利用乾淨及積垢奈米薄膜去除Carbamazepine、Naproxen與Sulfamethoxazole機制之研究

Abstract

本研究利用奈米薄膜處理程序針對三個目標污染物(Carbamazepine、Naproxenc和Sulfamethoxazole)進行研究，評估其處理效果並決定去除機制。本實驗採取掃流式過濾方式，以減緩通量衰減的速率。利用HPLC進行水樣分析，並使用SEM及AFM分析薄膜表面物化特性改變。 本實驗針對不同pH值及不同積垢物質研究其目標汙染物對於去除率及通量衰減的影響，並分析其溶液與薄膜特性的改變。奈米薄膜的去除機制包含篩除、靜電斥力及吸附，研究結果顯示在不同pH值之下，奈米薄膜處理程序對於三個目標污染物皆有良好的去除率。研究並發現，在pH值較高的情況下，去除率較佳。本研究藉由加入腐植酸跟鈣離子模擬水中天然有機物及金屬離子在過濾程序中的積垢行為；研究結果發現，積垢薄膜去除率較乾淨薄膜低。 在積垢的過程中，因為積垢物質的分子大小比薄膜孔洞大很多，標準阻塞(standard blocking)並不是主要的積垢機制。薄膜積垢主要是由其他的機制所組成的，包含孔洞阻塞(pore blocking)和濾餅生成機制(cake layer formation)。 本次研究中探討薄膜在吸附實驗中的吸附機制，結果顯示薄膜的吸附能力在0.02 到 0.33 μg/cm2之間，乾淨薄膜相較於積垢薄膜有較佳的吸附能力，此結果與文獻所示並不一致。推測因本研究的吸附實驗過程為批次實驗，而在其他的文獻中，吸附能力則是利用過濾過程序所得結果計算出來的，因此，數據處理方法不同，導致乾淨薄膜與積垢薄膜吸附能力趨勢與文獻結果不同。 本實驗利用模式探討不同去除機制的去除率，研究中將實驗數據帶入模式，整合並發展出一個不同的方法來預測積垢後的薄膜孔洞大小，最後利用所得參數與結果來討論機制的去除率。

In this study, three target compounds were used to evaluate the performance of a nanofilter in removing these compounds and to determine the removal mechanisms in the filtration experiment. Nanofiltration membrane was tested under cross-flow module in this research. The concentrations of effluent and membrane properties were characterized using HPLC, SEM, and AFM. This research investigated the effects of solute and membrane characteristics on the rejection and flux decline at various pH values and foulants. The rejection mechanisms of nanofiltration include size exclusion, electrostatic exclusion and adsorption. The fouling membrane was induced by adding the humic acid and calcium to act as natural organic matter and ion to foul the membrane. The filtration processes of the three compounds all have high rejection by the nanofiltration. But in the fouling membrane filtration process, the rejection efficiency of the fouled membrane was not as good as that of the clean membrane. Standard blocking was not the main fouling mechanism for the membranes, which indicated that the molecular size of foulant in the feed solution might larger than that of the membrane pore. Membrane fouling could be brought by the different fouling mechanisms, i.e., pore blocking and cake layer formation. Results from this study revealed that the adsorption capacity of the target compounds ranged from 0.02 to 0.33 μg/cm2. The clean membrane showed a better adsorption capacity than the fouling membrane. The adsorption mechanisms of the nanofiltration process were investigated in this study. The estimated adsorption capacity of the study disagreed with those reported in the literature due in part to the different methods used in conducting the adsorption experiments. The adsorption experiments this study were conducted in batch, whereas other researchers studied the adsorption during filtration runs. The procedure to discuss the rejection and fouling mechanism was studied. In this study develop a procedure including integrating the experimental data and predicted model. The procedure develops a different way to predict the pore size of the clean and the fouled membrane by the experimental design and the model.