Sol-Gel Derived Hybrid Polymer-Inorganic Membranes for Pervaporation Desalination Process

Abstract

Application of pervaporation to desalination involves the evaporation of water through hydrophilic non-porous membranes. Transport through the membrane is driven by a vapour pressure difference between the feed solution and the permeate vapour. It has the advantage that high salt rejection and potential low energy consumption. However, the low flux is still remained as the major technical challenge for commercial application of pervaporation processes for desalination. In this study, a hybrid polymer-inorganic membrane based on poly-(vinyl alcohol) (PVA) and inorganic silica was developed via a sol-gel method for desalination by pervaporation. Maleic acid was used as an additional crosslinking agent to improve the dense packing of polymer chains and also to improve the compatibility between the polymer and silica network. Results revealed that an uniform dispersion of silica nanoparticles less than 50 nm in the polymer matrix could be achieved. The swelling of PVA in water has been greatly suppressed by the addition of silica. Pervaporation testing of fabricated thin film composite membranes for brackish water desalination achieved high salt rejection (>99.5%). The flux was generally increasing with the feed temperature and a high flux of 9.84 kg/m·hr was achieved at a feed temperature 65°C and 6 Torr vacuum.