Adsorption of herbicide triclopyr on homoionic clays

The adsorption of the herbicide triclopyr on homoionic Fe3+ , Al3+ , Cu2+ , K+ and Na+ exchanged montmorillonite samples was investigated and the adsorption isotherm was described by the Fre-undlich equation. The adsorption capacity decreased in the order Fe3+ , Al3+ , Cu2+) , Ca2+ , K+ and Na+-clays. The triclopyr adsorption from chloroform solution was also studied by analytical, spectroscopic, and X- ray powder diffraction techniques. IR results suggested that the adsorption involved the formation of hydrogen bonds with water molecules in the interlayer and might have involved both the protonation of the pyridinenitrogen atom, due to a proton transfer from the acid metal - bound water , and also the formation of directbounds between the carboxylate groups and the exchange cations. The pesticide forming complexes with interlayer cations in montmorillite in soils might be extractable by solvents and was therefore releaed into the environment.