Discipline of Infestation Control and Protectants, Central Food Technological Research Institute, Mysore .570 013 Manuscript recessed 1 January 1966, revised 25 May 1987, accepted 6 June 1987 Complexation reaction of sodium metasilicate with a mixture of aluminium chloride and orthophosphoric acid has been studied in aqueous medium at 25º Soluble salts of sodium silicophosphates are formed at three different pH values corres­ponding to monosodium dihydrogen silicophosphate, disodium hydrogen

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... icophosphate and trisodium silicophosphate during neutralisation reaction between sodium meta-silicate and orthophosphoric acid. The presence of AlIII ions in this reaction shows precipitated aluminium silicophosphates of the compositions of Al(SiO2 PO4 and Al(SiO2)1.5PO4 as salts of di- and tri-sodium silicophosphates. Infrared spectra of these compounds suggest coordination of oxygen atoms to Al, Si and P. Based on these studies, procedures have been developed for the synthesis of aluminium silica-phosphates and these were characterised by analytical, ir and TGA data.