Release Behavior and Degradation Research of Controlled-Released Urea Encapsulated in Starch-Alginate Hydrogel

Authors

  • Siew Wei Phang
  • Lee Tin Sin
  • Soo-Tueen Bee

Abstract

This paper presents the synthesis of urea encapsulated in starch- and alginate- based controlled released fertilizer, using calcium chloride (CaCl2) as crosslinking agent. A series of micro-spheres-like beads of different composition were prepared by varying the amounts of starch, sodium alginate, urea and CaCl2, in accordance to robust parameter design (RPD) at four factor designs - L9 arrays with a total of nine formulations. It was found that the urea release rate was highly correlated with the swelling behavior of the samples, at a R2 of 0.737. Sodium alginate content played the most significant role in creating the size and shapes of the hydrogel; low alginate content create irregular shapes of the beads formed; high alginate content create viscos solution that could not be extruded via syringe. The urea release rate could be controlled by adjusting the starch and CaCl2 concentration. Increased in starch and alginate content, create a greater intermolecular interaction between sodium alginate and starch that lead to a significant reduction in the biodegradation process.

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Published

2020-01-19

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Section

Articles