Equilibrium thermodynamic inhibitors shift

In Figure 4.2d, the presence of a thermodynamic inhibitor (e.g., methanol) shifts the upper two-thirds of the line Q1Q2B to the left, approximately parallel (on a semilogarithmic plot of In P versus T) to the uninhibited line. With inhibitor, however, the transition temperature from water to ice (Qi) is decreased, so that the inhibited Lw-H-V line intersects the I-H-V at a lower point (labeled Qj for 10 wt% methanol and Qj for 20 wt% methanol). The inhibited three parallel lines represent Lw-H-V or Lw-H-Lhc equilibrium at methanol concentrations (marked 0%, 10%, and 20% MeOH) in the free water phase. 

At thermodynamic equilibrium, Ttj must vanish for every reaction otherwise, the equilibrium could be shifted by adding catalysts or inhibitors to alter the nonzero rates TZj. Formal proofs of this "detailed balance principle are presented by de Groot and Mazur (1962). Therefore, setting 7 = 0 at equilibrium and using Eq. (2.4-3), we get... 

The inhibition effects of type-III AFP and trehalose, two cryoprotecting materials produced in animals, on type-I CO2 clathrate-hydrates were examined. For comparison with the results of a previous study in which the lateral growth rates of COi-hydrate film were dependent on temperature, pressure and NaCl concentration, the solution droplet was observed in a high pressure vessel filled with CO2. Type-III AFP was found to increase the induction period and to reduce the lateral growth rate of C02-hydrate films. It worked well at low concentrations, indicating that AFP works as a kinetic inhibitor. It was also indicated that AFP would weaken the memory effect of C02-hydrate formation. Trehalose had similar inhibition effects on both the induction period and the lateral growth rate, but it had little apparent concentration-dependence on them. Since trehalose also causes the equilibrium conditions of the CO2 hydrate to shift to lower temperatures, it works not only as a thermodynamic inhibitor but also as a kinetic inhibitor, especially as an anti-agglomerant. 

Of the above-mentioned techniques, thermodynamic inhibitors, which include alcohols, salts, and glycols, are by far the most prevalent. For example, adding methanol to a natural gas will shift the equilibrium conditions so that a higher pressure is required to form hydrates, at a given temperature, as illustrated for methane in Fig. 3. Methods for estimating the saturation water content of natural gases and amounts of methanol or glycol required to suppress hydrate formation are discussed by Katz, Sloan,and Campbell. Current practice for the estimations is to use computer software based on phase equilibrium calculations. ... 

Hermans The stabilization of conformations with native properties, obtained by addition of substrates or inhibitors is most easily described strictly in terms of thermodynamics, as follows. A small subset of all possible conformations with native properties is stabilized by tertiary interactions. By definition, this set binds substrate (and inhibitor). All members of the set are highly folded one can detect this folding with physical measurements. This is the conformation observed under normal conditions. All other conformations together form the denaturated set many of these interact favorably with denaturants such as alcohols. Your experiments are a sort of thermodynamic titration you shift the equilibrium to be just in favor of the denatured species with a ligand (alcohol) which prefers the unfolded chain. However, with the inhibitor, you just shift the equilibrium both in favor of the native conformation. 

Note that conditional averages appear in AEc, but not in A S- We shall now reinterpret this observation from a chemical equilibrium point of view i.e., the quantity Ep g - (Ep)o will be related to the shift in the chemical equilibrium L H induced by the adsorption of G. To do that we adopt a mixture-model point of view of the same system. This approach will be generalized in Chapter 5 to treat any liquid and in particular aqueous solutions. In our model we have two states of the adsorbent molecules. The mixture-model approach follows from the classification of molecules in state L as L-molecule, and likewise molecules in state H as an //-molecule. This is the same procedure we have discussed in section 2.4. We now assign partial molecular quantities to the species L and H, viewing Ml and Mh as independent variables. Theoretically these are defined as partial derivatives of the corresponding thermodynamic functions (see below). From the physical point of view, these can be defined only if we have a means of varying Ml and Mh independently, e.g., by placing an inhibitor that prevents the conversion between... 

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