Electrodeposition of manganese metal from sulphate solutions in the presence of sodium octyl sulphate

Abstract

In the present paper the effects of anionic surfactant sodium octyl sulphate (SOS) on the electrodeposition of manganese from sulphate solutions were studied. It was observed that addition of SOS increases the current efficiency and hence decreases the energy consumption during electrodeposition of manganese. High quality manganese deposits with smooth and compact surfaces were deposited on 316 grade stainless steel substrate in the presence of SOS. The concentration of this anionic surfactant was varied over a relatively broad range to assess its effect on current efficiency, energy consumption, crystallographic orientations and deposit morphology of the electrodeposited manganese metal. The addition of SOS increased the cathodic efficiency of manganese metal from 59% to 67% when 20 mg.L-1 SOS was introduced into the electrolytic bath. X-ray diffraction studies revealed that (330,411) planes are the most preferred planes of crystal growth during manganese electrodeposition at a current density of 500 A . na(-2) resembling alpha-manganese irrespective of the concentration of additive. Scanning electron micrographs showed smooth, bright and uniform deposit morphologies when manganese was electrodeposited in the presence of 20 mg . L-1 SOS. Linear sweep voltammetry showed polarisation of the cathode indicating additive adsorption on it. (C) 2015 Elsevier B.V. All rights reserved.