聚電解質輔助薄膜過濾程序中之離子去除率與結垢分析

Ion Rejection and Fouling Analysis in Polyelectrolyte-Assisted Membrane Filtration Processes

邱垂煥(Chwei-Huann Chiou)

指導教授 ： 莊瑞鑫

元智大學/工程學院/化學工程與材料科學學系/碩士(1998年)

摘要

本論文主要討論以胺基系列之陽離子型水溶性聚電解質（Cationic polyelectrolytes）作為錯合劑。，輔助超過濾程序處理半鹽水與重金屬溶液，聚電解質選用聚乙烯亞胺（Poly（ethyleneine）；PEI），聚氯化己二烯二甲基胺（Poly（diallyl dimethylammnlium chloride ）；PDADMAC）和幾丁聚醣（Chitosan）。實驗中分別探討超過濾操作變數及聚電解質特性，對離子去除率、透過率及薄膜結垢之影響。
在本實驗中，以輔助一超過濾去除溶液中之陰、陽離子和重金屬離子，其離子濃度以毛細管電泳儀分析，而聚合物的量以總有機碳分析儀測定，由實驗結果得知陽離子去除率及總有機碳去除率有隨聚電解質分子量、濃度及pH值增大而增加，而透過液流速則相反。對多成分兩價離子競爭效應中則否。在半鹽水中陽離子最大去除率為70﹪（pH7），陰離子最大去除率為80﹪（pH2.5），而總有機碳去除率及透過率（JV/Jw）大於90﹪，在金屬溶液中pH>7時，Zn2+及Cu2+去除率皆大於80﹪，在多成分兩價離子競爭效應中，pH>8時Zn2+去除率大於80﹪，而Cu2+、Mg2+則不受pH值影響，去除率約在70~80﹪間。此外，由透過液的流速變化，可測得修正結垢指數（Modified fouling index；MFI），其中以幾丁聚醣結垢最嚴重，PDADMAC及PEI次之。
聚電解質再生，先利用酸化法處理再經超過濾程序，可達到很好的效果，而對聚電解質最終處理基本上以電解法可以有效的分離聚合物。

關鍵字

超過濾 ； 聚電解質 ； 去除率

並列摘要

In this paper, three weakly basic polyelectrolytes were used as complexing agents to enhance ultrafiltration (UF) of brackish water and heavy metal-bearing solutions. The polyelectrolytes used were polyethyleneine (PEI), polydiallyl dimethylammnlium chloride (PDADMAC) and chitosan. The influence of operating parameters on ion rejection, flux, and membrane fouling was investigated.
It was shown that the cation rejection and the total organic carbon（TOC） rejection increased with increasing the molecular weight and concentration of polyelectrolytes, and pH. there was a reverse tendency for permeate flux. This was not the case for multiple divalent cation solutions . The experimental results showed that for brackish water the maximum rejection of cation was 70 % (pH 7), the maximum rejection of anion was 80 % (pH 2.5), and both the TOC rejection and permeate flux are greater than 90 %. For the metal solutions, at pH > 7, the rejection of Zn2+ and Cu2+ were both greater than 80 %. For multiple divalent cation conditions, at pH> 8, the rejection of Zn2+ was greater than 80 %, and those of Cu2+and Mg2+ were not affected by pH and was keep nearly constant within 70~80 %. Besides, the optimal condition can be obtained and the membrane fouling It was studied with the modified fouling index (MFI). It was showed that chitosan fouling was the most serious, the PDADMAC was the next. The regeneration of polyelectrolytes could be done by acidification. For final disposal of the polyelectrolytes, the electrolysis method could be applied to destory the polymers.

並列關鍵字

Ultrafiltration ； polyelectrolyte ； Rejection

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