Removal of As(III) and As(V) from Drinking Water by Nanoscale Zero-valent Iron

Nanoscale zero-valent iron (NZVI) was synthesized in the laboratory for the removal of As(III) (arsenite) and As(V) (arsenate). Average BET surface areas of the particles was 49.16 m²/g, with diameter in the range of 20-40 nm. Batch and column experiments were conducted to investigate adsorption kinetics and efficiency of arsenic removal with NZVI. The results showed that both arsenate and arsenite could be removed efficiently by NZVI at pH 7, 22 ± 1°C. The removal rate for As(III) and As(V) was over 99.5% within 60 min using 0.25 g NZVI. The arsenic adsorption process followed the pseudo-first-order kinetic expression. The surface-area-normalized rate coefficient kSA was 3.42mL/m²·min for As(III). Based on the result, NZVI is a suitable sorbent to treat the drinking water containing arsenic due to its high reactivity.