Molecular Dynamics Simulation of Ozonation of p-Nitrophenol at Room Temperature with ReaxFF Force Field

Understanding the reaction mechanism of phenol ozonation in coking wastewater is very important for industrial applications of the ozonation process. Ozonation of p-nitrophenol in water at 300 K was simulated by ReaxFF force field molecular dynamics (ReaxFF MD) employing the GPU-enabled high-performance code of GMD-Reax and a unique code of VARxMD developed in authors' group. Evolution trends of aromatic ring opening, CO2 generation, dominant radicals (center dot OH, center dot O2, center dot O), and H2O clusters were obtained. The simulated CO2 generation and reduction of aromatic ring could be described with pseudo-first-order kinetics. Moreover, the reaction pathways for the ozonation of p-nitrophenol can be divided into three stages: hydrogen abstraction, opening of the six-membered-ring structure, and the breaking of C-C bonds. The simulations revealed the important role of radicals and water clusters in the ozonation of p-nitrophenol. This work is an attempt to investigate the ozonation mechanism of phenols in aqueous solutions at room temperature using ReaxFF MD, which should be helpful for further experimental or theoretical investigation of the mechanism.