Degradation of 1,4-dioxane in water using activated persulfate by different electrodes

[[abstract]]近年來，電化學過硫酸鹽氧化法開始被應用於廢水中有機污染物之處理，然而可能影響該系統去除污染物之因子及污染物去除之反應機制尚未被完整研究。本研究以批次實驗評估電化學過硫酸鹽氧化法對1,4-二氧陸圜(1,4-dioxane)之去除效率。由於1,4-dioxane極難降解，研究初期先以偶氮染料Reactive Black 5 (RB-5)進行測試，瞭解可行條件以做為後續1,4-dioxane處理之參考。本研究主要目的包含：(1)評估以不同電極/電壓下對過硫酸鹽試驗；(2)評估不同電極材料(Pt、Ti和石墨)活化過硫酸鹽去除水中RB-5和1,4-dioxane之影響；(3)瞭解1,4-dioxane於槽體中DOC濃度變化；及(4)電極特性對於去除RB-5和1,4-dioxane之效果。 不同電壓下活化過硫酸鹽實驗結果顯示，供應不同電壓下對過硫酸鹽降解效率為10V > 7 V > 5 V > 3 V > 1 V，證實施加電壓後應可活化活化過硫酸鹽。不同電壓條件下對RB-5去除實驗結果顯示，RB-5去除效率在10 V皆比其他伏特數高，顯示高伏特數時陰極提供之電子可有效活化過硫酸鹽。然而，單純氧化組與加電驅動過硫酸鹽氧化組對1,4-dioxane降解效率，石墨電極跟鉑/鈦電極比較後，鉑/鈦電極降解去除較好。將氧化劑調高為50 mM時，鉑/鈦電極在10 V下，在反應時間240分鐘後，1,4-dioxane之去除效率可得到99 %，相反石墨電極在氧化劑50 mM於10 V下，在反應時間240分鐘後，1,4-dioxane之去除效率為92%。實驗結果顯示，鉑/鈦電極在對降解1,4-dioxane有著很大的效用。未來將以增加電極表面積，以提升污染物去除能力與速率。電化學過硫酸鹽受限於許多因子，可能導致其降解效果變差，但在應用上仍有一定的潛力，本研究成果將有助於電化學氧化法未來之應用之可行性。[[abstract]]In recent years, electrochemical persulfate oxidation has been applied to the treatment of organic pollutants in wastewater. However, the mechanisms of the removal of pollutants in the system has not been well studied. In this study, batch experiments were performed to remove 1,4-dioxane and Reactive Black 5 (RB5) by electrochemical persulfate oxidation. The objectives of this study were to： (1) evaluate the activation/reaction of persulfate at different voltages. (2) assess the efficiency of electro-activated persulfate for the degradation of RB-5 and 1,4-dioxane using platinum, graphite, and TiO2 electrodes at different voltages. (3) assess the mineralization of 1,4-dioxane and RB5 degradation by electro-activated persulfate at different voltages. The experimental results of persulfate activation under different voltages show that the decomposition efficiency of persulfate under different voltages was 10 V > 7V > 5 V > 3 V > 1 V. The results demonstrate that the application of voltage can activate persulfate. The RB-5 removal was higher at 10 V than other voltages. The high voltages provided more electrons to the anode that effectively activated persulfate to remove the contaminant. The Pt/Ti electrodes had better performance for 1,4-dioxane degradation than graphite electrodes. When the concentration of persulfate increased to 50 mM, the removal efficiency of 1,4-dioxane by the Pt/Ti electrodes at 10 V reached 99% while the graphite electrodes caused 92% of 1,4-dioxane removal after 240 min of reaction. Electrode areas needs to be increase to enhance the removal of the contaminants in the future. Electrochemical persulfate oxidation is limited by many factors, which may affect the degradation of contaminants. However, this technology still has its potential for application. The results of this study will contribute to the future application of electrochemical persulfate oxidation.[[note]]碩