Please cite this article in press as: M. ˇ Cizmi ´ c, et al., Kinetics and degradation pathways of photolytic and photocatalytic oxidation of the anthelmintic drug praziquantel, J. Hazard. Mater. (2016), http://dx.doi.org/10.1016/j.jhazmat.2016.04.065 ARTICLE IN PRESS G Model HAZMAT-17673; No. of Pages 13 Journal of Hazardous Materials xxx (2016) xxx–xxx Contents lists available at ScienceDirect Journal of Hazardous Materials journal homepage: www.elsevier.com/locate/jhazmat Kinetics and degradation pathways of photolytic and photocatalytic oxidation of the anthelmintic drug praziquantel Mirta ˇ Cizmi ´ c a,∗ , Davor Ljubas b,∗∗ , Lidija ´ Curkovi ´ c c , Irena ˇ Skori ´ c d , Sandra Babi ´ c a a Department of Analytical Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Croatia b Department of Energy, Power Engineering and Environment, Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Croatia c Department of Materials, Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Croatia d Department of Organic Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Croatia h i g h l i g h t s • Degradation of scarcely investigated anthelmintic praziquantel (PZQ) was studied. • UV photolysis and photocatalytic oxi- dation on TiO 2 film with H 2 O 2 were used. • UV-C/TiO 2 /H 2 O 2 process yielded the highest degradation rate of PZQ. • Five degradation products were detected during the performed experiments. • Tentative structural formulae for degradation products were proposed. g r a p h i c a l a b s t r a c t a r t i c l e i n f o Article history: Received 5 February 2016 Received in revised form 13 April 2016 Accepted 26 April 2016 Available online xxx Keywords: Pharmaceuticals Praziquantel Photolysis and photocatalysis Titanium dioxide film Photodegradation pathway a b s t r a c t In this study, an anthelmintic drug, praziquantel(PZQ), was degraded using the direct photolysis, pho- tocatalysis, and oxidation processes including UV radiation, TiO 2 film, and hydrogen peroxide. The photolytic degradation with predominant wavelengths of 185/254 nm (UV-C) proved to be more effi- cient with a half-life of 3.13 min compared to the radiation of 365 nm (UV-A) where the degradation did not occur. In order to enhance the rate of PZQ photolytic degradation, H 2 O 2 was added, which resulted in two to three times higher degradation rates. In the photocatalytic degradation, TiO 2 film was used as catalyst. The degradation was ten times faster in the photocatalytic experiments where UV-C light (k = 0.2390 min −1 ) was used than in those with UV-A (k = 0.0201 min −1 ). Comparing the results from all performed experiments it can be concluded that the UV-C/TiO 2 /H 2 O 2 process yielded the highest degradation rate and complete degradation of PZQ was obtained in less than 7 min. The degradation of PZQ followed the first order kinetics in all the experiments. The photo degradation ∗ Corresponding author at: Department of Analytical Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Maruli ´ cev trg 19, 10000 Zagreb, Croatia. ∗∗ Corresponding author at: Department of Energy, Power Engineering and Environment, Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Luˇ ci´ ca 5, 10000 Zagreb, Croatia. E-mail addresses: mzrncic@fkit.hr (M. ˇ Cizmi ´ c), davor.ljubas@fsb.hr (D. Ljubas). http://dx.doi.org/10.1016/j.jhazmat.2016.04.065 0304-3894/© 2016 Elsevier B.V. All rights reserved.