Novel MWCNT-buckypaper/polyvinyl alcohol asymmetric membrane for dehydration of etherification reaction mixture: Fabrication, characterisation and application

• A novel membrane was developed to separate multi-component etherification mixtures.
• The asymmetric membranes show very high water-selective permeation.
• The pre-selective layer of purified MWCNT-BP enhances pervaporation performance.
• The hydrophilic behaviour and nanochannels of MWCNTs favour water permeability.

In this study, asymmetric membranes were prepared by first forming multi-walled carbon nanotube-buckypaper (MWCNT-BP) structures and later coating the structures with a thin layer of polyvinyl alcohol (PVA) to form novel MWCNT-BP/PVA asymmetric membranes. The resultant asymmetric membranes were used for the dehydration of a multi-component reaction mixture obtained from etherification through pervaporation. The asymmetric membranes exhibited improved mechanical properties relative to those of a pure PVA membrane. When the purified MWCNT-BP/PVA asymmetric membranes were applied in pervaporation, they exhibited significant two- and four-fold enhancements of the permeation flux and separation factor, respectively, compared to those of a pure PVA membrane. This effect was observed due to the hydrophilic group on the oxidised MWCNTs and the nanochannels of the pre-selective layer, which favour the permeation of water molecules.