Effect of Phenolic Hydroxyl Group in 4-hydroxybenzenesulfonic Acid on Tin Electrorefining Process

KeyWord:tin electrorefining; phenolic hydroxyl; deposition kinetics; surface morphology; current efficiency

Abstract:

      4-hydroxybenzenesulfonic acid (HBSA) has a strong odor and is harmful to human body. It is urgent to develop novel green additive to replace HBSA. Effects of HBSA and 4-methylbenzenesulfonic acid (MBSA) on dissolved oxygen concentration, Sn2+ stability, Sn2+ deposition kinetics, cathodic tin morphology and current efficiency during tin electrorefining process were investigated and compared through dissolved oxygen meter, galvanostatic polarization, linear sweep voltammetry and scanning electron microscope. The results show that phenolic hydroxyl groups is reductive, which can reduce the concentration of dissolved oxygen in electrolyte, inhibit the oxidative hydrolysis groups of Sn2+, and further relieve the depletion of Sn2+. This is beneficial to enhance current efficiency of tin electrorefining process. In addition, phenolic hydroxyl groups can regulate Sn2+ deposition path, impede Sn2+ cathode deposition, and further enlarge cathode polarization, which could contribute to a larger flatness and compactness of cathodic tin.