螯合劑存在對陽離子交換樹脂交換容量與分離效率之影響

Effect of Added Complexing Agents on Exchange Capacity and Separation Efficiency of Cationic Resins

王怡杰(Yi-Chieh Wang)

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(2001年)

摘要

在工業製程用水或廢水中，有些會同時存有重金屬離子及一些水溶性有機螯合劑，例如電鍍及印刷電路板等加工業、化學清洗液及受重金屬污染土壤復育用之淋洗液等。本文主要是討論不同量(a = 0~1)螯合劑(EDTA、NTA、IDA、Citrate)存在下，對陽離子交換樹脂處理重金屬溶液(Cu2+、Ni2+、Zn2+、Co2+)效能的影響。
單成分金屬離子溶液中，螯合劑會與金屬形成負價金屬螯合物而降低交換量。影響的程度與金屬離子濃度、螯合劑種類、螯合劑與金屬離子之濃度比值及pH值有關。另外，我們藉由實驗結果，以質能均衡計算出螯合劑存在時金屬對樹脂的結合常數，並與實驗結果作比較。
雙成分金屬離子溶液中，加入螯合劑會因金屬螯合物結合常數的不同，有助於選擇性分離；在探討各種螯合劑對Zn2+/Cu2+，Ni2+/Cu2+，Co2+/Cu2+雙成分系統選擇性交換的影響時，定義選擇係數為兩金屬交換量比值除以初濃度比值。在這樣的系統下，螯合劑可視為一種遮蔽劑(Masking agent)，其對選擇性係數增強的效果可達1.5~120倍，將所得結果整理後，可歸納出結合常數大小及結合常數差值對選擇性分離的影響，可供為日後實際應用或相關研究的初步參考。

關鍵字

交換容量 ； 選擇性分離 ； 重金屬 ； 螯合劑 ； 陽離子交換樹脂

並列摘要

Effluents containing heavy metals and water-soluble or complexing agents are often encountered in many industries, e.g., electroplating, metal finishing, printed circuit board processing, chemical cleaning, and washing remediation of metal-polluted soils. The effects of different dosages of complexing anions such as EDTA, NTA, IDA, and citrate on cation exchange of Cu2+, Co2+, Ni2+, and Zn2+ with strong acid resins were investigated of the research.
For single-metal systems, the amount of metal exchange decreased because of the formation of metal-complexed anions between complexing anions and metal ions. The extent of decrement depended on the concentration of metal ions, type of complexing anions, molar concentration ratio of metal to complexing ion, and solution pH. Besides, exchange equilibrium constants between the resins and metal ions were calculated.
For binary metal systems, selective separation was enhanced by adding of complexing anions due to the difference between their overall formation constants. Complexing anions acted as the masking agents in binary metal systems. Selectivity factor b was enhanced ranging from 1.5 to 120 times under the conditions studied. The present results revealed promising application potentials for metal separation.

並列關鍵字

exchange capacity ； selectivity separation ； heavy metal ； complexing agent ； cationic resin ； EDTA ； NTA ； citrate

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