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[en] An estimation of the dehydration kinetics of monohydrated D-glucose with the use of the Bayesian spectral source separation algorithm is described. The dehydration experiment was probed with the terahertz time domain spectroscopy (THz-TDS). Contrary to the widely used peak-area method, our approach to the quantitative analysis takes into account the full spectral information. The obtained concentration profiles at different temperatures were processed in order to measure the kinetics of the dehydration process. Our investigation shows that the proposed method may be used to estimate the evolution of concentration despite the overlapping peaks and multiple spectral sources in the observed spectra.
Journal
No abstract available
Journal
[en] Ulexite is one of the boron minerals, which include a respectable amount of hydration water. It can be used as a raw material in the production of boron compounds. Some part of water in the composition of ulexite can be removed from the solid matrix applying dehydration treatment, and a porous structure can be obtained to increase the reaction rate. In the present study, the effect of dehydration temperature on dissolution kinetics of ulexite in ammonium sulfate solutions was researched in a batch reactor utilizing the parameters of solution concentration, solid-to-liquid ratio, stirring speed and reaction temperature. It was determined that the dissolution rate of calcined material increased with increasing solution concentration and reaction temperature and with decreasing solid-to-liquid ratio. The highest dissolution rate was attained with the sample calcined at 150 °C. It was found that the dissolution rate fit to the first order pseudo-homogeneous model. The activation energy of the dissolution process was estimated to be 42 kJ·mol−1.
[es]
La ulexita es uno de los minerales de boro, que incluye una cantidad considerable de agua de hidratación. Se puede usar como materia prima en la producción de compuestos de boro. Una parte del agua existente en la composición química de la ulexita puede eliminarse de la matriz sólida aplicando tratamiento de deshidratación que permite obtener una estructura porosa, que aumenta la velocidad de reacción. En el presente trabajo, se estudió el efecto de la temperatura de deshidratación sobre la cinética de disolución de ulexita en soluciones de sulfato de amonio, en un reactor discontinuo estudiando los parámetros de concentración de solución, relación sólido/líquido, velocidad de agitación y la temperatura de reacción. Se determinó que la velocidad de disolución del material calcinado aumentaba al aumentar la concentración de la solución y la temperatura de reacción y con la disminución de la relación de sólido/líquido. La velocidad de disolución más alta se alcanzó con la muestra calcinada a 150 °C. Se encontró que la velocidad de disolución se ajusta al modelo pseudohomogéneo de primer orden. La energía de activación del proceso de disolución se estimó en 42 kJ·mol−Journal
Revista de Metalurgia; ISSN 0034-8570; 
; v. 54(1); 9 p
; v. 54(1); 9 p
[en] Conversion of cyclohexanol has been used to investigate the deactivation modes of the HZSM-5, AIPO4-5 and MnAPSO-5. Conversion of cyclohexanol as a test reaction was used to evaluate the activity of these catalysts
Journal
Buletin Kimia; ISSN 0127-8711; ; v. 13(2); p. 31-38
; v. 13(2); p. 31-38
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