Effect of surface coordination on 2,4-D sorption by kaolinite from methanol/water mixture

Minhee Kim, Seunghun Hyun

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The application of the cosolvency sorption model to predict the sorption of carboxylic acids in cosolvent systems was found to be problematic. The cause of the discrepancy was investigated by analyzing the solubility (Sm) and sorption (Km, linear sorption coefficient) of the pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) on metal-saturated kaolinites, as a function of methanol volume fraction (fc) and apparent solution pH. The possible formation of a coordination compound during the hydrophilic interaction of 2,4-dichlorophenoxyacetate in methanol-water mixture was identified using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The Sm of 2,4-dichlorophenoxyacetate increased with increasing fc. Thus, the shift of activity of solute occurred in the liquid phase was not significant for determining the cause of the positive Km-fc relationship. However, Km value of 2,4-dichlorophenoxyacetate on the metal-saturated kaolinite increased log-linearly with fc. The ATR-FTIR results on surface coordination of 2,4-dichlorophenoxyacetate on the metal-saturated kaolinite surface showed that bidentate coordination is more likely to occur instead of a bridging coordination with increasing fc. Therefore, it can be reasonably concluded that the positive Km-fc relationship is due to the charge-related hydrophilic interaction through bidentate coordination of 2,4-dichlorophenoxyacetate, and it increases with increasing positive charge density on the kaolinites, as a function of fc.

Original languageEnglish
Pages (from-to)329-335
Number of pages7
JournalChemosphere
Volume103
DOIs
Publication statusPublished - 2014 Jan 1

Fingerprint

Kaolin
2,4-Dichlorophenoxyacetic Acid
2,4 dichlorophenoxyacetic acid
kaolinite
Methanol
methanol
Sorption
sorption
Water
Metals
metal
reflectance
water
Carboxylic Acids
Charge density
Pesticides
Volume fraction
carboxylic acid
Fourier transforms
FTIR spectroscopy

Keywords

  • 2,4-Dichlorophenoxyacetic acid
  • Coordination type
  • Hydrophilic sorption
  • Methanol mixture

ASJC Scopus subject areas

  • Environmental Chemistry
  • Chemistry(all)

Cite this

Effect of surface coordination on 2,4-D sorption by kaolinite from methanol/water mixture. / Kim, Minhee; Hyun, Seunghun.

In: Chemosphere, Vol. 103, 01.01.2014, p. 329-335.

Research output: Contribution to journalArticle

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