Tunable affinity separation enables ultrafast solvent permeation through layered double hydroxide membranes

Membranes are playing increasingly important roles in purification and separation processes due to inherent advantages like facile, low-cost and green compared to the traditional thermal-driven processes. To enhance permeability to further augment the feasibility of membrane-filtration, emerging two-dimensional (2D) materials are promising as building blocks for making organic solvent nanofiltration (OSN) membranes. The key novelty of this study is the demonstration that, by simply altering the divalent cation type in the layered double hydroxide (LDH) crystal structure, the physicochemical activities of the membranes can be significantly enhanced to allow for the permeation of solvent at an ultrafast rate. Results show that the micrometre-thick LDH laminate supported on a nylon substrate not only provided superb solutes rejection, but also enabled nanofiltration permeances in aqueous and organic solvents (namely, acetone) as high as 298 and 651 l m(-2) h(-1) bar(-1), respectively. Both experiments and simulations suggest that the superior performance originates from the interfacial interactions between the solvent and LDH.