Competitive sorption between imidacloprid and imidacloprid-urea on soil clay minerals and humic acids

Weiping Liu, Wei Zheng, Jianying Gan

Research output: Contribution to journalArticle


Soil organic matter and clay minerals are responsible for the adsorption of many pesticides. Adsorption and competitive sorption of imidacloprid on clay minerals and humic acids (HA) were determined using the batch equilibration method. The sorption coefficient of imidacloprid on humic acids was significantly higher than that on Ca-clay minerals, indicating that soil organic matter content was a more important property in influencing the adsorption of imidacloprid. Competitive sorption was investigated between imidacloprid and its main metabolite imidacloprid-urea on HA and Ca-clay minerals. The results showed that the sorption capacity of imidacloprid on clay minerals and HA was reduced in the presence of the metabolite, implying that imidacloprid-urea could occupy or block adsorption sites of imidacloprid on soil, potentially affecting the fate, transport, and bioavailability of imidacloprid in the environment. The interactions between a Ca-clay or HA-clay mixture and adsorption of imidacloprid and imidacloprid-urea were studied using IR differential spectra on thin films made of the adsorbent. The possible mechanisms were discussed from the shift of characteristic IR absorption bands of imidacloprid and imidacloprid-urea after sorption.

Original languageEnglish (US)
Pages (from-to)6823-6827
Number of pages5
JournalJournal of Agricultural and Food Chemistry
Issue number23
StatePublished - Nov 6 2002
Externally publishedYes


  • Adsorption
  • Clay minerals
  • Competitive sorption
  • Humic acids
  • Imidacloprid
  • Imidacloprid-urea
  • Sorption

ASJC Scopus subject areas

  • Chemistry(all)
  • Agricultural and Biological Sciences(all)

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