Pharmaceutical Wastewater Treatment by Solar Photocatalysis Using TiO2

The aim of this work is to study the influence of various experimental parameters on the solar photodegradation of paracetamol using titanium dioxide. Paracetamol (C8H9NO2) is both an analgesic and antipyretic drug widely used to treat pain and fever. The presence of traces of this drug in drinking water poses a threat to environmental and human health, because until now it has been very difficult to identify with precision the potential long-term and chronic effects of its excessive ingestion. This organic substance is released into aqueous media by two main sources: the direct disposal of surplus drugs in households and the inadequate treatment of manufacturing effluents. To avoid the undesirable accumulation of this recalcitrant pollutant in water, it is essential to apply efficient treatment techniques such as photocatalysis. For this study, photocatalysis experiments were carried out under solar radiation. The results showed that the elimination of paracetamol by photolysis or by adsorption is almost negligible. However, solar photocatalysis was more efficient, allowing the removal of more than 95% of the pollutant after 230 min. The optimum conditions were using 0.5 g L−1 of TiO2 with 5 mg L−1 of paracetamol and at pH of 6.2. Trapping experiments demonstrated that ⋅OH radicals and electrons were probably the major species responsible for the photodegradation process and that the Langmuir–Hinshelwood model described well the kinetic.