大氣電漿處理之沸石複合薄膜於滲透蒸發的應用

Abstract

沸石薄膜廣泛的應用於滲透蒸發進行乙醇除水分離。在本研究中，我們提出一項新穎的合成後處理技術—大氣電漿(atmospheric-pressure plasma jet)，目的為提昇沸石薄膜對於醇類除水的分離效能。本論文中我們以FER、MOR、FER-MOR hybrid三種沸石薄膜作為研究的對象。經大氣電漿處理後，三種沸石薄膜之分離選擇率皆有所提升，FER沸石薄膜的水/乙醇選擇率由93提升至377；MOR沸石薄膜由141上升至286；FER-MOR hybrid沸石薄膜則由178上升至315，並可以在FER與MOR兩種沸石薄膜中觀察到分離水通量些微的上升。我們利用不同的材料檢測方法來釐清大氣電漿對於薄膜效能上升的機制為何。在大氣電漿作用之下，沸石薄膜的結晶性以及空氣通透性降低，這表明沸石薄膜晶界中的部份針孔缺陷可能因此減少，部分解釋了水/乙醇分離選擇率提升的原因。此外，在經過大氣電漿處理後的沸石薄膜表面經由水接觸角的量測顯示出表面變得更加親水，這是另一個增進水/乙醇分離效能的原因。我們預期大氣電漿處理技術將能夠有效套用於其他構型種類之沸石薄膜，並應用於乙醇除水分離程序中。

Zeolite membranes are widely used for the dehydration of alcohol via pervaporation. This work presents a novel post-synthesis atmospheric-pressure plasma jet (APPJ) treatment aimed at enhancing the water/ethanol separation factor for FER, MOR, and FER-MOR hybrid zeolite membranes. APPJ treatment was shown to increase the separation factor of the three membranes as follows: FER (93 to 377), MOR (141 to 286), and FER-MOR (178 to 315). Pure FER zeolite and MOR membranes increased the water flux slightly. APPJ treatment was shown to reduce crystallinity and air permeability, which suggests a partial elimination of pinholes at grain boundaries in the zeolite membranes and may partially explain the improvement in water/ethanol separation performance. The hydrophilic surface of the APPJ-treated samples, characterized by the water contact angle measurement, may also contribute to the improved separation performance. Note that the proposed APPJ treatment scheme is also applicable to other types of zeolite membrane for alcohol dehydration.