The Wetting of Calcite Surfaces

Abstract

Three established methods for deriving the surface energetic parameters for calcite were studied. These are based on the contact angle in air 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 these methods were not entirely in agreement, several interesting observations emerged. The contact angles of water on the heated and alkylketene-dimer-(AKD)-treated calcite samples were higher than the untreated sample, and were observed to decrease with time. These results strongly suggest that these treatments alter the calcite surface to reduce its 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 the results obtained using the more recent theory of adhesion of van Oss and Good which emphasizes the acid-base contribution of the surface and interacting liquid adhesion. These energy parameters were also determined for the calcite-water system.

Key Words:

• Calcite
• calcium carbonate
• contact angle
• surface energetics
• wetting
• work of adhesion
• acid-base interactions
• alkylketene dimer