| 摘要: | 電容去離子(capacitive deionization, CDI)是一個新興的水處理技術，近年來因功能不同而衍生出不同的 CDI 系統，其中透過改變陰極材料形成的混合式電容去離子(hybrid capacitive deionization, HCDI)系統，因為其具有良好的電吸附能力以及離子選擇性而受到人們的關注，在眾多材料中過渡金屬硫化物因其良好的比電容值和豐富的法拉第氧化還原反應，大量的應用在電池電極以及超級電容器當中。
在本研究中使用三元過渡金屬硫化物 CuCo2S4 作為 HCDI 系統的陰極，陽極則使用市售之活性碳粉末吸附水中的銅離子，與單純的活性碳電極做對比。透過循環伏安法進行 CuCo2S4 及活性碳電化學性能分析，發現 CuCo2S4 在水中具有銅離子時，會有氧化還原峰的出現呈現擬電容之特性，並具有比活性碳更高之比電容值。
在 CDI 實驗中，CuCo2S4 表現出比活性碳更好的銅離子吸附能力，之後透過加入離子交換膜與施加反向電壓進行銅離子回收，可以得到 78.04% 之銅離子回收率，具有良好的回收潛力。在競爭吸附實驗中觀察到 CuCo2S4 對於金屬陽離子的吸附量與一般活性碳有不同的結果，在三價鉻、鎳、銅離子的競爭吸附系統中，CuCo2S4 仍可以表現出對二價銅離子的選擇性吸附，影響吸附量多寡的主因不是離子價數以及離子的水合比，而是取決於電極材料對於該金屬離子的吸附能。
;Capacitive deionization (CDI) is an emerging water treatment technology that has, in recent years, evolved into different CDI systems with varying functionalities. Among these is the hybrid capacitive deionization (HCDI) system, which is created by altering the cathode material. HCDI has gained attention due to its excellent electro-adsorption capacity and ion selectivity. Among the many materials used, transition metal sulfides are widely applied in battery electrodes and supercapacitors because of their high specific capacitance and abundant Faradaic redox reactions.
In this study, the ternary transition metal sulfide CuCo2S4 was used as the cathode in an HCDI system, while commercially available activated carbon powder was employed as the anode to adsorb copper ions from water. The performance of the CuCo2S4 cathode was compared to that of the activated carbon electrode. Through cyclic voltammetry, the electrochemical properties of CuCo2S4 and activated carbon were analyzed. It was found that when copper ions were present in water, CuCo2S4 exhibited characteristic of pseudo-capacitance and demonstrated a higher specific capacitance than activated carbon.
In the CDI experiments, CuCo2S4 demonstrated superior copper ion adsorption capacity compared to activated carbon. By incorporating an ion exchange membrane and applying a reverse voltage, a copper ion recovery rate of 78.04% was achieved, indicating strong recovery potential. In competitive adsorption experiments, it was observed that CuCo2S4 showed different adsorption behaviors for metal cations compared to activated carbon. In a competitive system involving trivalent chromium, nickel, and copper ions, CuCo2S4 maintained selective adsorption of divalent copper ions. The primary factor influencing the adsorption capacity was not the ion valence or hydration ratio, but rather the adsorption energy of the electrode material for the specific metal ion. |
