Controlled release behavior of sulfentrazone herbicide encapsulated in Ca-ALG microparticles: preparation, characterization, mathematical modeling and release tests in field trial weed control

The use of herbicides is important to eliminate losses of weed interference on crops. However, excessive and inappropriate employment of these substances can cause serious consequences to the environment. In this way, the release system is very attractive for the weed control in the agriculture area. The aim of this work was to study a new delivery system for sulfentrazone herbicide encapsulated into the calcium alginate (Ca-ALG) microparticles for the weed control. The alginate microparticles were prepared via ionotropic gelation method and characterized by using optical microscopy, scanning electron microscopy, and thermogravimetric and differential thermal analysis. The controlled release (M _t /M _∞ vs. time) of the sulfentrazone herbicide was also analyzed using UV–Vis spectroscopy where we proposed different mathematical models to understand the mechanisms of controlled release of the herbicide. Furthermore, the release tests in field trial weed control were conducted using bioindicator species (Cucumis Sativus—Cucumber) to study the phytotoxicity evaluation caused by the Ca-ALG microparticles at different concentrations and their relationship with leaching depth. The results showed that the Ca-ALG microparticles exhibited good encapsulation efficiency (%EE): 76.11, 78.62, and 80.42% for the 4, 5 and 6 g L⁻¹ concentration of herbicide. The release rates in the region I were 39.2, 46.5, and 35.5 mg s⁻¹ for the 4, 5, and 6 g L⁻¹ of herbicide concentration, respectively. The Ca-ALG microparticles containing sulfentrazone herbicide demonstrated potential application in controlled release platforms in agricultural as well as for controlling of weeds and minimization of leaching processes.