Transforming solid coal waste into a reactive catalystCoal gangue stockpiles occupy large tracts of land and pose environmental risks, including soil erosion and metal leaching. Oxidant activation: Once reconstructed, coal gangue helps activate PMS to generate reactive species, including sulfate radicals, hydroxyl radicals, and singlet oxygen, or drive direct electron transfer to degrade target pollutants. Tailor metal additions: Secondary active components should be carefully matched to the surface chemistry, electronic structure, and defects of the reconstructed gangue matrix. Future studies must evaluate real industrial wastewater, long-term catalyst durability, metal leaching risks, degradation product toxicity, and overall processing costs. By addressing solid waste management and persistent water pollution simultaneously, reconstructed coal gangue offers a potential dual-purpose strategy for environmental remediation.