| 摘要: | 磷酸鹽類在我們的日常生活中無所不在，常被用來作為食品添加劑以及化學肥料，或者是應用在TFT-LCD製程當中的蝕刻液體。當含磷廢液排放入自然水體可能會造成優養化現象，導致水質缺氧惡化。
本研究是以配製磷酸二氫鈉溶液模擬含磷廢液來進行電容去離子實驗，藉由改變不同操作參數：流速、電壓、濃度，以及酸鹼值來探討電容去離子的脫鹽性能。本研究是以製備活性碳電極作為電容去離子的電極材料來對於磷酸鹽類進行電容吸附實驗，並利用pseudo-first-order、pseudo-second-order、Elovich 和intra-particle diffusion四種動力學模式以及Langmuir和Freundlich兩種等溫吸附模式來對用活性碳電吸附磷酸鹽類進行模擬。
活性碳電極經由特性分析的結果顯示出以中孔洞分布居多，且具有良好的電化學穩定性。由電吸附結果得知磷酸鹽類在低流速、1.2伏特下，以及弱酸條件可以達到較優異的電吸附效果。另外在低濃度的條件下進行電吸附則是可以達到較高的脫鹽效果。活性碳電吸附磷酸鹽類的動力學模式符合Elovich 和intra-particle diffusion模式，其等溫吸附模式則是符合Freundlich模式。
;Phosphates are common inorganic salts in our lives and are often used as food additives, chemical fertilizers, etching liquids used in TFT-LCD processes, and etc. When phosphate is discharged into the natural water, it may cause the eutrophication and lead to deterioration of water quality.
In this study, capacitive deionization was employed to remove phosphate. Sodium phosphate (NaH2PO4) solution was prepared to simulate the phosphorus-containing wastewater. Activated carbon were used as electrode material of CDI to adsorb phosphates. The deionization efficiency was investigated by changing flow rate, voltage, initial concentration, and pH. Four kinetic models, including pseudo-first-order, pseudo-second-order, Elovich, and intra-particle diffusion models, were employed to fit the electrosorption kinetic of phosphate and two isotherm models, including Langmuir and Freundlich, were employed to fit the electrosorption equilibrium of phosphate.
The specific surface area and pore size distribution and cyclic voltammogram of the activated carbon electrode showed that the mesopore was the major structure and the AC electrode had good electrochemical stability. The results suggested that slow flow rate, voltage at 1.2 V, and low pH are good for the removal of phosphate by activated carbon electrodes via CDI. The adsorption kinetics could be described by the Elovich and the intra-particle diffusion models, and the Freundlich model agreed with the isotherm for the adsorption of phosphate on activated carbon electrode. |
