摘要
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 (k obs ) 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 k obs and persulfate dose exhibited a linear proportional relationship in the persulfate dose range of 4.2–42 μM. The k obs remained similar at pH 5 and pH 7 but significantly decreased at pH 9. A radical scavenging test indicated that SO 4 − • was the dominant species in 4-MBC degradation; the second-order rate constant of SO 4 − • with 4-MBC was calculated to be (2.82 ± 0.05) × 10 9 M −1 s −1 . During the UV/persulfate reaction, 4-MBC was continuously degraded, while SO 4 − • was gradually converted to SO 4 2− . 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. [Figure not available: see fulltext.]