Determination of the association and dissociation of humic acid fractions by small angle X-ray scattering

Journal of Research of the U.S. Geological Survey
By:  and 

Links

Abstract

A procedure has been devised for the fractionation of humic acid samples from different environments. This procedure involves fractionation of the sample by adsorption chromatography on a Sephadex G-50 column followed by chromatography on either a G-25 or a G-100 column. The fractions of the solutions are then examined by small angle X-ray scattering. Three different types of behavior have been detected among the humic acid fractions: (1) Some fractions show very little change in aggregation at pH values above 3.5. (2) One fraction forms aggregates at pH values above and below pH 7, but at pH 7 it is completely dissociated. (3) In some fractions the degree of aggregation decreases with increasing pH. However, even at pH values as high as 11.5 some large particles are still present. These differences in
association behavior are due to the interaction of different attractive and repulsive forces. In many aggregating systems only one type of
attractive force is dominant; however in humic acid systems hydrogen bonding, π bonding between planar aromatic moieties, and other
coulombic interactions apparently all play a role in the formation of molecular aggregates.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Determination of the association and dissociation of humic acid fractions by small angle X-ray scattering
Series title Journal of Research of the U.S. Geological Survey
Volume 1
Issue 6
Year Published 1973
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Description 7 p.
First page 701
Last page 707
Online Only (Y/N) N
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
Additional metadata about this publication, not found in other parts of the page is in this table