Interaction of Mineral Surfaces with Simple Carboxylic Acids In Aqueous And / or Solution In Hexane

Conference · Mon Jun 01 00:00:00 EDT 2009

OSTI ID:2001108

Thomas, Joan; Kelley, Michael

DRIFTS was used to investigate the adsorption of simple carboxylic acids to the surface of kaolinite clay and to alumina. Dry powder samples were examined without evacuation or blending with KBr. It was possible to determine monolayer coverage of the organic on the mineral surface from analysis of the spectra. Resolution of peaks from the organic was possible for coverage as low as 0.02 molecules / nm2. Studies were done with adsorption from aqueous solution and or solution in hexane. It should be noted that under atmospheric conditions, mineral surfaces have a surface layer of water approximately 3 molecules thick. At sub monolayer coverage, spectral features of salicylic acid deposited on gamma-alumina from hexane were not distinguishable from those deposited from water. But, greater surface loading could be achieved with adsorption from the organic solvent (hexane)and new peaks were observed. Adsorption of salicylic acid , from solution in hexane , onto kaolinite was also possible. In almost all cases, spectral features associated with the carboxyl moiety were substantially altered, indicating a significant role in the adsorption mechanism. The results using hexane as solvent compared with water suggest that the surface adsorbed hydroxyl and molecular water, present on mineral oxides under ambient conditions, are a key determinant of molecular adsorbate architecture.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 2001108
• Report Number(s): JLAB-FEL-09-1145; DOE/OR/23177-7152
• Country of Publication: United States
• Language: English