Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, Tianjin Key Laboratory of Urban Ecology Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China.
Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, Tianjin Key Laboratory of Urban Ecology Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China.
Chemosphere. 2018 Dec;212:784-793. doi: 10.1016/j.chemosphere.2018.08.127. Epub 2018 Aug 28.
The chlorinated phenoxy herbicide of 2,4-dichlorophenoxyacetic acid (2,4-D) was oxidized by thermally activated persulfate (TAP). This herbicide was studied for different persulfate dosages (0.97-7.29 g L), for varying initial pH levels (3-12) and temperatures (25-70 °C). Compared with Fe/PS, TAP could achieve a higher total organic carbon (TOC) removal under wider pH ranges of 3-12. Increasing the mole ratio of PS to 2,4-D favored for the decay of 2,4-D and the best performance was achieved at the ratio of 50. The 2,4-D degradation rate constant highly depended on the initial pH and temperature, in accordance with the Arrhenius model, with an apparent activation energy of 135.24 kJ mol. The study of scavenging radicals and the EPR confirmed the presence of both SO and OH. However, SO was the predominant oxidation radical for 2,4-D decay. The presence of both Cl and CO inhibited the degradation of 2,4-D, whereas the effect of NO could be negligible. Verified by GC/MS, HPLC and ion chromatography, a possible degradation mechanism was proposed.
2,4-二氯苯氧乙酸（2,4-D）的氯化苯氧类除草剂被热激活过硫酸盐（TAP）氧化。研究了不同过硫酸盐剂量（0.97-7.29 g/L）、不同初始 pH 值（3-12）和温度（25-70°C）下的这种除草剂。与 Fe/PS 相比，TAP 可以在更宽的 pH 值范围 3-12 下实现更高的总有机碳（TOC）去除率。增加 PS 与 2,4-D 的摩尔比有利于 2,4-D 的衰减，在摩尔比为 50 时达到最佳性能。2,4-D 的降解速率常数高度依赖于初始 pH 值和温度，符合阿仑尼乌斯模型，表观活化能为 135.24 kJ/mol。自由基清除和 EPR 的研究证实了 SO 和 OH 的存在。然而，SO 是 2,4-D 衰减的主要氧化自由基。Cl 和 CO 的存在都抑制了 2,4-D 的降解，而 NO 的影响可以忽略不计。通过 GC/MS、HPLC 和离子色谱验证，提出了一种可能的降解机制。
