The response to heating of an organophilic ZSM-5 sample after sulfamethoxazole (SMX) antibiotic adsorption [1] was investigated by in situ synchrotron X-ray powder diffraction in order to monitor the structural modifications induced by the regeneration treatment. This kind of information is crucial to design and optimize the regeneration treatment of zeolites with a very high potential for application in water remediation technologies. The evolution of the structural features was followed both in temperature ramp (25-575°C, heating rate 10 °C/min) and in isotherm mode (120 minutes at 575 °C) by 45 full profile Rietveld refinements (s.g. P212121). Our results show that temperature-induced transformations can be schematized into three main steps. In the 25-250 °C temperature range, the unit cell parameters (figure 1) slightly increase with increasing temperature. This process is accompanied by a regularization of the 10-ring channel apertures which become more homogeneous (figure 2). Between 250 and 575 °C, the evident slope change in the unit-cell volume indicates the SMX degradation and expulsion according to TG analyses [1]. The structural deformation mechanism observed was a cooperative anti rotation of the tetrahedra belonging to both sinusoidal and straight 10-ring channels as indicated by the changes in channel’s ellipticity (figure 2). The sequence of powder diffraction patterns refined using the Rietveld method during the isotherm show that the unit-cell parameters and the ellipticity maintains substantially unchanged. These results indicate that at 575 °C regeneration is completed and that the flexible ZSM-5 framework is very similar to the as synthesized material [2]. REFERENCES [1] S. Blasioli, C. T. Johnston, A. Martucci, L. Gigli, I. Braschi, A. Alberti, C. E. Gessa, Removal of sulfamethoxazole antibiotic from water by zeolites, 10th Congress of Italian Zeolite Association, Advances in Zeolites Science and Technology, 14-17 Settembre 2011, Napoli. [2] L. Pasti, A. Martucci, M. Nassi, A. Cavazzini, A. Alberti,R. Bagatin, Microporous and Mesoporous Materials 160 (2012) 182–193.
THE RESPONSE TO HEATING OF AN ORGANOPHILIC ZSM-5 AFTER SULFAMETHOXAZOLE ADSORPTION: AN IN-SITU TIME-RESOLVED POWDER DIFFRACTION STUDY
LEARDINI, Lara;MARTUCCI, Annalisa;
2012
Abstract
The response to heating of an organophilic ZSM-5 sample after sulfamethoxazole (SMX) antibiotic adsorption [1] was investigated by in situ synchrotron X-ray powder diffraction in order to monitor the structural modifications induced by the regeneration treatment. This kind of information is crucial to design and optimize the regeneration treatment of zeolites with a very high potential for application in water remediation technologies. The evolution of the structural features was followed both in temperature ramp (25-575°C, heating rate 10 °C/min) and in isotherm mode (120 minutes at 575 °C) by 45 full profile Rietveld refinements (s.g. P212121). Our results show that temperature-induced transformations can be schematized into three main steps. In the 25-250 °C temperature range, the unit cell parameters (figure 1) slightly increase with increasing temperature. This process is accompanied by a regularization of the 10-ring channel apertures which become more homogeneous (figure 2). Between 250 and 575 °C, the evident slope change in the unit-cell volume indicates the SMX degradation and expulsion according to TG analyses [1]. The structural deformation mechanism observed was a cooperative anti rotation of the tetrahedra belonging to both sinusoidal and straight 10-ring channels as indicated by the changes in channel’s ellipticity (figure 2). The sequence of powder diffraction patterns refined using the Rietveld method during the isotherm show that the unit-cell parameters and the ellipticity maintains substantially unchanged. These results indicate that at 575 °C regeneration is completed and that the flexible ZSM-5 framework is very similar to the as synthesized material [2]. REFERENCES [1] S. Blasioli, C. T. Johnston, A. Martucci, L. Gigli, I. Braschi, A. Alberti, C. E. Gessa, Removal of sulfamethoxazole antibiotic from water by zeolites, 10th Congress of Italian Zeolite Association, Advances in Zeolites Science and Technology, 14-17 Settembre 2011, Napoli. [2] L. Pasti, A. Martucci, M. Nassi, A. Cavazzini, A. Alberti,R. Bagatin, Microporous and Mesoporous Materials 160 (2012) 182–193.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
