Microwave discharge electrodeless mercury lamp (Hg-MDEL): An energetic, mechanistic and kinetic approach to the degradation of Prozac®

Abstract

A photochemical reactor composed of an Hg-MDEL was applied in photodegradation studies of fluoxetine (Prozac®). The reactor exhibited to be an efficient hydroxyl radical generation system, since the O•H quantification studies conducted with coumarin (COU), 4-hydroxycoumarin (4HC) and 7-hydroxycoumarin (7HC) solutions resulted in the kinetics constant of formation of O•H kOH = 3.14 ± 0.18 min−1. When the Hg-MDEL reactor was applied for degradation of Prozac®, the study of variation of the microwave power allowed a significant increase in the rate of degradation of the Prozac®, indicating that the hydroxyl radical formation is optimized through the adjustment of this parameter. An increase in the initial concentration of Prozac from 33 to 134 μmol L−1 resulted in a 21% decrease in the kinetic constant value, the mean kinetic constant was k = 10.64 ± 1.25 min −1 and R 2 = 0.943 ± 0.131. The Prozac® photodegradation studies showed that the application of the pseudo-first-order kinetics should be limited to the time of up to 0.50 min for the respective system, due to the influence exerted by the transformation products. In general, the total removal of Prozac® was 100% for its highest concentration (134 μmol L−1) at the time of 0.75 min. As for the solution of Prozac® 101 μmol L−1, the energy consumption was 6 kW h g−1, achieving a removal of 99%. Finally, the photochemical system presented in this work demonstrates a high efficiency in the formation of hydroxyl radicals, a high degradation rate of organic compounds (Prozac®, COU and 7HC) and low energy consumption.