Speciation of Al3+ in fairly concentrated solutions(20-200 mmol L-1) at I = 1 molL-1 (NaNO3), in theacidic 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). Manydifferent 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 andenthalpy changes at different temperatures are reported.