WITHDRAWN: Novel polysulfone membrane covalent bearing functionalized ionic liquids and its catalytic performance for biomass inulin hydrolysis

Abstract

Abstract Polysulfone powders covalently linked with acidic ionic liquids (ILs) as catalyst (PSF-ILs) were synthesized. It was prepared into casting solution to fabricate membrane via non-solvent induced phase separation method. Chemical structure of the PSF-ILs was confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance. The microstructure of PSF-ILs membranes was characterized by the scanning electron microscopy, pore size, porosity and contact angle measurements. The effects of the covalently incorporated ILs on the water flux, bovine serum albumin rejection and especially catalytic performance were investigated systematically to elucidate the microstructure-performance relationships. The structure of the membrane was regulated subtly by varying solvent or polymer concentration. Compared with the finger-like membrane, the resultant sponge-like membrane exhibited better catalytic performance for inulin hydrolysis due to higher porosity and specific surface area. Moreover, the effects of membrane thickness, porosity, reaction temperature and flux on catalytic performance of membrane that was constructed as a reactor were investigated. Interestingly, the turnover number of PSF-ILs membrane, i.e. the number of products generated by each active site of catalyst in unit time, was higher than the homogeneous ILs and PEK-C-ILs powders. Furthermore, the extended trial of the membrane demonstrated its reusability with only a little loss of catalytic activity. This novel catalytic membrane was first designed and prepared, not only subtly avoided the recycling of homogeneous ILs catalyst, but also effectively strengthened the mass transfer of substrates between the bulk of the feed and active sites on the pore wall, consequentially, improved the catalytic activity of ILs.