Physical characterization of chitosan/gelatin-alginate composite beads for controlled release of urea

Indumathi Sathisaran; Murugesan Balasubramanian

doi:10.1016/j.heliyon.2020.e05495

Physical characterization of chitosan/gelatin-alginate composite beads for controlled release of urea

Heliyon. 2020 Nov 14;6(11):e05495. doi: 10.1016/j.heliyon.2020.e05495. eCollection 2020 Nov.

Authors

Indumathi Sathisaran^{1

2}, Murugesan Balasubramanian²

Affiliations

¹ Department of Biological Engineering, Indian Institute of Technology, Gandhinagar, Palaj, Gujarat 382355, India.
² Department of Biotechnology, K. S. Rangasamy College of Technology, Tiruchengode 637215, Tamil Nadu, India.

Abstract

Polymer-based controlled-release formulations are gaining significant advantage over chemical fertilizers in recent years as they contribute to the preservation of soil fertility by reducing soil pollution in farm lands. In this work, urea (a nitrogen source fertilizer) has been entrapped within chitosan-alginate and gelatin-alginate composite beads at three different concentrations. The physical properties of the polymer composite beads namely the diameter, porosity, yield percentage, Carr's index and Hausner's ratio were determined. These fertilizer-loaded beads were also characterized by Scanning Electron Microscopy (SEM) and Fourier Transform-Infra Red (FT-IR) spectroscopy. Urea enhanced swelling of chitosan-alginate beads through the creation of pores whereas in the case of gelatin-alginate formulations, urea decreased the swelling. The swelling of the polymer composite beads was found to be maximum at pH of 5.6 when compared to that of pH conditions, 7 and 8.5. The chitosan-alginate composite beads were found to possess better fertilizer entrapping efficiency than the gelatin-alginate composite beads. The in vitro urea release studies demonstrated that the urea-entrapped gelatin-alginate beads exhibited slower urea release than that of the chitosan-alginate beads. These controlled release urea formulations were found to follow quasi-fickian diffusion mechanism.

Keywords: Agroecosystem; Alginate; Bioaccumulation; Chitosan; Controlled release; Gelatin; Physical properties; Plant growth; Quasi-fickian diffusion; Soil biology; Soil chemistry; Soil fertility; Soil health; Swelling; Urea.