Construction of the micro-electrolysis system by Fe0 and clay-carbon derived from oil refining for the removal of ozone disinfection by-products

Abstract

In this work, the construction of iron-cetyltrimethylammonium chloride modified spent bleaching earth carbon (Fe/CTAC-SBE@C) micro-electrolysis system was first proposed for bromate removal in water. The effects of system parameters including Fe to CTAC-SBE@C mass ratio, CTAC concentration, total dosage, temperature, initial pH and reaction atmosphere were studied. Bromate removal efficiency increased with the decrease of Fe/SBE@C mass ratio from 4/1–3/1, and the further decrease of the mass ratio (from 3/1–1/4) led to the decrease of bromate removal efficiency. CTAC modification could provide the active electron transport paths (SBE@C-CTAC+-BrO3-) theoretically for bromate improved removal, and the optimal CTAC concentration was 25 mmol/L. It was found that pH was a key factor of micro-electrolysis reaction, and bromate removal decreased with the increase of pH, while the removal under neutral (pH=7) and basic (pH=9) conditions still could reach more than 75%. Surprisingly, the coexisting of Cl-, SO42- and NO3- as the electrolytes could penetrate the passivated films on the surface of iron and promote bromate removal; air atmosphere was more favorable to bromate removal than nitrogen atmosphere. In addition, based on product determination and characterization data, the removal mechanism of bromate mainly included CTAC-SBE@C adsorption and electrochemical reduction.