Chemical mass transfer

Ghiorso, M. S. (1985a). Chemical mass transfer in magmatic processes. I. Thermodynamic relations and numerical algorithms. Contrib. Mineral. Petrol., 90, 107-20. 

Karpov, I. K., Chudnenko, K. V. Kulik, D. A. 1997. Modeling chemical mass transfer in geochemical processes Thermodynamic relations, conditions of equilibria, and numerical algorithms. American Journal of Science, 297, 767-806. 

Delivery Heat transfer Chemical Mass transfer... 

The atmosphere, ocean, and biosphere leave their record in sedimentary rocks. It is likely that this record reflects both secular and cyclic evolutionary processes. The cyclic processes involve chemical mass transfer of materials in and out of global reservoirs like the atmosphere, ocean, and sedimentary rocks. If inputs and outputs of these reservoirs are nearly balanced so that over long periods of geologic time the mass and composition of the reservoirs remain constant, a quasi-steady state is maintained. Hand-in-hand with this cyclicity go changes in Earth s surface environment reflecting secular evolution of the planet, an aging process. 

Symbols for Chemical Mass Transfer and Reaction Rates f tortuosity tensor... 

Purposes These codes can speciate an aqueous solution and allow for chemical mass transfer processes. They can also simulate hydrodynamic advection and dispersion of chemical constituents in a porous medium. 

Modeling Dynamic Hydrothermal Processes by Coupling Sulfur Isotope Distributions with Chemical Mass Transfer Approach... 

The EQPS code is composed of of approximately 3500 lines of FORTRAN statements, including comments and local graphics interface. The code does not involve any machine restrictions. CPU time for each of the examples presented below is approximately 35 seconds on a Micro VAX II when chemical mass transfer pathway data is read from EQ6 tabular files. 

Ghiorso M.S. and Carmichael I.S.E., 1985, Chemical mass transfer In magmadc processes. II. Applications in equilibrium crystallisation, fractionation and assimilation. Contrib, Mineral, Petrol, 90, 121-141. 

When a set of rate data is obtained, the first step in the analysis is to ascertain which regime of mass transfer applies to the data. The quantity which is measured is the total mass transfer rate V the chemical mass transfer coefficient can be extracted from the data provided the driving force and the interface area are known. The key to the identification of the regime is the dependency of V on the operating variables. The latter are the degree of mixing as represented by k the interface area A the liquid volume V temperature and the physical driving force a -a. ... 

Correlations for chemical mass transfer coefficients, and were not regarded as necessary as they differ for different chemical systems and reactions employed. On the other hand, correlations for k a and k can be adapted to other physical systems by just making a diffusivity correction. Mass transfer coefficients assessed with absorption and chemical reaction can then be estimated using Equations (18) and (19) together with the enhancement factor calculated specifically for the chemical system of interest. 

Area-based physical mass transfer coefficient, m/s Area-based chemical mass transfer coefficient, m/s Volumetric physical mass transfer coefficient, 1/s Volumetric chemical mass transfer coefficient, 1/s Second order reaction rate constant, 1/s Generalized variable for a second-order reaction,... 

As can be noted from the schematic diagram, if the solute pulse is retarded, the area under each of the retardation pulse curves remains constant as the pulse travels downward through the unsaturated zone toward the aquifer. This indicates that the total contaminant load is transferred to the aquifer. By contrast, the retention pulse shows decreasing areas under the pulse curves. This indicates partitioning by chemical mass transfer and irreversible sorption, and resultant dilution of contaminant concentrations. If proper design procedures are used, no transfer of contaminants to the aquifer should occur, thereby fulfilling the requirements for contaminant containment using the natural attenuation capability of the soil substrate liner system. 

Replacement of the metal ions can also occur as the pH of the system becomes more acidic. Under such circumstances, the hydrogen ions will replace the metal ions. It is however not always easy to fully distinguish between mechanisms responsible for retention and retardation of contaminants in the transport process. In the upper left box (chemical mass transfer box) shown in Fig. 3 the first set of interactions (sorption and desorption) are perhaps the simplest of those which occur, as discussed above. Accumulation processes such as complexation. 

A common procedure presently used is to specify a limiting maximum value of hydraulic conductivity for the engineered clay barrier for control of transport and transfer of contaminants to the substrate (Jessberger 1995 Yong 1996 Manassero et al. 1997) However, this approach does not necessarily pay attention to the specific role of chemical mass transfer and/or the natural attenuation phenomenon. Contaminant retardation occurs via control on the limiting hydraulic conductivity. If retention... 

Chemical mass transfer responsible for partitioning of contaminants constitutes a significant part of the processes involved in the transport and fate of contaminants. In the longer term, the redox environment (pE) and subsequent reduction-oxidation reactions will ultimately determine the final fate of the contaminants. The assessment of whether retention or retardation processes are responsible for the observed partitioning and hence the attenuation of contaminants within the soil matrix, is vital and critical in the evaluation of the natural attenuation capability of the soil barrier system. The dilemma facing both regulatory agencies and practitioners is obvious If potential pollution hazards and threats to public health and the environment are to be minimized or avoided, How can one ensure that the processes for contaminant attenuation in the substrate are the result of (irreversible sorption) retention... 

Rochelle, C. A., Bateman, K. Macgregor, R., Pearce, J., Savage, D Wetton, P. 1998. The Evaluation of Chemical Mass Transfer in the Disturbed Zone of a Deep Geological Disposal Facility for Radioactive Wastes. IV. The Kinetics of Dissolution of Chlorite and Carbonates at Elevated pH. Nirex Report NSS/R368. 

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