Ion-specific parameters

Table 4 Ion-specific parameters a) and bi (after Parkhurst et al. 1980 and ( ) Truesdell a. Jones 1974)...

In more concentrated solutions, additional mutual interactions must be considered, which can only be described in terms of ion-specific parameters. We will not do that here, but instead use an expression that, again, does not require any species-specific parameters, yet tends to yield a reasonably good description for the average behavior of more concentrated solutions (even though it may not represent any particular solution very well). This is the so-called Davies expression,... 

The presence of electrolytes in the liquid affects gas solubility. Henry s constant for a pure solvent (Ho) can be corrected with the so-called salting-out factors (h) that are ion-specific parameters. Schumpe [6] has suggested the following equation for electrolyte mixtures ... 

The summation extends over all the ionic species present in the (aqueous) solution, including cases of electrolyte mixtures, is an ion-specific parameter, relatively... 

In this study, the ePC-SAFT EOS as well as the MSA-NRTL model were applied to describe thermodynamic properties of numerous aqueous electrolyte solutions. Whereas only activity coefficients are obtained by the G model, volumetric properties can be calculated with an EOS. Ion-specific parameters were used independent of the electrolyte which the ions are part of. The model parameters possess a physical meaning and show reasonable trends within the ion series. Two ion parameters are needed in ePC-SAFT, whereas six parameters are necessary for applying MSA-NRTL. Next to the standard alkali halide electrolyte systems, both models even capture the non-ideal behaviour of solutions containing acetate or hydroxide anions where a reversed MIAC series is experimentally observed. Until now, thermodynamic properties of more than 120 aqueous systems could be successfully modelled with ePC-SAFT. The MSA-NRTL parameter set has also been applied to a couple of systems (so far 19 solutions). Implementing an ion-pairing reaction in ePC-SAFT,... 

Nevertheless, the example 17 has been available since 1989. This was the first case where all the optical and ion-binding parameters of a functioning device were quantitatively predictable from model compounds within experimental error. The only exception was the emission quantum yield of the switched- on state which deviated negatively by 30%. Part of this deviation was caused by the different solvent conditions which were necessary for examining the model lumophore. This was an illustration of rather exact molecular engineering since the specifications at... 

The multifaceted behavior of transition metal complexes calls for not only theoretical explanations within a common conceptual framework but also theoretical tools that are powerful enough to predict the chemical and magnetic behavior of open-shell transition metal ions. Specifically, one looks for theoretical methods to calculate geometries and relative energies for stable species and transition states as well as for methods that allow one to determine spectroscopic parameters with sufficiently predictive accuracy. 

For ions of the same charge, the only parameter in the model presented above that can give rise to an ion specificity is the distance of closest approach rs — rm. 

Ninham and Yaminsky [26], and Karraker and Radke [18] realized that the van der Waals interactions between the ions and interface are not screened by the electrolyte and hence might become more important than the image force, at large electrolyte concentrations. Recognizing that the hydration of ions might also play a role, Bostrom et al. [16,17] showed that the van der Waals interactions alone (with suitable values selected for the interaction parameters) might account for the ion specific effects. 

When the waste contains more complex molecules such as compounds refractory to oxidation with OH radicals, as well as in the presence of inorganic ions which can be precursor of long-life oxidants, the Faradic yield cannot be calculated by (8.3) and different alternatives have been proposed. Faouzi and co-worker (Faouzi et al. 2006) proposed a comparison between electrochemical oxidation at BDD anodes and Fenton and Ozone treatments for the removal of dyes a specific parameter OCC (oxygen-equivalent chemical-oxidation capacity) was proposed which is defined as the kg of 02 equivalent to the quantity of oxidant used in each AOP to treat 1 m3 of wastewater. As highlighted by the authors, the parameter OCC may only give information on the chemical efficiency of the oxidants, but it does not give any information related to the real cost of the treatment, as the oxidants can... 

The finite-ion-size model yielded agreement with experiment at concentrations up to 0.1 N. It also introduced through the value of a, the ion size parameter, a specificity to the eiectrolyte (making NaCi different from KCl), whereas the point-charge model yielded activity coefficients that depended only upon the valence type of electrolyte. Thus, while the limiting law sees only the charges on the ions, it is biind... 

The use of pyrolysis GC-MS is still not common in the analysis of biopolymers and biocomposites because of the large quantity of parameters to be controlled for the development of a method. It is not easy, in a dynamic system, to transfer from a flow of inert gas (Pyr-GC) to vacuum conditions (MS). On the other hand, quantification is based on the fact that degradation is ion-specific, and that a given substance always produces the same fragments. This is not the case with biopolymer additives, especially in natural products, where fragmentation can proceed in several directions. This requires the use of internal standards and multiple measurements of each sample. Therefore a complete quantification requires considerable time and effort. 

When [M-H] serves as a precursor ion for MS/ MS, [M-H-CO2] and [M-H-141] were generated as product ions (listed in Table 2), and they are very useful for the confirmation of penicillins. After a series of detailed examinations, the other MS/MS conditions including the compound-specific parameters were selected. To provide the applicability of the present method, the fortified bovine tissues, at a concentration of 0.05 mg/kg of each six penicillins, were analyzed. As shown in Fig. 2 left, all six penicillins from the liver sample appeared as separate peaks on the mass chromatograms monitored at [M-H-141] under ESI LC/MS/MS conditions. Fig. 2 right shows the tandem mass spectra of the penicillins recorded at the top of each peak on the mass chromatograms shown in Fig. 2 left. All of these mass chromatograms and tandem mass spectra of fortified samples were almost the same as for the respective standards. Based on the results of the analyses of the fortified samples at 0.02 mg/kg, the lower limit of confirmation of the present method for muscle sample was estimated to be 0.02 mg/kg for all six penicillins, and those for kidney and liver were between 0.02 and 0.03 mg/kg. 

The interactions between the charged fibres can be divided into ion non-specific and ion-specific parts. Ion non-specific part is the electrostatic interaction or repulsion between the ions and the charged matrix of the fibre wall. The strength of this interaction is assumed to depend only on the charge of the ionic species. The ion-specific part of the interaction contains the specific complexation of metal ions with the bound acidic groups and the adsorption of ions into polarised surfaces. By its very nature, the ion-specific interactions can be used to describe a more complex pattern of observed phenomena than non-specific interactions, but they also require a larger number of individually fitted numerical parameters in a model. 

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