Synergistic mechanisms in Fenton-like reactions: Coal gasification fine slag-loaded Fe-Al LDH catalysts for phenolic wastewater degradation.

Abstract

Coal gasification fine slag (CGFS), a typical coal-based solid waste, poses significant environmental challenges with an annual output exceeding 50 million tons in China. The complex distribution of carbon and ash components necessitates the development of a material that can effectively harness both carbon and ash for comprehensive utilization. While layered double hydroxides (LDHs) exhibit catalytic potential, their performance is often limited by severe particle aggregation. Herein, we engineered a robust carbon-anchored Fe-Al-LDH composite (CGFS-LDH) through hydrothermal co-precipitation, demonstrating exceptional efficacy in H₂O₂ activation for phenol degradation. Remarkably, CGFS-LDH achieved 100 % removal of 200 mg L^-1 phenol within 60 min. Advanced characterization (XPS, XRD, EPR, LC-MS, and electrochemical analysis) revealed that CGFS serves dual roles: as a structural scaffold preventing LDH aggregation and as an electron shuttle promoting Fe²⁺/Fe³⁺ redox cycling. Although trace amounts of Fe (0.2 wt%) and Al (0.3 wt%) leached due to dynamic precipitation-dissolution equilibrium, the catalyst maintained outstanding stability over multiple cycles, with negligible activity loss. This work introduces an effective strategy for the comprehensive utilization and high-value transformation of CGFS, while also providing novel insights into the development of highly efficient and stable porous nanocomposites catalysts.