Novel biodegradable nanocomposite hydrogels based on biopolymers and various montmorillonite contents as high-strength coating membranes for efficient slow-release fertilizers

Slow-release fertilizers (SRF) have emerged as a sustainable remedy to the environmental problems caused by conventional water-soluble fertilizers. They have demonstrated their efficacy in reducing fertilizer dosage applications, enhancing fertilizer utilization efficiency, minimizing losses, and ultimately improving crop yield. This study developed biodegradable nanocomposite hydrogels (BHM) as a promising approach by combining cassava starch (Cst), polyacrylamide (PAM), natural rubber (NR), and various montmorillonite (MMT) contents (0-10 wt%) and fabricating via free-radical polymerization and semiinterpenetrating polymer network technology, crosslinked by glutaraldehyde. Notably, the addition of MMT played a crucial role and significantly improved the tensile strength, biodegradability, and N release efficiency of the BHM hydrogels. BHM3 (3 wt% MMT) demonstrated the highest swelling ratio of 7074% and improved N release efficiency, mechanical strength, and biodegradation rate by 39.1%, 260% and 58%, respectively, compared to BHM0. The FWBHM formulations (urea coated with BHM and wax layers) also exhibited good biosafety. Finally, FWBHM3 yielded acceptable growth rates, a greater yield, and a 4-fold lower price than commercial SRF. These findings provide a promising route for developing new nanocomposite hydrogels based on Cst, NR, and MMT components with high swelling and water-retention, high strengths, and excellent biodegradation with greater slow-release duration and sustained environments. (c) 2023 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.