Influence of malonic acid and triethyl-benzylammonium chloride on Zn electrowinning in zinc electrolyte

The influence of malonic acid and other additives has been investigated during the electrowinning of zinc from acid sulphate solutions containing manganese ions. It was found that adding malonic acid “MA” increased the current efficiency and decreased the anodic and cathodic potentials and the cell voltage in the standard electrolyte. Adding malonic acid to the industrial electrolyte containing antimony impurity also led to an increase in the current efficiency. Triethyl-benzylammonium chloride “TEBACl” was the best additive to improve current efficiency with the presence of 5 mg/L Ni2+ impurity and it also counteracted the deleterious effect of Sb3+ better than the other additives such as polyethylene glycol, sodium lauryl sulphate, perfluoro-heptanoic acid and malonic acid—these were not as good as glue and chloride ion together. Adding 2 mg/L of “TEBACl” to sulphuric acid solution with the presence of nickel ions increased the cathodic potential of hydrogen evolution on the zinc deposit, much more than that of 100 mg/L “MA”.