Preparation and characterization of potassium nitrate controlled‐release fertilizers based on chitosan and xanthan layered tablets

Abstract

Solid polymeric matrices based on xanthan and chitosan and using KNO 3 as a model agrochemical were prepared by direct compression, with a view to evaluating their potential as controlled-release fertilizers (CRFs). The swelling behavior, surface characteristics, and durability in soil of the tablets were studied. The release data were treated with a power law model in order to understand the delivery kinetics of KNO 3 . This proved to be non-Fickian diffusion, with release exponents ranging from 0.80 to 0.88, highlighting the importance of polymer relaxation on drug release. The presence of drug-free surface layers was an important factor in modulating the release. When comparing experiments without and with stirring, the release time ratios between them were as high as 40, predicting a significantly greater release time in soils. In durability experiments in soil, the polymeric matrices lasted longer than 6 weeks. These results show that layered xanthan and xanthan-chitosan matrices perform as a promising system for developing CRFs.

Polymers and its applications in agriculture

“…Controlled-release fertilizer (CRF) has known factors that influence the rate and pattern of release, hence they can be controlled [10,12,13] . The pattern of release in water of slow-and controlled-release materials have been reported [12,[14][15][16] . The concept controlled nutrient release is not a recent innovation.…”

Separation and Speciation of Iron Ions by Using Colorimetric Hydrogels

“…Hydrogels have become more commonly used due to their swelling ability in aqueous media, responsiveness to environmental effects, and biocompatible and biodegradable nature. Hydrogels are the most intensively studied polymeric materials in the literature due to their applications such as drug delivery systems, antimicrobial materials, sensor, pharmacology, matrix materials for tissue engineering, catalyst support material, agriculture, separations and speciation, immobilization, and environmental technologies (34,(36)(37)(38)(39). Anionic hydrogels may be used for absorption and separation of metal ions.…”

“…This method includes addition of a metal ion selective molecule into the hydrogel structure during synthesis. Hydrogels, which are prepared by the method of molecular imprint, are disposable (39,43,44).…”

Synthesis Optimization and Characterization of Microencapsulated N-P-K Slow-Release Fertilizers

“…Slow/controlled release fertilizers have been based on urea-aldehyde resins, polyvinylidene chloride [14][15][16], hydrogel nanocomposites [17,18], kaolin-chitosan systems [19,20], polysulfones [21,22], polyamides [23], polyesters [24], polyvinyl alcohol [25], polyurethanes [26,27], and other hybrid systems [28]. Current trends focus on biopolymers [29].…”