4-Methylbenzylidene camphor (4-MBC), a widely used ultraviolet (UV) filter detected in various aquatic environments, has been shown to evoke estrogenic activity. In this study, the use of UV light-activated persulfate for 4-MBC degradation is evaluated for the first time. Our results showed that the combination of UV and persulfate (UV/persulfate) can significantly remove 4-MBC, with a pseudo-first-order rate constant (kobs) of 0.1349 min-1 under the conditions of [4-MBC]0 = 0.4 μM, [persulfate]0 = 12.6 μM, and initial pH = 7. The kobs and persulfate dose exhibited a linear proportional relationship in the persulfate dose range of 4.2-42 μM. The kobs remained similar at pH 5 and pH 7 but significantly decreased at pH 9. A radical scavenging test indicated that SO4-• was the dominant species in 4-MBC degradation; the second-order rate constant of SO4-• with 4-MBC was calculated to be (2.82 ± 0.05) × 109 M-1 s-1. During the UV/persulfate reaction, 4-MBC was continuously degraded, while SO4-• was gradually converted to SO42-. 4-MBC degradation involved the hydroxylation and demethylation pathways, resulting in the generation of transformation byproducts P1 (m/z 271) and P2 (m/z 243), respectively. The Microtox® acute toxicity test (Vibrio fischeri) showed increasing toxicity during the UV/persulfate degradation of 4-MBC. The 4-MBC degradation rate was markedly lower in outdoor swimming pool water than in deionized water. Graphical abstract.

中文翻译：

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紫外活化过硫酸盐氧化降解4-甲基亚苄基樟脑的动力学和机理。

4-甲基亚苄基樟脑（4-MBC）是在各种水生环境中检测到的一种广泛使用的紫外线（UV）过滤器，已显示出雌激素活性。在这项研究中，首次评估了UV光活化过硫酸盐对4-MBC降解的用途。我们的结果表明，在[4-MBC] 0 =的条件下，UV和过硫酸盐（UV /过硫酸盐）的组合可以显着去除4-MBC，其假一阶速率常数（kobs）为0.1349 min-1。 0.4μM，[过硫酸盐] 0 = 12.6μM，初始pH =7。在过硫酸盐剂量范围为4.2-42μM时，kobs和过硫酸盐剂量呈线性比例关系。在pH 5和pH 7时，穗轴保持相似，但在pH 9时，穗轴显着降低。自由基清除测试表明，SO4-•是4-MBC降解的主要物质。SO4-•与4-MBC的二阶速率常数经计算为（2.82±0.05）×109 M-1 s-1。在UV /过硫酸盐反应过程中，4-MBC连续降解，而SO4-•逐渐转化为SO42-。4-MBC降解涉及羟基化和去甲基化途径，分别导致转化副产物P1（m / z 271）和P2（m / z 243）的产生。Microtox®急性毒性试验（费氏弧菌）显示4-MBC的UV /过硫酸盐降解过程中毒性增加。室外游泳池水中的4-MBC降解速率明显低于去离子水中。图形概要。4-MBC降解涉及羟基化和去甲基化途径，分别导致转化副产物P1（m / z 271）和P2（m / z 243）的产生。Microtox®急性毒性试验（费氏弧菌）显示4-MBC的紫外线/过硫酸盐降解过程中毒性增加。室外游泳池水中的4-MBC降解速率明显低于去离子水中。图形概要。4-MBC降解涉及羟基化和去甲基化途径，分别导致转化副产物P1（m / z 271）和P2（m / z 243）的产生。Microtox®急性毒性试验（费氏弧菌）显示4-MBC的紫外线/过硫酸盐降解过程中毒性增加。室外游泳池水中的4-MBC降解速率明显低于去离子水中。图形概要。