Hydrolysis products of water treatment chemical aluminium sulfate octadecahydrate by electrospray ionization mass spectrometry

Hydrolysis and speciation of aluminium sulfate octadecahydrate Al2(SO4)3·18H2OAl2(SO4)3·18H2O was studied by electrospray time of flight mass spectrometry (ESI TOF MS). Several novel polymeric species were determined. Highly charged polymers, characterized by other methods, such as the Keggin cation [Al13O4(OH)24(H2O)12]7+ and the octameric aluminium hydroxide cluster [Al8(OH)14(H2O)18](SO4)5 16H2O, were found using ESI-MS as the anions [Al13O4(OH)25(SO4)4]2− and [Al8O(OH)14(SO4)5(H2O)4]2−. All the main species identified contained sulfate or hydrogen sulfate. The compositions of the determined ions mimicked those of several stable mineral forms.

Graphical abstractHydrolysis and speciation of Al2(SO4)3·18H2O was studied by ESI TOF MS. Several polymeric species, whose compositions mimic those of stable mineral forms, were determined.Figure optionsDownload full-size imageDownload as PowerPoint slide