Atmospheric binding

Roadbed Stabilization/Dust Control. One of the earliest uses of calcium chloride was for dust control and roadbed stabilization of unpaved gravel roads. Calcium chloride ia both dry and solution forms are used both topically and mixed with the aggregate. When a calcium chloride solution is sprayed on a dusty road surface, it absorbs moisture from the atmosphere binding the dust particles and keeping the surface damp. Calcium chloride does not evaporate, thus this dust-free condition is retained over along period of time. 

A rational description of ionic atmosphere binding is provided by the Poisson-Boltzmann equation and the cylindrical cell model. Figure 1 is an example of such computations and shows the variation of the local concen-... 

With the discussion of previous sections as background, the observed enthalpy of binding may be considered to contain three contributions (1) the enthalpy change due to the atmospheric binding of surfactant cations to the PSS- anion, A/7a, (2) the heat effect accompanying the aggregation of the bound surfactant molecules into polyelectrolyte induced micelles, A//m, and (3) the enthalpy change, A// due to other specific interactions of surfactant micelles with the polyelectrolyte chain ... 

The AH , term results from the part of the binding process in which the Na+ ions, electrostatically bound to the polyion (atmospheric binding), are replaced by the monovalent surfactant cations. This contribution is assumed to be small in comparison with the other two and can be neglected. When the surfactant micelles form in the presence of a hydrophilic polyelectrolyte, the third contribution, AH in Eq. 4 may be assumed to be much smaller than the second term, since only pine electrostatic interactions are expected to act between hydrophilic polyion and ionic micelle. However, the AH, term in the case of interaction between a hydrophobic polyelectrolyte and surfactant micelle may not be neglected. To confirm this, it is instructive to... 

The observable properties of a polyelectrolyte depend upon the distribution of small ions in its neighborhood. This distribution is affected by two types of "binding" (20, 21). The first involves the binding of counterions to specific sites of the macroion, i.e., "site-binding" (20). The second involves the binding of counterions anywhere in the vicinity of the macroion, i.e., "ionic-atmosphere-binding". The site-binding of phosphates to nonpolar amides is unique. 

In effect, the amount and sign of the difference between measures of ionic-atmosphere-binding and site-binding, i.e.. 

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