Hydrothermal Synthesis of Sodium Zirconium Silicates and Characterization of Their Properties

By studying reactions in the system Zr(OC 3 H 7 ) 4 −silicic acid (Na 2 SiO 3, Na 2 Si 3 O 7 )−NaOH−H 2 O under mild hydrothermal conditions (180−190 °C) the formation of three novel layered sodium zirconium silicates, Na 2 Zr 5 Si 2 O 15 ·3H 2 O, Na 2 Zr 5 Si 2 O 15 ·4H 2 O, and Na 2 ZrSi 3 O 9 ·3H 2 O, and five other compounds: Na 4 Zr 2 Si 3 O 12, Na 3 HZrSi 2 O 8, Na 4 Zr 2 Si 5 O 16 ·H 2 O, Na 4 ZrSi 3 O 10, and Na 2 ZrSi 3 O 9 ·2H 2 O, have been found. All the synthesized materials were characterized by elemental analysis, TGA, X-ray, IR, and 29 Si MAS NMR spectroscopy. The ion-exchange behavior of sodium zirconium silicates toward alkali, alkaline-earth, and some di- and trivalent metal cations was studied.