Silica Fume-Derived Functional Silicon-Based Materials: From Waste Valorization and Controlled Synthesis to Environmental Remediation

The ferrosilicon and metallic silicon smelting industry produces tens of millions of tons of silica fume (SF) solid waste cumulatively. The stockpiling of SF has caused prominent ecological and environmental problems, while its high-value silicon resources remain underdeveloped. Silicon-based materials derived from SF via alkaline extraction and controlled functionalization show great potential for valorization. This review systematically discussed the physicochemical characteristics and pretreatment activation mechanisms of SF, elaborated process regulation rules for typical preparation routes including alkaline leaching, sol–gel, template-directed synthesis, hydrothermal, and microwave-assisted methods, and analyzed the coupled effects of key parameters such as pH, template/surfactant ratio, and aging conditions on pore structure, morphology, and surface chemical properties. It also summarized research progress and engineering exploration in environmental remediation, including heavy metal adsorption, organic pollutant removal, and CO2 capture. Current research still faces several practical limitations, including raw material impurity fluctuations, synthesis scale-up obstacles, insufficient understanding of multi-scale pollutant removal mechanisms and incomplete long-term service evaluation under complex conditions. Future efforts should deepen thermodynamic and kinetic analyses of material preparation and conversion, as well as material–pollutant interfacial interactions. Quantitative evaluation systems should also be established for long-term performance and low-carbon resource benefits under actual working conditions. Furthermore, multi-condition coupled intelligent preparation and performance regulation technologies should be developed and the transition from laboratory fundamental research toward engineering, quantitative, and intelligent applications should be promoted. This review could provide a theoretical basis and technical reference for the high-value resource utilization of SF and potentially low-carbon environmental remediation.