Pb / PbO2-polypyrrole composite anode and preparation method thereof

Abstract

The invention discloses a Pb / PbO2-polypyrrole composite anode and a preparation method of the Pb / PbO2-polypyrrole composite anode. The composite anode is composed of a Pb substrate and a PbO2-polypyrrole film layer on the surface of the Pb substrate. The preparation method comprises the following steps that pyrrole, nitric acid and a lead nitrate solution serve as electrolyte, and the PbO2-polypyrrole film layer is deposited on the surface of the Pb substrate through electrochemical oxidation. Polypyrrole is good in conductivity, the resistance of the composite electrode can be remarkably reduced, and the anode potential is reduced. In addition, polypyrrole and PbO2 are subjected to electrochemical oxidation codeposition, the compactness of the film layer and the bonding strength of the film layer and a substrate can be improved, and the stability of the film layer is improved.

Description

Technical Field

[0001] This invention relates to the field of materials preparation, and in particular to a lead-based composite anode and its preparation method. Background Technology

[0002] Lead and lead alloys are widely used in non-ferrous metal electrowinning processes due to their low cost and simple preparation. During electrowinning, the lead-based anode primarily undergoes the oxygen evolution reaction (OER), while the Pb substrate undergoes electrochemical oxidation, gradually forming an oxide film on its surface. Because the OER and film formation processes occur simultaneously, the oxide film has a loose and low-density structure, resulting in poor adhesion to the substrate. Consequently, the lead-based anode oxide film is constantly in a cycle of peeling-repair-peeling, leading to rapid corrosion of the anode substrate and an unsatisfactory service life. Summary of the Invention

[0003] In view of the problems of loose and porous oxide film layer on the surface of lead-based anode and unsatisfactory bonding stability with the substrate, this patent proposes a Pb / PbO2-polypyrrole composite anode and its preparation method.

[0004] The Pb / PbO2-polypyrrole composite anode proposed in this invention consists of a Pb matrix and a PbO2-polypyrrole film layer on the surface.

[0005] The method for preparing Pb / PbO2-polypyrrole composite anode proposed in this invention uses 0.01-0.50M pyrrole, 0.10-0.50M nitric acid, and 0.10-1.00M lead nitrate solution as electrolytes to deposit a PbO2-polypyrrole film on the surface of a Pb substrate through electrochemical oxidation.

[0006] Preferably, the electrochemical oxidation employs a constant current polarization method with a current density of 5~50 mA cm⁻¹. -2 .

[0007] Preferably, the electrolyte temperature is controlled at 20~80℃. Preferably, the electrochemical oxidation time is 20 min to 20 h.

[0008] Preferably, after electrochemical oxidative deposition of PbO2-polypyrrole, the composite anode is removed from the solution and dried at a temperature of 25-60°C.

[0009] The technical principles and effects of this invention are as follows: (1) Pyrrole can be electrochemically oxidized and polymerized in acidic solutions: In acidic solutions, pyrrole can be oxidized and polymerized by oxidants or electrochemical methods to generate polypyrrole with good electronic conductivity.

[0010] (2) Co-deposition of PbO2 and polypyrrole: In an acidic solution, by controlling a certain current density, Pb in the solution can be deposited. 2+Simultaneous oxidation deposition with pyrrole monomers. The deposited PbO2-polypyrrole coating can compensate for the poor conductivity of the PbO2 film, thereby reducing the ohmic voltage drop and anode potential of the composite anode.

[0011] (3) Polypyrrole deposition can improve the density of the oxide film and its bonding strength with the substrate: As an organic polymer, polypyrrole has high elasticity and good viscosity, which can regulate the microstructure of PbO2 deposits, improve the density of the composite film, and improve the bonding strength between the oxide film and the Pb substrate, thereby improving the stability of the film during the service of the composite anode and extending the service life of the composite anode. Detailed Implementation

[0012] The present invention will be described in detail with reference to the following embodiments.

[0013] Example 1 Using a solution of 0.50 mol / L PbNO3, 0.10 mol / L HNO3, and 0.10 mol / L pyrrole as the electrolyte, a Pb plate was used as the anode and a graphite plate as the cathode, at 30℃ and 10 mA cm⁻¹. -2 Electrochemical oxidation was performed at the anodic current density, and after 2 hours of oxidation, the composite anode was removed and dried at 50°C. This lead-based anode was then subjected to constant current polarization (500 A / m) in a simulated zinc electrowinning electrolyte. -2 After 72 hours, the anode potential was 70 mV lower than that of the traditional Pb-Ag (0.6 wt.%) plate, and the anode weight loss rate was reduced by 40%.

[0014] Example 2 Using a solution of 0.30 mol / L PbNO3, 0.20 mol / L HNO3, and 0.20 mol / L pyrrole as the electrolyte, a Pb plate was used as the anode and a graphite plate as the cathode, at 50 °C and 20 mA cm⁻¹. -2 Electrochemical oxidation was performed at an anodic current density. After 10 hours of oxidation, the composite anode was removed and dried at 35°C. This lead-based anode was then subjected to constant current polarization (500 A / m) in a simulated zinc electrowinning electrolyte. -2 After 72 hours, the anode potential was 60 mV lower than that of the traditional Pb-Ag (0.6 wt.%) plate, and the anode weight loss rate was reduced by 60%.

[0015] Example 3 Using a solution of 0.70 mol / L PbNO3, 0.20 mol / L HNO3, and 0.35 mol / L pyrrole as the electrolyte, a Pb plate was used as the anode and a graphite plate as the cathode, at 70℃ and 5 mA cm⁻¹. -2Electrochemical oxidation was performed at an anodic current density of [value missing], and after 20 hours of oxidation, the composite anode was removed and dried at 60°C. This lead-based anode was then subjected to constant current polarization (500 A / m) in a simulated zinc electrowinning electrolyte. -2 After 72 hours, the anode potential was 80 mV lower than that of the traditional Pb-Ag (0.6 wt.%) plate, and the anode weight loss rate was reduced by 66%.

Claims

1. A Pb / PbO2-polypyrrole composite anode, characterized in that, It consists of a Pb matrix and a PbO2-polypyrrole film layer on the surface.

2. A method for preparing the Pb / PbO2-polypyrrole composite anode as described in claim 1, characterized in that, Includes the following steps: Using 0.01-0.50M pyrrole, 0.10-0.50M nitric acid, and 0.10-1.00M lead nitrate solution as electrolytes, PbO2-polypyrrole film was deposited on the surface of a Pb substrate through electrochemical oxidation.

3. The method as described in claim 2, characterized in that, Electrochemical oxidation employs constant current polarization with a current density of 5–50 mA cm⁻¹. -2 .

4. The method as described in claim 2, characterized in that, The electrolyte temperature is controlled between 20 and 80°C.

5. The method as described in claim 2, characterized in that, The electrochemical oxidation time is 20 min ~ 20 h.

6. The method as described in claim 2, characterized in that, After electrochemical oxidation deposition of PbO2-polypyrrole, the composite anode is removed from the solution and dried at a temperature of 25-60℃.