Carbon-containing solid-phase determinations

Lan] studied transfer processes and phase boundary reactions during the carbon exchange between the carbon containing gas phase and solid Cu-Fe alloy with 4 at.% Cu at 900 to 1000°C in H2-CH4 mixtures. The diffusion coefficient, transition coefficient and the Biot index were determined. 

Ageno and Valla equilibrated their solid phase with water under a carbon dioxide containing atmosphere in a closed vessel at 25°C. The Ni(II) concentration and the partial pressure of CO2 were determined experimentally. Column 2 of their table on carbonate solubilities is labelled incorrectly. Under the conditions prevailing in their study an elementary stoichiometric consideration prediets ... 

The simplest type of phase behavior to understand is the solubility of a solid solute, such as naphthalene, in a supercritical fluid. When the solute is a crystalline solid, the solid phase may be assumed to be pure and only the supercritical phase is a mixture. Imagine solid naphthalene in a closed vessel under one atmosphere of carbon dioxide at 40°C. The reduced temperature and reduced density of CO2 are 1.03 and 3.7x10 respectively. At this pressure, the gas phase is ideal and the naphthalene solubility is determined by its vapor pressure. As the container volume is decreased isothermally, the solubility initially decreases when the gas phase is still nearly ideal. As the pressure is increased further, however, the gas phase density becomes increasingly nonideal and approaches the mixture critical density (near the critical density of CO2 because the gas phase is still mostly CO2). The reduced density of CO2 increases rapidly near the critical region as shown in Figure 2. The solvent power of CO2 is related to the density which leads to a rapid solubility increase. A brief description of intermolecular interactions is helpful in understanding this behavior. 

An activated carbon in contact with a metal salt solution is a two-phase system consisting of a solid phase, which is the activated carbon surface, and a liquid phase which is the salt solution. The solution contains varying amounts of different metal ion species and their complexes so that the interface between the two phases will behave as an electrical double layer and determine the adsorption processes taking place in the system. The adsorptive removal capacity of an activated carbon for metal cations from the aqueous solutions generally depends on the physicochemical characteristics of the carbon surface, which include the surface area, pore-size distribution, electrokinetic properties, and the chemical structure of the carbon surface, as well as on the nature of the metal ions in the solution. 

Interparticle contact is of critical importance to the behavior of lithium batteries. Most lithium-ion electrodes contain 2 to 15 wt% conductive filler, such as carbon black, in order to maintain contact among aU the particles of active material and in order to reduce ohmic losses in the electrodes. Presently, there are few models available for predicting contact resistance, and the effect of the weight fraction of conductive filler on the overall electronic conductivity of the composite electrode must be determined experimentally. Doyle et al. [35] demonstrate how the fuU-cell-sandwich model can be used to determine what minimum value of effective electronic conductivity is needed to make solid-phase ohmic resistance negligible. Then, one need only measure the effective conductivity of the composite electrode as a function of filler content, and one need not run separate experiments on complete cells to determine the optimum filler content. Modeling techniques for predicting effective electroitic conductivities of composite electrodes are under development, and hold promise to aid in optimizing filler shape and volume fraction [85]. 

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