THE WETTING OF CALCITE SURFACES

Three established methods for deriving the surface energetic parameter s for calcite were studied. These are based on the contact angle in ai r using various wetting liquids, and submerged systems in water and in alkanes. Two variations of these methods that require less elaborate experimental procedures were also explored. Although the results of th ese methods were not entirely in agreement, several interesting observ ations emerged. The contact angles of water on the heated and alkylket ene-dimer-(AKD)-treated calcite samples were higher than the untreated sample, and were observed to decrease with time. These results strong ly suggest that these treatments alter the calcite surface to reduce i ts stability toward water. The work of adhesion determined in alkanes and water suggests that water interacts so strongly with calcite that it cannot be displaced by alkanes. This conclusion is reinforced by th e results obtained using the more recent theory of adhesion of van Oss and Good which emphasizes the acid-base contribution of the surface a nd interacting liquid adhesion. These energy parameters were also dete rmined for the calcite-water system.