Carbon dioxide adsorption isotherm study on mine waste for integrated CO2 capture and sequestration processes

•CO2 adsorption capacity enhanced with the increase in specific surface area and Mg complex.•Both mechanical and chemical activations reduce the CO2 adsorption capacity per surface area.•The disordered structure of mechanically-activated serpentine promotes CO2 chemisorption.•Mine waste rock is potential for using in an integrated capture and sequestration process.

This paper investigates the potential of mine waste as a mineral sorbent for CO2 capture and sequestration during gas–solid phase. The experiments tested the isotherm of pure CO2 adsorption with partial pressure from 10− 5 to 1 bar at ambient temperature. Chemical and mechanical activations were used as pre-treatment methods to enhance CO2 adsorption capacity. The CO2 adsorption capacity of mineral sorbents was determined and compared among various materials. The mechanisms of CO2 adsorption on mineral sorbents also analyzed through studying the isotherm. Results indicate that CO2 adsorption capacity is enhanced with an increase in surface area, micropore volume, and weight ratio for Mg to Si, and with a decrease in forsterite crystal structure disorder. Both activation methods reduced the CO2 adsorption capacity per surface area by reducing the weight ratio of Mg to Si in chemical activation, and disordering forsterite crystal structure in mechanical activation. With the increase of serpentine content in mineral sorbents, the CO2 adsorption mechanism changed from physisorption to chemisorptions. Mechanical activation on mine waste activated the serpentine content and promoted CO2 chemisorption. At present, 480 s of mechanical activation on mine waste material in an IsaMill has 17.83 m2/g of specific surface area, 6.96 × 10− 3 cm3/g of micropore, and 5.84 × 1013 m/m3 of dislocation density on forsterite, yielding 2.73 mg CO2 per g samples. Mechanically-activated mine waste is suitable for industrial application for integrated CO2 capture and sequestration.

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