Crosslinked polybenzoxazine based membrane exhibiting in-situ self promoted separation performance for pervaporation dehydration on isopropanol aqueous solutions

The performance of pervaporation dehydration of a crosslinked polybenzoxazine membrane (CR-PBz-M) on isopropanol (IPA) aqueous solutions has been studied. Compared to the feature showing in dry state, CR-PBz-M exhibits a change in micropore size distribution from a single distribution to a bimodal pattern in wet state being swollen with the feeding solutions. The presence of two groups of micropores in different sizes attributes to the high pervaporation dehydration performance of the membrane, in which the small micropores resist to the permeation of IPA molecules so as to contribute to the high membrane selectivity and the large micropores and high micropore volume fraction contribute to the high permeation fluxes. This feature of CR-PBz-M demonstrates an in situ self-promoted characteristic for pervaporation dehydration membranes. A permeation flux of 330 g h(-1)m(-2) and a 100% of water in the permeate side has been recorded on pervaporation dehydration on a 70 wt% IPA aqueous solution.