LAUSR

Abstract Acetylsalicylic acid (ASA) is a model pollutant and a representative of the emerging pharmaceutical micropollutants whose mineralization across several advanced oxidative processes takes hours to complete. This work devotes to optimize and understand the kinetic conditions to mineralize ASA using Photo-Fenton process with UVA radiation in a tubular photochemical reactor. The optimization employs a statistical tool termed factorial design (FD) that studies how the concentrations of ASA, Fe 2+ and H 2 O 2 affects the mineralization over a larger interval of concentrations. The factorial design indicates that the initial concentration of H 2 O 2 is a crucial variable to achieve a fast rate of ASA mineralization. Using optimized contents of both H 2 O 2 and Fe 2+ (45 Mm and 1.5 mM, respectively) in the Photo-Fenton process (H 2 O 2 /Fe 2+ /UVA), mineralization around 90% is reached in about 10 min, the fastest rate ever observed, enabling to treat 0.012 m 3  h −1 per tubular reactor. The underlying reason for such outstanding performance is attributed to the optimized 4.5-folds excess of [H 2 O 2 ], i.e. the ratio of H 2 O 2 concentration used at the initial time to that required for complete mineralization of the theoretic TOC. Measurements of the remaining concentration of H 2 O 2 strongly indicates that excess of [H 2 O 2 ] optimizes the instantaneous concentration of radical OH. As a conclusion, the stoichiometric excess of [H 2 O 2 ] is an important parameter to be optimized for achieving the highest degree of mineralization at the shortest time when using the photochemical reactor, in turn, decreasing costs related to the total energy consumed both by the lamp and by the recirculation pump.