Characteristics and environmental benefits of CO₂ mineralization using a recyclable chelating agent in concrete...

Concrete product manufacturing faces two coupled challenges: substantial solid waste generation and CO₂ emissions. While CO₂ mineralization can address both, conventional routes rely on high reagent use and generate wastewater, limiting sustainability. Recyclable chelating agent-assisted CO₂ mineralization offers a more sustainable alternative, yet its cycle-resolved practicality and net environmental benefits remain unclear. This study assessed the characteristics of such CO₂ mineralization processes through experiments using green chelating agent GLDA as the extractant and sludge cake collected from a concrete pole facility as the feedstock. Over ten successive reuse cycles, the efficiency of Ca extraction by the GLDA solution remained stable, yielding a 25% reduction in residue mass. The extracted Ca was selectively carbonated as CaCO₃ after heating the solution to 95 °C, mineralizing 156 g CO₂ per kg of sludge cake. A prospective, gate-to-gate life-cycle assessment (LCA) based on experimental results demonstrates a 16.1% reduction in global warming potential at concrete manufacturing plants. It also reveals a 1.2-10.0% decrease across other key environmental categories, including abiotic depletion potential (fossil fuels) and acidification potential, primarily driven by residue reduction. These findings position recyclable chelating agent-assisted CO₂ mineralization as a scalable option that couples waste minimization with permanent CO₂ storage for the concrete products industry.