由阳光诱导的微塑料(MPs)的光降解在决定其运输中起着至关重要的作用,命运,以及对水生环境的影响。溶解黑碳(DBC),源自热解碳,由于其强大的光敏能力,可以潜在地介导MPs的光降解。这项研究研究了热解木材衍生的DBC(5mgC/L)对紫外线辐射下水溶液中聚苯乙烯(PS)MPs光降解的影响。结果表明,由于羟基自由基(•OH)和单线态氧(1O2)在苯环上的快速攻击,PSMPs的光降解主要发生在苯环而不是脂肪族链段。DBC的光敏性加速了PSMPs的降解,主要归因于•OH的产量增加,1O2和三重激发态DBC(3DBC*)。值得注意的是,DBC介导的光降解与其分子量(MW)和化学性质有关。含有更多羰基的低MWDBC(<3kDa)产生更多的•OH和1O2,加速了MPs的光降解。然而,高MWDBC(>30kDa)中的高级芳香酚清除·OH并产生更多的O2·-,抑制MPs的光降解。总的来说,这项研究为紫外线诱导的MPs光降解提供了有价值的见解,并强调了DBC对MPs转化的潜在影响。
Photodegradation of microplastics (MPs) induced by sunlight plays a crucial role in determining their transport, fate, and impacts in aquatic environments. Dissolved black carbon (DBC), originating from pyrolyzed carbon, can potentially mediate the
photodegradation of MPs owing to its potent photosensitization capacity. This study examined the impact of pyrolyzed wood derived DBC (5 mg C/L) on the photodegradation of polystyrene (PS) MPs in aquatic solutions under UV radiation. It revealed that the
photodegradation of PS MPs primarily occurred at the benzene ring rather than the aliphatic segments due to the fast attack of hydroxyl radical (•OH) and singlet oxygen (1O2) on the benzene ring. The photosensitivity of DBC accelerated the degradation of PS MPs, primarily attributed to the increased production of •OH, 1O2, and triplet-excited state DBC (3DBC*). Notably, DBC-mediated
photodegradation was related to its molecular weight (MW) and chemical properties. Low MW DBC (<3 kDa) containing more carbonyl groups generated more •OH and 1O2, accelerating the photodegradation of MPs. Nevertheless, higher aromatic phenols in high MW DBC (>30 kDa) scavenged •OH and generated more O2•-, inhibiting the photodegradation of MPs. Overall, this study offered valuable insights into UV-induced
photodegradation of MPs and highlighted potential impacts of DBC on the transformation of MPs.