Bead gels based on carrageenan-cassava bagasse as a urea controlled release fertilizer

The use of fertilizer with high doses resulted in most of the urea wasted in the environment. Therefore hydrogel for urea controlled release is developed. Cassava bagasse is waste produced from tapioca flour processing. In this research, bead hydrogels based on carrageenan-cassava bagasse were prepared and used to control the rate of urea release. This research studied the ability of carrageenan-cassava bagasse mixture to form a bead gel and the effect of carrageenan-cassava bagasse mixture composition on the amount of urea that can be stored and the amount of urea released in water media. Beads of carrageenan-cassava bagasse were prepared based on a different mixture of carrageenan-cassava bagasse with a weight ratio of 1:0.5; 1:1 and 1:2. The carrageenan-cassava bagasse structure was physically crosslinking using KCl and CaCl₂ solution and then followed by chemically crosslinking using glutaraldehyde solution (4%) as the crosslinker. The amount absorbed of urea in the bead gel was determined by swelling degree measurement in urea solution. The percentage of urea released from bead gel was determined by measuring urea’s concentration in various time of immersion in water. The result showed that bead gel form based on carrageenan-cassava bagasse was successfully prepared. The swelling degree of beads gel was decreased with the increasing of cassava bagasse amount in ratio blend. Bead gel 1: 2 showed the highest percentage of urea release at 68.02 % and 70.94 %.