Sorption of acidic organic solute onto kaolinitic soils from methanol-water mixtures

Juhee Kim, Minhee Kim, Seunghun Hyun, Jeong Gyu Kim, Yong Sik Ok

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The fate of the acidic organic solute from the soil-water-solvent system is not well-understood. In this study, the effect of the acidic functional group of organic solute in the sorption from cosolvent system was evaluated. The sorption of naphthalene (NAP) and 1-naphthoic acid (1-NAPA) by three kaolinitic soils and two model sorbents (kaolinite and humic acid) were measured as functions of the methanol volume fractions (f c ≤ 0.4) and ionic compositions (CaCl 2 and KCl). The solubility of 1-NAPA was also measured in various ionic compositions. The sorption data were interpreted using the cosolvency-induced sorption model. The K m values (= the linear sorption coefficient) of NAP with kaolinitic soil for both ionic compositions was log linearly decreased with f c. However, the K m values of 1-NAPA with both ionic compositions remained relatively constant over the f c range. For the model sorbent, the K m values of 1-NAPA with kaolinite for the KCl system and with humic acid for both ionic compositions decreased with f c, while the sorption of 1-NAPA with kaolinite for the CaCl 2 system was increased with f c. From the solubility data of 1-NAPA with f c, no significant difference was observed with the different ionic compositions, indicating an insignificant change in the aqueous activity of the liquid phase. In conclusion, the enhanced 1-NAPA sorption, greater than that predicted from the cosolvency-induced model, was due to an untraceable interaction between the carboxylate and hydrophilic soil domain in the methanol-water system. Therefore, in order to accurately predict the environmental fate of acidic pesticides and organic solutes, an effort to quantitatively incorporate the enhanced hydrophilic sorption into the current cosolvency-induced sorption model is required.

Original languageEnglish
Pages (from-to)22-29
Number of pages8
JournalJournal of Environmental Science and Health - Part B Pesticides, Food Contaminants, and Agricultural Wastes
Volume47
Issue number1
DOIs
Publication statusPublished - 2012 Jan

Keywords

  • 1-Napthoic acid
  • cosolvency
  • kaolinitic soil
  • sorption

ASJC Scopus subject areas

  • Food Science
  • Pollution

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