Procedure of synthesis of thaumasite

In this work, synthesis procedures to obtain thaumasite were revised. Synth esis of thaumasite applying Struble's method (mix of two cold sugary soluti ons containing CaO and Na2SiO3 + Na2SO4 + Na2CO3, respectively, in stoichio metric proportions) was carried out. Amorphous calcium carbonates and calci um silicate hydrates (intermediate products) were obtained at the very begi nning stages of the reaction, which evolved with time forming thaumasite. T haumasite polluted by calcite and calcium silicate hydrate was obtained aft er 2 years of reaction. Pure thaumasite was obtained when initial solutions contained less sodium carbonate and sodium silicate than the stoichiometri c proportions, The synthesized thaumasite was characterized by X-ray diffra ction (XRD), FTIR, SEM/EDX, and NMR. (C) 2001 Elsevier Science Ltd. All rig hts reserved.