THE INFLUENCE OF ELECTROPOSITIVE AND ELECTRONEGATIVE ELEMENTS ON PROTON BINDING TO GAMMA AL2O3 IN AQUEOUS SUSPENSIONS

The effect of electronegative (F) and electropositive (Na) dopants on the proton affinity distribution (PAD) of surface hydroxyls at the alumina/water interface was determined and compared with the changes in the hydroxyl region of infrared spectra collected after dehydration of the same samples. The comparison between the two is based on the assumption that the local configuration of OH groups at the oxide/solution interface is similar to that used in the assignment of IR bands for hydroxyls on partially dehydrated surfaces, i.e., assignments from models assuming perfect crystal planes. A common structural model is used to correlate the changes observed in proton affinity distributions with those recorded in IR spectra after doping alumina with either F or Na. (C) 1994 Academic Press, Inc.