Abstract
The dissolution mechanism and stability of a synthetic hydrated aluminium phosphate, AlPO4·1.5H2O (AlPO4-H3) was investigated at 22 °C over the pH range 2.4 to 8.8. AlPO4·1.5H2O was found to be more soluble than the better known dihydrate (variscite, AlPO4·2H2O) hence proving to be metastable. This material was determined to undergo incongruent dissolution at pH around 3.0 and higher producing initially amorphous Al(OH)3 which gradually (within 30-day dissolution period) converted to the stable gibbsite phase. Upon evaluation of the experimental data with PHREEQC it was possible to calculate the solubility product (log Ksp ) and the standard Gibbs free energy of formation (ΔGf,0 ) for AlPO4·1.5H2O to be respectively −20.46±0.40 and −1980.5±2.0 kJ mol−1 at 22 °C.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
