Photosonoelectrochemical analysis of Lawsonia inermis (henna) and artificial dye used in tattoo and dye industry

[Display omitted] •Lawsonia inermis donot undergo degradation upon exposure to PSEC perturbation.•Commercial lawsone oxidizes on PSEC perturbation to 3-ethoxy napthaquinone.•PPD degraded to 1-amino cyclobutadiene on PSEC perturbations. Photosonoelectrochemical (PSEC) analysis of Lawsonia inermis, lawsone and ƥ-Phenylenediamine were investigated in ethanol to understand the degradation mechanism and harmful byproducts. To simulate the operating conditions of the tattoo ink, dye solutions were exposed to appropriate sonication, UV irradiation and electrochemical perturbations. Analyses of the dyes were done before and after PSEC perturbations employing UV–vis, FTIR, HPLC, 1H NMR and 13C NMR studies and degradation pathway is provided. The PSEC studies inconjunction with the spectroscopic and HPLC analysis identified formation of byproducts such as 3-ethoxy naphthaquinone from lawsone and 1-Amino cyclobutadiene from ƥ-Phenylenediamine demonstrating the harmfulness of utilizing these dyes over henna by tattoo and hair dye industries.