Abstract: A solid ion-exchange material useful for removing heavy metals or radionuclides from an aqueous or gaseous solution comprising a modified clinoptilolite, and methods of using same are provided.

Abstract: A method for removing heavy metals or radionuclides from an aqueous solution comprising contacting the aqueous solution with an ion exchange material selected from a solid ion exchange material, a liquid ion exchange material, or mixtures thereof, wherein the ion exchange material is prepared by the process comprising: contacting clinoptilolite with an alkaline solution at a temperature of about 85° C. to about 300° C. and for a sufficient time to form a treated slurry comprising a solid fraction and a liquid fraction, and optionally separating the solid fraction from the treated slurry and washing the solid fraction to produce the solid ion exchange material; and optionally recovering the liquid fraction of the treated slurry to produce the liquid ion exchange material. A process for producing the above ion exchange materials useful for removing heavy metals or radionuclides from an aqueous solution, and the solid and liquid ion exchange materials produced by the process.