Fast and efficient removal of As(III) from water by CuFe2O4 with peroxymonosulfate: Effects of oxidation and adsorption

Although oxidation of As(III) to As(V) is deemed necessary to promote arsenic removal, the oxidation process usually involves toxic byproducts, well-defined conditions, energy input or sludge generation. Moreover, extra operations are required to remove the resulting As(V). A heterogeneous catalytic process of CuFe 2 O 4 with peroxymonosulfate (PMS) is established for As(III) oxidation and adsorption. The PMS can be activated by CuFe 2 O 4 to generate radical species for As(III) oxidation. The CuFe 2 O 4 /PMS has a stronger affinity for arsenic than CuFe 2 O 4 alone. Oxidation and adsorption promote each other. As a result, the heterogeneous catalytic process is more efficient for As(III) removal than a preoxidation of As(III) followed by adsorption. The adsorption capacity for As on CuFe 2 O 4 /PMS reached up to 63.9 mg/g, which is much higher than that of As(III) (36.9 mg/g) or As(V) (45.4 mg/g) on CuFe 2 O 4 alone. The process can work effectively over a wide range of pH values (3–9) and temperatures (10–40 °C). Coexisting ions such as sulfate, carbonate, silicate and humic acid have an insignificant effect on As(III) removal. The As(III) (1415 μg/L) can be completely oxidized to As(V) and rapidly removed to below 10 μg/L (less than 15 min) using CuFe 2 O 4 (0.2 g/L)/PMS(100 μM). Moreover, the As(III) (50 μg/L) can be completely oxidized and removed within 1 min. The proposed process is easily applicable for the remediation of As(III)-contaminated water under ambient conditions.