In situ ultrasonic measurements: a powerful tool to control the synthesis of zeolites from coal fly ash
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An in situ ultrasonic diagnostic technique was applied to monitoring the hydrothermal synthesis of zeolite A and X of clear solution extracted from alkaline fused class F coal fly ash. In this context, kinetic evaluations based on in situ ultrasonic diagnostic data displayed an important approach to study the synthesis process. The impact on nucleation and crystal growth was demonstrated by variation of a few relevant parameters such as reaction temperature, amount of water, Na2O and ageing time, including templated colloidal synthesis mixtures as model solution. To complement the kinetic analysis, ex situ techniques such as ICP, X-ray diffraction, scanning electron microscopy and dynamic light scattering were used to investigate liquid phase and reaction products extracted from the reaction mixture during the synthesis.
KeywordsIn situ Ultrasound Coal fly ash Colloidal synthesis Kinetics Zeolite A, X Sodalite
This work was conducted at the University of Erlangen-Nürnberg, Germany, concerning some parts as a supplement to the PhD thesis of N. Musyoka. The author would like to thank Prof. W. Schwieger for providing the ultrasonic device and DAAD and the German Research Foundation (DFG) for funding. Thanks are also addressed to H. Baser to reflect parts of the results of his PhD thesis. We are also grateful to R. Müller for ICP analysis an gradually acknowledge L. Petrik from the University of the Western Cape, South Africa, for providing the coal fly ash from Eskom used in this study.
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