Kinetics and mechanism of chlorinated aniline degradation by TiO2 photocatalysis

Photooxidation of 4-chloroanaline (4-CLA) in UV/TiO2/H2O2 system was investigated in the following working conditions: pH 4; [TiO2] = 50–500 mg/L; [H2O2] = (0.1–10)x10-3 M; tirr = 5–180 min A pollutant degradation pathway by four possible routes was proposed, according to organic intermediates identified by gas-chromatography coupled with mass spectrometry-screening method. Based on experimental results can be concluded that after 90 min of irradiation, 4-CLA was completely degraded in the presence of H2O2 (1x10-3 M). Mineralization yields of organic chlorine and nitrogen were 88% for prolonged irradiation time (180 min). These results are consistent with the proposed degradation pathway that presents as intermediates, aromatic compounds like 4-chlorophenol, 4-aminophenol, 4-chloronitro- benzene, and aniline. The presence of these intermediates in irradiated samples is also supported by 82.4% TOC removal yield obtained at prolonged irradiation time.