GLUTAMIC ACID AS AN ADDITION AGENT IN THE ELECTRODEPOSITION OF COPPER

Abstract

The polarization–time curves obtained in the presence of glutamic acid generally showed two distinct polarization levels, one corresponding to an induction period following an initial rapid increase of polarization from the standard surface value, and the other corresponding to a steady state period following a second rapid increase of polarization. The polarization at both levels increased with increase of glutamic acid concentration and decreased with increase of sulphuric acid concentration in the electrolyte. In general, the induction period increased, and eventually became irreproducible, with increased sulphuric acid and copper sulphate concentrations, decreased glutamic acid concentration, decreased current density, increased temperature, and addition of chloride. Addition of sufficient chloride prolonged the induction period indefinitely at a polarization level corresponding to the presence of chloride alone. Following the induction period, the concentration polarization increased with glutamic acid concentration and was considerably higher than the value obtained during the induction period. Addition of chloride decreased the concentration polarization.