Substrate capable of erasing noble metal and application thereof
Technical Field
The invention relates to an erasable noble metal substrate and application thereof, belonging to the field of material chemistry.
Background
The rise of the industrial revolution makes human life and production unable to leave electric power, and the application of the electric power brings convenience and high efficiency which are difficult to quantify for people. The metal is contained in almost every electronic device regardless of the use of the metal in power transmission or device terminals, because the metal is the most cost-effective power medium in the prior art in view of conductivity and economic cost. However, when the human beings abandon and replace the electronic devices on a large scale every year, the metals, particularly the noble metals, are also abandoned in large quantities, and part of the abandoned noble metals enter the soil, the ocean and the rivers to bring feared heavy metal pollution to the ecological environment; and the other part is wasted due to improper recovery measures, and huge economic losses are brought.
Aiming at the recycling of precious metals, the currently adopted methods mainly comprise a physical method and a chemical method. The physical method mainly adopts a crushing and sorting method, and the method has the disadvantages of complicated steps, low sorting accuracy and dependence on large-scale equipment; the chemical method mainly refers to a heat treatment method by utilizing high-temperature incineration and a strong acid treatment method, the former has great environmental pollution and large energy consumption, and the latter is very dangerous to operate.
It is in view of the large-scale precious metal waste per year and the subsequent difficult precious metal recovery, we will address these problems from the source of precious metal product production, proposing an erasable precious metal substrate and an application thereof. The substrate can realize the high-efficiency erasure of the noble metal on the substrate under extremely mild conditions, and the noble metal is effectively recovered in the form of metal cations. The method is simple and mild, has the possibility of large-scale industrial application, and has great application value for recovering the noble metal materials in the circuit.
Disclosure of Invention
The technical problem is as follows: the invention aims to provide a substrate capable of erasing noble metals and application thereof, which can realize effective recovery of noble metals under the conditions of normal temperature and normal pressure, no strong acid, strong base and no large-scale equipment, and is an economic noble metal recovery method capable of being applied in a large scale; meanwhile, the method has excellent space controllability, can realize the erasure of the noble metal at a specific position on the substrate, and has considerable potential for the research and development of advanced functional materials.
The technical scheme is as follows: the invention provides an erasable noble metal substrate, which is of a two-layer structure, wherein the lower layer is a substrate, and the upper layer is a polyphenol substance coating modified on the substrate.
Wherein:
the substrate is any water-insoluble material with an interface, and comprises a two-dimensional or three-dimensional material, such as glass, silicon, quartz, plastic, metal, fabric or PE (polyethylene) sheet.
The polyphenol substance is a polymer formed by oxidizing a phenolic micromolecule substance, wherein the phenolic micromolecule substance comprises dopamine hydrochloride, tannic acid, caffeic acid or gallic acid and derivatives thereof.
The preparation method of the erasable precious metal substrate comprises the following steps: and soaking the substrate material into a solution of a phenol micromolecule substance, standing or stirring for 1-72 h, taking out, alternately cleaning by using ethanol and pure water, and drying at room temperature to obtain the substrate capable of erasing the noble metal.
The polyphenol substance solution is prepared by dissolving polyphenol substances such as dopamine hydrochloride in 10mM Tris-HCl buffer (pH 8.5) to obtain a polyphenol substance solution with a concentration of 0.01-10 mg/mL.
The invention also provides the application of the substrate capable of erasing the precious metal, which is applied to erasing and recovering the precious metal, and comprises the following steps:
1) preparing a noble metal coating on the surface of the erasable noble metal substrate;
2) soaking the substrate with the noble metal coating into a recovery solution, and after reacting for a period of time, the noble metal coating can be erased spontaneously;
3) and recovering the noble metal from the recovered solution after the reaction.
Wherein:
the noble metal is metal Ag or metal Au.
In the step 1) of preparing the noble metal coating on the surface of the erasable noble metal substrate, the preparation method of the noble metal coating is not limited, and the preparation method includes but is not limited to magnetron sputtering, plasma beam evaporation, atomic layer deposition, chemical reduction, photo reduction or electroplating.
Soaking the substrate with the precious metal coating in the step 2) into a recovery solution, wherein the recovery solution is an ethanol water solution, a KI solution or a sodium thiosulfate solution.
The concentration of ethanol in the ethanol aqueous solution is 1-100 vol%; the KI solution is characterized in that the KI concentration is 10-200 mg/mL, and the solvent is ethanol, water or a mixed solution of ethanol and water; the concentration of the sodium thiosulfate in the sodium thiosulfate solution is 1-100 mmol/L, and the solvent is ethanol, water or a mixed solution of ethanol and water.
