Water purification performance and energy consumption of gradient nanocomposite membranes

Reverse Osmosis (RO) membrane-based desalination technology accounts for 2/3 water desalination installation capacity all over the world but suffers from intensive energy consumption, where the membrane filtration process accounts for ~71% of total energy consumption. In this research, gradient membranes were designed and assembled with graphene oxide and celluloses laminates, and then used for RO desalination. The water flowing path was tuned by graphene oxide sizes while salt/water separation was tailored by the graphene oxide interlayer crosslinking. The resultant gradient nanocomposite membranes demonstrated a water yield as high as 21.34 L h⁻¹ m⁻² bar⁻¹ with a salt rejection rate of 96.08% when the graphene oxide lateral size was reduced to 300 nm, and such a yield was 5 times higher than that of current commercial RO membranes. In addition, such a gradient nanocomposite membrane also resulted in a 35.8% energy-saving in the membrane filtration process. Furthermore, the gradient nanoporous structure also exhibits decent scalability and long-time stability.