Quantum chemical calculation of the reactions between the side-chain active groups of coal and hydroxyl radical catalyzed by an external electric field

The current work probes the influence of an electric field on the reactions of side-chain active groups (-CH 3 , -COOH, and -OH) of coal interacting with hydroxyl radical (•OH). The level M062X/6–311 +G(d,p) of DFT was employed to obtain the optimized molecular models and the corresponding thermodynamic parameters for the entire elementary reactions under varying electric field intensities of 0－0.02 a.u. Additionally, the bond dissociation energy, reaction energy barrier, front molecular orbital, and electrostatic potentials of the optimized molecular models were calculated based on the frontier orbital and quantum chemistry theories. Results suggest that both the intensity and direction of the electric field pose various effects on the stability of the chemical bond, and a greater electric field intensity would increase the influence on the bond dissociation energy. Moreover, a smaller angle between the bond involved in the reactions and the electric field direction decreases the reaction energy barrier while increasing the occurrence possibility of reactions. Additionally, the electric field impacts the reaction rate of elementary reactions by affecting the electrostatic interaction among reactant molecules, thus affecting the front molecular orbital and changing the reactants’ reactivity. This work provides theoretical guidance for developing technologies for mitigating coal combustion-derived environmental pollutants.