Synthesis and application of PDMS/OP-POSS membrane for the pervaporative recovery of n-butyl acetate and ethyl acetate from aqueous media

Abstract

Herein, octaphenyl-polyhedral oligomeric silsesquioxane (OP-POSS)/polydimethylsiloxane (PDMS) hybrid membranes were prepared for the recovery of n-butyl acetate and ethyl acetate via pervaporation. The affinity of PDMS/OP-POSS membranes for n-butyl acetate and ethyl acetate 1 solvents was determined by solubility parameters and equilibrium swelling experiments; the diffusion coefficients were determined by dynamic swelling experiments. The membranes were characterized using SEM, EDS, AFM, CA, FTIR, XRD and TGA to investigate the surface morphology, elemental distribution, roughness, hydrophobicity, intermolecular interactions, crystallinity and thermal stability, respectively. The effect of the OP-POSS content, feed concentration and temperature on membrane performance was investigated through pervaporation experiments. The swelling degree and penetrant mobility through the membranes significantly increased with increasing OP-POSS content. For dilute aqueous solutions containing n-butyl acetate or ethyl acetate, the total flux increased by increasing the OP-POSS content from 0 wt% to 10 wt%; the separation factor first increased followed by a decrease. The permeation flux and separation factor attained a maximum of 348 g∙m−2 h−1 and 221, respectively, at 6 wt% OP-POSS loading for a 0.5 wt% n-butyl acetate aqueous solution and 1694 g∙m−2 h−1 and 137, respectively, for a 4 wt% ethyl acetate aqueous solution, at 40 °C. The newly designed PDMS/OP-POSS membrane can be of significant assistance in separating n-butyl acetate, ethyl acetate and other similar compounds from aqueous mixtures on an industrial level.