Mechanochemical degradation treatment of TBBPA: A kinetic approach for predicting the degradation rate constant

Persistent organic pollutants (POPs) have been banned from production and use. The brominated flame retardant TBBPA is a type of POP and has been widely used in plastics to enhance their fire resistance. However, because the natural degradation of TBBPA is a difficult process, it is particularly important to propose an appropriate treatment method. Hence, the mechanochemical degradation of TBBPA is a feasible method because it does not require high temperature heating and does not produce secondary pollutants after the reaction is completed. In this study, we performed a series of TBBPA degradation experiments with a planetary ball mill and confirmed the degradation efficiency and the rate under various conditions. Then, we conducted a discrete element method (DEM) simulation to compute the collision energies in the ball mill. By comparing the degradation rate and collision energies, we revealed that the mechanochemical degradation rate of TBBPA can be predicted by a normal collision energy computed by DEM simulation. This kinetic approach enables us to predict the rate constant and consequently, the energy consumption for the mechanochemical treatment. The predictability of these parameters will encourage the further application of mechanochemical reaction in the field of POPs treatment.