Rates of cylindrical and spherical copper anodes dissolving into concentrated NaCl water solution calculation during electrolysis and temperature increasing

Abstract

Our experimental investigations show that rate of copper anodes degradation decreases during electrolysis in concentrated NaCl solution in water (5 mol/kg or 23 %, freezing point equals −22°C, pH 6.5–7.5) at electric current density about 3000 A/m2 (or 30 A/dm2 = 3 mA/mm2) with temperature increasing from room temperature to 100 °C. Electric current value also increases with temperature increasing. Really, such result is unexpected. General quantity of the H+ and Cl− ions decreases during electrolysis at all temperatures since the H2 and Cl2 gases are formed near electrodes. General quantity of the Cu+ and Cu2+ ions decreases with temperature increasing too. We guess that one reason only should be for electric current value increasing: average charge of copper ions increases from +1 at room temperature to +1.5 at 100 °C and to +2 at 180°C. Corresponding mathematical model is proposed for the analysis. Literature experimental data are used too.

Keywords

• Electrocoagulation
• Electrolysis
• Faraday's law
• Electrochemical corrosion
• Copper
• Mathematical modelling