Cyanide-free copper electroplating using glycerol: modeling and simulation

Abstract

The electroplating of copper on Cu-Zn alloy substrates (brass) is normally carried out using alkaline cyanide baths. However, cyanide copper baths are toxic, requiring care with regard to the environment and the health of the worker. This work studies the modeling and optimization of the electrodeposition of copper on a brass substrate using an electrolytic bath containing cyanide-free glycerol. A central composite experimental design was carried out to evaluate the effects of the factors glycerol concentration, time and amperage on the process, with the cathodic current efficiency as the response. The tests were carried out in a Hull cell, a miniature unit of an industrial electrodeposition system. The results showed that the estimated model is predictive (R² equal to 0.9279), with the effects of the linear and quadratic terms of amperage, linear of glycerol concentration and the effects of interactions between glycerol concentration and time being significant. The best test resulted in a cathode current efficiency of 57% and an energy consumption of 234.40 kWh/kg, which represented the highest copper deposition and the lowest energy consumption. The deposits generated had a reddish orange color, characteristic of metallic copper, uniformity of the layer, levelness and brightness.