ALUMINUM SPECIATION AND EQUILIBRIA IN AQUEOUS-SOLUTION .4. A POTENTIOMETRIC STUDY OF ALUMINUM ACETATE COMPLEXATION IN ACIDIC NACL BRINES TO150-DEGREES-C

The molal formation quotients for Al(Ac)(n)(3-n) were measured potenti ometrically from 25 to 150 degrees C at ionic strengths of 0.1, 0.2, 0 .3, 0.6, and 1.0 mol kg(-1) in an aqueous NaCl medium. The titrations were carried out over the pH range 1.9 to 3.1 in a hydrogen-electrode, concentration cell. Aluminum acetate species with values of ligand nu mber, ($) over bar n, from one to three were detected, although the st ability fields in which they represented a significant fraction of the total aluminum were limited to restricted conditions of temperature a nd ionic strength. Two empirical equations were formulated containing four adjustable parameters to describe the temperature and ionic stren gth dependencies of the formation equilibrium quotients for Al(Ac)(2+) and Al(Ac)(2)(+). Limited thermodynamic data are presented for the Al (Ac)(3) degrees species. Comparisons are made with the limited thermod ynamic information available in the literature.