This patent application relates to an invention for a new silicotitanate molecular sieve ion exchange material for the capture and immobilization of divalent cations from aqueous and/or hydrocarbon solutions, including elements such as radioactive strontium or industrial RCRA metal cations. The invention also relates to the ability to either recycle the captured metal for future use or to encapsulate the cation through thermal treatment of the molecular sieve to a condensed phase.