Polyethersulfone/silica composite membrane for desalination

In this study, polyethersulfone (PES) membranes for desalination were prepared under different evaporation temperatures. The morphology of the PES membranes was evaluated using scanning electron microscopy, which revealed that at a low evaporation temperature (30 °C and 40 °C) the membranes had a porous structure (the pore size in the range of 11–20 μm), whilst at a high evaporation temperature (50 °C and 60 °C) they had a more dense structure. To improve the desalination efficiency of the PES membrane, silica was generated in-situ in the PES membrane via a sol–gel reaction. The advantage of this technique was to give a good silica dispersion under a mild synthesis condition for the silica compared to the conventional direct mixing method. The effect of the in-situ silica content generated in the PES membrane on its hydrophilicity, mechanical properties, permeate flux, and salt rejection was investigated. The PES membrane prepared under an evaporation temperature at 60 °C with 7% by weight in-situ silica showed the highest permeate flux (19.55 kg/m2h) and salt rejection (98.9 %). Accordingly, this membrane can be applied to deliver high quality fresh water for daily life.