Faculty of Energy, Environmental Science and Engineering, University of Science and Technology Beijing, Xueyuan Road 30, Haidian District, Beijing, China.
Faculty of Health Sciences, University of Ljubljana, Zdravstvena pot 5, 1000 Ljubljana, Slovenia.
Chemosphere. 2017 Sep;182:238-244. doi: 10.1016/j.chemosphere.2017.04.125. Epub 2017 May 6.
Stability studies of two avobenzone transformation products: chloro-avobenzone [2-chloro-1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione] and dichloro-avobenzone [2,2-dichloro-1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione] have been performed at different pHs values as well as under UV A light and compared with the stability of avobenzone, one of the mostly used UV A filter present in sunscreens. We have additionally investigated the possibility of application of TiO photocatalysis as a method for the removal of them. Results have shown the differences in pH stability of all three studied compounds with much slower degradation rate under neutral conditions in comparison to the acidic ones for all three studied compounds. In the case of photolytic experiment, performed under UV A light, dichloro-avobenzone exhibited the lowest UVA stability (half-life 22.4 ± 0.7 min), while avobenzone and chloro-avobenzone are much more stable and have shown quite similar degradation pattern (half-lives 126 ± 16 min and 128 ± 25 min). Under the photocatalytic conditions the less stable was dichloro-avobenzone (half-life 14.1 ± 0.6 min), while chloro-avobenzone and avobenzone were much more stable (half-lives 41 ± 3 min and 79 ± 13 min). Dichloroavobenzone is significantly more reactive than avobenzone and its monochloro-derivative. On the basis of the formation of various stable degradation products, including substituted acetophenones, benzoic acids and phenols, identified by GC-MS, the degradation pathway has been proposed.
两种阿伏苯宗转化产物（氯阿伏苯宗[2-氯-1-(4-叔丁基苯基)-3-(4-甲氧基苯基)-1,3-丙二酮]和二氯阿伏苯宗[2,2-二氯-1-(4-叔丁基苯基)-3-(4-甲氧基苯基)-1,3-丙二酮]）在不同 pH 值下以及在 UV A 光下的稳定性研究，并与阿伏苯宗（防晒霜中最常用的 UV A 滤光剂之一）的稳定性进行了比较。我们还研究了 TiO 光催化作为去除它们的方法的可能性。结果表明，所有三种研究化合物在中性条件下的 pH 稳定性存在差异，与所有三种研究化合物的酸性条件相比，降解速度较慢。在 UV A 光下进行的光解实验中，二氯阿伏苯宗表现出最低的 UVA 稳定性（半衰期 22.4±0.7 分钟），而阿伏苯宗和氯阿伏苯宗则更稳定，表现出非常相似的降解模式（半衰期 126±16 分钟和 128±25 分钟）。在光催化条件下，最不稳定的是二氯阿伏苯宗（半衰期 14.1±0.6 分钟），而氯阿伏苯宗和阿伏苯宗则更稳定（半衰期 41±3 分钟和 79±13 分钟）。二氯阿伏苯宗的反应活性明显高于阿伏苯宗及其单氯衍生物。根据 GC-MS 鉴定的各种稳定降解产物（包括取代苯乙酮、苯甲酸和苯酚）的形成，提出了降解途径。
