Cross-linked membranes based on acrylated cyclodextrins and polyethylene glycol dimethacrylates for aromatic/aliphatic separation

The cost and energy efficient separation of aromatic/aliphatic and isomeric mixtures using membranes is a great challenge for the petrochemical industry However since these mixtures are causing strong swelling effects with most of the polymeric membrane materials, especially at elevated temperatures, cross-linking is necessary in many cases. Furthermore highly selective membranes can be reached, if the well-known ability of cyclodextrins to form host-guest interactions with specific substrates is used Therefore in this work, cross-linked polymers based on PEG-DMA (polyethylene glycol dimethacrylate) and acrylated cyclodextrins have been prepared and investigated in pervaporation experiments using toluene/cyclohexane mixtures at 60 degrees C Thereby membranes with different ratios of PEG-DMA having diverse molecular weights as well as membranes with acrylated alpha-cyclodextrin and acrylated P-cyclodextrin, respectively have been investigated Also membranes without any acrylated cyclodextrins have been prepared as a reference In this case, an aliphatic triacrylate with a similar molecular weight as the cyclodextrin acrylate has been used as a multifunctional cross-linker The separation experiments using a toluene/cyclohexane mixture showed that especially the membranes based on PEG-DMA and acrylated beta-cyclodextrins obtained high selectivities already at low aromatic concentrations in the feed, e g with a toluene content of 10 wt.% in the feed a selectivity of alpha = 14 and a permeability of 0 3 kg mu m m(-2) h(-1) was found at 60 degrees C feed temperature (C) 2010 Elsevier B V. All rights reserved