Buffer Curves and Acid Strength of Humic Acid and Two Resins1
- J. T. Gilmour and
- N. T. Coleman2
Two humic acids, Cellex-CM, and IRC-50 were placed in 10-1, 10-2, and 10-3M NaCl or CaCl2 and titrated potentiometrically with NaOH or Ca(OH)2, respectively. Titration curves of Cellex-CM and IRC-50 in the NaOH-NaCl system showed parallel 1 pH unit displacements for a 10-fold change in NaCl concentration, while humic acid showed a 0.5 pH unit displacement. Buffer curves of humic acid, Cellex-CM, and IRC-50 in the Ca(OH)2-CaCl2 system showed a 0.4 pH unit displacement for a 10-fold change in CaCl2 concentration. The regular displacement of buffer curves led to development of a theory using ion exchange and surface ionization of H that described the buffer curves and assigned a salt independent pKa to the weak acid adsorbents.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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