[Removal of arsenite from drinking water by activated carbon supported nano zero-valent iron]

Nano zero-valent iron was loaded onto activated carbon by deoxidizing Fe2+ in aqueous solution and approximately 8.2% (wt) of iron was loaded it. The size of the needle-shaped iron particles in the pores of carbon was (30-500) x (1 000-3 000) nm. The adsorption capacity for arsenic was approximately 1.997 mg/g activated carbon supported nano zero-valent iron (NZVI/AC) in the 2 mg/L As(III) solution at pH 6.5 and (25 +/- 2) degrees C. The uptake of arsenic by NZVI/AC was rapid in the first 12 h (94.3%) and equilibrium was achieved at 72 h (99.86%). As(III) was partly oxidized by the absorbent in the process of absorption. The presence of phosphate and silicate ions significantly decreased arsenic removal rate while the effect of other common ions such as sulfate, carbonate and oxalate was insignificant. NZVI/AC was effectively regenerated after adsorption of arsenic when elution was applied with 0.1 mol/L NaOH solution. The results suggest that NZVI/AC is an ideal candidate for the treatment of arsenic contaminated drinking water.