CO2-triggered instantaneous weathering upcycles industrial solid wastes into safe land reclamation substrate

Pedogenic functionalization represents a promising strategy for the large-scale ecological reutilization of industrial solid wastes. However, the transformation of basic metallurgical slags into functional soil-like substrate is severely constrained by the sluggish kinetics of natural weathering. In this study, an accelerated aqueous CO 2 weathering approach was developed to achieve the rapid structural reconstruction of basic steel slag (SS). Comprehensive multi-scale characterizations revealed a Dissolution-Repolymerization-Precipitation mechanism, in which CO 2 -induced cleavage of Ca-O-Si bonds promoted and then the formation of a hierarchical core-shell structure composed of neo-formed carbonates and a mesoporous silica-gel network. Consequently, the pH of SS decreased dramatically from 12.3 to 7.93, accompanied by the formation of a favorable toward a soil-like substrate . Moreover, the reconstructed mineral matrix enhanced ecological safety through the physical encapsulation and chemical immobilization of trace heavy metals. This study provides an efficient and scalable waste-to-Technosol pathway that integrates industrial solid waste valorisation, carbon capture, and ecological landscape restoration.