利用金屬氧化物活化過硫酸鹽降解2,4-二氯酚

Abstract

過硫酸鹽包含過單硫酸鹽 (PMS) 和過二硫酸鹽 (PDS) ，已被做為高級氧化程序 (advanced oxidation processes, AOPs) 之氧化劑。由於過硫酸鹽結構特性穩定，因此需透過活化產生自由基或其他反應性物質進行污染物的降解。文獻中已指出過硫酸鹽降解污染物的機制主要可以分為自由基途徑 (radical pathway) 及非自由基途徑 (non-radical pathway) 。本研究使用氧化銅 (CuO) 、氧化鎂 (MgO) 、四氧化三鐵 (Fe3O4) 、銅鐵複合氧化物 (CuFe2O4) 、鎂鐵複合氧化物 (MgFe2O4) 及銅鎂鐵複合氧化物 (CuβMgγFeφO) 活化過硫酸鹽去除水中之2,4-二氯酚，並探討在不同劑量下，2,4-二氯酚的降解效率以及系統中存在之活性物質。研究結果指出，使用CuβMgγFeφO (100 mg/L) 活化PMS (1000 μM) 時，可以在90分鐘內完全去除2,4-二氯酚 (50 μM) 。此反應的反應速率會隨著PMS的初始濃度及CuβMgγFeφO劑量的增加而加快。透過XPS表面分析、自由基捕捉實驗及電子自旋共振分析，發現硫酸根自由基 (sulfate radical, SO4•−) 和單線態氧 (singlet oxygen, 1O2) 及三價銅離子 (≡Cu3+–O–Cu3+≡) 存在於CuβMgγFeφO活化PMS降解2,4-二氯酚之系統中，其中以1O2為主要之反應性物質，因此可以判斷此降解機制主要藉由非自由基途徑進行。

Persulfates, including peroxymonosulfate (PMS) and peroxydisulfate (PDS), have been used as the oxidants in the advanced oxidation processes (AOPs). Persulfates are stable in water and require activation to generate radicals or other reactive species for pollutant degradation. Persulfates degradation can be classified into radical and non-radical pathways. In this research, the removal efficiency of 2,4-dichlorophenol (2,4-DCP) by metal oxide-activated persulfates was investigated. Six metal oxides including CuO, MgO, Fe3O4, CuFe2O4, MgFe2O4, and CuβMgγFeφO were employed. The results showed that CuβMgγFeφO-activated PMS achieved the most effective degradation of 2,4-DCP. The degradation kinetics increased with the increasing initial PMS concentration and the dosage of CuβMgγFeφO. XPS surface analysis, radical quenching tests, and electron paramagnetic resonance (EPR) experiments indicated the presence of sulfate radical (SO4•−), singlet oxygen (1O2), and ≡Cu3+–O–Cu3+≡ in the system, in which 1O2 was identified as the primary reactive species for 2,4-DCP degradation. The results suggested that the activation of PMS by CuβMgγFeφO for the degradation of 2,4-DCP primarily proceeds as a non-radical process.