Temperature-induced atomic intrinsic sites evolution during waste dyeing sludge into the wealthy iron-based catalyst to sustainable decontamination

Although the worldwide spike in the production of dyeing sludge offers a tantalizing resource to be harnessed, effective waste-to-wealth strategies remain elusive due to its intricate toxic organic matter and metallic elements. Here, we developed a temperature-rebuilding strategy to transform discarded dyeing sludge into an iron-based catalyst with favorable charge transfer for the highly efficient and sustainable Fenton-like catalytic degradation of ppm-level contaminants in wash-tank water. Using X-ray diffraction, X-ray photoelectron spectroscopy, and synchrotron X-ray absorption spectroscopy, we could precisely track and identify the gradual formation of inherent sites (i.e., Fe₂(SO₄)₃, FeOOH, and Fe_1-xS) towards active sites (i.e., FeS and Fe⁰) at crystal, surface, and atomic levels. Benefiting from the reconstruction of iron sites, BC-800 effectively decomposed peroxymonosulfate into multiple radicals and nonradicals through electronic structure modulation, which enabled nearly 100 % degradation and over 60 % mineralization rate of common aromatic compounds within 30 min via ring-opening and dechlorination/substitution pathways. More delightedly, the BC-800 maintained excellent Fenton-like activity across a broad pH or multiple anions coexisted, and its device allowed extended parachlorophenol degradation for over 1 d. This work proposes a feasible “waste control by waste” approach to the reutilization of dyeing sludge, encouraging a potential solution for sustainable wastewater treatment.