Thermally processed eggshells as a renewable source of calcium carbonate for industrial use

Calcium carbonate (CaCO₃) is a vital industrial material used extensively in pharmaceuticals, food production, construction, and environmental remediation. Current CaCO₃ sourcing methods, primarily reliant on mining limestone and chalk, present significant environmental challenges, including habitat destruction, high energy consumption, and carbon emissions. To address these concerns, this study explores the potential of agrifood waste, specifically eggshells, as a circular and sustainable source of CaCO₃. Eggshells, are a rich and readily available biogenic source of CaCO₃ thus, exploiting them as an alternative source of CaCO₃ can reduce waste production while providing an eco-friendly alternative for the shoemaking industry. However, when considering its incorporation into thermoresistant plastic, like the one used to produce shoe soles, its protein content can represent a limitation to its application, as previous works have shown it to be correlated with non-compliant soles. Thus, the current work exploited the transformation of eggshells into an enriched mineral substrate for incorporation into thermoplastic materials used in the production of shoe soles.