Rotating cylinder electrode study of the effect of activated polyacrylamide on surface roughness of electrodeposited copper

The development of a new organic additive based on polyacrylamide is reported for copper electrowinning (EW) and electrorefining (ER) in which a rotating cylinder electrode (RCE) is applied as a novel method of determining surface roughness. The effect of hydrodynamics of the electrolyte (Cu2+ = 36 g/L; H2SO4 = 160 g/L and Cl− = 25 mg/L) on the surface roughness of the copper deposit was first validated against the literature. The effect of the preparation of polyacrylamide (PAM) on the surface roughness was then assessed. PAM (MW 15 million Dalton) was dissolved at 50 °C in full-strength and systematically half-strength standard electrolyte and in water and alkaline solutions and dosed to the electrolyte prior to copper electrowinning for 6 h using the RCE at 50 °C. The lowest surface roughness (6.59 μm ± 0.49) was obtained when PAM was prepared in 16-fold diluted electrolyte giving a block copolymer hydrolysis product named ‘activated polyacrylamide’ (APAM) in this work.