Co-removal of phenol and Cr(VI) by high gravity coupled heterogeneous catalytic ozonation-adsorption

In this study, the co-removal of phenol and Cr(VI) from wastewater by high gravity coupled heterogeneous catalytic ozonation and adsorption was innovatively proposed. The presence of Cr(VI) was found to enhance the mineralization of phenol, while ozonation of phenol facilitated the adsorption of Cr(VI) through increased electrostatic attraction and reduction reactions. This synergistic effect was effectively exploited with the Fe-Mn/ AC catalyst, achieving impressive removal efficiencies of 98.9 % for Cr(VI) removal and 98.5 % for phenol mineralization. The synergistic mechanisms of catalytic ozonation and adsorption were investigated using density functional theory (DFT), revealing that the adsorption energy of ozone at surface Lewis acid sites and oxygen vacancies on Fe-Mn/AC catalyst decreased significantly after Cr(VI) adsorption. Specifically, the values decreased from-0.3 eV and-1.32 eV to-1.79 eV and-4.26 eV, respectively. These results were further corroborated by NH3-temperature-programmed desorption (NH3-TPD) and electron spin resonance (ESR) analyses, which demonstrated an increase in Lewis acid and oxygen vacancies on the Fe-Mn/AC catalyst surface in the presence of Cr(VI). Overall, the co-removal strategy of Cr(VI) and phenol using catalytic ozonationadsorption under high gravity conditions represents a novel method that leverages synergistic effects. This method not only offers a promising approach for addressing organic compounds and heavy metals in industrial wastewater but also underscores the potential of integrating advanced oxidation processes with adsorption techniques for efficient water treatment applications.