Surface-functionalized silica nanoparticles as fillers in polydimethylsiloxane membrane for the pervaporative recovery of 1-butanol from aqueous solution

BACKGROUNDHybrid materials are being developed with improved separation properties as pervaporation (PV) membranes. Mixed matrix membranes (MMMs) containing surface-functionalized fumed silica (SiO2) nanoparticles in polydimethylsiloxane (PDMS) were investigated for PV recovery of 1-butanol. The MMMs were characterized through water contact angle, pure 1-butanol sorption, degree of swelling and 1-butanol partition coefficients. ResultsMost MMMs outperformed pure PDMS for the PV of 1.5% (w/v) 1-butanol at 40 degrees C. Functionalized SiO2 fillers enhanced the affinity of 1-butanol to the MMMs (K-BuOH(G)) which consequently improved 1-butanol permeability more than that of water. Thus the MMMs exhibited better separation efficiencies, but those with octyl-functionalized (Si-DMOS) and phenyl-functionalized SiO2 (Si-DMPS) exhibited the best PV performance. Filler loading of 10wt% Si-DMOS and Si-DMPS were found optimal for the PV performance of both MMMs. With temperature, component fluxes of both MMMs increased whereas permeability decreased. Based on PV separation index, both MMMs performed better than PDMS at 60 degrees C, Si-DMPS/PDMS MMM outperformed PDMS even at 70 degrees C. CONCLUSIONImproved performance of PV membranes was achieved when nonporous functionalized SiO2 nanoparticles, especially when Si-DMPS is used as the filler. The MMMs developed may also be useful for organic compounds recovery from dilute aqueous solutions. (c) 2013 Society of Chemical Industry