(475d) Regeneration and Framework Stability of Heavy Metal Exchanged Nanoporous Zincosilicates

This presentation will report our findings of the framework stability and the regeneration properties of nano-structured porous zincosilicates that have previously captured mercury and lead from aqueous systems. Zincosilicates have similar framework structures to aluminosilicate zeolites, however they typically have a higher ion density due to the need for two counter cations per zinc in the framework as opposed to the one-to-one ratio of counter cation per aluminum of traditional zeolites. Molecular sieves containing zinc in the framework also have the ability to form three-membered rings (3MR) which lead to large void spaces in their structure. Interestingly, microporous zincosilicates do not have ?cages? in their structure, which leads to all the cations being accessible. These features lead to high capture capacities especially for divalent heavy metals ions such as lead and mercury. Our results have shown that zincosilicates capture high capacities of heavy metals very rapidly indicating a highly favorable thermodynamic process. We will report the structural changes after ion exchange, quantify the reversibility of the ion exchange, and the subsequent structure after the heavy metal reversal process in aqueous systems for a series of zincosilicates, such as VPI-7, VPI-9, VPI-10, and CIT-6.