LAUSR

Abstract A detailed investigation on the photocatalytic degradation and mineralization of lignocaine, a local anesthetic, under UV irradiation has been carried out in this study. The dose of TiO2 was optimized initially and was found as 250 mg L−1 for the degradation of 2 mg L−1 concentration of lignocaine. The scavenging experiment using isopropanol and methanol revealed that the degradation is mainly controlled by hydroxyl radical. A fast disappearance of the parent compound (within 1 h) and nearly 75% of mineralization (after 6hr) were observed using this method. The relatively low mineralization efficiency is due to the evolution of various transformation products during the degradation as identified by high-resolution mass spectrometry (LC-Q-TOF-MS). Ten well-separated product peaks were observed in the total ion chromatogram (TIC) for 30 min irradiated sample of lignocaine. Based on the formation of these products, a degradation mechanism is proposed involving mainly hydroxylation, N-de-ethylation, and hydrogen abstraction. As part of mineralization study, the evolution of various inorganic ions was analyzed and the ammonium ion is found as the major inorganic species. A detailed mechanism is proposed for the inorganic ion release as well.