Speciation of Al3+ in fairly concentrated solutions (20-200 mmol L-1) at I = 1 mol L-1 (NaNO3), in the acidic pH range, at different temperatures.

The hydrolysis of Al3+ was studied in aqueous 1 mol L-1 NaNO3 solution at different concentrations (20-200 mmol L-1) and temperatures (283.15 - 343.15 K) by potentiometry (ISE-H-, glass electrode). Many different speciation models were considered in the calculations and it was found that the best model is represented by the following species: Al(OH)2+, Al3(OH)45+, Al13(OH)327+. Hydrolysis constants and enthalpy changes at different temperatures are reported. [ABSTRACT FROM AUTHOR]