Honeycomb-like biochar framework coupled with FeO/FeS nanoparticles as efficient heterogeneous Fenton catalyst for phenol degradation.

Achieving an efficient and stable heterogeneous Fenton reaction over a wide pH range is of great significance for wastewater treatment. Here, a pollen-derived biochar catalyst with a unique honeycomb-like structure, coupled with the dispersion of magnetic FeO/FeS (Fe/S) nanoparticles, was synthesized by simple impregnation precursor, followed by pyrolysis. The prepared Fe/S-biochar catalyst demonstrated outstanding phenol degradation efficiency across a wide pH range, with 98% of which eliminated even under neutral conditions (pH 7.0). The high catalytic activity was due to the multilevel porous structure of pollen-derived biochar provided enough active sites and allowed for better electron transfer, then increases oxidation ability to promote the reaction. Moreover, the acid microenvironment formed by SO group from Fe/S composite extended the pH range for Fenton reaction, and S facilitated the conversion of Fe to Fe, resulting in remarkable degradation efficiency. Further, biochar can effectively promote cycling stability by limiting Fe leaching. This work may provide a general strategy for designing 3D framework biochar-based Fe/S catalysts with excellent performance for heterogeneous Fenton reactions.