赤铁矿
光解
电子顺磁共振
光降解
傅里叶变换离子回旋共振
光激发
激进的
溶解有机碳
环境化学
单线态氧
电喷雾电离
化学
质谱法
矿物学
光催化
光化学
氧气
核磁共振
有机化学
激发态
催化作用
物理
核物理学
色谱法
作者
Xiaopeng Huang,Duo Song,Qian Zhao,Robert P. Young,Ying Chen,Éric Walter,Nabajit Lahiri,Sandra D. Taylor,Zheming Wang,Kirsten Hofmockel,Fernando L. Rosario‐Ortiz,Gregory V. Lowry,Kevin M. Rosso
标识
DOI:10.1021/acs.est.3c08752
摘要
Solar photoexcitation of chromophoric groups in dissolved organic matter (DOM), when coupled to photoreduction of ubiquitous Fe(III)-oxide nanoparticles, can significantly accelerate DOM degradation in near-surface terrestrial systems, but the mechanisms of these reactions remain elusive. We examined the photolysis of chromophoric soil DOM coated onto hematite nanoplatelets featuring (001) exposed facets using a combination of molecular spectroscopies and density functional theory (DFT) computations. Reactive oxygen species (ROS) probed by electron paramagnetic resonance (EPR) spectroscopy revealed that both singlet oxygen and superoxide are the predominant ROS responsible for DOM degradation. DFT calculations confirmed that Fe(II) on the hematite (001) surface, created by interfacial electron transfer from photoexcited chromophores in DOM, can reduce dioxygen molecules to superoxide radicals (•O2–) through a one-electron transfer process. 1H nuclear magnetic resonance (NMR) and electrospray ionization Fourier-transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) spectroscopies show that the association of DOM with hematite enhances the cleavage of aromatic groups during photodegradation. The findings point to a pivotal role for organic matter at the interface that guides specific ROS generation and the subsequent photodegradation process, as well as the prospect of using ROS signatures as a forensic tool to help interpret more complicated field-relevant systems.
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