Solar photocatalytic degradation of acetaminophen with TiO₂ P25 immobilized on a glass plate by heat attachment method

In this study, photocatalytic degradation of acetaminophen (ACE) in aqueous solutions under simulated solar light was studied using TiO₂ P25 immobilized on a glass plate by heat attachment method. The major factors affecting the removal of ACE, namely the amount and layers of TiO₂ P25 immobilized, flow rate (Qv) and initial ACE concentration, were analyzed. The structural features of the TiO₂ P25 immobilized were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). TiO₂ was successfully immobilized on the glass plate with the structure of anatase and rutile characteristic of the pattern unmodified TiO₂ P25. SEM micrographs of surface coats of TiO₂ P25 immobilized on glass plates revealed microfractures, which are probably due to the different thermal expansions among the different layers of TiO₂ P25 induced by the subsequent thermal treatment. The adsorption in the dark of ACE on the immobilized P25 and direct photolysis of ACE were studied, being negligible in both cases. The optimal operating conditions were 5 mg L⁻¹ of ACE, 0.28 g of TiO₂ P25 immobilized and a Qv equal to 14 mL s⁻¹. Under these optimal conditions, 100% removal of ACE was achieved after 3 h of reaction. Moreover, a pseudo-first order kinetic model represented well the experimental data. The immobilized TiO₂ P25 was regenerated six times, with no noticeable loss of photoactivity, confirming the high stability achieved by the immobilization procedure, which makes this procedure promising for real applications.