preparation of polymer inclusion membrane based on natural hydrophobic deep eutectic solvent for extraction of co(ii)

In recent years, environmental-friendly extraction methods have been introduced as the alternative to conventional extraction procedures. in this particular field, a novel class of solvents known as deep eutectic solvents (des) has arisen as a new and very promising tool. compared with conventional organic solvents, natural deep eutectic solvents have attracted considerable attention due to the fact that they not only are eco-friendly, non-toxic, and biodegradable organic compounds but also have a low cost, being easy to produce in the own laboratory [1,2]. in this research, a natural deep eutectic solvent (ndes) has been synthesized by mixing thymol and menthol, and then used as carrier to prepare a homogenous and flexible polyvinylchloride (pvc)-based polymer inclusion membrane (pim) for the recovery of co(ii) in aqueous system. a series of characterizations and conditions optimization experiments have been performed on the prepared pims. it was found that pim composed of 60 wt% pvc and 40 wt% ndes had excellent selectivity and could achieve the quantitative extraction of co(ii) from aqueous solution. under the optimal conditions, 98.1% of cobalt was extracted by the optimized pim. besides, the elaborated pim had high reusability and stability, which still had an extraction efficiency of 92.4% after four consecutive extraction experiments. these results all confirm the advantages of the newly developed pim in the extraction and recovery of cobalt, and it will be expected to realize a wide range of economic and practical value.