Coated NPK Fertilizer Based on Citric Acid-Crosslinked Chitosan/Alginate Encapsulant

Abstract

A coated nitrogen-phosphorus-potassium (NPK) fertilizer was prepared via crosslinking chitosan and alginate using citric acid. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), particle size analysis, and zeta potential measurement showed the successful crosslinking, appropriate size, and colloidal stability of the coated NPK fertilizer. The encapsulation capability of the crosslinked chitosan/alginate (Chi/Alg) was studied using fluorescence spectroscopy and NPK analysis. The release behavior studies under various pH conditions showed that Chi/Alg NPK conformed to the standards of controlled release fertilizer with a maximum release rate of 40% for 30 days. The investigation of the release mechanism using Korsemeyer-Peppas mathematical model showed that the release of nutrients is governed by both coating material relaxation and diffusion process.

Keywords

• controlled release
• npk fertilizer
• encapsulation
• crosslinking