SUPERABSORBENT PRUNUS DOMESTICA AND TANNIN GRAFTED HYDROGEL WITH EXTENDED RELEASE OF PESTICIDE DINOTEFURAN FOR AGRICULTURAL APPLICATION

Abstract

The development of sustainable agricultural systems requires innovative and environmentally friendly materials which effectively address huge challenges such as water shortage, extensive pesticide use, and decrease in productivity of crops. In the present era, polymer-based delivery carriers have emerged as an excellent tool because of their high capacities to absorb water, controlled release behaviour and biodegradability. In the present study, natural polymers derived from gum of Prunus domestica and Tannin from Acacia catechu have been employed to prepared grafted hydrogels intended for agricultural applications. The individual hydrogels, namely PD-g-SAH and AC-g-SAH, along with the combined hydrogel system PDAC-g SAH, were synthesized through a free-radical copolymerization process using N, N′ methylenebisacrylamide (N, N MBA) as the crosslinker. Naturally derived components were incorporated to maintain sustainability. A comparative study of the synthesized hydrogel formulations was performed to test their swelling index, water retention capacity (WRC) and release duration in distilled water. Among the synthesised hydrogels, the combination was proven to be superior with respect to individual hydrogels in terms of swelling index, water retention capacity (WRC) and release study, indicating its potential to maintain soil hydration over extended periods. Such properties are highly useful in agricultural fields where effective water management is essential for plant growth and productivity, especially in drought-prone areas. Grafting process, thermal behaviour, strength and surface morphology were confirmed using the characterization techniques. Fourier-transform infrared spectroscopy (FT-IR) and 13C nuclear magnetic resonance (13C NMR) analyses verified the presence of functional groups and successful copolymerization within the hydrogel matrix. X-ray diffraction (XRD) studies revealed the structural arrangement and degree of crystallinity, while scanning electron microscopy (SEM) provided information regarding the porous surface morphology responsible for enhanced swelling and pesticide encapsulation. Thermogravimetric analysis (TGA) IV demonstrated the thermal stability of the synthesized materials, and rheological investigations confirmed their mechanical strength and viscoelastic properties, which are important for practical agricultural applications. The prepared hydrogels were further evaluated as controlled-release carriers for the pesticide dinotefuran. The pesticide loading efficiencies after 48 hours were recorded as 54.97% for PDAC-g-SAH, 47.27% for PD-g-SAH, and 31.49% for AC-g-SAH, indicating that the combined hydrogel possessed the highest loading capacity due to its improved network structure and porosity. Release studies showed that the dinotefuran was released gradually and continuously from the hydrogel matrices over time, minimizing the sudden release of pesticide into the environment. The release kinetics were best explained by Korsmeyer–Peppas, Higuchi, and first-order kinetic models, suggesting that diffusion-controlled mechanisms played a significant role in pesticide release. The extended-release behaviour of the PDAC-g-SAH hydrogel highlights its capability in reducing pesticide loss caused by leaching, runoff, and evaporation. This not only improves the persistence and utilization efficiency of dinotefuran but also lowers the frequency of pesticide application, thereby reducing environmental contamination and economic costs for farmers. Overall, the study demonstrates that the developed natural polymer-based hydrogel system represents a promising and eco-friendly strategy for water conservation and controlled pesticide delivery, supporting the advancement of sustainable and efficient agricultural practices.