COD removal from real dyeing wastewater by electro-Fenton technology using an activated carbon fiber cathode

This study investigated the efficiency of COD removal from real dyeing wastewater by using Fe2+ in combination with electrogenerated hydrogen peroxide at the PAN (polyacrylonitrile) based activated carbon fiber cloth cathode. A systematic study of COD removal percentage was carried out at different oxygen sparging rates, applied current densities, Fe2+ concentrations, solution pHs and temperatures. The electro-Fenton technology can successfully remove COD from the complex real dyeing wastewater. Over 70% of COD can be removed after 240 min of treatment. The COD removal efficiency increased significantly with the oxygen sparging rates up to 150 cm3/min. The highest COD removal efficiency, 75.2%, was achieved at an applied current density of 3.2 mA/cm2; COD removal efficiency deteriorated at higher current densities because the rates of side reactions increased. The results showed that the optimal solution pH was 3. Increasing the solution pH rapidly decreased COD removal efficiency. Conversely, COD removal efficiency increased with increasing Fe2+ concentrations up to 2 mM. Temperature had a slightly negative effect on COD removal efficiency.