Agar-gelatin-derived hydrogel-based controlled delivery devices for linuron herbicide to prevent environmental hazards

Abstract

Innovation in agriculture chemicals and delivery systems is essential for the production of food for sustainable development. Herein, natural polymers and agar-gelatin-derived controlled delivery devices for linuron herbicide to prevent environmental and health hazards. These hydrogels were designed by the graft-copolymerization reaction of poly(methacrylamide) [poly(MAAm)] on agar-gelatin for use as controlled-release formulations (CRF). Copolymers were characterized by Copolymers were characterized scanning electron micrographs (SEM), Atomic force microscopy (AFM), X-ray diffraction (XRD) Fourier transform infrared spectroscopy (FTIR), ¹³C-nuclear magnetic resonance (NMR), and thermogravimetric analysis -differential thermogravimetry (TGA-DTG) techniques. SEM shows the uneven surface morphology, and AFM showed a rough surface with an average roughness value of 137.50 nm in the polymeric matrix. The amorphous nature of the polymer was confirmed with XRD techniques. Grafting of the poly(MAAm) on the agar and gelatin was confirmed by FTIR and ¹³C NMR spectra. Agar-gelatin-cl-poly(MAAm) hydrogels absorbed water at 4.05 ± 0.32 g per gram, which is useful for soil water retention. Release of the linuron herbicide occurred in a controlled manner during 72 h of observations and followed non-Fickian diffusion mechanism. The slow release of the linuron from the hydrogel is a useful observation for preventing leaching and evaporation loss of herbicide. In the soil column, the release of linuron occurred in a slow and sustained manner for 240 h. A soil adsorption study showed a decrease in ground water ubiquity score (GUS) for linuron-encapsulated hydrogel as compared to commercial formulations. It can reduce groundwater contamination risk due to the leaching of the linuron herbicide. Degradation of CRF may improve micronutrient and soil quality.