Authors:A. Aagli, N. Tamer, A. Atbir, L. Boukbir, and M. El Hadek
Solubility of calcium sulfate in concentrated aqueous chloride solutions is of particular significance in chloride hydrometallurgy and various crystallization processes, such as the production of potassium sulfate from phosphogypsum and potassium chloride. This paper examines an example of the second type of application in which gypsum and potassium chloride are reacted to form K2SO4. The solubility of phosphogypsum in aqueous solutions of KCl, HCl, and mixtures of both has first been measured at various temperatures and concentrations. The parameters investigated are HCl concentration up to 6M, KCl concentration up to 180 g L-1 and temperature from 25 to 80°C. In addition, the influence of co-existing chloride salts, such as (HCl+KCl), on the solubility of calcium sulfate is estimated from 25 to 80°C. The solubility increases obviously with the temperature increment as it does initially with acid concentration, reaching a maximum of about 3M HCl, 130 g L-1 KCl and then drops. At the same time, the solubility of CaSO4·2H2O decreases with increasing KCl concentration.
disability due to conversion disorder: a prospective control group study. Journal of Neurology, Neurosurgery and Clinical Psychiatry , 63: 83–88.
Binzer, N., Kullgren, G. (1998): Motor conversion disorder. Psychosomatics , 39: 519
biomass-derived materials such as bio-ethanol for the problems of exhaustion of petroleum resources and global warming. Therefore, propylene production from bio-ethanol is highly desirable. Processes for the conversion of methanol to olefins (MTO) are well
Iso-conversional methods are used for non-isothermal analysis, in which the transformation rate at a constant extent of conversion is only a function of temperature as suggested by Vyazovkin et al. [ 1 – 4 ] and
method, which can not detect the complex nature of the solid-state reaction, has been replaced by multiple scan method at different heating rates using iso-conversional and iso-temperature calculation procedures [ 12 – 14 ]. Among the iso-conversional
Authors:S. X. S. Costa, M. R. Galvão, D. P. Jacomassi, M. I. B. Bernardi, A. C. Hernandes, A. N. de Souza Rastelli, and M. F. Andrade
employed, as well as to the composite resin composition and degree of conversion [ 6 ].
Composite resins are set via exposure to light of a certain wavelength and an intensity that initiates the generation of free radicals that propagate
Authors:Kate Poiesz, Carol Grundner, and Nancy Redman-Furey
Characterization of the solid-state form (hydrate
or polymorph) of a pharmaceutical active is a key scientific and regulatory
requirement during development of and prior to seeking approval for marketing
of the drug product. A variety of analytical methods are available to perform
this task. By nature of the fundamental information it provides, TG-DTA offers
advantages over other methods in regards to monitoring and quantitation of
hydration state changes. In a single experiment with only a few milligrams
of sample, TG-DTA perceives minor changes in phase, quantitates total water
content and percent conversion, and illustrates hydrate type. All of this
is accomplished without the necessity of generating time-consuming standard
curves representing the differing ratios of hydrated to anhydrous forms. This
study describes the use of TG-DTA to monitor and quantitate humidity induced
solid–solid phase conversion of nitrofurantoin and risedronate. Percent
conversion was qualitatively observed by both TG and DTA signals and quantitated
by the TG.