Sonophotocatalytic degradation of paracetamol using TiO2 and Fe3

Abstract The degradation of paracetamol was studied by sonolysis, photocatalysis and sonophotocatalysis in the presence of homogeneous (Fe 3+ ) and heterogeneous (TiO 2 ) photocatalysts using 213 kHz ultrasound (US). The degradation rates obtained for sonolysis, photocatalysis and sonophotocatalysis using TiO 2 (1 g/L) were about 8.3, 30.2 and 40.2 × 10 −7  M min −1 , respectively. In the case of reactions involving Fe 3+ , the degradation rates obtained were 26.1, 18.6 and 46.7 × 10 −7  M min −1 for US + Fe 3+ , UV + Fe 3+ and US + UV + Fe 3+ , respectively. The above results indicate that the combination of sonolysis with photocatalysis (TiO 2 or Fe 3+ ) results in an additive effect from combining the two processes, with a synergy index value of ∼1.0. There was no synergistic effect in total organic carbon (TOC) removal in sonophotocatalysis with TiO 2 , whereas the mineralization process was synergistic when sonophotolysis was carried out in the presence of Fe 3+ . Further studies with electrospray mass spectrometry analysis revealed the formation of a hydroxylated derivative of paracetamol during sonolysis.