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

Under oxic condition,As(Ⅲ) is more mobile in natural waters and with less removal efficiency in water treatment process than As(Ⅴ).In order to remove As(Ⅲ) and As(Ⅴ) from drinking water,nanoscale zero-valent iron(NZVI) was synthesized in laboratory.Average BET surface area of the synthesized particles was 49.16 m2/g with diameter range of 20~40 nm.Batch experiments were carried out to study the removal efficiency of inorganic arsenic and reaction kinetics of NZVI.The results showed that both arsenate and arsenite compounds could be removed efficiently by NZVI at pH=7 and under 20℃.The removal rate for As(Ⅲ) and As(Ⅴ) was over 99.5% within 60 min by 0.25 g NZVI for the sample solution with 968.6 /L of As(Ⅲ) and 828.9 μg/L of As(Ⅴ).The reaction followed the first-order kinetic equation and the normalized reaction rate coefficients were 1.3 mL/(m2·min) and 1.64 mL/(m2·min) for As(Ⅲ) and As(Ⅴ) respectively.Based on the experiment results,NZVI has been proved to be a suitable sorbent for removal of arsenic from drinking water due to its high reactivity.