Sustainable recovery of viscous oil from emulsions through nanofibrous hollow membrane extraction

Concurrent oil and water recovery from emulsions present a great challenge to membrane-based separation techniques. In this study, we invent a novel nanofibrous hollow membrane extraction technology to recover oil and water from oily emulsions for the first time. The nanofibrous poly(vinylidene fluoride) (PVDF) hollow fiber contactor was capable of continuously extracting oil assisted by hexane. A massive cumulative oil flux (up to 2.3 × 10 4  g/m 2 ) was obtained in the continuous extraction of 200 h. High value and viscous lubricant oil were recovered with a purity of 99.90 ± 0.03 %, and total organic carbon of the feed solution was reduced by more than 70 %. Density functional theory (DFT) calculations were carried out to evaluate binding energies between oil molecules, PVDF materials and extractants, indicating the emulsification, convalesce and transfer process. The proposed hollow membrane extraction strategy offers a promising way to achieve viscous oil recovery and water purification simultaneously.