Bead Gel dari Karagenan-Carboxymethylcellulose dengan Crosslinking Glutaraldehid sebagai Controlled Release Urea

This research made bead gel as controlled release fertilizer (CRF) to control the release of urea to the environment. Bead gel was made from carrageenan and carboxymethylcellulose (CMC) and the bead gel was crosslinked with glutaraldehyde. The aims of this research were to study the effect of carrageenan-CMC ratio in the mixture towards the bead gel ability to absorb urea and to study the concentration of glutaraldehyde effect on the bead gel stability. K-Carrageenan extracted from Euchema cotonii was mixed with CMC to prepare bead gel with the weight ratio of 1:0, 1:0,5, and 1:1. The mixture was dropped into aqueous KCl-CaCl2 to form bead gel and then dried. The dried bead gel was soaked in glutaraldehyde solution (1% or 4%wt), and then the bead gel was heated at 110°C for 25 minutes. The crosslinked bead gel was loaded with urea in a beaker glass containing urea solution. After loading process, the bead gel was put into water to release the urea from the bead gel. The results showed that the highest amount of urea adsorbed was obtained by the weight ratio of carrageenan-CMC 1:1. Bead gel with concentration of glutaraldehyde 4% was more stable in aqueous solution