title: H-binding of size- and polarity-fractionated soil and lignite humic acids after removal of metal and ash components.
abstract: A fractionation technique, combining dialysis removal of metal and ash components with hydrofluoric acid and pH 10 citrate buffer followed by chromatography of dialysis permeate on XAD-8 resin at decreasing pH values, has been applied to lignite humic acid (lignite-HA) and soil humic acid (soil-HA). H-binding data and non ideal competitive adsorption-Donnan model parameters were obtained for the HA fractions by theoretical analysis of H-binding data which reveal a significant increase of the carboxyl and the phenolic charge for the lignite-HA fractions vs. the parental lignite humic acid (LParentalHA). The fractionated lignite-HA material consisted mainly of permeate fractions, some of which were fulvic acid-like. The fractionated soil-HA material consisted mainly of large macromolecular structures that did not permeate the dialysis membrane during deashing. Chargeable groups had comparable concentrations in soil-HA fractions and parental soil humic acid (SParentalHA), indicating minimal interference of ash components with carboxyl and phenolic (and/or enolic) groups. Fractionation of HA, combined with theoretical analysis of H-binding, can distinguish the supramolecular vs. macromolecular nature of fractions within the same parental HA.
authors.affiliation: Laboratory of Physical Chemistry, Department of Environmental and Natural Resources Management, University of Patras, Seferi 2, 30100, Agrinio, Greece, drosos.marios@gmail.com.
authors.forename: Marios
authors.initials: M
authors.lastname: Drosos
authors.forename: Jerry A
authors.initials: JA
authors.lastname: Leenheer
authors.forename: Apostolos
authors.initials: A
authors.lastname: Avgeropoulos
authors.forename: Yiannis
authors.initials: Y
authors.lastname: Deligiannakis
mesh_terms: D005591:Chemical Fractionation; D003031:Coal; D006812:Humic Substances; D006859:Hydrogen / Q000737:chemistry*; D008670:Metals / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*
chemical_list: D003031:Coal; D006812:Humic Substances; D008670:Metals; D012987:Soil; D006859:Hydrogen