Despite its widespread industrial and residential uses for production of potable water, the reverse osmosis (RO) desalination process has some drawbacks by discharging harmful concentrated saline water as reject stream. A hydrophobic porous membrane can treat such environmentally unfriendly RO reject stream via Membrane Distillation (MD) process. Here, we describe preparation of superior polyvinylidenefluoride (PVDF) membrane modified with superhydrophobic silica nanoparticles for desalination application. Superhydrophobicity (contact angle of 1518) of silica nanoparticles of 7 nm sizes was achieved by reaction of the silica particles with octadecyltrichlorosilane in toluene to form ASiAOASiA links with C18 alkyl chain. A homogeneous polymer dope mixture containing a desired amount of modified silica colloids suspended in toluene was used for the membrane preparation. The PVDF membrane with optimal silica content exhibited excellent flux with >99% salt rejection efficiency when used for MD at room temperature from the saline water feed of 3.5 wt % NaCl. The prepared hydrophobic PVDF membrane has the potential for MD application in treating the RO reject stream and other aqueous industrial effluents. V C 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46043.

Organosilica‐polyvinylidenefluoride nanocomposite membrane has shown excellent performance in emerging technology of membrane distillation process for treatment of highly saline water stream. In present work, a systematic study using capillary flow porometry was carried out to evaluate the constricted part of the flow‐through pores, which is active pores of the nanocomposite membranes. Mean flow pore size and distributions of the membrane pores were found to be influenced due to the phenomenon of micro‐gelation by air exposure prior to the immersion in the coagulation bath of the preparation method, polymer concentration, polymer chain length and nature of the solvent in the casting dope solution. The best membrane in terms of the largest mean flow diameter of 0.12 μm with narrow distribution of flow‐through pores were observed in the membrane with optimum organosilica content of 1.4 wt%.