Multifunctional role of monosodium glutamate in carbonation of low-carbon ferrochrome slag: Reaction process and microstructural evolution

The mineral carbonation of industrial solid wastes presents a promising route for CO₂ sequestration and upcycling into valuable construction materials. However, enhancing the carbonation efficiency and mechanical properties of complex, multiphase slags like low-carbon ferrochrome slag (LCFS) remains a challenge. This study investigated the role of monosodium glutamate (MSG) as a green accelerator in enhancing the carbonation performance of low-carbon ferrochrome slag (LCFS). Through systematic experiments under varied MSG dosages (0.0–1.2 wt%), CO₂ uptake, compressive strength, and reaction kinetics were evaluated using carbonation heat, thermogravimetry (TG), X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Results revealed that MSG addition transformed the single exothermic peak of the carbonation reaction (observed in MSG-free systems) into a dual-peak regime. These findings revealed MSG’s capacity to decouple and optimize reaction stages: delaying early carbonation (0–60 min) to prevent premature passivation while accelerating later carbonate growth. Such stage-specific regulation enables tailored microstructures, balancing CO₂ diffusion (via controlled porosity) and matrix densification. At the optimum dosage of 0.8 wt%, MSG enhanced mid-to-late stage carbonation by stabilizing amorphous calcium carbonate (ACC)via chelation. This yielded peak compressive strength and CO₂ uptake values of 223.3 MPa and 24.1 %, respectively, corresponding to dramatic enhancements of 93.3 % and 31.0 % over the control group. However, overdosage (1.2 wt%) suppressed both peaks, reverting to a flattened profile due to surface passivation. This work pioneers amino acid-assisted carbonation, offering a sustainable pathway to high-performance, carbon-negative construction materials. • Single peak of the carbonation reaction of LCFS transforms into a dual-peak. • MSG delays early carbonation while accelerates later carbonate growth of LCFS. • Compressive strength of LCFS with 0.8 % MSG reaches to 223.3 MPa increasing by 93.3 %.