Double-xerogel network composite zeolite granules targeting dual-functional fertilizers

Abstract

Food security remains a global challenge due to rapid population growth, intensive agricultural practices, and freshwater scarcity. This study presents the development of dual-functional composite granules combining sodium alginate (SA), gelatin, GIS-type zeolite, and CuO/ZnO nanorods for enhanced water retention and controlled micronutrient release. The GIS-type zeolite exhibited high water adsorption capacity (0.75 g H₂O/g), while the incorporation of gelatin significantly increased the swelling ratio from 0.6 to 1.7, improving water retention and soil conditioning. CuO and ZnO nanorods embedded within the composite granules facilitated the controlled release of copper and zinc ions under acidic conditions (pH 4). The release of Cu²⁺ followed super case II transport (n = 0.98–1.10), while Zn²⁺ release followed an erosion-driven Weibull model. Water retention in soil increased by 20 % with gelatin-based granules after 7 days, and the water holding capacity of soil improved by 15 %–20 %. The composite granules demonstrated excellent mechanical stability, with a compressive stress of 1.5–5.5 MPa. This dual-functional system offers a sustainable approach to enhancing soil fertility and addressing micronutrient deficiencies while improving water retention in agricultural soils.