Truesdell-Jones equation

Truesdell-Jones Equations, Specific Ion-Interaction Theory... 

Figure 4.4 Comparison of the ion activity coefficient of Ca as computed using different approaches. These include I) the Davies equation (2) the mean salt approach using the Macinnes convention, and Truesdell-Jones equation (curve labeled Mean salt TJ) (3) the specific ion interaction (SIT) equation and (4) the extended Etebye-Hiickel equation.

Chemical analyses of 10 groundwaters from springs and wells in carbonate rocks are shown in Table 6.7, along with their apparent CO2 pressures and saturation indices with respect to calcite and dolomite, which have been calculated using the computer model SOLMINEQ.88 (Kharaka et al. 1988). The composition of seawater and its modeled carbonate-mineral saturation state is also shown. SOLMINEQ.88 calculates the concentrations of ion pairs, such as CaHCO and MgSO, and uses the Truesdell-Jones equation to compute ion activity coefficients. (See Chap. 4.)... 

WATEQ DEBYE-HUCKEL equation (Truesdell Jones 1974)... 

The water is dominantly a NaCl brine with important amounts of Ca and Mg. The analysis indicates a stoichiometric ionic strength of 2,88 mol/kg, too high to justify use of the Davies equation. Because solubility of the akaline earth sulfates is directly proportional to the activity coefficients of Ca ", Sr +, Ba +, and SO ", we are interested in their values in the brine. We will compute the activity coefficients using the Truesdell-Jones (TJ) and SIT models. 

Values for the thermodynamic stability constants of inoiganic complexes (with HCO, CO3 , S0 , Cl and 0H ) and organic complexes (except for Cu) of trace metals and major ions were chosen principally from the compilation by Zirino and Yamamoto [ 10] Tor Cd, Whitfield and Turner [11 ]for Pb, Van den Berg [9 ]for Cu, and Truesdell and Jones [12] for major ions. The formation of polynuclear complexes has generally been discounted (except for Pb). The activity coefficients of all species have been calculated using the Davies equation [l3 ]. The stability constants of humic complexes of Cu ( Cu-L been calculated in this work. 

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