Investigation of optimal conditions for zinc electrowinning from aqueous sulfuric acid electrolytes

摘要

Results are reported of an experimental investigation of the effects of aqueous zinc(II) and sulfuric acid concentrations on current efficiencies and deposit morphologies of metallic zinc, aimed at designing a process for zinc recovery from solid industrial wastes by leaching and electrodeposition. Voltammetry and chronopotentiometry of additive-free solutions of zinc(II) sulfate and sulfuric acid were used to determine the zinc(II) reduction kinetics, prior to investigating the deposition in a Hull cell to observe the effects of the current density and the bath composition on current efficiencies and deposit morphologies. For a current density of 45 mA cm(-2), best performance was obtained with zinc(II) concentrations of the same order of magnitude as the H+ concentration; too acidic solutions resulted in lower current yields and pronounced 3-D growth of the deposit.