Ponente
Descripción
Comprehensive study on Cu2+, Zn2+ and Ag+ ion-exchange kinetic in mordenite under the action of microwave radiation.
Inocente Rodríguez-Iznaga1, Elena Smolenteseva2, Vitalii Petranovskii2, Sergio Fuentes-Moyado2, Felipe Castillón-Barraza2 and Julia Kotolevich2.
1Instituto de Ciencias y Tecnología de Materiales (IMRE) – Universidad de La Habana, 10400, Cuba. email: inocente@imre.uh.cu
2Centro de Nanociencias y Nanotecnología (CNyN) - UNAM, Ensenada, B.C. 22860, México.
Ion exchange is one of the most widely used processes to modify zeolites and develop new materials with catalytic properties, biocide activity, improved thermal and chemical stability, etc [1]. The process used traditionally is the hydrothermal treatment of zeolite with solutions contenting cations, applied over hours and days. However, there are other methods that allow the ionic-exchange time to be reduced, such as using microwave radiation [1,2]. However, the reported studies are limited to the use of this advanced method in synthesis and modification of zeolite. There are no reported studies on the ion-exchange kinetic, which would allow them to be carried out more efficiently. In this work, a comprehensive study on the kinetic of ion exchange of Cu2+, Zn2+ and Ag+ cations in synthetic Na-mordenite zeolite by microwave radiation assisted at different temperatures and times is presented. The study was assisted by different characterization techniques (XRD, UV-Vis spectroscopy and TEM) and determinations of ion-exchange kinetic parameters. The obtained results lead to conclusion that the use of microwave radiation does not affect the mordenite structure. The ion-exchanges are completed at very-short times (~30 min), independently of the used temperature (30oC and 100oC). It was observed an important reversibility in the ion-exchanges, mainly to the higher temperature (100oC). It was associated with a parallel exchange of H3O+ cations formed in solution as a result of metal aqua-complex hydrolyses, which should be potentiated by microwave radiation. The silver exchange is accompanied of the degradation of Ag+ to form aggregated elemental species.
Acknowledgements: Thanks are given to E. Aparicio, I. Gradilla, J. Peralta, J. Gonzalez and E. Flores for technical assistance. The research was supported by Programa de Estancias de Investigación (PREI)‐2022 de la DGAPA, UNAM, México and the grants SENER-CONACYT-Hydrocarbons No 117373, DGAPA‐PAPIIT IG101623 and CONACYT “Basic Science Project A1‐S‐33492”.
References:
[1]- I. Rodríguez‐Iznaga, V. Petranovskii, F. F. Castillón‐Barraza, S. Fuentes‐Moyado, F. Chávez‐Rivas, A. Pestryakov. Mordenite‐Supported Ag+‐Cu2+‐Zn2+ Trimetallic System: A Variety of Nanospecies Obtained via Thermal Reduction in Hydrogen Followed by Cooling in an Air or Hydrogen Atmosphere. Materials 16 (2023) 221.
[2]- I. Rodríguez-Iznaga, M. G. Shelyapina, V. Petranovskii. Ion Exchange in Natural Clinoptilolite: Aspects Related to Its Structure and Applications. Minerals 12 (2022) 1628.
