Aluminum Hollow Fiber Membranes with Photocatalyst for Seawater Desalination Pretreatment

• Main Authors: Fang-Ting Tao, 陶方廷
• Other Authors: Hsuan Chang
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/nm9a39

碩士 === 淡江大學 === 化學工程與材料工程學系碩士班 === 106 === This thesis investigated the performance of seawater desalination pretreatment by using aluminum hollow fibers combined with a photocatalyst. The hydrophilic ceramic membrane with pore size of 0.2 m operated in cross-flow mode was employed for studying the separation of the humic acid in a synthetic seawater. The experimental study includes the use of straight membrane filtration as well as the addition of ZnO photocatalyst into the seawater with ultraviolet light irradiation before the membrane filtration. The first part was studying membrane filtration (MF) only. The second part was the membrane filtration with the addition of a photocatalyst (ZnO). The experiments were conducted with different feed flow rates, transmembrane pressures, humic acid concentrations and pH values. The experiments with ZnO were conducted with different amounts of ZnO and various UV irradiation durations. The performance parameters studied include the normalized filtration flux, humic acid rejection, total resistance and resistance distribution. The results of the membrane filtration experiments showed that the flux increased with the increase of feed flow rates, but decreased with the increase of humic acid concentrations and pH values. The pH value affects the precipitation of inorganic salts in seawater and an optimal pH value was identified for the maximum flux. The total resistance –time curves showed downward concave pattern which implied that the decrease of filtration flux was due to the cake formation. The reversible resistance is the dominant contributor to the total resistance. The experimental results of photocatalyst addition showed that the normalized flux could be significantly increased. The optimum ZnO dosage is 0.75 g/L. The maximum humic acid rejection was obtained with a 15 minute-irradiation. The addition of ZnO substantially reduced the fraction of reversible resistance and as the result, the dominant contributor of the total resistance became the membrane resistance. In this study, the filtration flux reaches up to 720 LMH, the pseudo-steady state normalized flux is between 0.06 and 0.45, and the humic acid rejections were between 0.72 and 0.97.