Potential effects of nano-fumed silica particles (NFS)/PVDF mixed matrix hollow fiber membrane on the performance of direct contact membrane distillation

Hydrophobic nano-fumed silica (NFS) was incorporated in polyvinylidene fluoride (PVDF) hollow fiber (HF) membrane for improving direct contact membrane distillation (DCMD) performance. The NFS/PVDF mixed matrix hollow fiber membrane was fabricated by the phase inversion process. The potential effects of increasing the percentage of NFS additive (0–6 wt.%) in the dope solution on the hollow fiber membrane characteristics such as viscosity, membrane morphology, porosity, hydrophobicity, Fourier transformed infrared spectroscopy, and permeability were investigated. The performance outcomes showed that the dope solution incorporated with 1.5 wt.% NFS exhibited the most promising HF membrane for membrane distillation (MD). The optimal HF membrane demonstrated the highest flux through shorter and narrower finger-like structure formation and targeted high porosity. The addition of NFS particle content in the dope solutions enhanced the hydrophobicity of the fabricated membranes while slightly decreasing the porosity due to increasing the viscosity of the dope solution. With a steady flux of 9.25 kg/m² h compared with the neat membrane at 70°C/20°C of feed/permeate temperatures, 8 h operation, and above 99.9% salt rejection, this PVDF/NFS mixed matrix hollow fiber membrane could be of excellent potential and sustainability in desalination process through DCMD.