Heat-Driven Persulfate Activation for Alizarin Degradation: Kinetics, Mechanism, and DFT Study

The current research was done to investigate the removal of Alizarin in the heat-activated sulfate radical-based advanced oxidation process in the batch system. The removal efficiency was evaluated based on the change in operating parameters, including pH (۳-۱۰), process temperature (۵۰-۸۰ °C), oxidant/pollutant molar ratio (۲۰/۱-۸۰/۱), and initial pollutant concentration (۲۵-۱۵۰ mg/L). From the results, the Alizarin oxidation was almost pH independent, and the final removal rate was about ۹۰% in all experiment pHs. The maximum decolorization efficiency of about ۹۵% was achieved when the process temperature reached ۸۰ °C, along with the activation energy of +۱۳۴.۷ kJ/mol, which indicated the endothermic oxidation process. Moreover, the Alizarin removal was ۹۴% at an initial concentration of ۲۵ mg/L and a maximum oxidant per pollutant molar ratio of ۸۰, and it fell to ۲۴% as the initial concentration rose to ۱۵۰ mg/L. Density Functional Theory (DFT) calculation was employed to identify the degradation mechanism of Alizarin, which revealed that the molecule has a high electron-accepting ability with significant reactivity. The effect of different oxidants was investigated, and the results show that more COD removal was observed when persulfate was used as an oxidant compared to hydrogen peroxide.

کلیدواژه ها:

Advanced oxidation ، Heat Activation ، Kinetics study ، Density functional theory