Use of Ultrafiltration Membranes for the Separation of TiO2 Photocatalysts in Drinking Water Treatment

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• 作者：Soo-Ah Lee ; Kwang-Ho Choo ; Chung-Hak Lee ; Ho-In Lee ; Taegwhan Hyeon ; Wonyong Choi ; and Heock-Hoi Kwon
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2001
• 出版时间：April 4, 2001
• 年：2001
• 卷：40
• 期：7
• 页码：1712 - 1719
• 全文大小：258K
• 年卷期：v.40,no.7(April 4, 2001)
• ISSN：1520-5045

文摘

This study investigated the ability of cross-flow ultrafiltration (UF), combined with photocatalyticreactions, to separate TiO₂ photocatalysts from treated water in photocatalytic drinking watertreatment. The effect of natural organic matter (i.e., humic acids) and cross-flow velocities onUF fluxes and organic removal was explored with and without UV irradiation in thephotocatalytic reactor. The interaction between the two solutes in the system, humic acids andTiO₂ photocatalysts, played a significant role in the formation of dense cake layers at themembrane surface, leading to a greater flux decline during ultrafiltration of TiO₂ particles.According to visual observations of the used membranes and the estimation of back-transportvelocities of the solutes, a substantial amount of TiO₂ deposited on the membrane induces morehumic acids to accumulate at the membrane through the adsorption of humic acids onto TiO₂particles. The humic-acid-laden TiO₂ particles offered more than four times higher specific cakeresistance with a substantially increased compressibility coefficient than TiO₂ particles alone.The higher the cross-flow velocities, the greater the UV₂₅₄ removal achieved. This was becausethe rise of cross-flow velocities contributed to the reduction of concentration polarization at themembrane surface, thereby resulting in a decrease of the driving force for humic acids to passthrough the membrane. When photocatalytic reactions took place with UV illumination, UV₂₅₄removal efficiencies of the permeate were improved markedly, and also the permeate flux waskept at a constant level without any sign of fouling. Although humic acids were not completelymineralized by photocatalysis, the degradation of the humic acids helped to enhance the UFflux, as they were transformed to less adsorbable compounds.