Arsenite adsorption on some materials containing iron. Effect of anionic species [articol]

Abstract

The effects of arsenic pollution are serious and dangerous to human life. Especially long-term ingestion of contaminated water can cause various forms of cancer. Therefore, solving these problems raised by water pollution is done by removing of arsenic, ensuring the necessary conditions for consumption, in terms of concentration of arsenic. The main method for the removal of arsenic from water is the physical-chemical treatment. In the present paper is investigated the effect of the presence of some anionic species (nitrate, phosphate, chloride and carbonate) in arsenic containing water on the adsorption of arsenic (III) on two iron containing materials: a waste material and a synthetic material. The waste material used for arsenic adsorption experiments was a sludge resulting from hot-dip galvanization. The synthetic material was Fe2O3 obtained through annealing of Fe(COO)2· 2H2O at 800°C. For the studies a synthetic solution containing 100 μg As(III)/L has been used. It has been separately studied the influence of each anionic species at two concentrations: 10 mg/L and 100 mg/L, respectively. It has been also studied the influence of all mixed anionic species at two total concentrations: 10 mg/L and 100 mg/L, respectively. The adsorption experiments have been carried out at different contact times (1, 2, 3, 4, 8 and 24 h). The experimental results showed that when the sludge is used as adsorbent material the increase of anionic species concentration has a positive influence on arsenic adsorption. In the case of the synthetic material this influence is negative. When the synthetic solution contained a mixture of all studied anionic species, regardless their concentration, the waste material presented a higher efficiency of arsenic removal process in comparison with the synthetic material.