Effect of organic impurities on the morphology and crystallographic texture of zinc electrodeposits

Abstract

This work describes the effect of some organic impurities on the quality of zinc deposits and on the efficiency of the electrowinning process. The presence of some organics (i.e., flotation collectors, flocculant and lubricating oil) in the sulfate electrolyte was shown to significantly decrease current efficiency, thereby increasing energy consumption. Microscopic and texture analyses revealed that the individual addition of these organics to the electrolyte leads to the formation of pores on the deposits, variations in their grain size, and orientation changes resulting in crystallographic randomization with a trend to reorient the crystals from a “perpendicular to the plane” to an “in plane” random distribution. The Zn electrodeposit's features are expected to affect mechanical properties and, in turn, the effectiveness of the stripping operation.