AL-27 MAS NMR INVESTIGATIONS OF SODIUM ALUMINATES FORMED FROM HIGH PH SOLUTIONS - EVIDENCE OF A COMPLEX POLYMER CONTAINING BOTH 4-COORDINATE AND 6-COORDINATE ALUMINUM

Aluminium-27 MAS NMR studies of sodium aluminates and aluminium hydroxides (OH/Al = 5.3-3.9) formed through varying degrees of acid hydrolysis have revealed four-and-six coordinate aluminium species, suggesting the formation of complex polyoxoanion and/or polymeric intermediates in alkaline solution.