Decontamination of Arsenite Polluted Water by a Zirconium Oxide Based Sorbent

Pollution of Arsenite As(III) in the water is an issue of serious concern because of its seriously negative impacts on human health. In this study, the adsorption behaviors and mechanism of arsenite onto a zirconium oxide based sorbent are investigated. To explore the adsorption behaviors of arsenite onto the sorbent, the effect of pH, natural organic matters and coexisting ions on the adsorption of arsenite, the adsorption kinetics, as well as the adsorption isotherm were investigated. The pH effect studies showed that the sorbent exhibited high As(III) adsorption capacity at a wide pH range, and the optimal pH value for As(III) removal is between 9 to 10. The kinetics study illustrated that most of the uptake of As(III) onto the sorbent took place in the first 20 hours, and the adsorption equilibrium could be obtained within 48 hours. The adsorption isotherm study demonstrated that the sorbent was efficient for As(III) removal from aqueous solution, and the maximum adsorption capacity for As(III) was around 1.8 mmol/g at optimal pH. The adsorption isotherm was found to be well described by Langmuir model. The existence of humic acid, silicate, sulfate, phosphate or fluoride does not obviously effect the adsorption of As(III) onto the sorbent. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses together with the adsorption studies indicated that ion exchange played an important role in the adsorption process, and the hydroxyl functional group was involved.