Comparison of Copper-crosslinked Carboxymethyl Cellulose Versus Biopolymer-based Hydrogels for Controlled Release of Fertilizer

Abstract

ABSTRACT This work deals with evaluating the hydrogel prepared from copper-crosslinked carboxymethyl cellulose as a controlled release system of fertilizer. In this respect, the behavior of gel was compared with gels prepared from polycationic biopolymer (trimethyl chitosan; Tri.M.Ch), individual or as a crosslinking agent of carboxylate-containing cellulose derivatives (CMC) and oxidized cellulose nanoparticles (OC.NPs). The swelling behavior of gel was preliminarily examined as a key factor for gel application. It is worth noting that the swelling capacity of CMC-Cu(II) gel was very higher (2350% at 250 min) than other gels (Tri.M.Ch, CMC-Tri.M.Ch andOC.NPs.Tri.M.Ch), where their swelling capacities ranged 100–300%. Moreover, it provided more sustained release rate of monoammonium phosphate (MAP-fertilizer) loaded hydrogels, similar toCMC-Tr.M.Ch, with maximum ~87–88%; while the gels of Tr.M.Ch. and Tr.M.Ch.-OC.NPs achieved maximum release reached 96–100%. The release of MAP from the hydrogels was followed by a Fickian or quasi-Fickian diffusion mechanism. The trend of hydrogels for MAP release was reflected in the nutrition value (NPK) of onion planted on gel-treated sand loamy soil.