Surface active sites introduced onto calcium carbonate powder by a new surface preparation process

A new process was proposed to introduce active sites onto calcium carbonate powder. The process consists of three steps: (i) chemical surface modification, (ii) surface oxidation and (iii) surface hydroxylation. Repeating this process can increase the amount of new active sites. IR spectroscopy confirmed the process. The surface density of modifiers was evaluated from measuring the specific surface area and weight loss of the samples caused by the combustion of the modifiers. In one process 1.15 nm−2 modifiers were introduced onto the sample. The process can introduce new active sites quantitatively without influencing the properties of the sample substrate and can also improve its thermostability. Surface acidity increased until four cycles in the repeated modification process; however, it decreased after the fourth cycle. This result was ascribed to a change in the surface binding state by introducing the new active sites and such a conclusion was explained by results of X-ray photoelectron spectroscopy.