Environmental Science and Pollution Research

, Volume 24, Issue 22, pp 18458–18469 | Cite as

Hydroxyl radical-mediated degradation of diclofenac revisited: a computational approach to assessment of reaction mechanisms and by-products

  • Sesil Agopcan Cinar
  • Asu Ziylan-Yavaş
  • Saron Catak
  • Nilsun H. Ince
  • Viktorya Aviyente
Research Article


Advanced oxidation processes (AOPs) are based on the in situ production of hydroxyl radicals (•OH) and reactive oxygen species (ROS) in water upon irradiation of the sample by UV light, ultrasound, electromagnetic radiation, and/or the addition of ozone or a semiconductor. Diclofenac (DCF), one of the emerging organic contaminants (EOC), is of environmental concern due to its abundancy in water and is known to be subjected to AOPs. The current study uses density functional theory (DFT) to elucidate the mechanisms of the reactions between •OH and DCF leading to degradation by-products, P1-P9. The initial encounter of DCF with •OH is proposed to lead to either the abstraction of a hydrogen or the addition of the hydroxyl radical to the molecule. The results showed that OH addition radicals (R add) are both kinetically and thermodynamically favored over H abstraction radicals (R abs). The intermediate radicals give degradation by-products by subsequent reactions. The by-products P7 and P8 are easily formed in agreement with experimental findings. Finally, acute toxicities at three trophic levels are estimated with the Ecological Structure Activity Relationships program. DCF and most of the by-products were found to be harmful to aquatic organisms, P9 being the only by-product that is not harmful at all three trophic levels.


Diclofenac Degradation Toxicity Mechanism DFT Hydroxyl radical Sonolysis 



This work was supported by a grant from Tübitak (214Z198) and by the State Planning Organization of Turkey (DPT-2009K120520). S.A.Ç. acknowledges the TUBITAK BIDEB graduate student scholarship. The computational resources of the High Performance Computing Center and the National Center for High Performance Computing of Turkey (UHeM) under the grant number 5004052016 are gratefully acknowledged.

Supplementary material

11356_2017_9482_MOESM1_ESM.docx (5.7 mb)
ESM 1 (DOCX 5868 kb)


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Copyright information

© Springer-Verlag GmbH Germany 2017

Authors and Affiliations

  • Sesil Agopcan Cinar
    • 1
  • Asu Ziylan-Yavaş
    • 2
  • Saron Catak
    • 1
  • Nilsun H. Ince
    • 2
  • Viktorya Aviyente
    • 1
  1. 1.Department of ChemistryBogazici UniversityIstanbulTurkey
  2. 2.Institute of Environmental SciencesBogazici UniversityIstanbulTurkey

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