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

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.

Automated summary

In this study, a micro-electrolysis system using iron-cetyltrimethylammonium chloride modified spent bleaching earth carbon was proposed for the removal of bromate from water. The study found that the Fe/SBE@C mass ratio, CTAC concentration, pH, and reaction atmosphere all had an impact on the efficiency of bromate removal. The research also revealed that CTAC modification and electrochemical reduction were the main mechanisms involved in bromate removal.