Silica Filled Polyphenylsulfone/Polydimethylsiloxane Composite Membranes for Pervaporation Separation of Biobutanol from ABE Mixtures

Pervaporation separation of acetone-butanol-ethanol aqueous mixture was studied to recover butanol. Polyphenylsulfone supported polydimethylsiloxane coated membranes were developed with polyvinylpyrrolidone additive and with two fumed silica fillers; Aerosil R202, treated with polydimethylsiloxane and Aerosil R972, treated with dimethyldichlorosilane. Membranes were prepared with fillers in each layer of the membrane, in both layers and without any filler, to investigate the effect of the fillers on the membrane performance. Furthermore, the effect of the thickness of each membrane layer was investigated. An increase in PDMS layer thickness promotes separation factor and suppresses flux, while an increase in the PPSU layer thickness has an inverse effect. After pervaporation tests at various operating conditions, the best PV performance was achieved with the membranes including R972 particles in the support layer. In the concentration range of 2-5% BuOH of feed, the average separation factor increased from 7.6 to 30.6, and the average flux increased from 300 to 536 g.m-2 h-1 by the incorporation of 3% R972 silica in the support layer. The partial fluxes of the solvents obtained from PV tests followed the order: butanol > water > acetone > ethanol. The developed R972 silica filled PPSU/PDMS membranes are found to be promising for butanol recovery from binary and quaternary aqueous mixtures.