Abstract: A new family of rare-earth silicate compositions and the synthetic methods used to prepare them. The materials have open-framework structures and are characterized by their ion-exchange properties. They are represented by the following empirical formula: Ar+pMs+1-xM?t+xSinOm where A is an exchangeable cation such as sodium, M is at least one element selected from the group of rare-earth elements, and M? is a framework metal having a valence of +2, +3, +4, or +5. The rare-earth silicate materials have utility in various cation-exchange applications such as dialysis and removal of toxic metals from the gastrointestinal tract.

Abstract: A process for removing Pb2+, Hg2+, K+ and NH4+ toxins from bodily fluids is disclosed. The process involves contacting the bodily fluid with an ion exchange composition to remove the metal toxins in the bodily fluid, including blood and gastrointestinal fluid. Alternatively, blood can be contacted with a dialysis solution which is then contacted with the ion exchange composition. The ion exchange compositions are represented by the following empirical formula: Ar+pMs+1-xM?t+xSinOm A composition comprising the above ion exchange compositions in combination with bodily fluids or dialysis solution is also disclosed. The ion exchange compositions may be supported by porous networks of biocompatible polymers such as carbohydrates or proteins.

Abstract: A process for removing Pb2+ toxins from bodily fluids is disclosed. The process involves contacting the bodily fluid with an ion exchange composition to remove the metal toxins in the bodily fluid, including blood and gastrointestinal fluid. Alternatively, blood can be contacted with a dialysis solution which is then contacted with the ion exchange composition. The ion exchange compositions are represented by the following empirical formula: AmTiaNb1-aSixOy having either the pharmacosiderite, sitinakite, pharmacosiderite-sitinakite intergrowth topologies or mixtures thereof. A composition comprising the above ion exchange compositions in combination with bodily fluids or dialysis solution is also disclosed. The ion exchange compositions may be supported by porous networks of biocompatible polymers such as carbohydrates or proteins.