Review on CO 2 sequestration using iron and steel slags, synthesis of nanogels via the sol-gel method: applications and emerging trends

Carbon Capture Utilisation and Storage (CCUS) technologies have become increasingly important to mitigate greenhouse gas emissions and combat climate change. One promising avenue of CCUS is the use of industrial waste streams as feedstock for CO2 sequestration. Iron and steel slag, by-products of steel manufacturing, have shown potential as effective CO2 adsorbents. This current work thus provides a comprehensive review of the production chemical composition of iron and steel slags and its use in CO2 sequestration, the synthesis of nanocomposite hydrogels via the sol–gel method, its applications and emerging trends in CO2 sequestration. The sol–gel process is a viable synthesis technique for nanocomposite hydrogels, offering high surface area, tunable porosity, and enhanced reactivity suitable for CO₂ sequestration. The review highlighted high calcium oxide content and reactive sites in the slags, facilitating CO₂ sequestration through carbonation. Challenges such as limited adsorption capacity and structural degradation over time will be addressed by incorporating slag into hydrogel matrices. The findings further suggest that iron and steel slags can improve hydrogel functionality, adding mechanical resilience and promoting chemical fixation of CO₂ molecules. The study concluded that slag-based nanocomposite hydrogels offer a promising, sustainable solution for industrial CO₂ sequestration, with future research needed to optimise these materials for scalable applications in environmental remediation.