Applicability of Supported Liquid Membranes for Extraction of Zn2+ and Ni2+ in Water Using Cyclohexylamine as a Carrier

Abstract

Zn2+ and Ni2+ are frequently reported in wastewater effluents with concentrations much greater than the permitted limits and thus pose a huge threat to living beings. Therefore, researchers are gaining much focus on removing these metals from water bodies. This study performed two sets of experiments to study the comparative extraction efficiencies of Zn2+ and Ni2+ from water samples using a supported liquid membrane (SLM), carrier, and solvent. For this purpose, the chloride salts of both Zn2+ and Ni2+ were used to study the movement of both ions from the acidic feed phase to the basic strip phase through SLM equilibrated with cyclohexylamine, which acts as a carrier for the transportation of Zn2+ and Ni2+. The conditions were optimized while studying four different parameters to maximize the transport of ions from the feed to the stripping phase. However, the acid concentration was kept constant at 1 M for all the experiments. Separate experiments were carried out to study the movement of Zn2+ and Ni2+ ions. The distribution coefficient, permeability coefficient, flux, and extraction efficiencies of both ions were calculated against different parameters. A comparative analysis found that Zn2+ ions have a greater tendency to move to the strip phase than the Ni2+ ions under a similar set of parameters. Extraction time reveals that approximately 87% of the Zn2+ ions moved to the stripping phase from the feed phase at the end of the 120th min of the experiment. In contrast, only 72% of the Ni2+ ions could move to the stripping phase under similar conditions. Current studies indicate that the extraction methodologies based on SLM can effectively remove Zn2+ and Ni2+ from water samples.