丙烯酸－－聚嗍碸接枝滲透蒸發薄膜分離乙醇水溶液之研究

Photografted Polyacrylic Acid／Polysulfone Membranes for Dehydration of Ethanol Solution by Pervaporation

本研究以親水性丙烯酸（Acrylic acid）單體進行高分子光接枝聚合反應製備超薄複合膜應用於滲透蒸發分離水／乙醇共沸混合物之研究，本研究以UV光進行光聚合反應，研究中探討濃度及時間變化之光起始方式，對親水性單體丙烯酸進行高分子光聚合反應程度之影響，研究中對稱型式之聚嗍碸超過濾膜做為支撐層，並探討其表面型態及其對滲透蒸發分離性能之影響。本研究發現親水性單體丙烯酸的濃度提高而選擇性則先上升而後下降，親水性單體丙烯酸之中當濃度點達3%時能有效地覆蓋薄膜孔洞，因親水性單體丙烯酸進行高分子光接枝聚合反應有良好的接枝效果導致滲透蒸發有效提升滲透蒸發分離係數（PSI），利用滲透蒸發的操作條件改變，高分子光接枝聚合膜應用於高濃度乙醇水溶液俱有明顯選擇性優勢；由研究另一發現光接枝聚合反應時間的增加也會造成選擇性先增加而後降低，當光接枝聚合反應愈久時間，因光降解而導致膜產生裂紋，則選擇性會降低。

The ultra thin skin layer of photografted membranes can be prepared by photograft acrylic acid on porous polysulfone membranes and it was well applied for the dehydration of water from ethanol solution by pervaporation process. UV（320nm） was used as the radiation source in this photo polymerization. The degrees of grafting of composite membrabes were carried out with various monomer concentrations and radiation times. The pervaporation separation performance and membrane morphology were made to investigate the enhancement of hydrophilic polymer on the skin layer. It was found that the thickness of skin layer of grafting polymer first increased up to 3% monomer grafting and then decreased with increasing the monomer concentration in photo polymerization. Based on the pervaporation separation index （PSI） measurements, it was found that the grafting polyacrylic acid significantly enhanced the hydrophilicity of skin layer. The FTIR spectra evidenced that H bonding of water were superiors to ethanol in the grafting skin layer. It was also found that the higher expose in UV radiation degraded the polymer chain and destroys the surfaces' morphology of grafted membranes.