DESALINATION
The challenge for large-scale desalination is to improve the performance of membranes used for reverse osmosis. One promising method is to introduce artificial water channels (AWCs) into synthetic membranes, to imitate the aquaporins of biological proteins for transporting water. Although AWCs have been a research topic for many years, large-scale performance has not been feasible under the harsh osmotic pressure and salinity conditions. Now, a hybrid approach that combines a polyamide matrix and AWCs into a single structure has been developed by an international team of researchers from Saudi Arabia (KAUST) and Italy (Politehnico di Torino) and coordinated by scientists from the Institut Européen des Membranes (IEM; Montpellier, France; www.iemm.univ-montp2.fr).
Their membranes, which take the form of a sponge superstructure, have been tested under industrial conditions and shown to outperform conventional membranes, as reported in Nature Nanotechnology last month. According to the article, these biomimetic membranes can be easily scaled for industrial standards, provide 99.5% rejection of NaCl or 91.4% rejection of boron, with a water flux of 75 Lm−2 h−1 at 65 bars and 35,000 ppm NaCl feed solution, representative of seawater desalination. “This flux is more than 75% higher than that observed with current state-of-the-art membranes with equivalent solute rejection, translating into an equivalent reduction of the membrane area for the same water output and a roughly 12% reduction of the required energy for desalination,” according to the abstract. The technology has been patented.