Enhancing VOCs/N2 separation by embedding VOC-philic bis(2-ethylhexyl) adipate into polydimethylsiloxane matrix to form oleogel membranes

Oleo gel membrane has emerged as a promising candidate for separating and recovering volatile organic compounds (VOCs) from gaseous streams. In this work, polydimethylsiloxane (PDMS) was used as a matrix to accommodate VOC-philic bis(2-ethylhexyl) adipate (DEHA) for enhanced VOC/N2 separation. The tunable crosslinking degree of PDMS provides an adaptable polymeric scaffold for immobilizing oil, which demonstrates high permeabilities and good selectivity for various VOC/N2 mixtures. The DEHA loading in the membrane could reach 32 wt%, and the membrane permselectivity to various VOCs was significantly improved. The mass transport in the PDMS /DEHA oleo gel membranes was investigated, and the experimental data were analyzed based on the Maxwell model that correlated the composition of the membrane in terms of DEHA content relative to PDMS. The membrane was found stable over a 60-day long-term performance evaluation, during which the membrane was exposed to different VOC/N2 mixtures and conditions.