Today, biphasic aqueous systems have received more attention than conventional separation methods due to their advantages, such as biocompatibility, low cost, and easy operation. The extraction of cobalt ions from the aqueous phase with the absence and the presence of other ions was investigated using polyethylene glycol, and ammonium sulfate salt without using an extractant. The efficiency was evaluated using operating parameters such as aqueous pH, salt and polymer concentrations, phase volume ratio, and initial metal concentration. The higher temperature, and the lower aqueous pH showed a maximum transfer rate for cobalt ions into the PEG1000 phase. Extraction efficiency under optimal conditions equal to 50% (w/w) polyethylene glycol 1000, 4 M ammonium sulfate, aqueous pH = 2, and 15 min extraction time was over 98%. Results from infrared spectroscopy, and thermo-gravimetric analysis illustrated the presence of the PEG-cobalt ion complex. The observation demonstrated that the biphasic system is the proper technology for wastewater purification.
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