A systematic study of the effects of solvents on phenanthrene photooxidation Ravi Shankar a, b , Joon Geon An a , Andrew Loh a, b , Un Hyuk Yim a, b, * a Oil & POPs Research Group, Korea Institute of Ocean Science & Technology, Geoje 53201, Republic of Korea b Marine Environmental Science, Korea University of Science and Technology, Daejeon 34113, Republic of Korea highlights graphical abstract  Solvent effects on the photooxidation of phenanthrene were elucidated.  Tiered instrumental analysis was applied to identify photooxidation products.  Photooxidation rate was higher in non-polar solvents than in polar solvents.  Acetonitrile produced photooxidation-interfering compounds.  A solvent selection guide for photo- oxidation was provided. article info Article history: Received 12 September 2018 Received in revised form 28 December 2018 Accepted 30 December 2018 Available online 2 January 2019 Handling Editor: Keith Maruya Keywords: Phenanthrene Photooxidation Solvents Photoproducts FTIR GCeMS abstract A systematic study of the photooxidation of phenanthrene under simulated environmental conditions was conducted in vitro using polar (methanol, acetonitrile) and non-polar (isooctane, hexane) solvents as media. In all solvents, phenanthrene concentration decreased exponentially as exposure time increased. Fourier-transform infrared spectroscopy (FTIR) and gas chromatographyemass spectrometry (GCeMS) analysis were used to investigate the structural changes induced by photooxidation. After 24 h of photooxidation, FTIR showed the formation of characteristic bands of carboxylic acid in all solvents. In non-polar solvents, characteristic phenanthrene peaks were completely depleted after 48 h. In polar solvents, phenanthrene peaks disappeared at a slower rate, with peaks in acetonitrile disappearing at 72 h and methanol persisting at trace levels at 96 h. The reaction rate was higher in non-polar solvents. The obtained half-lives were observed in the following order: isooctane (13.2 h) > hexane (13.5 h) > methanol (18.0 h) > acetonitrile (22.8 h). FTIR and GCeMS results were in good agreement and showed the formation of carboxylic acids, aldehydes, and ketones in polar solvents and carboxylic acids, alkanes, and alkanoic acids in non-polar solvents. Products such as primary amides induced by solvent effects were observed in acetonitrile. Based on the results, the solvents were rated and a solvent selection guide for photooxidation of PAHs was provided. © 2019 Elsevier Ltd. All rights reserved. 1. Introduction Polycyclic aromatic hydrocarbons (PAHs) are toxic and ubiqui- tous environmental pollutants (National Research Council, 1983) that are derived from natural sources including volcanoes and * Corresponding author. Marine Environmental Science, Korea University of Sci- ence and Technology, Daejeon 34113, Republic of Korea. E-mail address: uhyim@kiost.ac.kr (U.H. Yim). Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere https://doi.org/10.1016/j.chemosphere.2018.12.206 0045-6535/© 2019 Elsevier Ltd. All rights reserved. Chemosphere 220 (2019) 900e909