Calcium-rich biochar-enhanced Cu-Al2O3 fenton-like catalyst with dual reaction centers for efficient decomplexation of Ni-EDTA

In this study, a calcium-rich biochar (CRB)-enhanced dual reaction center (DRC) Fenton-like catalyst, Cu-Al2O3CRB, was synthesized for the decomplexation of a typical heavy metal complex pollutant, Niethylenediaminetetraacetic acid (Ni-EDTA), in industrial wastewater. After a 90-minute reaction, the removal rate of Ni(II) could reach 95.2%, regardless of the initial solution pH. Various characterization analyses confirmed the formation of electron-rich Cu regions and electron-deficient Al and C regions in the Cu-Al2O3-CRB catalyst. The catalytic oxidation experiments, chronoamperometry tests, and reactive oxygen species (ROSs) detection further revealed the roles of biochar and CaCO3 on the catalytic behavior of Cu-Al2O3-CRB catalyst. The presence of biochar not only enhanced the loading of Cu species but also introduced additional electron transfer channels, while CaCO3 further interacted with biochar/Cu species to amplify the electron cloud density surrounding Cu. The improvement of electronic polarization facilitated the activation of H2O2 and the generation of center dot O2-, 1O2 and center dot OH. Contrary to conventional interfacial reactions, the weak adsorption between Cu-Al2O3-CRB and Ni-EDTA due to the electrostatic repulsion, led to the decomplexation reactions primarily occurring in the solution phase, rather than on the catalyst surface. This study sheds light on the potential of Cu-Al2O3-CRB as a DRC catalyst and emphasizes the significance of contaminant properties when using this kind of catalysts.