Ion Exchange for the Denitrification of Zeolite Cancrinite
Ashleen M. Rivera-Velez, Pablo Duarte-Ulloa, and Maria Martinez-IŅesta. Chemical Engineering, UNIVERSITY OF PUERTO RICO MAYAGUEZ CAMPUS, P.O. Box 9046, Mayaguez, PR 00681
Zeolites are aluminosilicates hydrated crystalline minerals, that when dehydrated develop a porous structure with microporous diameters. This porous structure form cavities occupied by large ions and molecules of water with great freedom of movement to allow ion exchange and reversible dehydration. The zeolites can be natural or synthetic, although the synthetic are preferred for their design and their chances of composites chemically pure character, as opposed to changes that may present the natural zeolite. They are commercially used mostly as adsorbing material but new applications have been adapted worldwide to discover hidden potential in the nanostructure field. Cancrinite (CAN) is a synthetic zeolite based on a three-dimensional linkage of [AlO4] and [SiO4] tetrahedral and one-dimensional pore structure. In cancrinite pores are occupied by molecules of negative charges (NO3¯), as well as Van Der Waals forces adhering them to the vacancies of the pore, which are offset by cations in the interior of the structure. In this work, cancrinite has been exposed to ion exchange with calcium chloride (CaCl2) at different temperatures under autogenous pressures to recover these vacant spaces in the pore. Zeolites samples are been analyzed using x-ray diffraction (XRD) for the characterization of the structure in order to identify any changes in the original structure of the zeolite.