Humic Acid‐Functionalized Hydrogels: A Dual Platform for Controlled Release of Dinotefuran and Enhanced Water Retention

ABSTRACT The extensive use of neonicotinoid insecticides, particularly dinotefuran, poses risks of groundwater and soil contamination. This study developed a humic acid‐based ammonium humate‐grafted poly(sodium acrylate) hydrogel (HA‐g‐SAH) via free‐radical copolymerization to enable controlled pesticide release. HA‐g‐SAH was characterized by 13 C CPMAS NMR, FT‐IR, XRD, SEM, and TGA to confirm its structural integrity and stability. Swelling performance of different formulations revealed significant effects of biopolymer, initiator, and crosslinker concentrations, with HA‐g‐SAH achieving a maximum swelling index of 320.92 g·g − 1 , compared with 162.27 g·g − 1 for the control (ctrl). Network parameters were also calculated. Dinotefuran loading efficiency reached 65.24%, exceeding that of the ctrl hydrogel (54.35%). Release experiments demonstrated a gradual, extended pesticide release: HA‐g‐SAH released 78.45% of dinotefuran (49 h), while the ctrl released 64.21% (33 h). Kinetic modelling indicated that the release followed a non‐Fickian diffusion mechanism, best described by the Korsmeyer–Peppas and Weibull models. Soil amendment studies further showed that HA‐g‐SAH significantly enhanced water retention capacity (79.46% at 1% hydrogel), outperforming the ctrl (58.49%). These findings highlight that HA‐g‐SAH exhibits high swelling and extended pesticide release capacity. Thus, this study offers a sustainable strategy to reduce pesticide leaching and enhance agricultural productivity.