Mixed Matrix Membrane Incorporated With Inorganic Filler For Pervaporation Separate Alcohols Solution

The burning of traditional fossil fuels has brought a heavy burden to the environment,and bio-fuels have become research focus.Membrane pervaporation(PV)technology has some advantages such as low energy consumption,continuous operation,no need to introduce new chemical substances,environmental protection and so on.This technology can be also used to separate and purify bio-fuels.Research and development of PV membrane materials has become the breach of the further development of the technology.The trade off effect between membrane selectivity and permeability makes the development of pure organic membrane curbed.Mixed matrix membrane combines the advantage of filling materials and organic polymer,has attracted many attentions of the researchers.Porous materials(ZIF-8 and ZSM-5)were used fill polydimethyl-si loxane(PDMS),and the polyether imide(PEI)as support layer,to preparation of mixed matrix membrane,pervaporation separation of ethanol solution,and study the influence of filling quantity and operating conditions on membrane performance;The mass transfer analysis of the pervaporation process was developed,and the association formula of the group of transmitted prime numbers was established.To prepare the modified mixed matrix membrane ZIF-8 and ZSM-5 were coated with n-octyl triethoxy silane(OTES)on surface and studied the performance of pervaporation for ethanol separation.The effects of the filling amount and operating conditions on the modified ZIF-8 mixed matrix membrane performance to separate butanol solution were studied.ZIF-8 and ZSM-5 mixed membrane pervaporation separation ethanol solution showed that ZIF-8 and ZSM-5 filled PDMS pervaporation performance can be improved,and filling within a certain range,the membrane permeability and selectivity rising at the same time,break through the trade-off effect.When the filling amount of ZIF-8 and ZSM-5 was 10%,the performance of the membrane reached the optimal value,the separation factors increased by 18%and 24.75%.Respectively,the flux increased by 54.75%and 76.41%.The permeability and selectivity of ZSM-5 mixed matrix membrane is better than ZIF-8.Operating conditions of mixed matrix membrane pervaporation performance impact study found that the feed temperature,concentration and flow rate promote mass transfer process.The flux and temperature conforms to the Arrhenius equation,filled with porous membrane activation energy is bingger than the PEI/PDMS composite membrane,porous material filling increases the visible membrane for temperature sensitivity.The temperature rising selectivity of alcohol,and flow have no influence on selectivity,when concentration was 4.934×104 g·m-3,the selectivity reach maximum.The mass transfer analysis of the membrane shows that the mass transfer coefficient of the membrane with porous materials has been greatly increased,and 10%of ZIF-8 and ZSM-5 have been filled with PDMS,which increases the mass transfer coefficient of the membrane by 5.14 times and 8.42 times.The correlation formula of the prime-number group was established,and the relations between the mass transfer coefficient of liquid phase k1 and Re were calculated.OTES coating modified ZIF-8 and ZSM-5 effectively improved the compatibility between porous materials and organic polymers,and enhanced membrane selectivity.Resulting in a slight lost of permeability flux.The effect of OTES coating modification on ZSM-5 performance was more significant than that of ZIF-8.The modified ZIF-8 mixed matrix membrane permeates and vaporizes to separate butanol aqueous solution,it suggests that the influence of the modified ZIF-8 filling amount and separation factor on the separation performance of butanol solution is basically the same as that of ethanol.However,butanol has better solubility and diffusivity than ethanol in the membrane,so the separation factors and permeation flux of butanol solution are higher than that of ethanol solution.