After the reaction in the step 2) is carried out for a period of time, the reaction time is 10 s-120 min.
After the reaction in the step 2) is carried out for a period of time, the reaction process is carried out under the irradiation of ultraviolet light.
The reaction process is carried out under the irradiation of ultraviolet light, the wavelength of the ultraviolet light is less than 365nm,the illumination intensity of the ultraviolet light is 0.1-1000 mW/cm-2The illumination time is 10 s-120 min.
Has the advantages that: compared with the prior art, the invention has the following advantages:
1. the base capable of erasing the precious metals has universality, the base has no selectivity on substrate materials, and any material, such as glass, silicon, quartz, plastic, metal, woven fabric and the like, can be used for preparing the base capable of erasing the precious metals;
2. the application of the substrate capable of erasing the noble metal can realize effective erasing of the noble metal coating, the reaction condition is mild, acid and alkali are not added, the reaction can be carried out at normal temperature and normal pressure, large-scale equipment is not relied on, the reaction time is short, and the substrate has the basis of large-scale application;
3. the substrate capable of erasing the precious metal and the application of the substrate capable of erasing the precious metal can realize targeted erasing of the metal coating in a specific area, and have good space controllability.
Drawings
FIG. 1 is a schematic view of a method for preparing an erasable noble metal substrate according to the present invention;
FIG. 2 is a scanning electron microscope image of a metal coating on an erasable noble metal substrate provided by the present invention;
FIG. 3 is a scanning electron microscope image of a metal coating on an erasable noble metal substrate prepared according to the present invention after being erased;
wherein: a substrate a, a polyphenol substance coating b and a noble metal coating c.
Detailed Description
The present invention will be further illustrated with reference to the accompanying drawings and specific examples, which are carried out on the premise of the technical solution of the present invention, and it should be understood that these examples are only for illustrating the present invention and are not intended to limit the scope of the present invention.
Example 1
The base with the erasable precious metal has a two-layer structure, wherein the lower layer is a substrate glass slide a, and the upper layer is modified on a substrate by a hydrochloric acid dopamine coating b, and the preparation method comprises the following steps: the slide a is soaked in dopamine hydrochloride solution (2mg/mL, 10mM tris-HCl buffer solution, pH 8.5), after 24h soaking, the material is taken out, washed alternately with ethanol and pure water, and dried at room temperature, to obtain a substrate with dopamine hydrochloride coating b, i.e., a substrate on which precious metals can be erased.
Use of an erasable precious metal substrate for erasing a recycled precious metal, comprising the steps of:
1) soaking the substrate capable of erasing noble metals into 0.1mol/mL silver nitrate solution (water as solvent), and irradiating the substrate soaked in the silver nitrate solution by using ultraviolet light with the wavelength of 365nm at the irradiation intensity of 5mW/cm2The irradiation time is 30min, after the irradiation is finished, the substrate is taken out of the solution, is alternately cleaned by using ethanol and pure water, and is dried at room temperature, so that the preparation of the silver coating c on the surface of the material is finished, as shown in figure 2;
2) the substrate with silver coating c was immersed in absolute ethanol and subjected to ultraviolet light (5 mW/cm) at a wavelength of 254nm2) The silver coating c can be spontaneously erased after the irradiation for 1 hour; after the completion of the light irradiation, the substrate was taken out from the solution, washed alternately with ethanol and pure water, and dried at room temperature to obtain a substrate from which the silver coating c was erased, as shown in fig. 3;
3) recovering noble metals in the recovery solution after the reaction: silver in the recovered solution after the reaction exists in a form of cation, and reducing agents such as ascorbic acid, sodium citrate, hydroxylamine hydrochloride and the like are added for secondary reduction and recovery.
Example 2
The base with the erasable precious metal is of a two-layer structure, wherein the lower layer is a substrate fabric a, and the upper layer is modified by a caffeic acid coating layer b, and the preparation method comprises the following steps: soaking the fabric a in a caffeic acid solution (1mg/mL, 10mM tris-HCl buffer solution, pH 8.5), taking out the fabric a after soaking for 24h, alternately washing the fabric a with ethanol and pure water, and drying the fabric a at room temperature to obtain a substrate with a caffeic acid coating b, namely a substrate capable of wiping off precious metals.
