Innovative PVDF@PFTES mixed matrix membranes for improved desalination via vacuum membrane distillation

This study investigates the preparation and performance evaluation of flat sheet polyvinylidene fluoride (PVDF) membranes, fabricated via the phase inversion method. Varying amounts of powdered activated carbon (CNM/PAC) comprising high hydrophobic carbon nanomaterials (0.1, 0.2, 0.3, 0.4, and 0.5 wt. %) are incorporated into the polymeric matrix, and then, modified by dip coating in a solution of 1H, 1H, 2H, 2HPerfluorodecyltriethoxysilane (PFTES)/hexane at varying concentration. The modified membranes were systematically assessed for their performance in vacuum membrane distillation (VMD), focusing on key metrics such as permeate flux, gain output ratio (GOR). Results disclosed that the chemically modified membrane 0.4 % CNM/PAC/PVDF with 2 % PFTES (2 %FM4) had superior stability compared to the unmodified membranes, demonstrating a higher water contact angle of 124° and a permeate flux of 16.61 L/m².h. Moreover, the salt rejection remained consistent at 99.9 % over prolonged operation of 96 hours, using simulated seawater. The GOR value displayed around 44 % increment at optimum operating condition (65°C feed temperature, 0.6 L/min feed flowrate and 21kPa(abs) vacuum pressure), imparting an enhancement in the thermal efficiency.