Development of robust superhydrophobic PFA/TMI/PVDF membrane by electrospinning/electrospraying techniques for air gap membrane distillation

In this present study, the fabrication of electrospun nanofiber membranes with various hydrophobic polymers containing varying ratios of TMI & PFA (a, a-dimethyl meta-isopropenylbenzyl isocyanate-perfluoroalkoxy alkane) and styrene or polyacrylonitrile (PAN) was conducted to enhance air gap membrane distillation (AGMD) performance. Electrospinning and electrospraying were combined to fabricate an electrospun nanofiber membrane. Different membrane properties such as contact angle, thickness, liquid entry pressure (LEP) and mechanical strength were examined for the evaluation of nanofiber membranes. The performance of fabricated electrospun membranes was examined in AGMD application for 2 h using 0.1 wt% NaCl solution. Then, the optimized membrane was further tested for 2 h using synthetic and real geothermal water. Results demonstrated that a fabricated membrane with 20 wt% TMI & PFA and 80 wt% styrene increased the contact angle to 154.8° and the LEP to 77.6 kPa. The salt rejection was 99.7% and permeate water boron concentration was 0.108 mg B/L for modified membrane (M1) compared with 98.01% and 0.305 mg B/L for pure PVDF membrane. These results indicate that this superhydrophobic membrane, fabricated by a combined electrospin/electrospray technique, shows high promise for MD applications.