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<p>Water scarcity and inefficient nutrient utilization are major bottlenecks in sustainable agriculture. Conventional superabsorbent polymers (SAPs) enhance soil water retention but lack integrated nutrient delivery, limiting their agronomic efficiency. In this study, Starch(ST)/Polyvinyl alcohol(PVA) hydrogel nanocomposites incorporating fertilizer-loaded nanozeolites to achieve simultaneous water retention and controlled nutrient release. Fertilizers including KNO₃, NH₄Cl, KMnO₄, urea were pre-immobilized within nanozeolite pores before incorporation, ensuring high loading efficiency and uniform dispersion within the hydrogel matrix. Hydrogels were synthesized via solution blending and thermal gelation, with nanozeolites acting as physical crosslinkers and ion-exchange reservoirs. Comprehensive characterization using FTIR, XRD, SEM, and EDX confirmed strong polymer–nanozeolite interactions, preserved zeolite crystallinity, and effective nutrient incorporation. Swelling studies revealed pH- and temperature-responsive behavior, with a non-linear dependence on nanozeolite content, moderate loadings enhanced water uptake, whereas higher loadings increased crosslink density and limited swelling. Ion chromatography showed sustained nitrogen and potassium release following a Fickian diffusion plus ion-exchange mechanism, with KNO₃-loaded nanocomposites exhibiting the highest encapsulation and slow-release efficiency. The nanocomposite containing 30 wt% fertilizer-loaded nanozeolite exhibited a balanced swelling–release profile approaching the theoretical characteristics of an ideal controlled-release agricultural system, where water absorption capacity and nutrient diffusion are temporally synchronized. Collectively, this work provides mechanistic evidence that coupling nanozeolite-mediated nutrient immobilization with a biodegradable ST/PVA hydrogel matrix enables programmable water–nutrient co-delivery. The proposed platform advances next-generation agricultural SAPs by integrating structural tunability, environmental responsiveness, and ion-regulated release behavior, thereby contributing to improved resource-use efficiency and precision farming strategies.</p>

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Starch/polyvinyl alcohol/encapsulated zeolite superabsorbent nanocomposite for urea slow-release fertilizer

  • 期刊论文

  • 发表日期：

    2026年6月15日

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  • Sahar Amiri

摘要

Water scarcity and inefficient nutrient utilization are major bottlenecks in sustainable agriculture. Conventional superabsorbent polymers (SAPs) enhance soil water retention but lack integrated nutrient delivery, limiting their agronomic efficiency. In this study, Starch(ST)/Polyvinyl alcohol(PVA) hydrogel nanocomposites incorporating fertilizer-loaded nanozeolites to achieve simultaneous water retention and controlled nutrient release. Fertilizers including KNO₃, NH₄Cl, KMnO₄, urea were pre-immobilized within nanozeolite pores before incorporation, ensuring high loading efficiency and uniform dispersion within the hydrogel matrix. Hydrogels were synthesized via solution blending and thermal gelation, with nanozeolites acting as physical crosslinkers and ion-exchange reservoirs. Comprehensive characterization using FTIR, XRD, SEM, and EDX confirmed strong polymer–nanozeolite interactions, preserved zeolite crystallinity, and effective nutrient incorporation. Swelling studies revealed pH- and temperature-responsive behavior, with a non-linear dependence on nanozeolite content, moderate loadings enhanced water uptake, whereas higher loadings increased crosslink density and limited swelling. Ion chromatography showed sustained nitrogen and potassium release following a Fickian diffusion plus ion-exchange mechanism, with KNO₃-loaded nanocomposites exhibiting the highest encapsulation and slow-release efficiency. The nanocomposite containing 30 wt% fertilizer-loaded nanozeolite exhibited a balanced swelling–release profile approaching the theoretical characteristics of an ideal controlled-release agricultural system, where water absorption capacity and nutrient diffusion are temporally synchronized. Collectively, this work provides mechanistic evidence that coupling nanozeolite-mediated nutrient immobilization with a biodegradable ST/PVA hydrogel matrix enables programmable water–nutrient co-delivery. The proposed platform advances next-generation agricultural SAPs by integrating structural tunability, environmental responsiveness, and ion-regulated release behavior, thereby contributing to improved resource-use efficiency and precision farming strategies.