Use of an erasable precious metal substrate for erasing a recycled precious metal, comprising the steps of:
1) carrying out physical vapor deposition of a silver coating c on the substrate capable of erasing the noble metal in a vapor deposition mode, taking the material out of the vacuum chamber after the vapor deposition is finished, alternately cleaning the material by using ethanol and pure water, and drying the material at room temperature to finish the preparation of the silver coating c on the surface of the material;
2) after immersing the substrate having the silver coating layer c in a solution of sodium thiosulfate (the concentration of sodium thiosulfate is 18mmol/L, the solvent is a mixed solution of ethanol and water, wherein the concentration of ethanol is 50 vol%) overnight, taking out the material from the solution, alternately washing with ethanol and pure water, and drying at room temperature, the substrate having the silver coating layer c erased is obtained;
3) recovering noble metals in the recovery solution after the reaction: and (3) the silver in the recovered solution after the reaction exists in a form of cation, and the obtained substrate with the silver coating c removed or the substrate with the prepared polyphenolic substance coating is soaked in the recovered solution, and is subjected to ultraviolet irradiation (the wavelength is 365nm) to obtain secondary deposition of the silver for recovery and utilization.
Example 3
The substrate capable of erasing noble metals is of a two-layer structure, the lower layer of the substrate is a substrate silicon wafer a, and the upper layer of a tannin coating layer b is modified on the substrate, and the preparation method comprises the following steps: 1) the silicon wafer a was immersed in a tannic acid solution (0.2mg/mL, 10mM tris-HCl buffer, pH 8.5), stirred for 24 hours, and then taken out, washed alternately with ethanol and pure water, and dried at room temperature to obtain a substrate having a tannic acid coating b, i.e., a substrate on which a noble metal was erased.
Use of an erasable precious metal substrate for erasing a recycled precious metal, comprising the steps of:
1) carrying out physical vapor deposition on the substrate which can be erased with precious metal to obtain a gold coating c in a vapor deposition mode, taking the substrate out of the vacuum chamber after the vapor deposition is finished, alternately cleaning the substrate with ethanol and pure water, and drying the substrate at room temperature to obtain the gold coating c on the surface of the material;
2) soaking the substrate with the gold coating c into a KI solution (the KI concentration is 100mg/mL, and the solvent is a mixed solution of ethanol and water, wherein the concentration of the ethanol is 50vol%) ultraviolet light at a wavelength of 254nm (10 mW/cm)2) Irradiating for 1h, taking the material out of the solution after finishing the irradiation, alternately cleaning the material by using ethanol and pure water, and drying the material at room temperature to obtain the substrate with the gold coating c erased;
3) recovering noble metals in the recovery solution after the reaction: gold in the recovered solution after reaction exists in a form of cation, and reducing agents such as sodium borohydride and sodium citrate are added for secondary reduction and recovery.
Example 4
The base with the erasable precious metal has a two-layer structure, the lower layer is a substrate PE sheet a, the upper layer is decorated with a gallic acid coating b, and the preparation method comprises the following steps: 1) the PE piece a was immersed in a gallic acid solution (2mg/mL, 10mM tris-HCl buffer, pH 8.5), and after 24 hours of immersion, the PE piece was taken out, washed alternately with ethanol and pure water, and dried at room temperature to obtain a substrate having a gallic acid coating b, i.e., a substrate on which noble metals were wiped off.
Use of an erasable precious metal substrate for erasing a recycled precious metal, comprising the steps of:
1) immersing the substrate capable of wiping off the noble metal into a chloroauric acid solution of 10mmol/mL (the solvent is water, and the pH is adjusted to 7 by using sodium hydroxide), and then irradiating the substrate immersed in the chloroauric acid solution by using ultraviolet light with the wavelength of 365nm at the irradiation intensity of 5mW/cm2The irradiation time is 10min, the material is taken out of the solution after the illumination is finished, the material is alternately cleaned by using ethanol and pure water, and the material is dried at room temperature, so that the preparation of the gold coating c on the surface of the material is finished;
2) the substrate having the gold coating layer c was placed in a KI solution (KI concentration was 50mg/mL, and the solvent was a mixed solution of ethanol and water, wherein the concentration of ethanol was 50 vol%) overnight, and then taken out of the solution, washed alternately with ethanol and pure water, and dried at room temperature, to obtain a substrate on which the gold coating layer c was erased.
3) Recovering noble metals in the recovery solution after the reaction: and (3) allowing gold in the reacted recovery solution to exist in a form of cations, soaking the obtained substrate with the gold coating c removed or the substrate with the prepared polyphenol substance coating in the recovery solution, and performing ultraviolet irradiation (the wavelength is 365nm) to obtain secondary deposition of gold for recovery and utilization.
It should be noted that, for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be construed as the protection scope of the present invention.