Electrocatalytic oxidation of sulphide using a pencil graphite electrode modified with hematoxylin

The present study describes a new approach for the investigation of electrocatalytic oxidation of sulphide using a pencil graphite electrode modified with hematoxylin (PGE/HMT). Adsorption procedure was used for the preparation of the modified electrodes. It was observed that PGE/HMT showed a significant electrocatalytic activity toward sulphide oxidation. Cyclic voltammetric studies showed that the peak potential of sulphide shifted from +480 mV at bare PGE to +220 mV at PGE/HMT. The electrocatalytic currents obtained from amperometric measurements at +200 mV versus Ag/AgCl/KClsat and at pH 8.0 BR buffer solution containing 0.1 M KCl were linearly related to the concentration of sulphide. The calibration graph consisted of a linear segment of 1–200 μM with a detection limit of 0.4 μM (based on 3sb). The proposed method was successfully applied to the determination of sulphide in waste waters and was compared with the spectrophotometric method.