کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
608354 880580 2012 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
The effect of various treatment conditions on natural zeolites: Ion exchange, acidic, thermal and steam treatments
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی شیمی کلوئیدی و سطحی
پیش نمایش صفحه اول مقاله
The effect of various treatment conditions on natural zeolites: Ion exchange, acidic, thermal and steam treatments
چکیده انگلیسی

Two different natural zeolites having different phase compositions were obtained from different regions of Turkey and modified by ion-exchange (0.5 M NH4NO3) and acid leaching using 1 M HCl. The natural and modified samples were treated at low temperature (LT), high temperature (HT) and steam (ST) conditions and characterised by XRF, XRD, BET, FTIR, DR–UV–Vis, NH3-TPD and TGA. Ion-exchange with NH4+ of natural zeolites results in the exchange of the Na+ and Ca2+ cations and the partial exchange of the Fe3+ and Mg2+ cations. However, steam and acidic treatments cause significant dealumination and decationisation, as well as loss of crystalline, sintering of phases and the formation of amorphous material. The presence of mordenite and quartz phases in the natural zeolites increases the stability towards acid treatment, whereas the structure of clinoptilolite-rich zeolites is mostly maintained after high temperature and steam treatments. The natural and modified zeolites treated at high temperature and in steam were found to be less stable compared with synthetic zeolites, resulting in a loss of crystallinity, a decrease in the surface area and pore volume, a decrease in the surface acidity as well as dealumination, and decationisation.

Figure optionsDownload high-quality image (78 K)Download as PowerPoint slideHighlights
► The extraction of the embedded iron in natural zeolites into the extra-framework.
► The homogenisation of zeolites via ion exchange, acid and steam treatments.
► Determination of a relationship between the composition and stability of the zeolites.
► Improvement of characteristics of natural zeolites by a range of chemical and temperature treatments.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Colloid and Interface Science - Volume 372, Issue 1, 15 April 2012, Pages 130–140
نویسندگان
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