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Effects of polymeric charge variations on the proton‐metal ion equilibria of humic materials
Author(s) -
Wilson Donald E.,
Kinney Patrick
Publication year - 1977
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1977.22.2.0281
Subject(s) - chemistry , humic acid , metal , cationic polymerization , metal ions in aqueous solution , ion , dissociation (chemistry) , inorganic chemistry , proton , dissociation constant , acid dissociation constant , electrostatics , monomer , chemical physics , computational chemistry , organic chemistry , polymer , aqueous solution , fertilizer , biochemistry , physics , receptor , quantum mechanics
Except for specific molecular weights, humic materials have many of the chemical and physical characteristics of enzymes. Thus modified equations from the biochemical literature can provide a theoretical description of proton‐metal ion interactions on humic substances. For a given ionizable group type, the members of the group are chemically identical within experimental error, and the observed variations in dissociation of humic acid and bonding strength of metal ion as a function of pH are quantitatively related to the electrostatic interaction between the cationic species and the negatively charged humic polyion. This approach allows experimental determination of intrinsic constants for dissociation of acid and formation of metal ion, i.e. equilibrium constants which are independent of all electrostatic effects. The intrinsic constants obtained for a few humic materials are compared to those of possible monomeric units. In addition, the intrinsic constants have been coupled with other experimental parameters to predict the concentration of metal ion bound to humic materials as a function of pH.