Synthesis, Characterization, and Controlled Release Property Evaluation of Carboxymethyl Cellulose/Alginate (CMC/Alg) Encapsulated NPK Fertilizers

Abstract

This work described the successful preparation of encapsulated nitrogen-phosphorus-potassium (NPK) fertilizers with the use of carboxymethyl cellulose/alginate (CMC/Alg) blend employing citric acid (CA) as the crosslinking agent. The study involved the preparation, characterization, release studies, and efficacy evaluation of the said fertilizer system. Fourier transform infrared (FTIR) and fluorescence spectroscopic methods, scanning electron microscopy (SEM), particle size analysis, and zeta potential measurements showed the successful formation of spherical particles with varying sizes (ranging from 733–1200 nm) via crosslinking. Release profiles of the CMC/Alg NPK conformed to the standards of controlled-release fertilizer with a maximum release rate of 50% for CMC/Alg NPK in 30 d. Investigation of the release mechanism using the Korsmeyer-Peppas mathematical model showed that the release of nutrients is governed by both coating material relaxation and diffusion processes. Controlled release behavior was demonstrated as confirmed in the efficacy evaluation of the prepared fertilizer in a 2-mo pot experiment using mung bean.