Direct sulfation kinetics of limestone modified by wood vinegar under O₂/CO₂ atmosphere

The direct sulfation reaction of limestone modified by wood vinegar, a kind of waste liquid, was investigated by thermogravimetic analysis method under O₂/CO₂ atmosphere. The results show that the direct sulfation performance of limestone can be effectively improved by wood vinegar modifying in the experimental temperature range (1 023~1 173 K). The phase composition analysis measured by XRD shows that the major composition in the modified limestone is hydration calcium acetate. The structure of limestone modified is much looser than that of original limestone, which is conducive to the direct sulfation reaction. The direct sulfation rate constant (k_s) and product-layer diffusivity (D_eff) in Arrhenius expressions were calculated according to the shrinking unreacted core model. The kinetic calculation results show that the diffusion impact of limestone modified by wood vinegar on the direct sulfation process is less than that of original limestone, which means that the limestone modified by wood vinegar has a lower diffusion resistance.