Efficient recovery of Au(III) through PVDF-based polymer inclusion membranes containing hydrophobic deep eutectic solvent

Abstract A novel extractant, hydrophobic deep eutectic solvent (DES) has been synthesized by mixing tetraoctylphosphonium bromide (P8888Br) and di-(2-ethylhexyl) phosphoric acid (P204), and then used as carrier to prepare a homogenous and flexible polyvinylidene fluoride (PVDF)-based polymer inclusion membrane (PIM) for the recovery of Au(III) in hydrochloric acid system. A series of characterizations and conditions optimization experiments have been performed on the elaborated PIMs. It was found that PIM composed of 70 wt% PVDF, 5 wt% NPOE and 25 wt% DES had excellent selectivity and could achieve the quantitative extraction of Au(III) from mixed metals solution. Under the optimal conditions, 99.1% of gold in the feed phase was selectively transported to the receiving phase by the optimized PIM with a high permeability coefficient of 3.52 × 10−5 m s−1, realizing the enrichment and recovery of gold. Besides, the elaborated PIM had high reusability and stability, which still had an extraction efficiency of 92.4% after five consecutive transport experiments. These results all confirm the advantages of the newly developed PIM in the extraction and recovery of gold, and it will be expected to realize a wide range of economic and practical value.