Hierarchically porous glass–ceramics by alkaline activation and crystallization from municipal solid waste incineration ashes

As a hazardous waste, municipal solid waste incineration (MSWI) fly ash poses a serious threat to the environment, and considerable efforts have been made to achieve its harmless treatment. Herein, a novel approach for handling MSWI fly ash has been proposed to prepare porous glass–ceramics by alkali activation–crystallization, which overcomes the difficulty of controlling air bubbles under high temperatures. MSWI bottom ash rich in Al2O3 and SiO2 are co-treating as raw material to develop glass framework structure. The alkali activation mechanism shows that the development of MSWI ashes based basic glass from monomer to silica–aluminate gel under alkaline condition. The influence of H2O2 addition on the morphology and physical properties of porous glass–ceramics were evaluated. Porous glass–ceramics with uniform hierarchical pore structure have been fabricated at 3 mol/L NaOH, a solid loading of 55 wt%, and 1–4 wt.% H2O2, then crystallization treatment at 1150 °C for 2 h, the porosity and the bulk density of which varies from 77.22 to 82.94% and 0.68–0.91 g/cm3 respectively, while their relatively high compressive strength ranges from 1.62 MPa to 3.85 MPa. Attributed to the hierarchical porous structure, uniform distribution of pores and excellent physical properties, porous glass–ceramics has potential applications in construction, filtration, and adsorption materials, providing a convenient and feasible method for the efficient and comprehensive utilization of MSWI ashes.