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Table 1 PhreeqC 3 modelling results: aqueous activities, solubility products (K SP), and saturation indices (SI)

From: How well suited are current thermodynamic models to predict or interpret the composition of (Ba,Sr)SO4 solid-solutions in geothermal scalings?

  [Ba2+] (mol/kgw) [Sr2+] (mol/kgw) [SO4 2−] (mol/kgw) log10(K SP): barite log10(K SP): celestine SIa barite SI celestine
Molalities 3.86 E−5 5.14E−3 4.89E−3
Pitzer: 230 bar, 100 °C 8.35E6 2.12E3 4.10E5 9.36 7.02 −0.11 −0.04
Pitzer: 1 bar, 70 °C 1.09E5 2.57E3 5.00E5 9.54 6.93 0.28 0.04
Pitzer: 1 bar, 25 °C 1.91E−5 3.36E−3 5.35E−5 −9.84 −6.66 0.85 −0.09
Pitzer: 1 bar, 25 °C (no ana.-expr.) 1.91E5 3.36E3 5.35E5 9.97 6.63 0.98 −0.12
SIT: 1 bar, 25 °C 6.62E−6 2.74E−4 (1.54E−3, incl. SrCl+) 1.24E−4 −9.97 −6.62 0.88 −0.85 (−0.10, incl. SrCl+)
  1. The values highlighted in italics are those considered in solid-solution thermodynamic calculations
  2. kgw kg water
  3. aSI = log10([Me2+][SO4 2−]/KSP)