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- Author or Editor: K. M. Abd El-Rahman x
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Temperature dependence of the thermophysical properties of polycrystallene chalcogenide glasses
Mercury and antimony sulphides
The specific heat (C p), thermal conductivity (λ), thermal diffusivity (a), and electrical conductivity (σ) were measured for polycrystalline HgS and Sb2S3 in the temperature range 300–600 K. The measurements were performed with an experimental apparatus based on a socalled flash method. The results showed that the mechanism of heat transfer is mainly due to phonons, whereas the contribution of electrons and bipolars is very small indeed. The energy gap of the samples was also calculated.
The batch removal ofCs+, Sr2+, Ca2+and Mg2+ions from aqueous solutions using synthetic zeolite A was investigated. The influence of the initial ion concentration, pH and temperature was studied. The obtained isotherm data have been correlated with Langumir, Freundlich, and Dubinin-Radushkevich(D-R) isotherm models. The effect of the temperature on the equilibrium distribution values has been utilized to evaluate the standard thermodynamic parameters such as free energy (DG), enthalpy (DH) and entropy (DS). Based on the D-R isotherm expression, the maximum ion-exchange capacity and the mean free energy of each studied ion has been determined. The selectivity sequence, deduced from the equilibrium isotherm data is: Sr2+>Ca2+>Mg2+>Cs+>Na+.