Hydrophobic DD3R modified by perfluorooctyl-trimethoxysilane incorporates into PEBAX membrane for ethanol recovery via pervaporation

Abstract

A novel class of mixed-matrix membranes was synthesized through strategic integration of Polyether-block-amide (PEBAX) with Deca-dodecasil 3R (DD3R) zeolitic fillers, targeting efficiency-driven ethanol recovery in pervaporation separation systems. The DD3R molecular sieve was synthesized using adamantylamine (ADA) as a structure-directing agent and Sigma-1 seed crystals in a pure silicon precursor system. To improve compatibility with the polymer matrix, the DD3R particles were surface-modified with a silane coupling agent. Comprehensive characterization through Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectra (XPS), Water Contact Angle (WCA), X-ray diffraction (XRD), swelling degree tests, and mechanical properties confirmed the successful bonding of the silane coupling agent to both DD3R and PEBAX. The optimized membrane containing 0.75 ​wt% DD3R achieved a flux of 1152.06 ​g/m²h and a separation factor of 4.52 ​at 60°C with a 5 ​wt% ethanol feed concentration, representing a 115 ​% enhancement in flux and a 68 ​% increase in separation factor compared to the pristine PEBAX membrane. Additionally, the PEBAX/DD3R membrane displayed excellent long-term stability. This work provided a foundation for developing membranes with DD3R incorporated therein for a wide range of liquid or gas mixture separation processes.