Nanostructured PVDF membrane for MD application by an O2 and CF4 plasma treatment.

Recently, various nanotechnologies have been utilized with regard to membrane modification due to their high activities and the low cost of the nanomaterials involved. In order to enhance the hydrophobicity of the membrane surface for membrane distillation applications by decreasing the surface energy, a radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) process is suggested with surface nanostructuring and a subsequent hydrophobic coating step. In this research, a commercial PVDF membrane was modified by plasma treatments with the two different gases of O 2 and CF 4 . The water contact angles of the active layers increased from 73 to 117 and 101° and the fluxes of the treated membranes increased to 63 and 27.9% as compared to a virgin PVDF membrane when the feed used was D.I. water by the O 2 and CF 4 plasma modifications, respectively. Defluorination at the long exposure time (120 min) of the plasma treatment and increase of the overall hydrophobicity (the decrease of the contact angle hysteresis) by the HMDSO coating were the reasons of the flux variations for the plasma modified membranes. [ABSTRACT FROM AUTHOR]