Preprint Article Version 2 Preserved in Portico This version is not peer-reviewed

Evaluation of Kinetic Pseudo-Order in the Photocatalytic Degradation of Ofloxacin

Version 1 : Received: 29 November 2021 / Approved: 30 November 2021 / Online: 30 November 2021 (14:37:14 CET)
Version 2 : Received: 14 December 2021 / Approved: 15 December 2021 / Online: 15 December 2021 (08:24:46 CET)

A peer-reviewed article of this Preprint also exists.

Rytwo, G.; Zelkind, A.L. Evaluation of Kinetic Pseudo-Order in the Photocatalytic Degradation of Ofloxacin. Catalysts 2022, 12, 24. Rytwo, G.; Zelkind, A.L. Evaluation of Kinetic Pseudo-Order in the Photocatalytic Degradation of Ofloxacin. Catalysts 2022, 12, 24.


Ofloxacin is a highly efficient and widely used antibiotic drug. It is classified as a refractory pollutant due to its poor biodegradability. Consequently, it is commonly found in water sources, requiring efficient methods for its removal. Advanced Oxidation Processes (AOPs) offer efficient alternatives since those yield complete degradation not achieved in adsorption or membrane processes. Previous studies suggest ofloxacin degradation follows a pseudo-first or -second order processes, whereas for full removal of refractory pollutants – lower pseudo-orders are required. Monitoring the actual “pseudo-order” degradation kinetics of ofloxacin is needed to evaluate any proposed AOP process. This study presents a simple procedure to evaluate pseudo-orders of AOPs. Photolysis of 20 mM ofloxacin solutions follow pseudo-zero order kinetics, with half-life times (t1/2) of approx. 60 min. TiO2 heterogenous catalyst show to have no influence at low concentration (0.2 mg L-1) but a significant reduction of half-life time (t1/2 = 20 min) and increase in pseudo-order (0.8) is measured at 2.0 mg L-1. Similar results are obtained with homogenous catalysis by 2.0 mg L-1 H2O2. The combination of H2O2 and TiO2 catalysts shows additional reduction in half-time life with increase in the pseudo-order to 1.2. The conclusions are (1) heterogenous and homogenous photocatalysis can effectively degrade ofloxacin, (2) combined photocatalysis yields higher pseudo-order, being less prone to achieve full removal, (3) analysis of specific pseudo-orders in AOPs of refractory pollutants helps to further elucidate the efficiency of the processes.


ofloxacin; rate-law; pseudo-order; half-life time; homogeneous catalysis; heterogeneous catalysis; photodegradation


Chemistry and Materials Science, Chemical Engineering

Comments (1)

Comment 1
Received: 15 December 2021
Commenter: Giora Rytwo
Commenter's Conflict of Interests: Author
Comment: The article was peer reviewed, revision was recommended, The attached version is after introducing reviewers' suggestions
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