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Novel heterogeneous membranes for enhanced separation in organic-organic pervaporation

Year: 2020

Journal: J. Membr. Sci., Volume 599, APR 1

Authors: Knozowska, Katarzyna; Li, Guoqiang; Kujawski, Wojciech; Kujawa, Joanna

Organizations: PRELUDIUM 13 grant from The National Science Center (NSC) [2017/25/N/ST5/01097]; China-Poland Scientific and Technological Cooperation Committee [2018-37-4 00]; NSCMinistry of Science and Technology, Taiwan [2018/28/T/ST5/00411]

Keywords: Organic-organic pervaporation; Heterogeneous membrane; Aluminium oxide; Perfluroalkylsilane and alkylsilane modifiers; Hansen's solubility parameters

Novel heterogeneous membranes based on poly(ether block amide) and poly(dimethylsiloxane) were prepared and modified by incorporating the grafted alumina oxides into the polymer matrix. Membranes were subsequently used for separation of organic solvent mixtures (ethyl acetate/ethanol and ethyl acetate/isopropanol). There were four types of grafting compounds applied in this research: octyltriethoxysilane (C6), 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FC6), tetradecyltriethoxysilane (C12), 1H,1H,2H,2H-perfluorotetradecyltriethoxysilane (FC12). The influence of incorporation of grafted alumina oxide on physicochemical, equilibrium, transport, and separation properties was investigated. Pervaporation results were assessed using thickness-normalized Pervaporation Separation Index (PSIN) and separation factor (beta). Additionally, membrane performance and equilibrium properties were discussed using Hansen's Solubility Parameters. It was found that incorporation of grafted alumina oxide improved membranes performances. The best efficiency during the separation of ethyl acetate/ethanol and ethyl acetate/isopropanol mixtures was found for membranes modified by alumina oxides grafted with octyltriethoxysilane (beta(EtAc/EtOH) = 3.9, beta(EtAc/IPA) = 3.4) and 1H,1H,2H,2H-perfluorotetradecyltriethoxysilane (beta(EtAc/EtOH) = 4.3, beta(EtAc/IPA) = 3.6). Moreover, the presence of water traces (in the range 0.1-0.3 wt%) in feed and permeate was monitored and correlated to the membrane material features. It was found that the presence of water in permeate depends on the character of the membrane and the filler used. The enrichment factor of water for PDMS/(Al2O3+FC12) obtained during separation of EtAc/EtOH and EtAc/IPA was equal to 1.11 and 0.95, respectively.