Affordable Access

Publisher Website

Molecular weight fractionation of humic substances by adsorption onto minerals

Authors
Journal
Journal of Colloid and Interface Science
0021-9797
Publisher
Elsevier
Publication Date
Volume
264
Issue
2
Identifiers
DOI: 10.1016/s0021-9797(03)00444-2
Keywords
  • Adsorption And Deposition
Disciplines
  • Physics

Abstract

Abstract Molecular weight (MW) fractionation of Suwannee River fulvic acid (SRFA) and purified Aldrich humic acid (PAHA) by adsorption onto kaolinite and hematite was investigated in equilibrium and rate experiments with a size-exclusion chromatography system using ultraviolet (UV) light detection. The extent of adsorptive fractionation based on UV detection was positively correlated with the percent carbon adsorption for both humic substances (HS), although the specific fractionation pattern observed depended on the particular HS and mineral used. Higher MW fractions of SRFA, an aquatic HS, were preferentially adsorbed to both kaolinite and hematite whereas the fractionation trends for PAHA, a terrestrial peat HS, differed for the two minerals. The contrasting fractionation patterns for SRFA versus PAHA can be explained reasonably well by the different structural trends that occur in their respective MW fractions and the underlying adsorption processes. Rate studies of adsorptive fractionation revealed an initial rapid uptake of smaller HS molecules by the mineral surfaces, followed by their replacement at the surface by a much slower uptake of the larger HS molecules present in aqueous solution.

There are no comments yet on this publication. Be the first to share your thoughts.