XPS study on the carbonation process of Ca(OH)2

Abstract

Intermediates produced in the carbonation process of a Ca(OH)2 slurry were analyzed by X-ray photoelectron spectroscopy (XPS). The molar ratios of CO32- to Ca2+ of the intermediates, determined from the peak areas of Ca2p and C1s of XPS spectra, indicated that the rate of carbonation in the vicinity of the surface was comparable to that in the bulk. The binding energy of Ca2p3/2 was found to have shifted linearly toward higher binding energies with increasing formation of CaCO3. These facts support the view that decrease in the Ca2+ concentration in the early stages of the process was caused by the formation of an amorphous phase with the formula Ca1+xCO3(OH)2x·yH2O (x>0.05, y = 0.6-0.8)