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Browsing by Author "Akdeniz, Yelda"

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    Master Thesis
    Cation exchange in zeolites structure modification by using a microwave
    (Izmir Institute of Technology, 1999) Akdeniz, Yelda; Ülkü, Semra
    In this research, characterization and modification of clinoptilolite minerals from different deposits have been studied to determine its utility for different Clinoptilolite minerals obtained from the source located in Western (FTIR) to determine the structural properties. The FTIR spectra of the samples showed the characteristic vibrations of the clinoptilolite framework. Thermal properties were determined using Differential Thermal Analyzer (DTA), Thermal Gravimetric Analyzer (TGA), and Differential Scanning Calorimetry (DSC). The analysis showed that the structure of the samples were stable up to 650 DC and due to the Fe203 present in the tuff, phase inversion was observed. Accelerated Surface Area and Porosimeter (ASAP 2010) used to determine the adsorptionrelated properties using N2 and Ar adsorption isotherms. The samples showed different adsorption behaviour toward each gas. The pore size distribution of clinoptilolite samples showed that they have mesaporous structure.The clinoptilolite was modified by ion exchange using 1N NaCI salt solution in waterbath, and in microwave maintained at 80 DC for 10 min, 60 min and 120 min. The efficiency of each method on ion exchange was compared. The Na+ amount in the zeolite was found to be 2.25 and 3.24 % by weight after 2 hours of exchange in waterbath and microwave, respectively. The results showed that microwave method used for modification was more efficient.
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    Doctoral Thesis
    The effect of microwaves on ion exchange in zeolites
    (Izmir Institute of Technology, 2009) Akdeniz, Yelda; Ülkü, Semra
    Recent innovations of microwave field lead many scientists to focus on this phenomenon and it has been begun to be applied in different fields of zeolite applications. The purpose of this study is to determine the effect of microwave irradiation on ion exchange degree and on the structure of natural zeolite. The clinoptilolite rich mineral from Western Anatolia was used throughout the experiments. The ion exchange experiments were performed using AgNO3, Co.(NO3)26H2O and Cu (NO3)25/2H2O within 0.01M - 1M and 40 oC - 80 oC concentration and temperature range in conventional waterbath and microwave. Different solid and solution conditions on ion exchange degree were determined, as well. Metal exchanged minerals were characterized by using instrumental techniques. Antibacterial activity of the Agexchanged clinoptilolite against E. coli was determined by Kirby.Bauer method. The Ag +, Co2+ and Cu2+ amounts within the mineral increased with decreasing S/L while increased with increasing temperature and time. For some utilized parameters microwave treatment was effective however on the whole it did not significantly improved the degree of ion exchange compared to waterbath treatment. The inspection of XRD patterns and FTIR spectra of metal exchanged minerals confirmed that no transition of clinoptilolite phase and no shifts in peak positions occurred with exchange methods applied. The sorption processes are controlled mainly by external-phase mass transfer. Ag+, Co2+ and Cu2+ sorptions on NaCLI exhibited a good fit to Freundlich model and Langmuir models. All metal exchanged minerals showed considerable superiority against E.Coli.