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

Ofloxacin is an extensively used efficient antibiotic. However, since it is a refractory pollutant, it is found in water sources, requiring methods to remove it from the environment. Advanced Oxidation Processes (AOPs) offer efficient alternatives since it yields complete degradation not achieved in adsorption or membrane processes. Kinetics of degradation process require monitoring the "pseu-do-order" of it to deliver evaluation of the proposed AOPs. Most studies assume ofloxacin degra-dation follows pseudo-first or -second order processes, whereas for full removal of refractory pol-lutants – lower pseudo-orders are required. This study presents a simple procedure to evaluate pseudo-orders of AOPs. Photolysis of 20 M ofloxacin follows pseudo-zero order, with half-life time (t1/2) of ~ 60 min. Very low TiO2 concentration in heterogeneous catalysis (0.2 mg L-1) has no in-fluence but increasing catalyst to 2.0 mg L-1 reduces t1/2 to 20 min, increasing pseudo-order to 0.8. Similar results are obtained with 2.0 mg L-1 H2O2 homogenous catalysis. Combining H2O2 with TiO2 reduces t1/2, but pseudo-order increases further (1.2). The conclusions are (1) ofloxacin can be ef-fectively degraded by both heterogenous and homogenous photocatalysis, (2) combined photoca-talysis yields higher pseudo-order, being less prone to achieve full removal, (3) analysis of specific pseudo-order in AOPs of refractory pollutants helps to further elucidate the efficiency of the process presented.