Cellulose Acetate Microbeads for Controlled Delivery of Essential Micronutrients

Abstract

The controlled delivery of micronutrients to soil and plants is essential to increase agricultural yields. However, this is today achieved using fossil fuel-derived plastic carriers, posing environmental risks and contributing to global carbon emissions. In this work, a novel and efficient way to prepare biodegradable zinc-impregnated cellulose acetate beads for use as controlled release fertilizers is presented. Cellulose acetate solutions in DMSO were dropped into aqueous antisolvent solutions of different zinc salts. The droplets underwent phase inversion, forming solid cellulose acetate beads containing zinc, as a function of zinc salt type and concentration. Even higher values of zinc uptake (up to 15.5%) were obtained when zinc acetate was added to the cellulose acetate–DMSO solution, prior to dropping in aqueous zinc salt antisolvent solutions. The release profile in water of the beads prepared using the different solvents was linked to the properties of the counter-ions via the Hofmeister series. Studies in soil showed the potential for longer release times, up to 130 days for zinc sulfate beads. These results, together with the efficient bead production method, demonstrate the potential of zinc-impregnated cellulose acetate beads to replace the plastic-based controlled delivery products used today, contributing to the reduction of carbon emissions and potential environmental impacts due to the uptake of plastic in plants and animals.

Green fabrication of PHBV microbeads using a dimethyl isosorbide solvent for skin exfoliators

“…The process of preparing PHBV microbeads is green and facile, while the fabrication of other biodegradable microbeads such as chito-beads through reacetylation of chitosan to chitin in an inverse emulsion is somewhat cumbersome. 30 Cellulose microbeads 13,31 could also be prepared using the solvent-exchange method, but the solvents used to dissolve cellulose are dimethyl sulfoxide or ionic liquids which are not completely green. Therefore, the procedure using a green solvent to readily and rapidly manufacture PHBV microbeads is promising.…”

“…However, the smooth, dense shell reduces the diffusion rate of the solvent from inside the droplet. 31 As the benign solvent inside the droplet continues to diffuse into the water, the droplet progressively solidifies, creating internal pores and resulting in a hollow core structure. Thus, the surface of the spherical PHBV microbeads was smooth, while the interior was porous with a hollow core.…”

Harnessing Agri-Food Waste as a Source of Biopolymers for Agriculture

“…Cellulose and its derivatives possess numerous applications in agriculture, as they have been employed for the controlled release of fertilizers [81] and essential micronutrients [82]. Another use of cellulose is as a fruit coating agent for ripening delay [83] or as a hydrogel for drought management [84,85].…”