Influence of prolonged operation of CNM/PAC modified PVDF nanocomposite membranes in desalination via vacuum membrane distillation

This study investigates the morphological and performance changes in polyvinylidedne fluoride (PVDF) membranes resulting from the incorporation of carbon nanomaterial/powder activated carbon (CNM/PAC) and subsequent chemical modification with 1 H,1 H,2 H,2H-Perfluorodecyltriethoxysilane (PFTES) following a prolonged vacuum membrane distillation (VMD) operation (96 hrs). Membrane performance, including salt rejection, was systematically assessed before and after modification, along with detailed characterization using Fourier-Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), contact angle measurements, and Energy Dispersive X-ray spectroscopy (EDX) analysis. Additionally, antibacterial tests were performed to assess the membranes' effectiveness against gram-positive (S. aureus) and gram-negative (E. coli) bacteria. results demonstrated that the chemically-modified membranes manifested greater stability in permeate flux, with only a4.5 % decline, while maintaining a consistent salt rejection rate of99.9 % over the 96 hrs operation. Meanwhile, a20.2 % diminish in hydrophobicity was detected, primarily attributed to NaCl scaling deposits rather than intrinsic changes to the membrane surface, suggesting that hydrophobicity could be restored by removing foulants. Nonetheless, Antibacterial testing confirmed that the CNM/PAC/PVDF membrane possessed effective antibacterial properties against both S. aureus and E. coli, further enhancing its potential for long term desalination applications.