Highly Safe and Selective Liquid-liquid Micro-Extraction of Cobalt (II) Ions from aqueous samples with N, N’-disalicylidene-3, 4-diaminotoluene (H2dst) Dissolved in synthesized Supra Molecular Solvent

The separation of heavy metals from aqueous regions such as industrial and environmental waste waters has important aspects in the environmental and economic topics. The most applicable methods for the metal ions extraction from industrial waste waters are the liquid-liquid extraction and micro-extraction by organic solvents. In comparison of water-immiscible supra molecular solvents (SUPRAs) with other ordinary organic solvents used in the LL- extraction processes, SUPRAs possess some advantages such as: friendly environment, non-flammability, tunable polarity in dissolving the solutes with different polarities and high extraction capability of analysts in small volume of SUPRA. In this paper, the possibility of selective extraction of Cobalt (II) ions with SUPRAs composed of vesicles of decanis acid was studied. For this purpose, the extraction processes of Cobalt (II) ions from its aqueous solution alone and also its aq-solution mixture with other ions into SUPRA were investigated. The metal ions concentrations were determined by the flame atomic absorption spectroscopy. In order to achieve the selective extraction of Cobalt (II) ions into SUPRA, the presence of some Co2+ selective ligands such as: Bis (2-ethylhexyl) phosphate (D2EHPA), α-Nitroso-β-naphthol, N, N’-disalicylidene-3, 4-diaminotoluene (H2dst) dissolved in SUPRA were investigated. The results showed that H2dst was the best and chose as the selective ligand dissolved in SUPRA for the Co2+ extraction. In comparing of Co2+ extraction into SUPRA alone with its extraction into the solution of ligand (H2dst) in SUPRA, the results showed that the later was made significant increasing in Co2+ extraction percentage (about 50%). So, the experimental conditions for the selective separation of Cobalt (II) ions into the liquid phase composed of ligand H2dst dissolved in SUPRA were optimized. Under optimal conditions, 25ml of 1.5ppm Co2+ at pH 5, 10-2 M of H2dst dissolved in 710 μl SUPRA as a selective liquid phase for Cobalt (II) ions extraction and 10min extraction time at 25°C, quantitative extraction of Co2+ ions was observed about 99.21% ± 0.064 (n=10). To evaluate the selectivity of Cobalt (II) ions extraction, the separation processes were carried out from aqueous solutions containing Co+2 ions and other cations such as: Na+, K+, Fe+3, Mg+2, Sb+3, Cu+2, Ni+2 and Pb+2. The results showed that the efficiency of Cobalt (II) ions extraction towards Na+, K+, Fe+3, Mg+2, Sb+3 and Pb+2 ions were more significant than its extraction efficiency towards Cu+2 and Ni+2 ions. Also the matrix effect on Co+2 extraction efficiency into the liquid phase composed of H2dst dissolved in SUPRA was investigated. So, 1.5ppm of Cobalt (II) cation solution was spiked into Lead and Zinc flotation plant waste water. The results showed that the extraction efficiency of Co+2 ions from the matrix was highly selective and quantitative, about 96.64±0.051 (n=10).