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Table 1 Results (protonation constants, pKas, and mole number) for the calculation of species distribution models of the humic acid sample studied using the Best 7 program

From: Humic acid potentiometric response patterns: out-of-equilibrium properties and species distribution modeling

Model Standarda Costa et al.b Calculated model M1 Calculated model M2
Species   pKa mmol.g−1 % pKa mmol.g−1 % pKa mmol.g−1 %
Carboxylic 4.56 6.35 1.042 25 6.28 1.013 23 4.35 0.549 12
Phthalic 2.75 2.76 1.163 27 2.75 1.134 26 2.81 0.923 21
4.93 4.71    4.73    4.89   
Phenolic 9.82 9.66 0.666 16 9.73 0.938 22 9.87 0.688 16
Catechol 9.23 7.97 0.540 13 7.92 0.549 13 8.87 0.492 11
13.0 13.30    13.36    11.83   
Salicylic 2.81 3.29 0.810 19 3.08 0.715 16 2.79 0.600 13
13.4 13.40    13.39    13.39   
Supramolecular         6.65 1.147 26
Total    4.221    4.351    4.400  
  1. aStandard values obtained from [13, 19]
  2. bValues obtained from Costa et al. [14]