Development of Polybenzoxazine Membranes for Ethanol/Water Separation: Effect of Mixture Contents on Sorption and Swelling Behaviors

摘要

Nowadays,the biofuel derived from renewable resources such as bioethanol and biogas is one of the most interested researches due to the continuing increase of the price of fossil fuels. Bioethanol is especially attractive since it can be combined with gasoline to reduce the cost. Bioethanol can be obtained from several kinds of plants including corn,sugar cane etc. Fermentation is the typical process used to produce bioethanol. However,the products from this process contain not only ethanol but also other by-products such as water. Therefore,in order to use bioethanol with gasoline,the separation of bioethanol from other by-products is essential. Membrane separation is one of the most effective and energy-saving approaches. Polymeric membrane is specially preferred because the selectivity and permeability of polymeric membrane can be tailored to effectively separate all kind of chemicals. Polybenzoxazine (PBZ) is a class of phenolic resins that offers a number of outstanding properties including a high glass-transition temperature (Tg),high thermal stability,good mechanical properties,low shrinkage upon polymerization and excellent molecular design flexibility. The diamine based polybenzoxazines were generally synthesized via the time-consuming reflux process. However,we found the new technique which will be called "quasi-solventless" approach to prepare these diamine based polybenzoxazines in which the reaction time was certainly reduced. The performance and stability of polybenzoxazine membrane in solvents and mixed solvent media can be reduced due to the sorption and swelling of the membrane matrix As a result,it is important to understand these phenomena in order to optimize the system. The ethanol/water separation is the main focus of this research.