Bifunctional Fe for Induced Graphitization and Catalytic Ozonation Based on a Fe/N-Doped Carbon-Al2O3 Framework: Theoretical Calculations Guided Catalyst Design and Optimization

Heterogeneous catalytic ozonation is regarded as a feasible technology in advanced wastewater treatment. Catalytic performance, mass transfer, and mechanical strength are the key elements for large-scale applications of catalysts. To optimize those elements, Fe was selected for its dual role in graphitization and catalytic ozonation. A Fe/N-doped micron-scale carbon-Al2O3 framework (CAF) was designed and applied to a fluidized catalytic process for the treatment of secondary effluent from coal gasification. The chemical oxygen demand removal rate constant and the hydroxyl radical generation efficiency (R-ct) of the Fe/N-doped CAF were 190% and 429% higher than those of pure ozone, respectively. Theoretical calculations revealed that higher Fe valence promoted ozone decomposition, which implied increasing Fe-III content for further catalyst optimization. The rate constant and 12(ct), with a higher Fe-III-proportion catalyst were increased by 13% and 16%, respectively, compared to those with the lower one. Molecular dynamics and density functional theory calculations were performed to analyze the reaction kinetics qualitatively and quantitatively. The energy barrier corresponding to Fe-III configuration was 1.32 kcal mo1(-1), 27% lower than that for Fe-II configuration. These theoretical calculations guided the catalyst optimization and provided a novel solution for designing ozonation catalysts. The Fe/N-doped CAF demonstrated a great potential for practical applications.

Automated summary

Heterogeneous catalytic ozonation is considered a viable technology for advanced wastewater treatment, and Fe/N-doped CAF showed promising results in treating secondary effluent. Theoretical calculations guided catalyst optimization and provided a new direction for designing ozonation catalysts. Fe/N-doped CAF demonstrated great potential for practical applications.