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標題: | 腐植酸官能基特性對薄膜外加電場處理程序之影響 The effect of functional groups of humic acid on the fouling of Electrically enhanced membrane filtration |
作者: | Hsiang-Chieh Tseng 曾湘捷 |
指導教授: | 李公哲 |
關鍵字: | 天然有機物,官能基,羧基,酚基,外加電場薄膜程序,薄膜孔徑, Natural organic matter,Functional group,Carboxylic functional groups,Phenolic functional groups,electric Enhanced membrane process,Pore size, |
出版年 : | 2007 |
學位: | 碩士 |
摘要: | 本研究將腐植質以二級胺陰離子交換樹脂分離成羧基含量較高之水樣與酚基含量較高之水樣,進行UF薄膜外加電場過濾程序,並且於不同膜孔大小之薄膜及電場強度操作下進行實驗操作,以評估腐植質溶液於羧基與酚基不同比率之下對電場過濾之影響。
於施加電場的情況下,過濾通量與去除率方面皆隨電場強度增加而提升,顯見電泳作用能使帶負電之腐植質離開膜面,因此能減緩積垢提升通量,在50KDa及69.93V/cm電場強度操作下,羧基含量較多之水樣可比未加電場增加43.8%之通量,而酚基含量較多之水樣也增加34.9%,外加電場之優勢突顯在NOM之去除率,在300KDa及69.93V/cm電場強度操作下,羧基含量較多之水樣平均DOC去除率可達80.12%,而酚基含量較多之水樣為11.27%,而與未施加電場之NOM去除率比較,羧基含量較高之水樣於過濾前10分鐘即增加50.12%,酚基含量較高之水樣則僅增加17.55%,而上述實驗結果也驗證薄膜外加電場程序可以明顯提高過濾通量及去除效率,且對原水中之腐植質成分含官能基羧基比例較多之情況下,更顯外加電場之UF薄膜過濾應用潛力。再者於SUVA分析方面,羧基含量較高之水樣、酚基含量較高之水樣及腐植質原樣在外加電場薄膜過濾後,SUVA 值皆隨著電場強度的增加而有明顯降低之效果,顯示外加電場對於消毒副產物之有機前質的去除效率呈正相關。但不論施加多少電場強度,去除率仍與薄膜膜孔大小有關,顯示膜孔大小仍是影響去除率高低的重要因素,但於使用大孔徑薄膜時,施加電場能輔助提高去除率;不同官能基比例之水樣於外加電場程序的表現不論是因減緩積垢而增加過濾通量或是去除效率提升的表現,也都是羧基含量較高之水樣比較明顯,與粒子電泳動實驗比較,發現羧基含量較高水樣粒子電泳動能值較高,故可推論粒子電泳動能力與薄膜外加電場程序之成效具正相關性,易言之,也進一步可推論外加電場之UF薄膜過濾應用在腐植質成分含官能基羧基比例較多之原水,可具成本有效性。同時,由SEM分析顯示,含羧基較多之水樣的薄膜會因電泳作用形成結構較為鬆散之濾餅,而可在不影響NOM之去除率下,達成減緩通量衰減之功能。 In this study, humic acid was separated into two water samples: one has higher content of carboxylic functional groups, another has phenolic functional groups by secondary amine anionic exchanger resin. Via electrically enhanced membrane filtration, the efficiency of filtration of humic acid with various ratio of carboxylic and phenolic functional groups under different pore size of membrane and intensity of electric field was investigated. When electric field was applied, flux increased with the strength of the electric field. Employing pore size of 50KDa and electric field strength of 69.93V/cm, the flux of the sample with more carboxylic functional groups has 43.8% higher than that of water sample with no electric filed applied, and the flux of the sample with more phenolic functional groups has increased 34.9%. Electric field applied shows ascendancy on the rejection of NOM. While 300KDa pore size and 69.93V/cm application were employed, the average DOC rejection rates of water sample for higher carboxylic functional groups and for higher phenolic functional groups are 80.12% and 11.27% respectively. Compared the NOM rejection rate with no electric field applied, the former increased 50.12% before filtration, and the latter only increased 17.5%. According to the test results , electrically enhanced membrane filtration can appreciably increased the flux and the rejection, especially on the water sample with higher carboxylic functional groups. Furthermore, via electrically enhanced membrane filtration, SUVA level of the water sample containing higher carboxylic functional groups, higher phenolic functional groups, and humic acid solution would be reduced with increasing strength of electric field. It shows that, electric field applied and organic precursors of disinfection by-products have positive correlation. But, no matter how much strength of electric field was applied, rejection is still relevant to pore size of filter membrane. In briefing, pore size is an important factor to the effectiveness of the rejection. Increasing the flux by slow down the fouling, or the appearance of rejection, no mater in which event, the water with higher carboxylic functional groups has better performance. Comparing the experimental results of electrophoresis, the electrophoretic mobility of water sample with higher carboxylic functional groups is higher than that of phenolic functional groups. A positive correlation between the electrophoretic mobility and the performance of electrically enhanced membrane filtration was recognized. The conclusion could be drawn as: the technique of electrically enhanced membrane filtration is suitable for the water with higher carboxylic functional groups. Besides, SEM analysis shows that higher carboxylic functional groups water would form unstructured filter cake due to electrophoresis, and slow down the declination of flux without affecting the rejection of NOM. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/28842 |
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