Porous dissolution kinetics

Grathwohl, P. (1998). Diffusion in natural porous media contaminant transport, sorption/desorption and dissolution kinetics, Kluwer Publishers, Boston, MA. 

Baumann J., Buhmann D., Dreybrodt W. and Schultz H.D. (1985) Calcite dissolution kinetics in porous media. Chem. Geolog. 53, 219-228. 

Johns ML, Gladden LF (1999) Magnetic resonance imaging study of the dissolution kinetics of octanol in porous media. J Colloid Int Sci 210 261-270... 

Under either reducing or oxidizing conditions, the solubilization of arsenic from sulfide phases can be subject to kinetic limitations. Mass transfer constraints, particularly in porous media, can result in localized saturation conditions near the surface of the solid. For oxidative dissolution, depletion of dissolved oxygen may limit dissolution kinetics. Microorganisms may also play a role in catalyzing such oxidative dissolution as has been demonstrated for pyrite oxidation (88) and thus dissolution rates may reflect the level of microbial activity (which may be subject, for example, to nutrient limitation). Thus, although equilibrium calculations indicate solubility constraints on dissolved arsenic concentrations, actual concentrations may be lower than the predicted equilibrium values due to slow dissolution kinetics or greater due to slow precipitation kinetics. 

Grathwohl, P. (1998) Diffusion in Natural Porous Media Contaminant Transport, Sorption/De-sorption and Dissolution Kinetics, Kluwer Academic Publishers, Boston, p. 224. 

When the results for oxide growth and anion incorporation172,160 are compared with the kinetics of space charge accumulation in barrier and porous alumina films [see Section IV(1)], it can be concluded that anion incorporation modifies the electrostatics of the external oxide interface, thus influencing oxide dissolution and pore formation.172... 

The fundamental reason for the uneven distribution of reactions is that the rate of electrochemical reactions on a semiconductor is sensitive to the radius of curvature of the surface. This sensitivity can either be associated with the thickness of the space charge layer or the resistance of the substrate. Thus, when the rate of the dissolution reactions depends on the thickness of the space charge layer, formation of pores can in principle occur on a semiconductor electrode. The specific porous structures are determined by the spatial and temporal distributions of reactions and their rates which are affected by the geometric elements in the system. Because of the intricate relations among the kinetic factors and geometric elements, the detail features of PS morphology and the mechanisms for their formation are complex and greatly vary with experimental conditions. 

Bolton EW, Lasaga AC, Rye DM (1996) A model for the kinetic control of quartz dissolution and precipitation in porous media flow with spatially variable permeability Eormulation and examples of thermal convection. J Geophys Res 101 22,157-22,187 Bolton EW, Lasaga AC, Rye DM (1997) Dissolution and precipitation via forced-flux injection in the porous medium with spatially variable permeability Kinetic control in two dimensions. J Geophys Res 102 12,159-12,172... 

Partial blocking effect was first identified for pure iron in contact with aerated sulphuric acid medium [55]. Corrosion of carbon steel in sodium chloride media clearly showed the porous layer effect (see Section 5.2) [74]. The same effect was found for zinc corrosion in sodium sulphate [75] and the properties of the layer which was demonstrated to be formed of an oxide/hydroxide mixture were further used for building a general kinetic model of anodic dissolution [76], usable for measurement of the corrosion rate from impedance data. 

Recently, an exhaustive study of copper in sodium chloride medium was carried out on the basis of porous layer and partial blocking effects involving Cu20 and CuCl and also a kinetic model of dissolution was proposed, following the procedure of Chapter 4 [77]. 

Multiphase reactors include, for instance, gas-liquid-solid and gas-liq-uid-liquid reactions. In many important cases, reactions between gases and liquids occur in the presence of a porous solid catalyst. The reaction typically occurs at a catalytic site on the solid surface. The kinetics and transport steps include dissolution of gas into the liquid, transport of dissolved gas to the catalyst particle surface, and diffusion and reaction in the catalyst particle. Say the concentration of dissolved gas A in equilibrium with the gas-phase concentration of A is CaLt. Neglecting the gas-phase resistance, the series of rates involved are from the liquid side of the gas-liquid interface to the bulk liquid where the concentration is CaL, and from the bulk liquid to the surface of catalyst where the concentration is C0 and where the reaction rate is r wkC",. At steady state,... 

Daccord et al. (1993a, b) investigated systematically the types of patterns that develop by the etching of the porous medium, when the flow rate and the reaction rate (i.e., rate of dissolution) are varied. When the kinetics of the surface reaction is limited, the porous medium is etched in a uniform way on... 

A metal CMP process involves an electrochemical alteration of the metal surface and a mechanical removal of the modified film. More specifically, an oxidizer reacts with the metal surface to raise the oxidation state of the material, which may result in either the dissolution of the metal or the formation of a surface film that is more porous and can be removed more easily by the mechanical component of the process. The oxidizer, therefore, is one of the most important components of the CMP slurry. Electrochemical properties of the oxidizer and the metal involved can offer insights in terms of reaction tendency and products. For example, relative redox potentials and chemical composition of the modified surface film under thermodynamically equilibrium condition can be illustrated by a relevant Pourbaix diagram [1]. Because a CMP process rarely reaches a thermodynamically equilibrium state, many kinetic factors control the relative rates of the surface film formation and its removal. It is important to find the right balance between the formation of a modified film with the right property and the removal of such a film at the appropriate rate. 

Bolton E. W., Lasaga A. C., and Rye D. M. (1999) Long-term flow/chemistry feedback in a porous medium with heterogeneous permeability kinetic control of dissolution and precipitation. Am. J. Sci. 299, 1-68. 

Lichtner (2001) developed the computer code FLOTRAN, with coupled thermal-hydrologic-chemical (THC) processes in variably saturated, nonisothermal, porous media in 1, 2, or 3 spatial dimensions. Chemical reactions included in FLOTRAN consist of homogeneous gaseous reactions, mineral precipitation/dissolution, ion exchange, and adsorption. Kinetic rate laws and redox... 

Balskus, E.J., Triaca, W.E., and Arvia, A.J. (1972). Hydrogen evolution and dissolution on graphite electrodes in molten potassium bisulphate. II. Kinetics and mechanism of the reactions on porous graphite. Electrochim. Acta, 17, 45-62. 

This sequence is in good correlation with the kinetic diameter of gas molecules. The selectivity (relative to nitrogen) of gas separations increases in the same order, especiady at enhanced temperatures. This synchronous rise in permeabihty and selectivity of the above membranes was attributed to the complex mechanism of separation. It incorporates two processes occurring simidtaneously, namely the transport of gas molecides through free volume of porous hypercrosslinked polymeric particles and transportation of gas through the film of binder via gas dissolution mechanism [398]. 

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