Pure Cation or Anion Exchange

For prediction of multicomponent equilibria it is convenient if the binary parameters for the exchange of different counterions for the same reference ion have been deduced. For pure cation or anion exchange systems consideration of a three-component equilibrium with ions. A (reference ion), B and

Figure 11 Comparison of experimental data and predicted equilibria for the ternary system Cr/HCO37NO3~ on the strongly basic resin AMBERLITE IRA 410.

log QA = log KA + m(A, B) • [y(B) + y(C)] log QC = log KC + m(B,C) • y(C)

definition of m(i, j) contains the electric capacitance, C, we can make use of the well-known relationship for capacitances in series:

Figure 11 Comparison of experimental data and predicted equilibria for the ternary system Cr/HCO37NO3~ on the strongly basic resin AMBERLITE IRA 410.

C leads to the relationships:

Similar relationships are obtained for systems with more than three counterions. Examples of a comparison between experimental results and equilibria predicted from binary data are given in Figures 10-12.

For amphoteric sorbents the individual equilibrium parameters are already determined during evaluation of data. Therefore, no additional calculations are required. Figure 13 shows the comparison between experimentally determined oxide loadings and developments calculated by means of the set of equilibrium parameters determined previously. The data are plotted as relative loadings (q(i)/qmax) as a function of pH. The system contained the four components H +, Cl", SO2 3 and K+. Obviously, sulfate ions are preferred over chloride species. The constant sulfate loadings for pH values below 5 are due to the constant initial sulfate concentration in the system. Only minor loadings with monovalent cations are observed. There is excellent agreement with the predicted loadings.

Figure 14 shows the results from one experiment with activated carbon and protons, carbonate, sulphate, calcium, magnesium and potassium as counterions. The relative loadings with both carbonate and nitrate ions decrease with increasing pH of the solution, while the loadings of calcium and potassium slightly increase. Nevertheless their uptake

As has been demonstrated earlier, the binary parameters for the exchange of A versus B are the same as in the pure binary case. Also, the binary parameters for the exchange of A for C have been evaluated. In the above system, therefore, the parameters for the exchange of B for C are unknown. However, they can easily be calculated: the unknown parameter log KBC results from the definition:

For derivation of the unknown slope we make use of the fact that the sequence of layers can be considered as a series of layers of an electric capacitor. Since the

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Figure 12 Comparison of experimental data and predicted equilibria for the ternary system H+/Ca2 + /Cu2+ on the chelating resin LEWATIT TP 207. C0 (HCl) = 10 mmol L"1; C0 (CuCl2) = 10 mmol L"1. (From Horst and Holl (1997), copyright Academic Press.)

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Figure 12 Comparison of experimental data and predicted equilibria for the ternary system H+/Ca2 + /Cu2+ on the chelating resin LEWATIT TP 207. C0 (HCl) = 10 mmol L"1; C0 (CuCl2) = 10 mmol L"1. (From Horst and Holl (1997), copyright Academic Press.)

remains small, indicating that there is only a small capacity for the uptake of cations. Again, there is good agreement with the predicted developments.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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