摘要:
溢油事故发生后喷洒溢油分散剂是常用的应急措施之一,这使得溢油分散剂中的表面活性剂与石油中的重要污染物多环芳烃(PAHs)在海水中共存。光化学转化是水中PAHs的重要转化途径,这些共存表面活性剂如何影响PAHs在海水中的光化学消减还有待阐明。本研究选取溢油分散剂的重要活性成分吐温80和石油中2种不同类型的PAHs(菲和二苯并噻吩),通过光化学实验考察不同浓度吐温80对菲(PHE)和二苯并噻吩(DBT)在海水中的光降解速率常数和光解量子产率的影响,并通过量子化学计算的手段研究其影响机制。研究发现:吐温80可以使PHE和DBT的阳离子自由基回到稳定的基态,降低PHE和DBT的光解量子产率,从而抑制PHE和DBT的光降解。该结果表明,在评价溢油分散剂的风险性时不可忽视其对PAHs环境转化行为的影响。
Abstract:
Spraying a large amount of oil spill dispersants is one of the most common ways to deal with oil spill accidents, which lead to the coexistence of surfactants and polycyclic aromatic hydrocarbon (PAHs) pollutants from spilled oil. Photodegradation is a main transformation pathway of PAHs in sea water. However, effects of the surfactants on the photodegradation of PAHs in sea water are still need further clarification. In this study, a common surfactant in oil spill dispersants, Tween 80, was selected to investigate its effects on the photodegradation rates and quantum yields of two typical PAHs in oil, i.e., phenanthrene (PHE) and dibenzothiophene (DBT). The influence mechanism of Tween 80 was probed by the quantum calculation. The results showed that Tween 80 decreased the photodegradation rates of PHE and DBT, due to decreasing the quantum yields of PHE and DBT by reacting with the PAH cation radicals. It is indicated that the effects of the oil spill dispersants on the environmental transformation of PAHs should be considered when assessing its environmental risks.
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