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Whence Dynamical Systems
Published in LM Pismen, Working with Dynamical Systems, 2020
Chemical kinetics. The mass action law assumes that the reaction rate is proportional to the product of reactant concentrations. This, indeed, should be true if reactant molecules, present in macroscopic amounts, are uniformly distributed in space, and the reaction might occur when they collide at random. The probability of the reaction upon collision is measured by the reaction rate constant k. Thus, the change of the concentration ci of a chemical species due to a reversible reaction defined by (1.31) is c˙i=vi(k+∏i∈I−ci|vi|−k−∏i∈I+civi), where k± are rate constants of the direct and reverse reactions.
Modeling and Speciation Study of Uranium(VI) and Technetium(VII) with TBP
Published in Solvent Extraction and Ion Exchange, 2021
Pauline Moeyaert, Thomas Dumas, Dominique Guillaumont, Pier Lorenzo Solari, Claire Lefebvre, Alexiane Thevenet, Christian Sorel, Philippe Moisy
The technetium solvent extraction is a key aspect of the nuclear fuel reprocessing operations. We applied a thermodynamic approach based on the mass action law, simple solution concept, and Sergievskii-Dannus equations to model the extraction of technetium(VII) by the TBP. Without uranium, two species are identified: (HTcO4)(TBP)2 and (HTcO4)(TBP)3, while the co-extraction of technetium(VII) with uranium(VI) was correctly modeled with UO2(NO3)(TcO4)(TBP)2, UO2(NO3)(TcO4)(TBP)3 and UO2(NO3)(TcO4)(HNO3)(TBP)2 complexes. These results suggest that in the PUREX process chemical conditions; only one pertechnetate anion would replace one nitrate in the uranium coordination sphere.
Calorimetry for studying the adsorption of proteins in hydrophobic interaction chromatography
Published in Preparative Biochemistry and Biotechnology, 2019
Agnes Rodler, Rene Ueberbacher, Beate Beyer, Alois Jungbauer
Equation (30) assembles the mass action law, considering the dependence of the activity coefficients of the protein in the mobile phase and adsorbed to the stationary phase on salt concentration and loading, with the partition coefficient A (shown in Eq. 32). Via the relation in Eq. (12) chromatographic retention is introduced. In this model the parameters ν and ε are fitted.
The advantages of using a geochemical transport model including thermodynamic equilibrium, kinetic control and surface complexation to simulate the durability of concretes exposed to chlorides and sulphates
Published in European Journal of Environmental and Civil Engineering, 2019
Anthony Soive, Van-Quan Tran, Muriel Gasc-Barbier
Aqueous complexes are formed by interactions between primary species in the solution. These reactions are assumed to be at local equilibrium. Using the mass action law, the concentration of aqueous complexes can be expressed as a function of the concentration of primary species, as follows: