Preparation And Characterization Of Polyurethane Membranes With Modified Zeolite For Pervaporation Separation Of Phenol/Water Mixtures

pervaporation?PV?is one of the new membrane separation technologies with great prospect in phenol separation from water.Its efficiency of separation is determined by membrane materials.Polyurethane?PU?membrane has showed a high selectivity to phenol,but its flux is too low.The modification of PU membrane is necessary to promote its industrial application.In this paper,?-CD is grafted to the surface of ZSM-5 based on epoxy compounds,isocyanate,silane coupling agent as the bridge structures.The modified PU membranes are used for the separation of phenol/water mixture by pervaporation.The effects of the grafted structures on the separation performances are investigated.The main content is as follows:?1??-CD is grafted to the surface of ZSM-5 based on epoxy compounds?-CD is grafted to the surface of ZSM-5 via epoxy compounds as the bridging agent by“graft to”and“graft from”.The mixed matrix membranes?MMMs?are prepared using PU and ZSM-5 before and after modification.The effects of the grafted structures and the operating conditions on the separation performances are investigated.Compared with the pristine PU membrane,the flux and pervaporation separation index of MMMs are increased greatly with a limited decrease of selectivity.The MMMs with ZSM-5 modified by“graft from”show the best separation performance with a separation factor of 16.05,and a total flux of 43.35 kg·?m·m^-2·h^-1at 80?.?2??-CD is grafted to the surface of ZSM-5 based on isocyanateThree kinds of modified zeolites are prepared via bridging isocyanate,ZSM-5is successfully grafted first by TDI,secondarily grafted by?-CD,and finally attached by oleyl alcohol?OA?.Then the MMMs are prepared.The effects of grafted structure of ZSM-5 on separation performances of MMMs is studied systematically.After modification,the internal channel structure of zeolite is not changed,the modified ZSM-5 shows better compatibility and dispersion in PU than pristine ZSM-5.Depending on good affinity of?-CD to phenol,along with interaction between modified surface and PU,ZSM-5 grafted by TDI first and?-CD secondarily obtaines the optimal modification effect with the flux of 46.03 kg·?m·m^-2·h^-1 and the separation factor of 15.64 under 0.3%phenol content in feed at 80°C and 9%loading.?3??-CD is grafted to the surface of ZSM-5 based on silane coupling agentThe modified zeolite is prepared using coupling agents as the crosslinking agent,combining with isocyanate modification methods grafted TDI??-CD and TDI step by step.The effects of grafted structures and operating variables on the performance of MMMs are investigated.The results suggested that the increase feed temperature enhances both of flux and separation factor of MMMs and pristine PU membranes.And the rotating speed on the separation performances of membranes have apparent effects,they are largest integrated on 185 r/min.