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Competitive adsorption involving phosphate and benzenecarboxylic acids on goethite-Effects of molecular structures

Author:
  • Malin Lindegren
  • Per Persson
Publishing year: 2010
Language: English
Pages: 263-270
Publication/Series: Journal of Colloid and Interface Science
Volume: 343
Document type: Journal article
Publisher: Elsevier
Additional info: 1

Abstract english

The competitive adsorption between phosphate and either one of seven benzenecarboxylates (benzoate, phthalate, trimellitate, trimesoate, hemimellitate, pyromellitate, and mellitate) on the surfaces of fine-particulate goethite (alpha-FeOOH) was investigated as a function of pH. The series of ligands contained Molecules with an increasing number of functional groups as well as three structural isomers of the tricarboxylates. Thus, the effects of both the number of carboxylate groups and the relative positions of these groups on the competitive efficiency toward phosphate were probed ill this Study. Quantitative adsorption experiments in batch mode and infrared spectroscopy were collectively Used to evaluate the competitive adsorption reactions. Under the conditions probed, mono- and dicarboxylates had no detectable effect on phosphate adsorption whereas the ligands containing three or more carboxylate groups were able to partially outcompete phosphate. However, the pH dependency and the extent of these competitive effects were strongly dependent on (lie structure and composition of the benzenecarboxylate. The collective results showed that it was the competition for hydrogen-bonding surface sites rather than inner sphere Surface sites that primarily determined the outcome of the competitive adsorption experiments,and it was the ability of the organic ligand to act as hydrogen-bonding acceptor and/or donor in various parts of the pH range that also determined the competitive pH dependency. The importance of H-bonding for the competitive adsorption between phosphate and benzenecarboxylic acids suggested that H-bonding interactions contributed substantially to the stabilities of both the adsorbed benzenecarboxylates and the phosphate ions and that these interactions were structurally specific: i.e., they were sensitive to the locations and the directional properties of the H-acceptor and H-donor surface sites. (c) 2009 Elsevier Inc. All rights reserved.

Keywords

  • Earth and Related Environmental Sciences

Other

Published
  • ISSN: 1095-7103
Per Persson
E-mail: per [dot] persson [at] biol [dot] lu [dot] se

Professor

MEMEG

+46 46 222 17 96

+46 70 266 38 79

E-C350

50

Professor

Centre for Environmental and Climate Research (CEC)

+46 46 222 17 96

+46 70 266 38 79

D350

Ekologihuset, Sölvegatan 37, Lund

50