Reduction of Cr(VI) from the Electroplating Industry Using an Iron-BDD Electrochemical System.

An electrochemical system was carried out for Cr(VI) reduction from a sample of electroplating wastewater using an iron-boron doped diamond and iron-iron systems and varying current intensity (0.1 and 0.2 A). Also the behavior of nitrates, sulfates and chlorides were monitored in the wastewater. Kinetic results showed a total reduction of Cr(VI) in approximately 25 minutes, however, in both systems (iron-boron doped diamond and iron-iron) the Cr(VI) reduction rate was slower than the theoretical Cr(VI) reduction curve obtained by Faraday's Law. Therefore the presence of nitrate, sulfate and chloride ions in wastewater, significantly affects Cr(VI) reduction. The results showed that iron-boron-doped diamond at 0.2 A is an optimal electrochemical system, with 99.9 % efficiency of Cr(VI) reduction, which is attributed to Fe2+ ions generation by anodic electrodisolution and direct reduction of Cr(VI) at BDD surface cathode. Furthermore reduction of nitrate, sulfate and oxidation of chloride ions in the system was registered