Photocatalytic degradation, toxicological assessment and degradation pathway of C.I. Reactive Blue 19 dye

Efficient degradation of dye-based environmental pollutants and industrially contaminated wastewater remains a formidable challenge. The photo-assisted catalytic degradation of anthraquinone Reactive Blue 19 (RB-19) dye was investigated by varying the operational parameters such as reaction time, catalyst (titanium dioxide, TiO₂) loading, initial dye concentration, and hydrogen peroxide (H₂O₂) concentration. Pronounced dye degradation reaction was achieved at 1.0 g/L of TiO₂ after 180 min of degradation period with 0.3 × 10⁻³ mol/L of H₂O₂. UPLC/MS analysis scrutinized the intermediates and based on the electrospray ionization mass spectrometry (ESI-MS) analysis. A mechanistic degradation pathway has also been proposed. The complete degradation of RB-19 was confirmed by total organic carbon (TOC) and chemical oxygen demand (COD) analysis. Toxicity profile of untreated and photo catalytically-degraded dye was evaluated using three types of human cell lines, i.e., MCF 7, L 929 and HeLa cells. It was observed that transformed byproducts of RB-19 were less toxic than the original dye molecule. In conclusion, the UV/TiO₂ mediated process can promisingly degrade RB-19 dye under optimized conditions. It is evident from the data obtained that the newly developed UV/TiO₂-assisted mechanism could practically be used for the degradation of industrial dyes and/or dyes based waste effluents.