Assessment of surface heterogeneity of calcite and apatite: from high resolution gas adsorption to the solid-liquid interface

The surface heterogeneity of calcite and apatite was investigated by high r esolution adsorption isotherms of argon and nitrogen. The use of the deriva tive isotherm summation procedure reveals the presence of high energy adsor ption sites for nitrogen molecules. These sites are assigned to surface cal ciums and monohydrogenophosphate groups for calcite and apatite respectivel y. The comparison of gas adsorption results with experiments at solid-liqui d interfaces shows that nitrogen probes the same surface sites as benzoic a cid on calcite and decylammonium chloride on apatite. (C) 1999 Elsevier Sci ence B.V. All rights reserved.