Elevated Pervaporative Desulfurization Performance of Pebax-Ag⁺@MOFs Hybrid Membranes by Integrating Multiple Transport Mechanisms

Abstract

Polymeric dense membranes for separating molecules with similar properties in liquid mixture according to solution-diffusion mechanisms are often constrained by trade-off effects. Integrating a facilitated transport mechanism and a sieving mechanism into membranes is a preferred approach to address this issue. Herein, amine-functionalized titanium-based metal–organic frameworks (NH2-MIL-125(Ti)) immobilized with Ag+, Ag+@NH2-MIL-125(Ti), was synthesized and hybrid membranes were fabricated for pervaporative desulfurization. The immobilized Ag+ can form reversible π-complexation toward thiophene and achieve thiophene-selectivity transport via a facilitated transport mechanism; meanwhile, Ag+ can decrease the effective pore size of the MOFs to elevate the diffusion selectivity of thiophene via a sieving mechanism. Accordingly, the resulting Pebax membranes with 1.0 wt % Ag+@NH2-MIL-125(Ti) exhibit a permeation flux of 22.11 kg/(m2 h) and an enrichment factor of 5.92. Furthermore, the hybrid membranes display increased thermostability and antiswelling properties by the incorporation of Ag+@NH2-MIL-125(Ti). This study proposes a strategy for the rational design of MOFs as nanofillers and endow the membranes with superior separation performance by integrating multiple transport mechanisms.