Pressure and osmotically driven membrane processes: A review of the benefits and production of nano-enhanced membranes for desalination

This review focuses on current research attempts to develop nano-enhanced polymeric desalination membranes. The novel contribution made by this work as compared to many recent reviews on membrane enhancement is that a critical review is made of the effect that the morphological, optical and magnetic properties of the applied nanomaterials have on the efficiency of desalination membranes. The focus on nanomaterials in this review is on both applying new chemical compositions at various concentrations, and also on altering the nanomaterials' morphology and other properties to reach the optimal membrane efficiency for desalination applications. The synthesis route has a major role of tuning the physical and chemical properties of the nanomaterials, and hence, the membrane morphological parameters can be altered, all of which are summarised in this review. The review surveys different types of nanomaterials used for membrane fabrication, such as single elements, metal oxides and nanotubes. Furthermore, mixed oxide composites and polymer/nanomaterial combinations are also considered for membrane enhancement. A wide application range is investigated for modified membranes in pressure and osmotically driven membrane processes for desalination, including reverse osmosis, forward osmosis, osmotically assisted reverse osmosis and pressure assisted forward osmosis.