The treatment of trace As(III) from water by modified spent grains

Trace arsenic influences the safety of drinking water. Using spent grains modified by polyacrylamide (PAM) to adsorb arsenite [As(III)] has broken through the technical bottleneck of the traditional technology that purified water can only be treated using the method of oxidating As(III) to arsenate [As(V)]. When the concentration of the modifier PAM is 1%, adsorbent dosage is 3g/L, solution pH=6, contact time is 2h, the water with As(III) content is 0.1mg/L can be reduced to 0.01mg/L, which meet the limit in "Standard for Drinking Water Quality" (GB5749-2006). The adsorption kinetic of the As(III) upon spent grains modified by PAM (PSGs) has been studied and the adsorptional process was fitted to the pseudo-second-order equation. The activity of amide groups at the surface of PSGs has been strengthened through the Fourier transform infrared spectroscopy analysis. The effect of desorption by alkaline solution was better than that of acid solution. Based on the results of leaching toxicity experiment, spent PSGs can be directly landfilled.