Comparison of sorption domains in molecular weight fractions of a soil humic acid using solid-state 19F NMR

M. Khalaf, Scott D. Kohl, E. Klumpp, James A. Rice, E. Tombácz

Research output: Contribution to journalArticle

52 Citations (Scopus)

Abstract

Humic acid was fractionated into eight different molecular size components using ultrafiltration. Solid-state CPMAS 13C NMR demonstrated that fractions larger than 100 000 Daltons were primarily aliphatic in character, while fractions smaller than 30 000 Daltons were predominantly aromatic in character. Solid-state 19F NMR examination of the sorptive uptake of hexafluorobenzene (HFB) by HA and each of the fractions gave spectroscopic evidence for the existence of at least three sorption sites in the smaller molecular size fractions, while two predominant sorption sites could be established in the larger molecular size fractions. Sorbed HFB displayed higher mobility in the smaller, more aromatic fractions while HFB in the larger, more aliphatic fractions displayed lower mobility. The relative mobilities of HFB in each sorption domain suggest that the rigid domain may be composed of aliphatic carbon rather than aromatic carbon moieties. In larger size fractions, this domain may be the result of rigid, glassy regions composed of aliphatic molecules or side chains.

Original languageEnglish
Pages (from-to)2855-2860
Number of pages6
JournalEnvironmental Science and Technology
Volume37
Issue number13
Publication statusPublished - Jul 1 2003

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

Fingerprint Dive into the research topics of 'Comparison of sorption domains in molecular weight fractions of a soil humic acid using solid-state <sup>19</sup>F NMR'. Together they form a unique fingerprint.

  • Cite this