探討水中銅離子在陽離子交換膜的電對流傳輸特性及應用

The Study on the Transport Characteristics of Copper Cations Through a Cationic Exchange Membrane under Electroconvection Operation and the Application

黃文圻(Wen-Chi Huang)

指導教授 ： 章日行

朝陽科技大學/理工學院/環境工程與管理系/碩士(2010年)

摘要

本研究利用電流-電壓曲線和電化學阻抗譜分析Cu2+離子在陽離子交換膜的電對流傳輸行為，並藉由Cu2+離子在電對流區域之傳輸參數設計一連續式電透析系統處理0.01 M硫酸銅廢水，以評估電對流式電透析的可行性。經結果顯示，在不同硫酸銅濃度下三個典型區域(歐姆、極限和電對流區域)之電流密度皆與銅濃度成正比，而形成極限電流密度和電對流密度所需之薄膜電壓會隨著銅濃度增加而減少；在電場作用之下，歐姆區域和電對流區域之電流–電壓斜率變化一樣，這意味著歐姆區域銅離子的傳輸行為適合說明電對流區域。而交流阻抗譜中，在低頻區域(10-1-100 Hz)，陽離子交換膜的電雙層阻抗(CPEdl)分別依序為極限電流＞歐姆＞電對流，這意味著在電對流作用下可能擾亂薄膜表面擴散邊界層，進而減少電雙層的厚度。由一個溶液阻抗(Rs)、陽離子交換膜容抗(Cm)與其阻抗(Rm)以及常數相位元件(CPEdl)所組成的等效電路適合描述Cu2+離子在薄膜電雙層、薄膜本身與溶液間的傳輸行為。

本研究進一步以不同電流密度為操作參數探討Cu2+離子傳輸行為，結果顯示電對流作用下(依電流-電壓曲線) Cu2+離子的傳輸數與歐姆區域一樣，皆趨近於1，因此電對流操作在電透析系統可能有助於提升離子的傳輸效率；應用電對流操作於電透析系統 (依據傳輸數試驗之數據設計)，可有效移除水中銅離子，且陽離子交換膜於吸附飽和狀態下，Cu2+離子仍可傳輸過離子交換膜。

關鍵字

陽離子交換膜 ； 電透析 ； 電對流 ； 電化學阻抗譜 ； 傳輸數

並列摘要

This study has to discuss the transport characteristics of copper cations with the cationic exchange membrane (CEM) by the current-voltage relation (I-V curve) and the electrochemical impedance spectroscopy (EIS). The continuous electrodialysis treatment was designed by the transport characteristics of treating copper wastewater (0.01 M) under the electroconvection operation and for evaluating the feasibility.

The results of the current density was positive correlation between the copper concentration under the three classic regions that are ohmic, limiting current and electroconvection regions. The limiting current density and electroconvection current density of CEM voltage were reduced with the copper concentration increased. The I/V ratio of the ohmic and electroconvection regions are the same under the electric field condition that means the transport behavior of copper is applicable to description the ohmic and electroconvection regions. From the EIS diagrams, the magnitude order of the capacitance associated with the double layer (Cdl) is limiting current > ohmic > electroconvection. This implies the electroconvection may disturb the interface of the membrane and result in the reducing thickness of the double layer. An equivalent circuit composed of the Rs, Cm and Rm (parallel circuit represents the CEM), and constant phase element is quite suitable to describe the Cu2+ transport behaviors of the CEM-solution system.

This study has to discuss the transport behavior of copper cations in the different current density. The results were indicated the transport number of copper cations in the electroconvention region (according to I-V tests) is quite identical (namely 1.0). Therefore, the membrane may become more conductive during the electroconvection operation. In addition, Cu2+ ions still can penetrate through the CEM under the saturated condition and still maintain a stable cation removal efficiency rate.

並列關鍵字

Electrodialysis ； Cationic Exchange Membrane ； Electroconvection ； Electrochemical Impedance Spectroscopy ； Transport Number

參考文獻

黃鯤鵬，「以交流阻抗分析法量測高方向性氧化鋅奈米柱陣列電性之研究」，碩士論文，國立成功大學化學工程研究所，台南市 (2006)

林暐智，「超級電容器交流阻抗分析與燃料電池車之能量管理系統設計」，碩士論文，國立清華大學動力機械工程學系，新竹市 (2006)。

黃俊傑，「交流阻抗法研究含氯環境下苯駢三氮五圜對銅之腐蝕抑制行為」，碩士論文，元智大學化學工程研究所，桃園縣 (2002)。

Bouhidel, K.E. and Oulmi, K. “Concentration Polarization in Electrodialysis: Buffer Solutions Experimental Method,” Desalination, Vol. 132, pp. 199-204 (2000).

Bouchekima, B. “Solar Desalination Plant for Small Size use in Remote Arid Area of South Algeria for the Production of Drinking Water,” Desalination, Vol. 156, No.1-3, pp. 353-354 (2003).