Effect of Surface Acidity of Al2O3 on Its Interactions with Lubricant Additives

• Published in: Langmuir Vol. 18; no. 21; pp. 7936 - 7942
• Main Authors: Templer, Mark, Chvedov, Dmitri
• Format: Journal Article
• Language: English
• Published: American Chemical Society 15.10.2002
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la011833l

The effect of the surface acidities of various aluminum oxides on the energy of adsorption of selective organic species has been studied by means of flow adsorption microcalorimetry. The strength of interaction of dioctyl sebacate (one typical lubricant additive) with the surface of Al2O3 depends on the amount of surface water and on the charge of surface hydroxide groups, with the positive and neutral charges being favorable. Temperature affects dioctyl sebacate adsorption by partially removing water molecules from the surface and exposing active sites, which then become available for adsorptive interactions. Al2O3 surfaces of various acidities have also been characterized using flow microcalorimetry and 1-butanol as a probe molecule. The adsorption capacity of 1-butanol on acidic Al2O3 is twice as much as that on the neutral and basic oxides.