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.
Wang et al. (2025) studied this question.