Measurements of Al(NO{sub 3}){sub 3} activities in aqueous nitrate solutions

Aluminum nitrate activity coefficient obtained by vapor pressure osmometry are compared with activity coefficients derived from nitric acid extraction measurements using Bromley's correlation. This solvent extraction approach was possible because of the poor extraction of Al{sup 3+}(D{sub Al} {le} 10{sup {minus}3}) by the chosen solvents. The solvent compositions were 0.25M CMPO (octyl(phenyl)-N,N-diisobutylcarbamoyl-methylphosphine oxide) in tetrachloroethylene (TCE) and 0.25M CMPO with 0.75M tributyle phosphate (TBP) in TCE. In both approaches, nitric acid was used to supress the hydrolysis of Al{sup 3+}. At high ionic strengths, the two techniques yielded very similar activity coefficients for Al(NO{sub 3}){sub 3}. However, at intermediate and very low ionic strengths, the two procedures produced activity coefficients which differed considerably from each other. 2 figures, 3 tables, 18 references.