Efficient degradation of p-arsanilic acid with arsenic adsorption by magnetic CuO-Fe3O4 nanoparticles under visible light irradiation

A bifunctional CuO-Fe3O4 material was synthesized and employed for the photocatalytic degradation of p-arsanilic acid (p-ASA) under visible light irradiation and simultaneous removal of the released inorganic arsenic by adsorption from solution. The effects of major factors, including solution pH, bicarbonate ion, halide ion and humic acid, on the p-ASA degradation were investigated. Under various water quality conditions, an excellent removal of p-ASA could always be achieved by the CuO-Fe3O4 photocatalytic process and p-ASA could be completely converted to As(V) within 36 min. Simultaneously, the released As(V) could be adsorbed onto the surface of CuO-Fe3O4 nanoparticles with high efficiency above 95% at initial pH range from 4 to 7. The presence of humic acid significantly weakened the degradation of p-ASA by scavenging .OH, and slightly inhibited the As (V) removal. On the basis of the UV-vis,FTIR, XPS analysis and the major degradation products detected, the mechanism of the p-ASA photocatalytic degradation and the released As(V) adsorption by CuO-Fe3O4 nanoparticles was given, and the degradation pathway of p-ASA during the photocatalytic process was also taken into consideration. Combined with the photocatalytic property and the high adsorption capacity of As(V), the synthesized magnetic CuO-Fe3O4 nanoparticles have significant potential applications for controlling the risk of pASA in wastewater.