Combination of carbon black-ZnO/UV process with an electrochemical process equipped with a carbon black-PTFE-coated gas-diffusion cathode for removal of a textile dye

The aim of this work was to enhance the efficiency of a photocatalytic process involving carbon black (CB)-modified ZnO nanoparticles using an electrochemical process consisting of powdered activated carbon (PAC), carbon nanotubes (CNTs), and CB-polytetrafluoroethylene (PTFE)-coated gas-diffusion cathode (GDC) to degrade Acid Red 18. Hydrogen peroxide generated by PAC-PTFE-, CNT-PTFE-, and CB-PTFE-coated GDC was 58.45, 100.9, and 112.3 μM, respectively. The efficiency of the combined process equipped with CB-PTFE-coated GDC was assessed as the function of different operational parameters. With the increase of initial pH from 3 to 10, decolorization efficiency decreased from 94.5% to 57.61%. Increasing the dye concentration from 2 to 20 mg/L led to a decrease in the decolorization efficiency from 100% to 50.45%. The increase of the current intensity from 30 to 300 mA resulted in increasing decolorization efficiency from 37.45% to 95.31%. TOC analysis showed 51.13% mineralization of 10 mg/L dye solution in 20 min.