Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Article Citation - WoS: 13Citation - Scopus: 14Characterization and Dehydration Behavior of a Natural, Ammonium Hydroxide, and Thermally Treated Zeolitic Tuff(Taylor and Francis Ltd., 2011) Narin, Güler; Balköse, Devrim; Ülkü, SemraAqueous NH4OH-treated and subsequently calcined forms of local natural zeolitic tuff were characterized by different techniques including scanning electron microscopy (SEM), X-ray powder diffraction, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), volumetric N2 adsorption at -196°C, thermogravimetry (TG), differential scanning calorimetry (DSC), and transmittance infrared spectroscopy. The dehydration behavior of the samples was investigated using an in situ temperature-programmed diffuse reflectance Fourier transform infrared spectroscopy (TP-DRIFTS) method under vacuum. The DRIFTS spectra recorded yielded information about the effect of the NH4OH treatment and subsequent calcination on the dehydration behavior of the natural zeolite.Changes in the infrared bands corresponding to vibrations of the O-H and N-H bonds upon in situ heating under vacuum were analyzed.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.