Cyanide Oxidation from Wastewater in a Flow Electrochemical Reactor

In this paper, a flow reactor using the Ti/70TiO2/30RuO2 (w/w) DSA-type electrode was designed for the electrooxidation of cyanide in batch recirculating mode. The device performance was evaluated in terms of the decay of the cyanide concentration as a function of the current density, flow rate, and initial pollutant concentration. The experiments show that cyanide electrooxidation presents pseudo-first-order kinetics with respect to CN- ions. For the operational conditions used in the experiments, the rate constant for cyanide oxidation was in the range from 3 × 10-5 to 2 × 10-4 m s-1, with an optimum value of 1.5 × 10-4 m s-1 for a current density of 10 mA cm-2 and a linear speed of 0.22 m s-1. Using these parameters, 12 kWh is consumed for the oxidation of 1 kg of cyanide.