Controlled release of chlorpyrifos through crosslinked chitosan–guargum biopolymer based nano-formulation

Abstract

In the present study, we have synthesized chitosan and guargum-based nano-formulation containing chlorpyrifos pesticide in order to tune its release in water. The nano-formulations were characterized before and after loading of chlorpyrifos by fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and particle size analyzer (PSA) to study its morphology and chemical composition. Spherical nanoparticles (NPs) of about 200 nm, with a positive zeta potential, were obtained, and the prepared nano-formulation exhibited good stability upon storage at 25 °C for 60 days. The chlorpyrifos encapsulation efficacy was about 85% at pH 7 and 30 °C. The nano-formulations of chlorpyrifos have shown almost 25% slower release as compared to the conventional formulation. The prepared nano-formulation released around 82 % chlorpyrifos in 15 days. Kinetics study revealed that the release rate of chlorpyrifos from the glyoxal crosslinked nano-formulation depends on the diffusion and polymeric matrix at lower pH, and only on diffusion at higher pH. The prepared nano-formulation containing chlorpyrifos did not exhibit any toxicity toward soil beneficial microbiota. The soil mobility study indicated that chlorpyrifos was detected up to the depth of 15–20 cm of soil in the case of nano-formulation while in the case of conventional formulation, it was detected up to the depth of 20–25 cm of soil.