Pervaporation Of Benzene/Cyclonexane Mixture Through Mwnts-AG~+/Chitosan Hybrid Membranes

Benzene/cyclohexane mixture is representative of aromatics/paraffin mixture system, the significance of the separating aromatic/paraffin mixed system not only lies in the process of petroleum chemical process but also relates about the increasingly serious environmental problems. Pervaporation (PV) is a novel, efficient, and low-energy separation technique that has attracted considerable research interests Functionalized multiwalled carbon nanotubes (MWNTs) were incorporated into a chitosan membrane for separation of benzene/cyclohexane mixtures by pervaporation. The original MWNTs were treated by mixed acid (H2SO4/HNO3=3/1) and then functionalized with isonicotinic acid. Ag+was grafted to the pyridine ring on the MWNTs by a complexation reaction. Membranes made of chitosan and Ag+/carbon nanotubes were prepared with polysulfone membranes as support. The surface structure of modified MWNTs was examined by FT-IR, TEM, EDS and XPS to assess its morphology. And the hybrid membranes were examined by SEM, TEM, EDS to observe the distribution of the MWNTs-Ag+in the membranes.The swelling and pervaporation characteristics of the membranes for separation of benzene/cyclohexane mixtures were investigated. The swelling degree of the membranes in benzene was more than2.5times that of the pristine chitosan membrane. The swelling degree was found to increase with the content of the MWNTs-Ag+in the membrane and the benzene content in the feed. Pervaporation results also showed that the MWNTs-Ag+/chitosan hybrid membrane separation performance is better than MWNTs/chitosan hybrid membrane and pristine chitosan membrane. The permeation flux of the membrane increased, the selectivity increased firstly and then decreased with the increased of the content of MWNTs-Ag+The selectivity reached7.89and the permeate flux was357.96g/(m2·h)(the mass ratio of benzene was50%, the temperature was20℃) when the percentage by weight of the MWNTs-Ag+to chitosan was1.5%. The Arrhenius activation parameter of1.5%MWNTs-Ag+/Chitosan(CS) hybrid membrane is4.28kJ/mol while1.5%MWNTs/CS membrane is10.6kJ/mol in50%benzene concentration in feed.The examining and pervaporating experiment shows that this experiment has successfully grafted silver ions on the MWNTs and prepared hybrid membrane which could separate benzene/cyclohexane mixture system with a good effectiveness.