Heterogeneous photoinduced degradation of amoxicillin by Goethite under artificial and natural irradiation

The photodegradation of Amoxicillin (AMX) in aqueous solution was investigated in heterogeneous phase with Goethite (α-FeOOH) under different experimental conditions. The Behaviour of AMX-Goethite system in absence of irradiation has shown that AMX disappears when the solution ages and this phenomenon is less favored when the medium became more acid. Upon irradiation at 365 nm a significant modification has been noticed on UV-vis spectra where an isosbestic point was detected at 247 nm. Moreover, the band at 230 nm is marked by a greater decrease for long time. Kinetic investigation was carried out illustrating that AMX photodégradation followed a pseudo-first order kinetics with rate constants k = 1.52 × 10−2 h−1. The AMX mineralization reaches 42% after 90 h of irradiation. Some parameters affecting the mechanistic process of the reaction have been examined. The photodegradation of AMX in the mixture AMX-Goethite under solar light was significantly accelerated in comparison with artificial irradiation at 365 nm.