Study On Modification Of Pervaporation Membrane Based On Cyclodextrin And Its Benzene/cyclohexane Separation Characteristics

Pervaporation is a new environmentally friendly separation technology that has unique advantages for the separation of near-boiling and azeotropic mixtures.In recent years,research on pervaporation membranes for the separation of organic compounds such as benzene/cyclohexane has received much attention,but how to obtain Solvent-based,high-resolution membrane materials still face challenges.In this paper,the aim is to develop pervaporation membranes for benzene/cyclohexane separation.Based on the specific structure of the macrocyclic compound cyclodextrin and its derivative polyrotaxane,cross-linked modified and co-deposited modified pervaporation membranes are designed and prepared.The relationship between preparation conditions,membrane properties and its separation mechanism were studied.The main research contents and conclusions are as follows:?1?Cyclodextrin cross-linking agent?CD=?and polyrotaxane cross-linking agent?PR=?with slide properties were prepared based on the macrocyclic compound cyclodextrin molecule,the EC/PVDF composite membrane was prepared by using ethyl cellulose?EC?as the activity layer membrane material,polyvinylidene fluoride?PVDF?as the supporting layer membrane material,then the membrane was crosslinked modified by using CD=?PR=and pentaerythritol triacrylate?PETA?,the separation behavior of the membrane on benzene/cyclohexane was studied.The results show that the cross-linked modified composite membranes have good mechanical properties and thermal stability,and the cross-linking improves the solvent resistance of the membrane.The results of pervaporation test show that the performance of PR=modified composite membrane is better than CD=and PETA composite membrane,the permeation flux of PR=modified composite membrane reaches 4332g·m^-2·h^-1,and the separation factor is 6.26,the excellent performance is closely related to the sliding/rotation characteristics of PR.?2?Based on the biomimetic strategy of dopamine-oxidizing self-adhesive,the cyclodextrin molecule was deposited on the surface of the EC membrane,and the PDA/CD_x-EC modified membrane was prepared.Characterization of infrared and X-ray electron spectroscopy proved the successful deposition and introduction of cyclodextrin molecules on the membrane surface,a 0.5-2?m thick layer appeared on the membrane surface,and the roughness of the membrane surface changed.The performance test results show that the adsorption rate of PDA/CD₂-EC modified membrane in benzene is significantly increased compared with the pristine membrane,because the cyclodextrin molecules have an important influence on membrane adsorption performance and separation behavior optimization.The separation factor of PDA/CD₂-EC modified membrane for benzene/cyclohexane system reaches 6.58,and the permeate flux reaches 1492g·m^-2·h^-1.