Alginate-chitosan hydrogel as controlled release of NPK macronutrient

Alginate-chitosan hydrogel as controlled release of Nitrogen, Phosphorus, and Potassium (NPK) macronutrient has been studied. Variations of alginate and chitosan mass, N; P and K concentration, pH solution, swelling ratio and mass ratio of alginate and chitosan were optimized. Hydrogel was prepared by mixing alginate, chitosan and CaCl<inf>2</inf> as a cross linker in the water media. Hydrogel product was characterized by Fourier Transform Infrared (FTIR). N; P; and K release were measured by UV-Vis spectrophotometer and Atomic Absorption Spectrophotometer (AAS). The result showed that addition of chitosan in the hydrogel caused a decrease of swelling ratio hydrogel and a decrease of N; P and K release. The release of N; P and K was affected by N; P and K concentration and pH solution. The higher N; P and K concentrations and lower pH solution caused an increase of release rate of N; P and K. The mechanism of N; P and K release from the alginate-chitosan hydrogel followed the Korsmeyer-Peppas model. The ratio of alginate and chitosan in the hydrogel also affected to the the release rate of N; P and K.