SiO2-PDMS-PVDF hollow fiber membrane with high flux for vacuum membrane distillation

In this study, hydrophobic asymmetric SiO2-PDMS-PVDF hollow fiber membranes were prepared for the vacuum membrane distillation (VMD). To make PVDF dope solution, hydrophobic nano-fumed silica (SiO2) and polydimethylsiloxane (PDMS) were used. The effects of SiO2 concentration on membrane parameters such as membrane morphology, hydrophobicity, porosity, thickness, pore size, liquid entry pressure, burst pressure, Fourier transformed infrared spectroscopy, thermal property, mechanical property and permeability were investigated. With the increasing of nano-particle concentration, membrane hydrophobicity, mechanical property and thermal stability improved. Furthermore, membrane VMD properties under various operation conditions were studied, the membranes showed a stable substantial flux of 44.27 LMH and a stable high salt rejection of over 99.9% under the optimum operation conditions of 75 °C, 35 g/L, 87 kPa, and 50 L/h. The results of our research demonstrated that the prepared hydrophobic asymmetric SiO2-PDMS-PVDF hollow fiber membranes not only had high permeability and good anti-wetting property but also exhibited a satisfying stability for the vacuum membrane distillation of desalination.