Energy-saving removal of methyl orange in high salinity wastewater by electrochemical oxidation via a novel Ti/SnO2-Sb anode—Air diffusion cathode system

• TSSA-ADC system was built for high salinity organic wastewater treatment.
• Active chlorine and H2O2 contributed to MO removal in the TSSA-ADC system.
• High efficiency and energy saving were found from the TSSA-ADC system.
• TSSA-ADC system could prevent scaling when treating wastewater with hardness ions.
• TSSA-ADC system possesses great potentials for organics removal with chlorine ion.

Electrochemical oxidation is an effective method in removal of organic pollutant from high salinity wastewater (NaCl), by producing active chlorine at anode or hydrogen peroxide at cathode. To solve the existing problems including low efficiency, high cost and energy consumption, a Ti/SnO2-Sb anode (TSSA)-air diffusion cathode (TSSA-ADC) system was investigated for methyl orange (MO) removal from NaCl solution, using single TSSA system as control. The phase composition of TSSA was examined by X-ray diffraction. Accumulated concentrations of active chlorine, hydrogen peroxide, MO removal rate, TOC, pH value were recorded at different current densities. The results indicated that Sb-doped rutile SnO2 was formed on the TSSA. The TSSA and the ADC exhibited good catalysis to chlorine evolution and oxygen reduction, respectively. Although MO were almost completely removed in both systems, higher TOC removal, shorter running time and lower energy consumption were attained in the TSSA-ADC system. pH value was more stable (6.0–6.4) in the TSSA-ADC system than that in the TSSA system (6.0–9.4), predicting its stronger capacity in anti-scaling when treating high salinity wastewater with hard ions like Ca2+ and Mg2+.

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