Dynamics water dynamic process

Gerente, C., Andres, Y, McKay, G., and Le Cloirec, P. Removal of arsenic(V) onto chitosan From sorption mechanism explanation to dynamic water treatment process. Chem. Eng. J. 158 (2010) 593-598. 

Figure 9 illustrates the fret that the release of biocide from the carriers is a dynamic process. Here a quantity of loaded carrier was slurried with a fixed volume of water and aliquots taken after 1 hour. From previous experiments it was found that after an initial period of rapid release, a steady-state concentration of free biocide was present in the aqueous extract. To probe the effects of repetitive extraction, the carrier was filtered from the slurry, the water replenished and the process repeated. It can be seen that only after ten successive extractions does the amount of the biocide OIT released by the carrier fall below the MIC. It should be noted that the conditions employed to illustrate this continuous release are rather more severe than would be experienced when the loaded carrier is incorporated in a coating (see Section 2.5). 

Payer80 states that the UNSAT-H model was developed to assess the water dynamics of arid sites and, in particular, estimate recharge fluxes for scenarios pertinent to waste disposal facilities. It addresses soil-water infiltration, redistribution, evaporation, plant transpiration, deep drainage, and soil heat flow as one-dimensional processes. The UNSAT-H model simulates water flow using the Richards equation, water vapor diffusion using Fick s law, and sensible heat flow using the Fourier equation. 

Drug dissolution is the dynamic process by which solid material is dissolved in a solvent and characterized by a rate (amount/time), whereas solubility describes an equilibrium state, where the maximal amount of drug per volume unit is dissolved. The solubility, as well as the dissolution, in a water solution depends on factors such as pH, content of salts and surfactants. 

The anions and cations in solution are normally hydrated and although hydration is a dynamic process, it is usually possible to identify a small number of water molecules in the hydration shell immediately surrounding the ion whose exchange rate is slow in comparison with other processes that might take place as the ions approach and recede from the interface. The picture of Figure 1.6 is, in any case, intended to represent a dynamic... 

One could go on with examples such as the use of a shirt rather than sand reduce the silt content of drinking water or the use of a net to separate fish from their native waters. Rather than that perhaps we should rely on the definition of a chemical equilibrium and its presence or absence. Chemical equilibria are dynamic with only the illusion of static state. Acetic acid dissociates in water to acetate-ion and hydrated hydrogen ion. At any instant, however, there is an acid molecule formed by recombination of acid anion and a proton cation while another acid molecule dissociates. The equilibrium constant is based on a dynamic process. Ordinary filtration is not an equilibrium process nor is it the case of crystals plucked from under a microscope into a waiting vial. 

At the same time, as the concentration decreases the exchange of water molecules by cooperative processes becomes easier and so significant fluctuations in the coordination numbers are observed, which are estimated to be about 1. At even lower concentrations, ion-water correlation patterns will become obscured and then undetectable. As an extrapolation, dynamic processes might contribute more and more to the description of the solution. The strong interaction between Li+ and OH2 (dH. i = 34 kcal/mole in the vapor phase 130>) may cause the cation-water complexes to remain quite well-defined tetrahydrates, on the average, despite all dynamic effects. 

It was postulated that the differences in enzyme activity observed primarily result from interactions between enzyme-bound water and solvent, rather than enzyme and solvent. As enzyme-associated water is noncovalently attached, with some molecules more tightly bound than others, enzyme hydration is a dynamic process for which there will be competition between enzyme and solvent. Solvents of greater hydrophihcity will strip more water from the enzyme, decreasing enzyme mobility and ultimately resulting in reversible enzyme deactivation. Each enzyme, having a unique sequence (and in some cases covalently or noncovalently attached cofactors and/or carbohydrates), will also have different affinities for water, so that in the case of PPL the enzyme is sufficiently hydrophilic to retain water in all but the most hydrophilic solvents. 

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