Removal of High Concentrations of Arsenite from Aqueous Solutions by the Emulsion Liquid Membrane Technique

Abstract

AbstractAs(III) is a dangerous species that contaminates groundwater resources and therefore water purification from this element is necessary. In this study, the removal of As(III) was investigated by the emulsion liquid membrane (ELM) technique due to the high toxicity levels of this species. The effect of various parameters such as hydrochloric acid and arsenic concentration in the feed solution, emulsion to feed ratio, surfactant concentration and type of carrier was evaluated on the arsenic separation efficiency. The results showed that the best type of carrier in terms of emulsion stability and separation efficiency of arsenic ions was di‐(2‐ethylhexyl) phosphoric acid (D2EHPA), and its optimal concentration was about 5 % (v/v). In addition, paraffin as the organic solvent performed better than the mixture of paraffin and kerosene in the separation of As(III) ions. The optimal conditions were obtained at 8 and 0.1 M HCl concentrations for the feed and the internal phases, respectively. Also, the emulsion to feed ratio of 1 : 4.5, the volume ratio of the internal phase to the membrane phase of 1 : 1 and the surfactant concentration of 5 % (v/v) led to achieving the maximum removal of arsenic ions. This work presents a broad perspective of removing As(III) ions from wastewater by carefully examining the parameters influencing the separation of this hazardous element through the ELM method.