Effect of water content on accelerated carbonation of municipal solid waste incinerator bottom ash for CO₂ capture

For comparison of different water-to-solid ratio for the accelerated carbonation of municipal solid waste incinerator (MSWI) bottom ash for CO₂ capture, it is necessary to understand the morphological changes of bottom ash as a carbonation reaction. Only the water-to-solid ratio (W/S) at atmospheric pressure was controlled from 0.3 to 10 dm³/kg and the CO₂ concentration was kept constant at 30% while the reaction temperature was held at 20°C. The result of an XRD analysis indicated that portlandite, ettringite, and hydrocalumite in untreated bottom ash could combine with CO₂ to form mainly an amorphous Al-material and calcite. In the case of 10 W/S, the amount of CO₂ reacted with bottom ash approached the maximum value after 120 min reaction time, whereas the reaction at 0.3 S/W was scarcely carbonated after 60 min because of encapsulation effect.