Understanding the process in the removal of dimethylarsenic by a zirconium-based nanoparticle

Abstract

Organic arsenic contamination in groundwater and surface water is one of threats to human beings. In this study, a novel zirconium-based nanoparticle was developed to remove dimethylarenic acid (DMA) from aqueous solution. The adsorption behavior was evaluated by various batch adsorption experiments. The pH effect study revealed that the maximum adsorption was achieved around pH 3.0. The ionic strength did not have significant effect on the uptake of DMA. The adsorption kinetics study showed that the adsorption equilibrium was established within 24 h; an intraparticle kinetics model fit the experimental data well. In the adsorption isotherm study, the Langmuir equation described the adsorption data better than the Freundlich equation; the maximum adsorption capacity of the sorbent was calculated to be 58.82 mg-As/g at the optimal pH. In the natural organic matters and coexisting anions effect studies, the presence of humic acid and coexisting anions have little effect on the uptake of DMA. The performance of the Zr-based NP was not largely inhibited in the presence of NOMs and coexisting anion. The FTIR and XPS spectroscopic analyses demonstrated that DMA was successfully adsorbed onto the sorbent and the adsorption mechanism was proposed to be ions exchange between arsenic and sulfate ions.