Abstract
This paper investigates a method to electro reduce toxic hexavelent chromium to trivalent state using rotating disc electrode (RDE) and rotating cylinder electrode (RCE) cell. Electrolysis of acidic hexavalent chromium solution using a rotating lead cathode reduces the hexavalent chromium Cr(6+) to trivalent chromium. The effect of chromium, sulphuric acid concentration, current density, time and speed of cathode rotation on current efficiency has been investigated under galvanostatic and linear sweep voltammetric techniques. The effect of these parameters on cell voltage and energy consumption has been also studied. It was found that the efficiency of the reduction method is directly proportional to the hexavalent chromium and sulphuric acid concentration. Trivalent chromium is successfully obtained from acidic industrial wastewater containing 1.5 g l(-1) Cr(6+). High current efficiency is attained at current density 225 mA cm(-2) for 80 minutes.