Removal of Lead from Water by Liquid-Liquid Extraction using trihexyltetradecylphosphonium Chloride in Different Diluents

Abstract

The feasibility of ionic liquid trihexyltetradecylphosphonium chloride [THTDP][Cl] as extractant in different diluents for the removal of lead (Pb) from water was investigated using laboratory scale liquid-liquid extraction. The tests were conducted using an extraction mixture which consisted of 5% (v/v) [THTDP][Cl] in different diluents, namely toluene and corn oil. In general, the extraction followed anion exchange mechanism and equilibrium extraction can be achieved at extraction time of 5-10 minutes. In addition, the extraction efficiency was found to decrease when the HCl concentration in Pb solution was increased from 1 M to 3 M for both types of diluents, as a result of competition between excessive Cl-and PbCl42-to form complex with [THTDP] cation. The extraction ability of Pb for [THTDP][Cl] was highly dependent on the types of diluents used where corn oil based extraction mixture showed lower extraction efficiency in comparison to toluene based extraction mixture, as a result of its higher viscosity.