Simultaneous Oxidation and Sequestration of Arsenic(III) from Aqueous Solution by Copper Aluminate with Peroxymonosulfate: A Fast and Efficient Heterogeneous Process

The major problem in arsenic (As­(III)) removal using adsorbents is that the method is time-consuming and inefficient owing to the fact that most of the adsorbents are more effective for As­(V). Herein, we report a new discovery regarding the significant simultaneous oxidation and sequestration of As­(III) by a heterogeneous catalytic process of copper aluminate (CuAl2O4) coupled with peroxymonosulfate (PMS). Oxidation and adsorption promote each other. With the help of the active radicals, the As­(III) removal efficiency can be increased from 59.4 to 99.2% in the presence of low concentrations of PMS (50 μM) and CuAl2O4 (300 mg/L) in solution. CuAl2O4/PMS can work effectively in a wide pH range (3.0–9.0). Other substances, such as nitrate, sulfate, chloride, carbonate, and humic acid, exert an insignificant effect on As­(III) removal. Based on X-ray photoelectron spectroscopy (XPS) analysis, the exposed reductive copper active sites might drive the redox reaction of Cu­(II)/Cu­(I), which plays a key role in the decomposition of PMS and the oxidation of As­(III). The exhausted CuAl2O4 could be refreshed for cycling runs with insignificant capacity loss by the combined regeneration strategy because of the stable spinel structure. According to all results, the CuAl2O4/PMS with favorable oxidation ability and stability could be employed as a promising candidate in real As­(III)-contaminated groundwater treatment.