Complete arsenite removal from groundwater by UV activated potassium persulfate and iron oxide impregnated granular activated carbon

Removal of toxic arsenite [As(III)] from the contaminated surface and groundwater is essential for human health. However, direct arsenite removal is difficult compared to arsenate [As(V)]. Therefore, the peroxidation of arsenite to arsenate is vital for its effective removal from water. Herein, we investigated the removal efficiency of arsenic from groundwater by oxidizing it with UV activated potassium persulfate (KPS) and subsequently adsorbing it on iron oxide impregnated granular activated carbon (FeO/GAC). A batch experiment was carried out to determine the adsorption kinetics and thermodynamics. Further, the effects of the adsorbent mass (FeO/GAC), C/Fe molar ratio, pH, arsenic concentration, competing anions, and humic acid in arsenic adsorption was studied. The characterization of FeO/GAC adsorbent was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), and zeta potential measurements. Using the UV activated KPS and FeO/GAC, a ∼100% removal amount was achieved for 10 ppm of the arsenic solution in 1 h. Also, the effect of pH showed the highest removal efficiency in the pH range of 6.0-7.0 and it decreased dramatically at higher and lower pH values. The groundwater collected from Cheongyang in South Korea was spiked with 10 ppm of the arsenic (III) and more than 82% removal of arsenic was achieved in 90 min even in the presence of natural contaminants. Therefore, the results suggest that the UV activated KPS with FeO/GAC provides an effective method for treating highly-arsenic-contaminated water sources and this may be a viable alternative method over the existing methods.