Semiconducting mineral induced photochemical conversion of PAHs in aquatic environment: Mechanism study and fate prediction

Zhengqing Cai; Fuquan Yang; Yanyu Song; Yongdi Liu; Wen Liu; Qilin Wang; Xianbo Sun

doi:10.1016/j.scitotenv.2022.160382

Semiconducting mineral induced photochemical conversion of PAHs in aquatic environment: Mechanism study and fate prediction

Sci Total Environ. 2023 Feb 20:860:160382. doi: 10.1016/j.scitotenv.2022.160382. Epub 2022 Nov 30.

Authors

Zhengqing Cai¹, Fuquan Yang², Yanyu Song², Yongdi Liu², Wen Liu³, Qilin Wang⁴, Xianbo Sun⁵

Affiliations

¹ National Engineering Research Center of Industrial Wastewater Detoxication and Resource Recovery, East China University of Science and Technology, Shanghai 200237, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200237, China.
² National Engineering Research Center of Industrial Wastewater Detoxication and Resource Recovery, East China University of Science and Technology, Shanghai 200237, China.
³ The Key Laboratory of Water and Sediment Sciences, Ministry of Education; College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
⁴ Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia.
⁵ National Engineering Research Center of Industrial Wastewater Detoxication and Resource Recovery, East China University of Science and Technology, Shanghai 200237, China. Electronic address: xbsun@ecust.edu.cn.

PMID: 36460111
DOI: 10.1016/j.scitotenv.2022.160382

Abstract

Semiconducting minerals (such as iron sulfides) are highly abundant in surface water, but their influences on the natural photochemical process of contaminants are still unknown. By simulating the natural water environment under solar irradiation, this work comprehensively investigated the photochemical processes of anthracene (a typical Polycyclic Aromatic Hydrocarbons) in both freshwater and seawater. The results show that the natural pyrite (NP) significantly promotes the degradation of anthracene under solar illumination via 1) NP induced photocatalytic degradation of anthracene, and 2) Fenton reaction due to the NP induced photocatalytic generation of H₂O₂. The material characterization and theoretical calculation reveal that the natural impurity in NP enlarges its band gap, which limits the utilization of solar spectra to shorter wavelength. The contribution of generated reactive intermediates on anthracene degradation follows the order of ¹O₂ >OH > O₂^- in freshwater and O₂^- >¹O₂ >OH in seawater. The photochemically generated H₂O₂ is a vital source for OH generation (from Fenton reaction). The steady-state concentration of OH, ¹O₂ and O₂^- in freshwater were monitored as 3.0 × 10^-15 M, 1.1 × 10^-13 M, and 4.5 × 10^-14 M, respectively. However, the OH concentration in seawater can be negligible due to the quenching effects by halides, and the ¹O₂ and O₂^- concentrations are higher than that in freshwater. An anthracene degradation kinetic model was built based on the experimentally determined reactive intermediates concentration and its second order rate constant with anthracene. Moreover, the anthracene degradation pathway was proposed based on intermediates analysis and DFT calculation, and its toxicity evolution during the photochemical process was assessed by quantitative structure-activity relationship (QSAR) based prediction. This finding suggests that the natural semiconducting minerals can affect the fate and environmental risks of contaminants in natural water.

Keywords: Fenton; Natural semiconductors; Natural weathering; PAHs; Photocatalytic.

MeSH terms

Anthracenes
Hydrogen Peroxide*
Minerals
Polycyclic Aromatic Hydrocarbons* / analysis
Water

Substances

Hydrogen Peroxide
Polycyclic Aromatic Hydrocarbons
anthracene
Anthracenes
Minerals
pyrite
Water