Electrochemical oxidation of sodium sulfide on rotating ring-disc electrode
(Department of Mineral Engineering, Central South University of Technology, Chang.sha 410083,P.R.China)
Abstract: A rotating ring (Pt) disc (Pt) electrode was employed to investigate the oxidation process of sodium sulfide (Na2S). It was reported that the oxidation intermediates and product of HS- were formed on the disc electrode and then reduced on the ring electrode. The results indicate that at a rotation rate of 20 Hz, when the disc electrode potential was -0.15 V (vs SHE) and higher, more extensive oxidation process took place via a series of electrochemical steps to produce sulfur (S). The products of oxidation intermediates (S2-x , S2-2) and sulfur (S) reduced either on the ring electrode with a set potential of -0.8 V (vs SHE), or on disc electrode with negative going potential sweep at about -0.5～ 0.55 V (vs SHE). The experimental results of voltammogram of ring disc electrode at sodium sulfide solution demonstrated that the first step was the oxidation of HS- and produce S2-x , and then the S2-x adsorbed integrated itself and formed sulfur (S).
Key words: rotating ring-disc electrode； electrochemical reaction； sodium sulfide