阅读说明：本技术 一种纳米银粉体的制备方法 (Preparation method of nano silver powder ) 是由 朱义奎 于 2020-07-03 设计创作，主要内容包括：一种纳米银粉体的制备方法,属于纳米材料制备领域。本发明的技术方案为：用于制备该纳米银粉体的电解液为硝酸银、柠檬酸、钼酸钠和磷酸钠的混合溶液,工作电极为废弃回收的银饰品等银材,铂网为对电极,先将电解液除氧,然后用恒流电源对工作电极进行恒电流极化,待铂网上还原沉积足够的银粉后,取下铂网,将其密闭在无水乙醇中超声清洗,接着抽滤、干燥,得到平均粒径为10～50nm的纳米银粉体。本发明提供的纳米银粉体的制备方法,工艺简单,不仅可以利用废弃银饰品等银材,而且制得的纳米银粉体的粒径容易控制、分散性好、纯度高、反应过程中银源稳定充足。(A method for preparing nano silver powder, belonging to the field of nano material preparation. The technical scheme of the invention is as follows: the electrolyte for preparing the nano-silver powder is a mixed solution of silver nitrate, citric acid, sodium molybdate and sodium phosphate, the working electrode is a waste recovered silver material such as silver ornaments, the platinum mesh is a counter electrode, the electrolyte is deoxidized, then a constant current power supply is used for carrying out constant current polarization on the working electrode, after enough silver powder is reduced and deposited on the platinum mesh, the platinum mesh is taken down, the platinum mesh is sealed in absolute ethyl alcohol for ultrasonic cleaning, and then the nano-silver powder with the average particle size of 10-50 nm is obtained by suction filtration and drying. The preparation method of the nano silver powder provided by the invention has simple process, can utilize waste silver ornaments and other silver materials, and has the advantages of easy control of the particle size of the prepared nano silver powder, good dispersibility, high purity and stable and sufficient silver source in the reaction process.)

1. A preparation method of nano silver powder is characterized in that an electrolyte for preparing the nano silver powder is a mixed solution of silver nitrate, citric acid, sodium molybdate and sodium phosphate, a working electrode is a waste silver material such as a silver ornament, a platinum net is a counter electrode, the electrolyte is deoxidized, then a constant current power supply is used for carrying out constant current polarization on the working electrode, after enough silver powder is reduced and deposited on the platinum net, the platinum net is taken down, sealed in absolute ethyl alcohol for ultrasonic cleaning, and then, the nano silver powder is obtained after suction filtration and drying.

2. The method for preparing nano silver powder according to claim 1, which is characterized by comprising the following steps:

(1) the waste and recovered silver ornaments and other silver materials are encapsulated by epoxy resin, and the fixed working area is 0.1cm according to the shape and the size of the silver materials²～10cm²；

(2) Preparing 0.01mol/L NaOH solution, cleaning the silver material and the platinum net, washing the silver material and the platinum net by deionized water, and then drying the silver material and the platinum net in a 50 ℃ drying oven;

(3) preparing 0.02-0.05 mol/L silver nitrate water solution A;

(4) adding a proper amount of citric acid, sodium molybdate and sodium phosphate into the solution A to obtain a solution B, wherein the citric acid, the sodium molybdate and the sodium phosphate in the solution B are respectively 0.02-0.05 mmol/L, 0.1mmol/L and 0.5 mmol/L;

(5) introducing inert gas into the solution B for 30-40 min to obtain a solution C;

(6) the working electrode and the platinum net are arranged in an electrolytic cell and are respectively connected with the positive electrode and the negative electrode of a constant current power supply;

(7) setting the constant current to be 1-300 mA, moving the solution C into an electrolytic cell, carrying out constant current polarization on a working electrode under the room temperature condition, and depositing simple substance silver atoms on a counter electrode;

(8) and (3) after finishing the constant current experiment, transferring the platinum mesh into absolute ethyl alcohol, sealing, ultrasonically cleaning for 5-10 min, then performing suction filtration, cleaning again, performing suction filtration again, and freeze-drying to obtain the nano silver powder with the average particle size of 10-50 nm.

3. The method for preparing the nano silver powder according to the claims 1-2, wherein the size of the working area is fixed in the step (1) to control the current density of the reaction, which is beneficial to regulating and controlling the particle size of the nano silver powder.

4. The method for preparing the nano silver powder according to the claims 1-2, wherein the citric acid, the sodium molybdate and the sodium phosphate in the step (4) not only play a role of a dispersing agent, but also play a role of a stabilizing agent, so that impurity elements such as copper, zinc and the like in the silver ornaments are prevented from polluting the electrolyte, and impurities such as gold and the like which are inactive to the silver are deposited at the bottom of the electrolytic cell.

5. The method for preparing silver nanopowder according to claims 1-2, wherein the inert gas is introduced in step (5) for removing dissolved oxygen in the solution.

6. The method for preparing nano silver powder according to claim 1 to 2, wherein the freeze-drying temperature in the step (8) is-25 ℃.

