A comparative approach of methylparaben photocatalytic degradation assisted by UV-C, UV-A and Vis radiations

Due to the widespread use of methylparaben (MEP) and its high chemical stability, it can be found in wastewater treatment plants and can act as an endocrine disrupting compound. In this study, the photocatalytic degradation and mineralization of MEP solutions were evaluated under UV-A, UV-C and Vis radiations in the presence of the photocatalyst TiO2. In this sense, the effects of the catalyst load, pH and MEP initial concentration were studied. Remarkably higher reaction rates and total photodegradation were achieved in systems assisted by UV-C radiation. The complete degradation was achieved after 60min of reaction using the MEP concentration of 30mgL(-1) at pH 9 and 500mgL(-1) TiO2. The experimental data apparently followed a Langmuir-Hinshelwood kinetic model, which could predict 88-98% of the reaction behavior. For the best photodegradation condition, the model predicted an apparent reaction rate constant (k(app)) equal to 0.0505min(-1) and an initial reaction rate of 1.5641mg (Lmin)(-1). Mineralization analyses showed high removal for MEP and derived compounds from the initial solution when using UV-C after 90min of reaction. The lower toxicity was also confirmed by in vivo tests using MEP solutions previously treated by photocatalysis. [GRAPHICS] .