Highly hydrophobic oil—water separation membrane: reutilization of waste reverse osmosis membrane

The increasing applications of seawater desalination technology have led to the wide usage of polyamide reverse osmosis membranes, resulting in a large number of wasted reverse osmosis membranes. In this work, the base nonwoven layer of the wasted reverse osmosis membrane was successfully modified into the hydrophobic membrane via surface deposition strategy including TiO2 and 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PFOTS), respectively. Various techniques were applied to characterize the obtained membranes, which were then used to separate the oil—water system. The optimally modified membrane displayed good hydrophobicity with a contact angle of 135.2° ± 0.3°, and its oil—water separation performance was as high as 97.8%. After 20 recycle tests, the oil—water separation performance remained more than 96%, which was attributed to the film adhesion of the anchored TiO2 and PFOTS layer on the surface. This work might provide a new avenue for recycling the wasted reverse osmosis membrane used in oily wastewater purification.