二氧化鈦溶液之過濾行為及其光觸媒性能

Flux behavior of titanium dioxide suspension and its photocatalyst performance.

張瑋展(Wei-Chan Chang)

指導教授 ： 鄭東文

淡江大學/工學院/化學工程與材料工程學系碩士班/碩士(2011年)

https://doi.org/10.6846/TKU.2011.00926

摘要

本研究主要使用掃流式陶瓷膜過濾系統，探討二氧化鈦粒子水溶液的過濾行為，及結合光觸媒反應操作，探討光觸媒分解染料之效果及回收粒子之性能。實驗參數有溶液的pH值、流體速度、通氣速度及透膜壓差。
從實驗的結果得知二氧化鈦在等電位點（pH 7）時粒子易凝聚，且形成的濾餅較鬆散受剪應力的影響大，因此pH 7的濾速較pH 5及pH 9來的高；當增加流體速度或通入氣體時，可以有效造成擾動，減少二氧化鈦粒子附著於膜面上。當pH = 5或pH = 9時，二氧化鈦粒子因帶電而均勻的懸浮於水中，過濾時因粒子體積小而堆積緊密，改變流體速度及通氣速度對提升濾速沒有明顯的幫助。隨著透膜壓差的增加，提升掃流速度有幫助減少濃度極化，及延後極限濾速的發生。氣液兩相流的操作方式對提升濾速的幫助最大，於本實驗中最大濾速發生於pH 7，流體速度0.2 m/s及通氣速度0.3 m/s的操作條件。
掃流過濾結合光觸媒反應操作，於pH 5條件下形成之TiO2動態膜有阻擋染料之功能，而回收之TiO2粒子有不錯的光觸媒效能，約為原始粒子性能之91~97%。

關鍵字

二氧化鈦 ； 氣液兩相流 ； 過濾行為 ； 光觸媒 ； 掃流

並列摘要

In this study, a tubular ceramic membrane was used in a cross-flow filtration system to discuss the flux behavior of the titanium dioxide solution, and the combination with photocatalyst reactor was also operated to investigate the performance of decolorization by titanium dioxide particles. The experimental parameters included transmembrane pressure, pH value, liquid velocity and gas velocity.
Experimental results showed that the TiO2 particles tended to coagulate and form a less compact cake at pH 7, thus, the permeate flux at pH 7 was higher than that at pH 5 or pH 9. The larger particles can be easily swept away from the membrane surface by the cross-flow velocity. At pH 5 or pH 9, the charged titanium dioxide particles form a tightness layer, thus the effect of cross-flow velocity becomes less significance. High cross-flow velocity induced a high mass transfer rate that could lower the trend to reach the limiting flux regime as increasing the transmembrane pressure. A significant flux enhancement was obtained by the addition of gas slugs into the liquid stream. An optimal operation was obtained at pH 7, UL = 0.2 m/s and UG = 0.3 m/s in this work.
Photocatalyst reactor combined with cross-flow filtration, the TiO2 dynamic membrane could inhibit the dye AO7 through the membrane at pH 5. The recovered TiO2 particles have a good photocatalyst performance which is equal to 91~97% of original TiO2 particles.

並列關鍵字

titanium dioxide ； gas-liquid two-phase flow ； flux behavior ； photocatalyst ； cross-flow

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