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Development of amine functionalized lignin-based hydrogels for controlled release of phosphate in acidic conditions
Date
2026-12-01
Abstract
The indiscriminate application of conventional fertilizers to enhance crop yields often results in significant environmental and economic drawbacks, primarily due to their high solubility and surface runoff losses. In this study, a biodegradable, dual-crosslinked double-network hydrogel system was developed using amine-functionalized biopolymers, namely sodium lignosulfonate modified with polyethyleneimine (PEI), poly(vinyl alcohol) (PVA) functionalized with 3 (dimethylamino)-1-propylamine (DMAPA), and chitosan rendered water soluble via modification with 2-(dimethylamino)ethyl methacrylate (DMAEMA). The synthesized aminated biopolymer-based hydrogel was employed to encapsulate struvite (MgNH4PO4⋅6H2O), a slow-release phosphate fertilizer. Comprehensive structural and physicochemical characterizations were performed using Fouriertransform infrared spectroscopy (FTIR), Nuclear Magnetic Resonance spectroscopy (NMR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). All pristine hydrogel formulations exhibited superior water-retention capability and non-Fickian swelling behaviour, achieving maximum swelling ratios of 1606 ± 42%. Phosphate release studies conducted in an acidic citric buffer (pH 4.01) demonstrated sustained nutrient release over 10 days. Kinetic modelling revealed a non-Fickian diffusion transport mechanism (n ≤ 1) and an anomalous diffusion-controlled release, consistent with the Higuchi model (R2 = 0.93). In contrast, first-order kinetics indicated deviation from classical concentration-independent release behaviour. Overall, the findings establish amine-modified biopolymer-based hydrogels as promising, eco-friendly carriers for controlled nutrient delivery, thereby providing a sustainable approach to enhancing fertilizer-use efficiency and reducing environmental impact in modern agriculture.
Supervisor
Description
Publisher
Elsevier
Citation
Sustainable Chemistry for Climate Action 9, 100225
Files
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Khan_2026_Development.pdf
Adobe PDF, 8.34 MB
ULRR Identifiers
Funding code
Funding Information
Sustainable Development Goals
External Link
License
Attribution-NonCommercial-ShareAlike 4.0 International