Controlled Delivery System for NPK Agrochemical Release from Chitosan Copolymer Hydrogels

Chitosan (CS) the polysaccharide was copolymerized with Poly (Vinyl Alcohol) (PVA) for the preparation of CS-co-PVA hydrogel and with Carboxymethyl Cellulose (CMC) for CS-co-CMC hydrogel. The prepared hydrogels were characterized by FTIR, thermal analysis (TGA and DSC), and SEM. The hydrogels were studied for agriculture applications, where their ability to swell and take large quantities of water many times its weight was exploited for water retention when the hydrogel was mixed with agricultural soil. For almost 40 days the soil in the soil/hydrogel sample was kept wet whereas the reference sample (without hydrogel) has a maximum of 20 days wet. The next application was loading the NPK fertilizer applied as a model into the prepared hydrogels and then allowing to release of the loaded fertilizer in a controlled manner and for long time intervals. Both hydrogels CS-co-PVA and CS-co-CMC have shown a high maximum loading percentage (L_max%) and a highly efficient loading percentage (EL%). Equivalent to the release character of both hydrogels has shown a controlled agrochemical deliver pattern.