Self-assembled polyelectrolyte surfactant nanocomposite membranes for pervaporation separation of MeOH/MTBE

Pervaporation separation of polar/non-polar mixtures is one of the attractive areas in membrane science and technology. In the present study, membranes with highly cross-linked nanometric selective layers were developed through layer-by-layer (LBL) assembly of polyanionic and cationic surfactants and explored for separation of methanol (MeOH)/methyl tert-butyl ether (MTBE) mixtures. Pristine polyelectrolyte surfactant complex (PELSC) composite membranes were fabricated by deposition of dilute and concentrated ionic solutions of sodium cellulose sulfate (NaCS) and hexadecylpyridinium chloride (HDPC) onto the polyacrylonitrile (PAN) ultrafiltration (UF) membrane supports. In addition, nanocomposite PELSC membranes containing different loadings of nano-sized SiO2 particles were fabricated, for the first time, by solution casting method. Morphological and Fourier transform infra-red (FTIR) characterizations confirmed homogeneous morphology of membranes and successful incorporation of nano-silica particles into nanocomposite precipitate. The effects of several fabrication (i.e., number of deposition steps and nano-silica loading) and operational parameters (i.e., feed temperature and concentration) on the separation performance of MeOH/MTBE were investigated. The results revealed that increasing feed temperature enhanced both flux and selectivity in case of pristine PELSC membranes. It was also observed that increasing nano-silica loading from 2 wt% to 10 wt% in nanocomposite PELSC membranes led to improvement in flux at the expense of selectivity. The highest flux (1.62 kg/m2 h) was obtained in nanocomposite PELSC membrane containing 10 wt% nano-silica particles. This study demonstrates successful development of unique structures of PELSC and nanocomposite PELSC membranes with considerable potential application for pervaporation separation of polar/non-polar mixtures.