Preliminary study on degradation mechanisms of plasma-treated DR1 by atomistic simulations

Abstract Cold atmospheric plasma (CAP) has emerged as a promising technology for the degradation of organic dyes, but the underlying mechanisms at the molecular level remain poorly understood. Using density-functional tight-binding (DFTB)-based quantum chemical molecular dynamics at 300 K, we have performed numerical simulations to investigate the degradation mechanism of Disperse Red 1 (DR) interacting with CAP-generated oxygen radicals. One hundred direct-dynamics trajectories were calculated for up to 100 ps simulation time, after which hydrogen-abstraction, benzene ring-opening/expanding, formaldehyde formation and modification in the chromophoric azo group which can lead to color-losing were observed. The latter was obtained with yields of around 6% at the given temperature. These findings not only enhance our understanding of CAP treatment processes but also have implications for the development of optimized purification systems for sustainable wastewater treatment. This study underscores the utility of DFTB simulations in unraveling complex chemical processes and guiding the design of advanced treatment strategies in the context of CAP technology.