Fe2O3/coal fly ash Fenton-like catalyst for the elimination of organic pollutants in wastewater: Kinetic, mechanism, and application feasibility

Fe2O3/CFA was prepared by loading Fe2O3 on the surface of raw coal fly ash (RCFA), and then used as a Fentonlike catalyst to treat refractory organic wastewater. The characterization results of SEM-EDX, XRD, XPS, XRF, and BET test indicate that Fe2O3 is successfully loaded on the surface of RCFA, while the adsorption performance is not significantly affected. Under optimal treatment conditions of p-nitrophenol (PNP) simulated wastewater (H2O2 dosage = 8 mmol/L, Fe2O3/CFA loading = 6 g/L, pH = 3, and T = 303 K), the removal rate of PNP reaches 97.7 % at 50 min. There exist hydroxyl radicals (center dot OH), superoxide radicals (center dot O-2) and singlet oxygen ( O-1(2)) in the Fenton-like system, and center dot OH is the primary reactive oxygen species in the removal of PNP center dot H2O2 dosage, Fe2O3/ CFA loading, and pH (i.e., [H+]) show different effects on the generation rate constant of hydroxyl radicals (k(center dot OH)), and the corresponding mathematic equation is k (center dot OH) = 6.51 center dot e (-(640.0/T)) center dot [H2O2](1.313) center dot [Fe2O3/CFA](1.093) center dot [H+](0.815). The Fenton-like process includes heterogeneous and homogeneous catalytic processes, and it is driven by the synergistic catalysis of multiple metallic elements; Fe and other metallic elements play major and auxiliary roles, respectively. In the advanced treatment of real coking wastewater, the catalytic capacity of Fe2O3/CFA can maintain 91.7 % in its 4th use, and the treatment cost is double dagger 4.15/ton, which can be decreased by further optimizing the preparation process of Fe2O3/CFA.

Automated summary

Fe2O3/CFA, prepared by loading Fe2O3 onto raw coal fly ash (RCFA), exhibits excellent catalytic performance in the treatment of refractory organic wastewater, showing high removal efficiency for p-nitrophenol (PNP) simulated wastewater under optimal conditions. The Fenton-like process involves the generation of various reactive oxygen species, with hydroxyl radicals (center dot OH) playing a crucial role in PNP degradation. Fe2O3/CFA maintains its catalytic capability in the advanced treatment of real coking wastewater, and further optimization of the preparation process can reduce the treatment cost.