Preparation and pervaporation performance of PVA membrane with biomimetic modified silica nanoparticles as coating

Polyvinyl alcohol (PVA) has been widely used in pervaporation dehydration due to its low price and good stability. However, the inherent "trade-off" effect of polymer membrane makes the pervaporation performance relatively limited. In this work, the rough and super-hydrophilic surface were constructed by biomimetic modification of silica (SiO2) coating on the PVA membrane, which achieved simultaneous growth of total flux and separation factor compared with the control, and overcame the "trade-off" effect. The morphology, structure and hydrophilicity of membranes were characterized. Results demonstrated that PVA/polydopamine (PDA)/SiO2 composite membranes had strong hydrophilicity and high surface roughness. In addition, the effects of SiO2 loading amount, operating temperature, feed ethanol concentration and long-term stability on the ethanol dehydration performance were investigated. For the PVA/PDA/SiO2-6 composite membrane, total flux was 1388 g m- 2 h-1, and the separation factor was 150(69 degrees C,90 wt% ethanol concentration), which was 1.8 times and 1.4 times that of the pristine PVA membrane, respectively.