Tailor‐made iron‐organic molecular cage embedded polydimethylsiloxane membranes via emulsion casting technique for efficient VOCs removal

Abstract

AbstractUrgent needs for the removal of volatile organic compounds (VOCs) from gas streams has stimulated a vigorous research for high‐performance separation membranes. Herein, porous iron‐organic molecular cage (Fe‐cage) embedded polydimethylsiloxane (PDMS) mixed miatrix membranes (MMMs) were fabricated through emulsion casting method for efficient VOCs removal. The membrane separation performance was systematically investigated by separating VOC/N2 gas mixtures under various operating conditions (e.g., feed concentration, operating temperature) using n‐hexane, n‐heptane, and cyclohexane as model organic vapors. It was found that the resultant membranes demonstrated homogeneous Fe‐cage dispersion and intimate interfacial adhesion. With the increase of the Fe‐cage loading, the MMMs demonstrated obviously improved permselectivity for the separation of n‐hexane/N2 and n‐heptane/N2. The MMM containing 4 wt% Fe‐cage showed a n‐heptane permeability of 1657 × 10−8 mol μm m−2 s−1 Pa−1 and a n‐heptane/N2 selectivity of 145 at 25°C when the feed concentration is 4.3 mol%. These values were 231% and 158% of those for the pristine PDMS membrane, respectively. Furthermore, the VOC permeability and VOC/N2 selectivity of the membranes increased with decreasing operating temperature or increasing feed concentration. Because of its excellent mixed‐gas VOC/N2 permselectivity, the Fe‐cage embedded PDMS membrane could find use in petrochemical applications such as gasoline vapor recovery.