Ionic liquid modified multiwalled carbon nanotube embedded styrene butadiene rubber membranes for the selective removal of toluene from toluene/methanol mixture via pervaporation

Abstract

Abstract Present work reports the fabrication of elastomeric membrane based on ionic liquid functionalized multiwalled carbon nanotubes (f-MWCNT) incorporated Styrene butadiene rubber (SBR) for the separation of azeotropic composition of toluene and methanol. The fabricated membranes were characterized by morphological analysis using transmission electron microscopy and glass transition temperature and heat capacity measurements by differential scanning calorimetry. Composite membranes demonstrate impressive separation performance with preferential selectivity towards toluene and 5 phr f-MWCNT loaded membranes was found to show the best result with respect to toluene flux and selectivity. Optimal separation performance with the permeation flux 225% of SBR control membrane and separation factor of 128 (1.6 times of SBR control membrane) is obtained for this membrane. The concurrent optimization of the physical and chemical structures of toluene permeation path on f-MWCNT surface provides the membrane with high-efficiency toluene permeation. Ionic liquid on MWCNT surface confer aromatic pi-pi interaction with toluene molecules leading to greater toluene affinity and higher repellency against methanol. Pervaporation characteristics of the membranes were also strongly influenced by the feed mixture composition. The study confirmed that increasing toluene concentration improved the toluene flux but reduced the separation factor. The experimental pervaporation fluxes were compared with the calculations based on modified Maxwell–Stefan equation. The model allows a good quantitative prediction of experimental flux values.