Heterogeneous photodegradation of paracetamol using Goethite/H 2 O 2 and Goethite/oxalic acid systems under artificial and natural light

Abstract

Abstract Heterogeneous photodegradation of paracetamol (PC) in the α-FeOOH (Goethite) used as a catalyst was studied in aqueous suspension up on irradiation at 365 nm and by solar light. The mechanism involves PC-Goethite system operate electron–hole pairs. The rate of photocatalytic degradation of PC is slow and follows pseudo-first order kinetics. The addition of H 2 O 2 in the previous solution leads to OH radicals formation via the Fenton system. Goethite in the presence of oxalic acid can form Goethite–oxalate complex on the surface. So under irradiation the photo-reduction of Goethite–oxalate complexes yields Fe(II) and oxalate radicals (C 2 O 4 ) − , which induces the formation of active species ( OOH\O 2 − ) leading to the Fenton reaction. The effect of catalyst loading, initial concentration of PC, hydrogen peroxide (H 2 O 2 ) and oxalic acid concentrations were determined. The optimal initial concentration of hydrogen peroxide and oxalic acid for the PC degradation with Goethite under the experimental conditions was found to be 5 × 10 −3 and 5 × 10 −4 mol L −1 respectively. The photodegradation of PC in the mixtures PC–Goethite, PC–Goethite–H 2 O 2 and PC–Goethite–oxalic acid under solar light was significantly accelerated in comparison with artificial irradiation at 365 nm.