Explorando diferentes energias em processos fotolíticos e fotocatalíticos visando à degradação de fármacos

Abstract

Fluoxetine (FLX) photodegradation studies were carried out using 2 (two) photoreaters (UV) and (UV/MW). The photo reactors were studied by measurements of spectral emission intensities, and emission intensity was verified above 100% for the UV/MW photoreactor when compared to the UV photoreactor for the wavelengths of 406, 437, 547 and 579 nm. It was identified that the UV/MW photoreactor presents high effectiveness in hydroxyl radical formation, allowing degradation of 99% of FLX to be achieved in times < 1.0 min, while similar degradation results are achieved only in times of 2 h for UV photoreactor. In addition, it was verified that in the FLX degradation stage, the energy consumption (kWhg-1) obtained for the UV photoreactor showed values 200 times higher than for the UV/MW system, proving that the UV/MW photoreactor has a significant advantage in relation to energy consumption. Different methods of TiO2 semiconductor syntheses were applied, being: solvothermal method assisted by microwave radiation, sonochemistry and modified polymeric precursors. Obtaining the photoactive phase (anatase) were more efficient for the solvothermal method assisted by microwave radiation. The application of the semiconductors in the UV photochemical system showed a higher effectiveness of the catalytic action by TiO2-US, for the applied conditions, evidencing conversions of FLX to its transformation products above 100% when compared to the other semiconductors. After the studies, the degradation kinetics for FLX were applied, with values of k = 0.11 min-1 / R2 = 0.999 (UV) and k = 10.14 min-1 / R2 = 0.956 (UV/MW). Finally, the photochemical degradation mechanism of FLX was proposed, based on the data obtained by UV/Vis HPLC (with analytical standards), complemented by the high-resolution LC/MS Q-TOF analyzes, being proven the photolysis, direct oxidation, radical oxidation and hydrolysis steps.