The aomogeneous and heterogeneous oxidation of organophosphate esters (OPEs) in the atmosphere: Take diphenyl phosphate (DPhP) as an example. (1st May 2023)

• Record Type: Journal Article
• Authors: Huo, Yanru; Li, Mingxue; Jiang, Jinchan; Zhou, Yuxin; Ma, Yuhui; Xie, Ju; He, Maoxia
• Is Part Of: Environmental pollution. Volume 324(2023)
• Publication Date: 2023-05-01
• Subjects: Organophosphate esters (OPEs) -- Ozonolysis -- Titanium dioxide (TiO2) -- Hydroxyl radicals ( -- OH) -- Adsorption; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2023.121395
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Organophosphate esters (OPEs) are widely detected in the atmosphere. However, the atmospheric oxidative degradation mechanism of OPEs has not been closely examined. This work took density functional theory (DFT) to investigate the tropospheric ozonolysis of organophosphates, represented by diphenyl phosphate (DPhP), including adsorption mechanisms on the surface of titanium dioxide (TiO2 ) mineral aerosols and oxidation reaction of hydroxyl groups (·OH) after photolysis. Besides, the reaction mechanism, reaction kinetics, adsorption mechanism, and ecotoxicity evaluation of the transformation products were also studied. At 298 K, the total reaction rate constants k O3, k OH, k TiO2-O3, and k TiO2-OH are 5.72 × 10 −15 cm 3 molecule −1 s −1, 1.68 × 10 −13 cm 3 molecule −1 s −1, 1.91 × 10 −23 cm 3 molecule −1 s −1, and 2.30 × 10 −10 cm 3 molecule −1 s −1 . The atmospheric lifetime of DPhP ozonolysis in the near-surface troposphere is 4 min, much lower than that of hydroxyl radicals (·OH). Besides, the lower the altitude is, the stronger the oxidation is. The TiO2 clusters carry DPhP promoting ·OH oxidation but inhibiting ozonolysis of DPhP. Finally, the main transformation products of this process are glyoxal, malealdehyde, aromatic aldehydes, etc., which are still ecotoxic. The findings shed new light on the atmospheric governance of OPEs. Graphical abstract: Image 1 Highlights: The k tot of DPhP oxidative reaction is k TiO2-OH > k OH > k O3 > k TiO2-OH . The atmospheric lifetime of DPhPs is τ O3 > τ TiO2-OH > τ OH > τ TiO2-O3 at 298 K. DPP on TiO2 clusters is spontaneous chemisorption. The TiO2 clusters promote ·OH oxidation but inhibit ozonolysis of DPhP. The decomposition of DPHP on TiO2 surface forms phenol.