Chlorobenzene adsorption/desorption confined into y zeolite: a combined in situ high-temperature synchrotron powder X-ray diffraction and chromatographic study

The occurrence and fate of fuel-based pollutants in the aquatic environment has been recognised as one of the emerging issues in environmental chemistry. Their harmful effects on the environment make very interesting their removal from natural water. Recently, it has been reported that hydrophobic zeolites are environmentally compatible materials, which have been employed as adsorbents for the removal of contaminants from water bodies [1-4]. Besides, these materials can be easily thermally regenerated without changing their initial features and reused in pollutants adsorption processes [5-8]. For this reasons the present work aims to investigate the structural modifications related to the regeneration of a hydrophobic Y zeolite (HSZ-390HUA, SiO2/Al2O3 = 200, Tosoh Corporation) after chlorobenzene (Cl-B) adsorption which is a common VOCs present in water. Indeed, structural and kinetic dynamic data are required to full understanding the above process but actually no in situ structural investigation of the kinetics desorption has been performed on zeolite FAU topology. Initially kinetics and adsorption isotherm batch data were obtained via Headspace Solid Phase Microextraction-GC. Then the desorption process was continuously monitored at the ID22 beamline (ESRF-Grenoble) as a function of temperature (heating rate 20°C/min) from room temperature up to 600°C. Rietveld refinements allowed as to determinate the variations of the framework geometry due to the heat-induced desorption of organic molecules. Moreover, the results indicate that after thermal treatment zeolite does not show any significant crystallinity loss. The sample regeneration is effective when it is thermally treated at about 300°C. Above this temperature, when all the organic have been ejected, non-equilibrium distortions in the framework are relaxed and channel apertures become more circular. Additionally, understanding this process can help in optimizing and the design the water remediation technologies (e.g. Permeable Reactive Barriers) and using zeolites as “molecular sieves” to remove fuels-based pollutants from water. [1] A. Martucci, I. Braschi, L. Marchese, S. Quartieri, Min. Mag., 2014, 1115–1140. [2] L. Pasti, A. Martucci, M. Nassi, A. Cavazzini, A. Alberti, R. Bagatin, Micropor. Mesopor. Mat., 2012, 182–193. [3] L. Pasti, E. Sarti, A. Cavazzini, N. Marchetti, F. Dondi, A. Martucci, J. Sep. Sci., 2013, 1604–1611; [4] A. Martucci, I. Braschi, C. Bisio, E. Sarti, E. Rodeghero, R. Bagatin and L. Pasti, RSC Adv., 2015, 86997-87006. [5] A. Martucci, E. Rodeghero, L. Pasti , V. Bosi, G. Cruciani , Microporous and Mesoporous Materials, 2015, 175-182. [6] E. Rodeghero, A. Martucci, G. Cruciani, R. Bagatin, E. Sarti, V. Bosi, L. Pasti, Catalysis Today, in press. [7] L. Pasti, E. Rodeghero, E. Sarti, V. Bosi, A. Cavazzini, R. Bagatin and A. Martucci, RCS Adv., submitted. [8] L. Leardini, S. Quartieri, G. Vezzalini, R. Arletti, Microporous and Mesoporous Materials, 2015, 226– 233.