以階層孔洞碳材提升電容去離子技術之脫鹽效能分析

Abstract

隨著工業開發及人口迅速增長，人們對水資源的需求量增加，水淡化技術逐漸受到重視。其中，電容去離子技術 (Capacitive deionization, CDI) 是一種新穎的水處理技術，以奈米碳材作為電極，經由電吸附程序，可達到移除水中帶電離子之目的。本研究以三維階層多孔碳球（Three-dimensional hierarchical porous carbon spheres, 3D-HPCS）作為電容去離子技術中的理想電極材料，而3D-HPCS特點為含有階層孔洞結構及良好的三維孔洞通道。研究中將多孔奈米碳材與不同孔洞結構特性的商用碳材相互比較，包含石墨(Graphite)、活性碳(Activated carbon, AC)和有序中孔碳材(Order mesoporous carbon, OMC)。藉由電化學實驗可分析離子於材料孔洞中的電吸附行為，實驗結果顯示3D-HPCS為一個較理想的電極材料，與其他材料相比，具有高的電雙層電容值、快速的離子傳輸通道和低的材料內電阻。除此之外，在CDI實驗中，3D-HPCS電極於0.5 ~ 10 mM 的氯化鈉水溶液中都有好的電吸附容量表現，於低濃度下(0.5 mM)，電吸容量為5.17 mg/g，當濃度提高至10mM時，電吸容量為33.86mg/g。最後由CDI實驗結果可得知3D-HPCS電極和其他材料相比，每單位克重具有較良好的脫鹽能力。因此，3D-HPCS可以作為一個理想的CDI電極材料。本研究結果可以提供新的CDI電極材料之研究方向。

Three-dimensional hierarchical porous carbon spheres (3D-HPCS) are rationally designed as electrode materials for capacitive deionization (CDI). The 3D-HPCS was observed with a hierarchal pores structure by SEM and TEM. As compared to Graphite, AC, and order mesoporous carbon (OMC) electrodes, 3D 3D-HPCS spheres have well pore properties with a specific surface of 644 m2/g and total pore volume of 0.86 cm3/g. In this work, the electrosorption behaviors of 3D-HPC electrode were investigated by the electrochemical experiments, including CV, EIS, GC, at different sodium chloride (NaCl) concentrations. From the experimental results, 3D-HPCS electrode has ideal electrical double layer capacitance and low inner resistance of ion transportation from bulk solution onto the electrode. Furthermore, the electrosorption capacity of 3D-HPCS electrode was 33.86 mg/g at 1.2 V in 10 mM NaCl solution. As evidenced, in comparison with other nanoporous carbon electrodes, the 3D-HPCS electrodes has the highest electrosorption capacity, indicating excellent desalting capability for CDI process. Consequently, the prepared 3D-HPCS electrodes has been demonstrated as a desirable electrode materials for CDI. The results can provide useful information to develop CDI electrode materials.