2D Vermiculite Nanolaminated Membranes for Efficient Organic Solvent Nanofiltration

Abstract

Membrane separation technology has found widespread application in molecular sieving and water reclamation. Its use in organic solvent nanofiltration (OSN) has been limited by the modest permeation rates and stability of existing membranes. In this study, 2D clay nanolaminated membranes are engineered, derived from the stacking of exfoliated vermiculite nanosheets, as a potential solution for OSN. The as-synthesized clay membrane displayed limited stability in both water and solvents due to rapid hydration or solvation of the nanosheets. To enhance the membrane's stability and sieving capabilities, cations of various valences (K+, Na+, Mg2+, Ca2+, Fe3+) are intercalated into the interlayer of the clay nanosheets. The resulting cation-treated clay membranes display considerable enhancement in structural stability in both aqueous and organic media. Subsequently, the solvent transport behavior and separation performance of these clay membranes are evaluated and described by molecular dynamic simulation and experiments. It is identified that Fe-intercalated nanolaminates demonstrate controllable stacking order, resulting in enhanced sieving performance with a rejection rate of over 95% for Methyl Orange and a methanol permeation rate of ≈165 L m−2 h−1 bar−1 [LMHB]. The findings of this work pave the way for the practical applications of 2D nanolaminated clay membranes in OSN.