The water contamination has increased significantly in recent years due to a very fast development of industries as well as of intense agricultural practices. As a matter of fact that the development of progress has given rise to a general improvement of the standard of living, but it had increased the environment pollution through the wide release of contaminants of emerging concern (CECs) [1]. In particular, the presence of these chemicals at ultra-trace levels causes the development of sublethal toxic effects in aquatic organisms and in human health [2]. 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. To support the traditional methods, new technologies which employ different types of materials have been developed. Among these technologies, adsorption method based on the use of adsorbent materials have been shown to be an effective and eco-friendly alternative. In particular, hydrophobic zeolites have proven to be very promising materials, which have been employed as adsorbents for the removal of contaminants from water bodies [3,4]. Indeed, zeolites represent an important adsorbents for the recovery of groundwater polluted by organic complexes and can be easily regenerated by thermal processes without changing their initial adsorption features [3,5]. 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. Specifically, time-resolved high-temperature synchrotron X-ray powder diffraction was used as a tool to understand the behaviour of hydrophobic ZSM-5 zeolite (SiO2/Al2O3 ~ 280) during the desorption of 1,2 dichloroethane, toluene, and methyl tert-butyl ether (adsorbed both as single component as well as binary mixtures). The structural modifications of ZSM-5 zeolite 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. [1] C. Perego, R. Bagatin, M. Tagliabue, R. Vignola (2013). Zeolites and related mesoporous materials for multi-talented environmental solutions. Microporous and Mesoporous Materials, 37 – 49. [2] M. Raghav, S. Eden, K. Mitchell, B. Witt (2013). Contaminants of Emerging Concern in Water. The Arroyo, 1 – 12. [3] E. Rodeghero, A. Martucci, G. Cruciani, R. Bagatin, E. Sarti, V. Bosi, L. Pasti (2016). Kinetics and dynamic behaviour of toluene desorption from ZSM-5 using in situ high-temperature synchrotron powder X-ray diffraction and chromatographic techniques. Catalysis Today, 118–125. [4] L. Pasti, E. Rodeghero, E. Sarti, V. Bosi, A. Cavazzini, R. Bagatin and A. Martucci (2016). Competitive adsorption of VOCs from binary aqueous mixtures on zeolite ZSM-5. RSC Advance, 54544–54552. [5] A. Martucci, E. Rodeghero, L. Pasti, V. Bosi, G. Cruciani (2015). Adsorption of 1,2-dichloroethane on ZSM-5 and desorption dynamics by in situ synchrotron powder X-ray diffraction. Microporous and Mesoporous Materials, 175-182.
CHROMATOGRAPHIC AND STRUCTURAL STUDY OF THE ADSORPTION/DESORPTION PROCESS OF ZSM-5 LOADED WITH VOLATILE ORGANIC COMPOUNDS
ELISA RODEGHERO
;ANNALISA MARTUCCI;LUISA PASTI;ELENA SARTI
2017
Abstract
The water contamination has increased significantly in recent years due to a very fast development of industries as well as of intense agricultural practices. As a matter of fact that the development of progress has given rise to a general improvement of the standard of living, but it had increased the environment pollution through the wide release of contaminants of emerging concern (CECs) [1]. In particular, the presence of these chemicals at ultra-trace levels causes the development of sublethal toxic effects in aquatic organisms and in human health [2]. 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. To support the traditional methods, new technologies which employ different types of materials have been developed. Among these technologies, adsorption method based on the use of adsorbent materials have been shown to be an effective and eco-friendly alternative. In particular, hydrophobic zeolites have proven to be very promising materials, which have been employed as adsorbents for the removal of contaminants from water bodies [3,4]. Indeed, zeolites represent an important adsorbents for the recovery of groundwater polluted by organic complexes and can be easily regenerated by thermal processes without changing their initial adsorption features [3,5]. 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. Specifically, time-resolved high-temperature synchrotron X-ray powder diffraction was used as a tool to understand the behaviour of hydrophobic ZSM-5 zeolite (SiO2/Al2O3 ~ 280) during the desorption of 1,2 dichloroethane, toluene, and methyl tert-butyl ether (adsorbed both as single component as well as binary mixtures). The structural modifications of ZSM-5 zeolite 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. [1] C. Perego, R. Bagatin, M. Tagliabue, R. Vignola (2013). Zeolites and related mesoporous materials for multi-talented environmental solutions. Microporous and Mesoporous Materials, 37 – 49. [2] M. Raghav, S. Eden, K. Mitchell, B. Witt (2013). Contaminants of Emerging Concern in Water. The Arroyo, 1 – 12. [3] E. Rodeghero, A. Martucci, G. Cruciani, R. Bagatin, E. Sarti, V. Bosi, L. Pasti (2016). Kinetics and dynamic behaviour of toluene desorption from ZSM-5 using in situ high-temperature synchrotron powder X-ray diffraction and chromatographic techniques. Catalysis Today, 118–125. [4] L. Pasti, E. Rodeghero, E. Sarti, V. Bosi, A. Cavazzini, R. Bagatin and A. Martucci (2016). Competitive adsorption of VOCs from binary aqueous mixtures on zeolite ZSM-5. RSC Advance, 54544–54552. [5] A. Martucci, E. Rodeghero, L. Pasti, V. Bosi, G. Cruciani (2015). Adsorption of 1,2-dichloroethane on ZSM-5 and desorption dynamics by in situ synchrotron powder X-ray diffraction. Microporous and Mesoporous Materials, 175-182.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
