Kinetic study of accelerated carbonation of municipal solid waste incinerator air pollution control residues for sequestration of flue gas CO2

Abstract

It is known that accelerated carbonation technology can stabilise municipal solid waste incinerator air pollution control (APC) residues through encapsulation of hazardous components and cementation by carbonate precipitation. The aim of this work was to investigate the possibility of sequestering flue gas CO₂ in APC residues with a view to reducing greenhouse gas emissions. The fundamental parameters affecting the carbonation process have been studied. An adverse effect of the CO₂ concentration was observed and the optimum water-to-solid ratio and temperature were 0.3 and 20–30 °C, respectively. The reaction consisted of two stages. Initially, the reaction rate was controlled by the movement of the carbonation interface and the activation energy at this stage was 14.84 kJ mol⁻¹; as the reaction proceeds, the rate controlling regime switched to gas diffusion through product layer control, and the activation energy was calculated to be 30.17 kJ mol⁻¹. The openness of the pores in the solid is the key to carbonation efficiency. 10–12% (w/w) of CO₂ can be trapped in APC residues during the carbonation process if flue gas is used.