Surface treatment of polyethersulfone membranes for applying in desalination by direct contact membrane distillation

In the present work, the surface of polyethersulfone (PES) membrane is treated by using tetraethylorthosilicate (TEOS) and trimethylchlorosilane (TMSCl) as grafting agents. Attenuated total reflection infrared spectroscopy (ATR-IR), scanning electron microscopy (SEM) coupled to an energy-dispersive X-ray spectrometer (EDX), atomic force microscopy (AFM), and optical contact angle measurement (OCA) are applied to identify and characterize the membranes. The water contact angle of as high as 150° is obtained for the treated membranes. The modified membranes are examined for desalination using a direct contact membrane distillation setup. Effects of different conditions in membrane preparation as well as operating parameters are investigated. A separation factor of 99.7% and comparable permeate fluxes to those of a commercial polytetrafluoroethylene (PTFE) membrane are obtained.