title: Effect of low-molecular-weight organic acids on photo-degradation of phenanthrene catalyzed by Fe(III)-smectite under visible light.
abstract: The photolysis of polycyclic aromatic hydrocarbons (PAHs) is potentially an important process for its transformation and fate on contaminated soil surfaces. In this study, phenanthrene is employed as a model to explore PAH photodegradation with the assistance of Fe(III)-smectite under visible-light while focusing on roles played by five low-molecular-weight organic acids (LMWOAs), i.e., malic acid, oxalic acid, citric acid, ethylenediaminetetraacetic acid (EDTA), and nitrilotriacetic acid. Our results show that oxalic acid is most effective in promoting the photodegradation of phenanthrene, while only a slight increase in the rate of phenanthrene photodegradation is observed in the presence of malic acid. Electron paramagnetic resonance experiments confirm the formation of CO2(-) radicals in the presence of malic and oxalic acid, which provides strong evidence for generating OH and subsequent photoreaction pathways. The presence of EDTA or nitrilotriacetic acid significantly inhibits both Fe(II) formation and phenanthrene photodegradation because these organic anions tend to chelate with Fe(III), leading to decreases in the electron-accepting potential of Fe(III)-smectite and a weakened interaction between phenanthrene and Fe(III)-smectite. These observations provide valuable insights into the transformation and fate of PAHs in the natural soil environment and demonstrate the potential for using some LMWOAs as additives for the remediation of contaminated soil.
authors.affiliation: Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011, China. Electronic address: jiahz@ms.xjb.ac.cn.
authors.forename: Hanzhong
authors.initials: H
authors.lastname: Jia
authors.affiliation: Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011, China; School of Geology and Mining Engineering, Xinjiang University, Urumqi 830046, China.
authors.forename: Hongxia
authors.initials: H
authors.lastname: Chen
authors.affiliation: Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011, China; School of Geology and Mining Engineering, Xinjiang University, Urumqi 830046, China.
authors.forename: Gulimire
authors.initials: G
authors.lastname: Nulaji
authors.affiliation: Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011, China.
authors.forename: Xiyou
authors.initials: X
authors.lastname: Li
authors.affiliation: Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011, China. Electronic address: cywang@ms.xjb.ac.cn.
authors.forename: Chuanyi
authors.initials: C
authors.lastname: Wang
mesh_terms: D000144:Acids, Acyclic / Q000737:chemistry*; D002384:Catalysis; D004785:Environmental Pollutants / Q000032:analysis* / Q000528:radiation effects; D005290:Ferric Compounds / Q000737:chemistry*; D008027:Light; D008970:Molecular Weight; D010616:Phenanthrenes / Q000032:analysis* / Q000528:radiation effects; D010782:Photolysis; D017640:Silicates / Q000737:chemistry
chemical_list: D000144:Acids, Acyclic; D004785:Environmental Pollutants; D005290:Ferric Compounds; D010616:Phenanthrenes; D017640:Silicates; C031181:phenanthrene; C033214:Smectite
keywords: Low-molecular-weight organic acids (LMWOAs); Phenanthrene; Smectite; Visible light photodegradation