Electrochemical Analysis of the Concentration of Cupric Chloride Complex in CuCl₂-NaCl Solution at Room Temperature

The electrochemical reaction mechanism of CuCl₂-NaCl weak acid solution was studied by the Tafel method and linear potential sweep voltammetry at room temperature. The exchange current densities at different concentration ratios of CuCl₂-NaCl solution were obtained from their polarization curves and the coordination number of the electrochemical reduction complex was calculated from electrochemical reaction order method. The electrochemical reduction on Pt electrode was further studied by linear potential sweep voltammetry. Finally, the concentration of the electrochemical reduction complex ion was calculated when the procedure was reversed. The results were shown that CuCl⁺ is the main cupric chloride complex in solution and the one for electrochemical reduction on Pt electrode. Two one-electron reduction steps of the copper chloride complex were observed on the surface of the Pt electrode. The first step was a one-electron-transfer reversible reduction process. The electrochemical reaction orders of CuCl⁺ and Cu in the system were both level one. In 4.000 mol/L NaCl+0.100 mol/L CuCl₂ solution, the concentration of the electrochemical reduction reactant (CuCl⁺) was 0.086 mol/L. The results provided important experimental evidences for electrochemical reduction mechanism of Cu²⁺ in aqueous solutions with highly concentrated chloride ions. This work can also be used as a reference for electrochemical analysis of dissolved metal complex in the fields of metallurgy, geology, geochemistry in the future.