Mechanism of ultrasonic enhanced acetic acid efficiently leaching of steel slag and synthesis of calcium carbonate whiskers

Addressing the dual challenges of environmental pollution and sustainable energy systems, this study investigates a novel CO2 sequestration technique via steel slag, a steel production byproduct. It introduces an ultrasonic enhanced leaching process using CH3COOH to extract calcium and magnesium from steel slag, facilitating the synthesis of CaCO3 whiskers. The results demonstrate that augmenting the ultrasonic power, increasing solid–liquid consistency, raising the initial reaction temperature, and utilizing a lower concentration of CH3COOH substantially improve the selective leaching rate of Ca + Mg. Kinetic analysis under ultrasonic conditions reveals a low activation energy of 11.45 kJ∙mol−1, indicating surface-controlled reaction kinetics in ultrasonic leaching process. Eventually, high-purity CaCO3 whiskers were synthesized under meticulously controlled conditions: employing 400 W of ultrasonic power, sustaining a reaction temperature of 70 °C, executing the procedure for 15 min with an initial solution pH of 9.2. This innovative approach not only contributes to reducing CO2 emissions but also promotes the reuse of steel slag, addressing environmental concerns and supporting sustainable energy systems. And it underscores the potential of integrating sustainable practices in the steel industry, aligning with global efforts in climate change mitigation and pollution reduction.