FisMat2017 - Submission - View

Abstract's title: Structural study of the adsorption and desorption process of Volatile Organic Compounds confined to the hydrophobic ZSM-5
Submitting author: Elisa Rodeghero
Affiliation: University of Ferrara
Affiliation Address: via Saragat, 1 - 44121 Ferrara
Country: Italy
Oral presentation/Poster (Author's request): Oral presentation
Other authors and affiliations: ANNALISA MARTUCCI 1, LUISA PASTI 2, ELENA SARTI 2 1 Department of Physics and Earth Sciences University of Ferrara, Ferrara, Italy 2 Department of Chemistry and Pharmaceutical Sciences University of Ferrara, Ferrara, Italy
Abstract

In recent few years, the release of organic contaminants in the environment has seriously compromise the water quality and its use. In particular, the major pollutants that contaminate natural water mainly derive from industrial processes, including chemical, petrochemical and pharmaceutical industries, but also from farm that use different topologies of pesticide. These chemicals are included in the general group of  Emerging Organic Contaminants, but among of these the Volatile Organic Compounds (VOCs) require the most attention due to their harmful effects both on the environment and human health, even at very low concentrations. Due to their the toxic effects also at long term, the removal or the reduce of concentrations of these class of contaminants from water bodies is today a very important objective.  Nowadays, the traditional wastewater treatments (i.e., vaporization, dilution, decomposition, and reactions to sunlight action) designed to degrade or remove these pollutants or reduce the levels of their concentrations are not completely effective and they need to a supporting technology. For instance, adsorption technologies based on the use of  adsorbent materials have been shown to be an effective alternative to substitute or support the traditional methods. In this application field, high-silica zeolites have proven to be very promising materials, which have been employed as adsorbents for the removal of contaminants from water bodies. Overall, zeolites represent an important eco-friendly adsorbents because they also can be easily regenerated by thermal processes and it is possible to reuse them for new adsorption cycles. On the basis of the above statements, the combination of chromatographic, diffractometric and thermogravimetric techniques has been employed to investigate the adsorptive-desorptive properties of hydrophobic synthetic zeolite as well as the temperature dependence of the desorption processes. Concerning the study of the desorption process, time-resolved high-temperature synchrotron X-ray powder diffraction was used as a tool to understand the structural modification undergoing on ZSM-5 framework (SiO2/Al2O3 ~ 280) during the desorption of single molecules and binary mixtures of 1,2 dichloroethane, toluene, and methyl tert-butyl ether. In particular, the structural modifications of ZSM-5 samples are monitored through thermal treatment from room temperature to 600°C. The results achieved by means of Rietveld refinements of the investigated compounds highlight the “out-of-equilibrium effects” that govern the adsorption/desorption dynamic conditions in ZSM-5 powders.