Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Article Citation - WoS: 3Citation - Scopus: 2Adsorption of No in Clinoptilolite-Rich Zeolitic Mineral by Concentration Pulse Chromatography Method(Elsevier Ltd., 2016) Narin, Güler; Ülkü, SemraThe equilibrium and kinetic parameters for NO adsorption in a clinoptilolite-rich natural zeolitic material from Turkey were determined using the concentration pulse chromatography method. Under the experimental conditions (carrier gas velocities and adsorption temperatures) the micropore diffusion resistance was found to be the mass transfer controlling step. Matching the first moment of the response peaks to the mathematical model the Henry's Law constants and heat of adsorption at zero loading were determined. The axial dispersion, external film, macropore and micropore diffusion coefficients, and activation energy for diffusion of NO in the micropores were calculated from the analysis of the second moments of the response peaks. For successive NO pulses without regeneration between the pulses, the retention times of the response peaks decreased and peak areas increased with the injection number indicating irreversible adsorption. The reversibly adsorbed NO could be desorbed by purging with an inert gas at the adsorption pressure and temperature. Temperature programmed desorption profile obtained by heating the NO saturated adsorbent to 400 °C under inert flow revealed presence of multiple irreversibly adsorbed species in NZ with different thermal stabilities. Desorption of these species was not achieved during the heating up to 400 °C which makes the natural zeolitic materıal suitable for NO storage rather than for cyclic adsorptive separation processes.Article Citation - WoS: 4Citation - Scopus: 4A Chromatographic Study of Carbon Monoxide Adsorption on a Clinoptilolite-Containing Natural Zeolitic Material(Taylor and Francis Ltd., 2004) Narin, Güler; Yılmaz, Selahattin; Ülkü, SemraIn this study, the equilibrium and kinetic parameters for CO adsorption on clinoptilolite-rich natural zeolitic material were determined by the concentration pulse chromatography technique. Experiments were carried out at different column temperatures (60-120°C) and interstitial carrier gas velocities (3.1-16.3 cm/s) using a clinoptilolite-rich natural zeolitic material packed column. The equilibrium and kinetic parameters were determined by matching the moments of the experimentally obtained response curves to the parameters in the mathematical model. The Henry's Law constants were found to decrease from 700 to 49 with increasing temperature. The heat of adsorption at low coverage was found to be 50.73 kJ/molK. The contributions from external film, macropore, and micropore diffusion resistances to mass transfer were determined, and the micropore diffusion resistance was found to be the major contributor. The micropore diffusivity as a function of crystal radius (Dc/rc 2) was determined and found to change between 5.72 × 10-4 and 1.34 × 10-2 s-1 in the temperature range studied.