Chemical Engineering / Kimya Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/14

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Author: search.filters.author.Akdeniz, YeldaPublisher: search.filters.publisher.Springer Verlag

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  • Article
    Citation - WoS: 26
    Citation - Scopus: 28
    Thermal Stability of Ag-Exchanged Clinoptilolite Rich Mineral
    (Springer Verlag, 2008) Akdeniz, Yelda; Ülkü, Semra
    Thermal stability of clinoptilolite rich mineral from Western Anatolia, Turkey and its Ag-exchange forms was investigated. Parent mineral of different sizes were heated up to 1000°C with heating rate of 2 and 10°C min -1 using differential thermal analyzer (DTA) and thermogravimetric analyzer (TG). Ag exchange was conducted both in conventional constant temperature waterbath and microwave at 40, 60 and 80°C. The exchanged minerals were then characteized by scanning electron microscopy (SEM), X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), DTA and TG. The particle size and heating rate do not have significant effect on the thermal behavior of the parent mineral and no structural changes were observed with Ag exchange, only decomposition temperature was lowered. It was finally concluded that, Ag-exchanged clinoptilolite rich minerals were less thermally stable compared to parent mineral that does not affect their use for possible applications.
  • Article
    Citation - WoS: 19
    Citation - Scopus: 21
    Microwave Effect on Ion-Exchange and Structure of Clinoptilolite
    (Springer Verlag, 2007) Akdeniz, Yelda; Ülkü, Semra
    The effect of microwave irradiation on the ion exchange degree and structure of clinoptilolite mineral has been examined in comparison with the conventional heat treatment in waterbath. Clinoptilolite-rich mineral from the Western Anatolia, Bigadiç region was used for the experimental study. The mineral was mainly clinoptilolite (80-85%) and additionally, quartz (5-10%), and analcime+mordenite (<5%) were found as co-existing minerals. The mineral was stable towards dehydration and maintains its original structure up to 800°C. The BET and Langmuir surface areas of the sample were found to be 22 and 17m2/g for N2 adsorption and 28 and 22m2/g for Ar adsorption, respectively. For the exchange experiments, clinoptilolite rich mineral was treated with 1N NaCl salt solution both in a microwave unit and waterbath for 10min, 1h and 2h at 80°C. The waterbath treatment with the same conditions was continued for two additional weeks. The chemical composition of the parent and Na-exchanged forms of the clinoptilolite rich minerals were analyzed by using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). Microwave treatment was found to be more rapid and effective for ion exchange compared to conventional waterbath treatment. Additionally, the XRD results reveal that microwave irradiation has zero effect on the structure of the clinoptilolite rich mineral.