Valorization of ladle furnace slag and functional enhancement of post-adsorption materials

Abstract

Carbonating metallurgical slags plays a pivotal role in achieving efficient mineral CO₂ sequestration and waste valorization. This research introduces a novel integrated approach that combines the carbonation of Ladle Furnace Slag (LFS) with the simultaneous degradation of Methyl Orange (MO) in synthetic water. The comprehensive characterization of LFS was conducted using X-ray Diffraction (XRD), X-ray Fluorescence (XRF), Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), Brunauer-Emmett-Teller (BET) analysis, and Scanning Electron Microscopy (SEM). The adsorption experiments reveal the high LSF capacity for MO degradation (149.25 mg/g) following pseudo-second-order kinetics (R² = 0.99) and Langmuir isotherm (R² = 0.98). The adsorption process was primarily governed by chemical and electrostatic interactions. Analysis of LFS-loaded MO indicated a reduction in Ca(OH)₂ phases, responsible for CO₂ mineralization and the formation of calcite (CaCO₃). Furthermore, the study explored the reusability of LFS-MO composites through chemical and thermal modifications. Pyrolysis of carbonated LFS with KOH impregnation exhibited potential for regenerating Ca(OH)₂ phases, while thermal modification induced significant mineral and microstructural changes, creating new active sites at various temperatures. Additionally, the Fenton-like reaction followed by thermal modification resulted in a highly organized and microporous LFS structure with enhanced surface area and porosity. Moreover, modification with ZnSO₄ followed by thermal activation promoted the formation of ZnO nanoxides on the LFS surface. This research proposes an innovative carbonating approach for metallurgical slags and wastewater treatment, extending their utility and enhancing industrial sustainability. Carbonated LFS-MO composites hold promise for applications in construction, CO₂ capture, and wastewater treatment, thereby fostering sustainable industrial practices with ongoing research and development efforts.