alkaline solution (pH=14, prepared with NaOH) (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 1g of commercial titanium dioxide catalyst was added. The mixture was irradiated with ultraviolet light and microwaved with 200W for 4h in air containing 20% ​​oxygen. The dissolution rates were 80% for Au, 50% for Pt, 70% for Pd, 10% for Ru, and 8% for Ir. No other non-precious metals were detected to dissolve.

[0142] Example 48

[0143] 1g of precious metal-containing ore was ball-milled and dispersed in a 200mL mixture of acetonitrile and an alkaline solution (prepared with NaOH) at pH 14 (volume ratio of acetonitrile:alkaline solution = 1:1). Then, 1g of commercial titanium dioxide catalyst was added. The mixture was irradiated with ultraviolet light for 4h in an ozone atmosphere with a gas concentration of 1ppm. The dissolution rates were 80% for Au, 60% for Pt, 80% for Pd, 10% for Ru, and 8% for Ir. No other non-precious metals were detected to dissolve.

[0144] Example 49

[0145] Titanium dioxide material containing 1% gold (Au / TiO2) was dispersed in a 20 mL mixture of acetonitrile and an alkaline solution (prepared with NaOH) at pH 12 (acetonitrile:alkaline solution = 3:1, by volume). Then, 50 mg of commercial titanium dioxide catalyst was added. The mixture was then subjected to low-intensity ultraviolet light (<20 mW / cm²) at different temperatures. 2 For the same irradiation reaction time, the dissolution effect of Au is as follows: Figure 8 As shown.

[0146] Example 50

[0147] 50 mg of carbon material (Pd / C) containing 5% palladium was dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH 12 (acetonitrile:alkaline solution = 1:1, by volume). Then, 50 mg of commercial titanium dioxide catalyst was added. The mixture was then subjected to low-intensity ultraviolet light (<20 mW / cm²) at different temperatures. 2 For the same irradiation reaction time, the dissolution effect of Pd is as follows: Figure 9 As shown.

[0148] Example 51

[0149] 50 mg of carbon material containing 5% platinum (Pt / C) was dispersed in 20 mL of a mixed solution of acetonitrile and an alkaline solution (prepared with NaOH) at pH 13 (volume ratio of acetonitrile:alkaline solution = 3:1). Then, 50 mg of commercial titanium dioxide catalyst was added, and the mixture was irradiated with ultraviolet light for 4 hours in an ozone atmosphere with a gas concentration of 1 ppm. The dissolution effect of Pt at different temperatures and for the same reaction time was as follows: Figure 10 As shown, the dissolution rate of Pt on carbon materials (Pt / C) containing 5% platinum increases significantly with increasing temperature, and the reaction rate at 60℃ is 1.8 times that at 25℃.

[0150] It should be noted that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A nitrile-containing alkaline solvent for efficiently selectively dissolving a noble metal, characterized by comprising a nitrile compound and an alkali. The nitrile compound and the inorganic strong base solution with pH=8-14 are mixed.

2. The nitrile-containing alkaline solvent for efficiently and selectively dissolving precious metals according to claim 1, characterized by, The volume ratio of the nitrile compound and the inorganic strong base solution with pH=8-14 is 1:0.01-19.

3. A method for efficient selective dissolution of noble metals, characterized in that, The steps include: The noble metal-containing material is placed in a nitrile-alkali solvent system formed by mixing a nitrile compound and an inorganic strong base solution with pH=8-14, and the noble metal is selectively dissolved by light irradiation under the action of oxygen and a photocatalyst.

4. The method of selectively dissolving noble metals according to claim 3, wherein The process of selectively dissolving the noble metal by light irradiation is accompanied by heating, and / or ultrasonic treatment, and / or microwave treatment.

5. The method of selective dissolution of noble metals according to claim 3, wherein The volume ratio of the nitrile compound and the inorganic strong base solution with pH=8-14 in the nitrile-alkali solvent system is 1:0.01-19.

6. The method of selective dissolution of noble metals according to claim 3, wherein The nitrile compound includes acetonitrile, propionitrile, butyronitrile, butanedinitrile, phenylacetonitrile, propenenitrile, p-methylbenzonitrile, cyanoacetic acid, malononitrile, cyanobenzyl, dicyandiamide, or any one or combination of the nitrile compounds.

7. The method of selective dissolution of noble metals according to claim 3, wherein The inorganic strong base solution with pH=8-14 contains lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, beryllium hydroxide, magnesium hydroxide, strontium hydroxide, or any one or combination of the composite bases.

8. The method of selective dissolution of noble metals according to claim 3, wherein The photocatalyst includes an organic photocatalyst, a metal oxide photocatalyst, a metal sulfide photocatalyst, a graphite-like carbon nitride compound g-C3N4, a Bi-based photocatalyst, a nanomaterial photocatalyst, or a photocatalyst formed by modification, surface modification, and mutual compounding of each of them.

9. The method of selective dissolution of noble metals according to claim 3, wherein The oxygen is oxygen in air, and / or pure oxygen introduced, and / or oxygen generated by a substance capable of generating oxygen.

10. The method of selective dissolution of noble metals according to claim 3, wherein The light irradiation covers deep ultraviolet light, ultraviolet light, visible light, and near-infrared light.

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