Co-oxidative removal of arsenite and tetracycline based on a heterogeneous Fenton-like reaction using iron nanoparticles-impregnated biochar

A highly efficient, eco-friendly and relatively low-cost catalyst is necessary to tackle bottlenecks in the treatment of industrial wastewater laden with heavy metals and antibiotic such as livestock farm and biogas liquids. This study investigated co-oxidative removal of arsenite (As(III)) and tetracycline (TC) by iron nanoparticles (Fe NP)-impregnated carbons based on heterogeneous Fenton-like reactions. The composites included Fe NP@biochar (BC), Fe NP@hydrochar (HC), and Fe NP@HC-derived pyrolysis char (HDPC). The functions of N and S atoms and the loading mass of the Fe NP in the Fe NP@BC in heterogeneous Fenton-like reactions were studied. To sustain its cost-effectiveness, the spent Fe NP@BC was regenerated using NaOH. Among the composites, the Fe NP@BC achieved an almost complete removal of As(III) and TC under optimized conditions (1.0 g/L of dose; 10 mM H2O2; pH 6; 4 h of reaction; As(III): 50 mu M; TC: 50 mu M). The co-oxidative removal of As(III) and TC by the Fe NP@BC was controlled by the synergistic interactions between the Fe NPs and the active N and S sites of the BC for generating reactive oxygen species (ROS). After four consecutive regeneration cycles, about 61 and 95% of As (III) and TC removal were attained. This implies that the spent carbocatalyst still has reasonable catalytic activities for reuse. Overall, this suggests that adding technological values to unused biochar as a carbocatalyst like Fe NP@BC was promising for co-oxidative removal of As(III) and TC from contaminated water.

Automated summary

This study investigated the co-oxidative removal of arsenite and tetracycline by iron nanoparticles-impregnated carbons, showing promising results for the removal of contaminants in contaminated water. The spent carbocatalyst still maintained reasonable catalytic activities after regeneration, suggesting potential for reusing the catalyst for further water treatment applications.