Movement of metolachlor in soil: effect of new organo‐clay formulations

Abstract

The use of commercially available formulations of metolachlor has resulted in its leaching and migration to water sources. Formulations of metolachlor designed to reduce its leaching in soil have been prepared by adding the herbicide dissolved in an organic solvent or in water to organo‐clay complexes. Best formulations were made when the organo‐clay complex was formed by adsorbing the monovalent organic cations benzyltrimethylammonium (BTMA) or benzyltriethylammonium (BTEA) onto sodium montmorillonite (Mont) at 0.5 or 0.8 mole kg−1 clay. Adsorption of metolachlor to organo‐clays followed the sequence Mont‐BTMA 0.5 > Mont‐BTMA 0.8 > Mont‐BTEA 0.8 > Mont‐BTEA 0.5 > Mont. Fourier transform infrared (FTIR) analysis demonstrated the occurrence of shifts of several peaks of adsorbed metolachlor relative to the free herbicide, indicating the existence of strong interactions between …