文摘
Polyethylene glycol (PEG) of three different molecular weights was used to prepare PEG/PVDF composite membranes for separating organosulphur compounds from n-heptane by pervaporation. All the composite membranes were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and positron annihilation spectroscopy (PAS). The effects of operating temperature, feed sulphur content, and organosulphur species on performance of PEG/PVDF composite membranes with different molecular weights were investigated. When the feed organosulphur was thiophene, the fluxes decreased with an increase in PEG molecular weight, however, the enrichment factors were in a different order: PEG membrane with molecular weight of 35 000 exhibited the highest enrichment factor of 12.59 for thiophene at 85 °C. When the feed organosulphur was 2-methylthiophene or 2,5-dimethylthiophene, it was found that the PEG membrane with molecular weight of 100 000 showed the highest enrichment factor. The results showed that PEG molecular weight has a considerable effect on separation performance for pervaporation desulphurization.
