Photodegradation of Naproxen Using Ag/AgCl–PANI Composite under Solar Light: Transformation Product and Reaction Kinetics

The photocatalytic degradation of organic micropollutant naproxen (NPX) was evaluated under solar light using Ag/AgCl–polyaniline (Ag/AgCl–PANI) photocatalyst. The degradation experiments were monitored using ultra-performance liquid chromatography (UPLC) coupled with electrospray ionization and tandem mass spectrometry. High stability and high photocatalytic degradation rate with a first-order kinetics behavior of NPX were observed. The degradation rate increases with increasing the photocatalyst dose and decreases with increasing the initial concentration of NPX. Besides, the highest photocatalytic activity of Ag/AgCl–PANI(5%) towards the removal of NPX was in basic media (pH 11). However, the complete mineralization of NPX needed more time than that of its photodegradation indicating the presence of NPX derived byproduct. The transformation products were identified by gas chromatography-mass spectrometry. The oxidizing species, h+ and $${\text{O}}_{2}^{{\bullet - }}$$ , caused electron transfer oxidation process and resulted in two different reaction pathways.