Slow-release fertilizers (SRFs) are of paramount importance in order to address the low nutrient use efficiency of conventional fertilizers. The unique properties of electrospun nanofibers facilitate reduced ‘burst release’ which is commonly encountered in many SRFs. In an initial effort towards the development of such a fertilizer with improved slow-release properties, electrospinning of a uniaxial 8.5 % w/v cellulose acetate nanofiber mat loaded with hydroxyapatite nanoparticles (HANPs), urea, and muriate of potash (MOP) as sources of phosphorus, nitrogen, and potassium was undertaken at 10% loading each. The solvent system employed was acetone to dimethylformamide in a 2:1 volume ratio. Fourier transform infrared spectroscopy (FTIR) analysis confirmed the successful loading of urea onto the nanofiber mat with characteristic peaks at 3482 cm^-1, 3363 cm^-1 1667 cm^-1, 1617 cm^-1, and 1444 cm^-1 that corresponded to N-H asymmetric and symmetric stretching, C=O stretching, N-H bending and N-C-N stretching respectively. Powder X-ray diffraction (PXRD) peaks indexed to hkl values of (002), (210), and (211) depicted the successful loading of HANPs onto the nanofiber mat. Furthermore, Raman analysis confirmed the successful loading of both urea and HANPs with the presence of N-C-N stretching peak and symmetric stretching peak of the phosphate respectively. In addition, EDX analysis confirmed the presence of MOP in the electrospun nanofiber mat. The scanning electron microscopy (SEM) images depicted smooth-surfaced nanofibers with and without aggregates for the nutrient-loaded nanofiber mat and neat nanofiber mat respectively. Also, a reduced nanofiber diameter was observed upon nutrient loading with respect to the neat nanofiber mat. Initial release studies in water at neutral pH have shown biphasic release curves for both HANPs and MOP, with only a burst release profile for urea thus showcasing its potential slow-release properties that could be harnessed with more modifications to the electrospun nanofiber mat.

Manesha Fernando

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