High-efficient treatment of wastewater contained the carcinogen naphthylamine by electrochemical oxidation with γ-Al2O3 supported MnO2 and Sb-doped SnO2 catalyst

Abstract

1-Naphthylamine wastewater causes severe environmental pollution because of its acute toxicity and carcinogenicity in humans, which makes it difficult to reuse by conventional technologies. In this study, we report an investigation of the electrochemical catalytic oxidation of 1-naphthylamine in synthetic wastewater in a 150mL electrolytic batch reactor with Ti/Sb–SnO2/PbO2 as anode and steel plate as cathode, where the reaction was assisted by MnO2 and Sn1−xSbxO2 composite materials as the catalyst and γ-Al2O3 as the carrier (MnO2–Sn1−xSbxO2/γ-Al2O3). The catalyst was synthesized by impregnating process and was characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The effects of pH and current density on the efficiency of the electrochemical degradation process were also studied. It was found that MnO2–Sn1−xSbxO2/γ-Al2O3 exhibited excellent catalytic activity in the electrochemical degradation of 1-naphthylamine wastewater. The results showed that the refractory organics in wastewater can be effectively removed by this process, and a chemical oxygen demand (COD) removal efficiency of 92.2% was obtained in 20min at pH 7.0 and current density was equal to 50mAcm−2. According to the experimental results, a hypothetical mechanism of electrochemical catalytic degradation was also proposed.