Efficient adsorption of arsenic in groundwater by hydrated iron oxide and ferromanganese oxide chitosan gel beads

Abstract

To address the arsenic contamination in groundwater, the hydrated iron oxide gel beads (CS-HFO) and iron manganese oxide gel beads (CS-FMO) adsorbents were prepared. The CS-HFO and CS-FMO adsorbents had porous and adsorption-friendly pore structures inside, with the average pore sizes of 3.45 nm and 7.78 nm, respectively. As compared to the CS-HFO adsorbent, the CS-FMO adsorbent had rich adsorption sites and oxidation capacity and displayed better adsorption performance. According to the Langmuir model, the saturation adsorption of As(V) and As(III) for CS-FMO adsorbent was calculated as 26.65 mg/g and 35.96 mg/g, respectively. After 10 cycles of regeneration, the CS-HFO and CS-FMO adsorbents demonstrated excellent sustainable arsenic removal ability, while the adsorption efficiencies of CS-FMO adsorbent for As(V) and As(III) were maintained over 60 % and 95 %, respectively. In addition, the competing pollutants and fixed-bed column experiments confirmed the high selectivity of the CS-HFO and CS-FMO adsorbents, which showed great promise for the future application of arsenic contamination removal from the actual groundwater environment.