In silico investigation of herbicide release from intercalated layered double hydroxides

Abstract

Excessive pesticide use may contaminate streams and surface water, posing a significant danger for the environment. The employment of slow-deliver formulations may circumvent this issue by reducing pesticide waste. In this work, computational simulations were performed to study the release of anionic herbicide species from the galleries of layered double hydroxides. Density Functional Theory was initially employed to construct the structural models of intercalated materials, which were later used for force-field based molecular dynamics. The calculated Gibbs free energy of the anion release indicated that the herbicide species are spontaneously exchanged with carbonate anions, demonstrating that the final intercalation with CO32− is favored. The molecular dynamics runs showed that the basal spacing increases in the presence of an aqueous solution, in certain cases even swelling the interlayer region. Based on the acquired data, a simple mechanism could be proposed for the release of anion species from layered materials.