Gellan gum-O,O′-bis(2-aminopropyl)-polyethylene glycol hydrogel for controlled fertilizer release

Abstract

A gellan gum–Jeffamine superabsorbent hydrogel was obtained with different crosslink densities using different amountsof (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride) and N-hydroxysuccinimide. Infrared spectroscopy and thermalanalysis confirm the crosslinking. A morphology analysis indicates denser structures for samples with higher crosslinking points. Theswelling degree in high-acyl gellan gum hydrogels was equivalent to 145 times their dry weig ht, and 77 times when low-acyl gellangum was used. Hydrogels also showed a 450 min water retention, as opposed to 280 min for pure water, evidencing good humiditycontrol, suitable for use in arid climates. They also demonstrated a maximum release of commercial fer tilizer of about 400 mg pergram for KH2PO4and about 300 mg per gram for NPK 20-5-20.