Technical Field

The invention belongs to the field of nano material preparation, and particularly relates to a preparation method of nano silver powder.

Background

Silver powder is a metal powder which is most widely applied in the electronic industry, particularly has small particle size, large specific surface, strong surface activity, high conductivity, broad spectrum of antibiosis and antiphlogosis, becomes a basic functional material of electronic paste such as thick films, resistors, ceramics, media and the like, and has important application in the fields of electric and electronic, chemical catalysis, composite materials, medical treatment and the like.

The silver powder is prepared by physical methods such as a gas phase evaporation condensation method, a grinding method, an atomization method and the like, and chemical methods such as a chemical vapor deposition method, a liquid phase chemical reduction method and the like, but the methods have the problems of high cost, such as the gas phase evaporation condensation method, the atomization method, the chemical vapor deposition method and the like, easy environmental pollution and agglomeration phenomenon caused by the liquid phase chemical reduction method, and the grinding method is difficult to obtain smaller particle size, low purity and the like.

Disclosure of Invention

Aiming at the technical problems, the invention provides a preparation method of nano silver powder, which takes waste silver ornaments and other silver materials and silver nitrate as silver sources, adds a stabilizer and a dispersant into electrolyte, and prepares the silver powder with good dispersibility, sufficient silver sources, high purity, high yield and grain diameter of 10-50 nm by using a constant-current polarization and reduction method.

In order to achieve the purpose, the technology of the invention adopts the following technical scheme:

the invention relates to a preparation method of nano-silver powder, wherein an electrolyte for preparing the nano-silver powder is a mixed solution of silver nitrate, citric acid, sodium molybdate and sodium phosphate, a working electrode is a waste and recovered silver material such as a silver ornament, a platinum mesh is a counter electrode, the electrolyte is deoxidized, then constant current polarization is applied to the working electrode, after sufficient silver powder is reduced and deposited on the platinum mesh, the platinum mesh is taken down and sealed in absolute ethyl alcohol, and the nano-silver powder is obtained by ultrasonic cleaning, suction filtration and drying.

The preparation method of the nano silver powder comprises the following preparation steps:

(1) the waste and recovered silver ornaments and other silver materials are encapsulated by epoxy resin, and the fixed working area is 0.1cm according to the shape and the size of the silver materials²～10cm²；

(2) Preparing 0.01mol/L NaOH solution, cleaning the silver material and the platinum net, washing the silver material and the platinum net by deionized water, and then drying the silver material and the platinum net in a 50 ℃ drying oven;

(3) preparing 0.02-0.05 mol/L silver nitrate water solution A;

(4) adding a proper amount of citric acid, sodium molybdate and sodium phosphate into the solution A to obtain a solution B, wherein the citric acid, the sodium molybdate and the sodium phosphate in the solution B are respectively 0.02-0.05 mmol/L, 0.1mmol/L and 0.5 mmol/L;

(5) introducing inert gas into the solution B for 30-40 min to obtain a solution C;

(6) the working electrode and the platinum net are arranged in an electrolytic cell and are respectively connected with the positive electrode and the negative electrode of a constant current power supply;

(7) setting the constant current to be 1-300 mA, moving the solution C into an electrolytic cell, carrying out constant current polarization on a working electrode under the room temperature condition, and depositing simple substance silver atoms on a counter electrode;

(8) and (3) after finishing the constant current experiment, transferring the platinum mesh into absolute ethyl alcohol, sealing, ultrasonically cleaning for 5-10 min, then performing suction filtration, cleaning again, performing suction filtration again, and freeze-drying to obtain the nano silver powder with the average particle size of 10-50 nm.

In the step (1), the preferable scheme is that the size of the fixed working area is used for controlling the current density of the reaction, which is beneficial to regulating and controlling the particle size of the nano silver powder.

In the step (4), the added citric acid, sodium molybdate and sodium phosphate not only play a role of a dispersant, but also play a role of a stabilizer, so that impurity elements such as copper and zinc in the silver material are prevented from polluting the electrolyte, and impurities inactive to silver, such as gold, are deposited at the bottom of the electrolytic cell.

In the step (5), it is preferable that an inert gas is introduced to remove dissolved oxygen in the solution.

The preferable scheme of the preparation method of the nano silver powder is that the temperature of freeze drying is set to be-25 ℃.

The invention has the beneficial effects that:

(1) the invention can provide abundant silver sources, and besides silver ions in the original silver nitrate solution are used as the silver sources, the silver material of the working electrode also provides abundant silver sources for the electrochemical process.

(2) The invention carries out electrochemical treatment on the silver materials such as the waste and recycled silver ornaments, the selected reagent is non-toxic and harmless, the invention is environment-friendly, the preparation process is simple, the cost is low, the nano silver powder can be obtained at normal temperature, the nano silver powder can be directly used in the fields of electric and electronic industry, chemical catalysis, composite materials, medical treatment and the like, and the invention has good social benefit and economic benefit.

Detailed Description

The present invention will be described in further detail with reference to examples.