Design of Suspension of Zinc Oxide for Fortification of Fertilizers

Funding Agency Details

Coromandel International Limited

Department

Chemistry & Chemical Engineering

Description

ZnO particles of sizes varying from microns to nanometers were synthesized. Stability of the suspension of ZnO was analyzed and optimized. Flowability characteristics of ZnO suspensions were studied. Toxicity assessment of Zinc Oxide was performed.

Problem Statement

1. Develop the technology for producing suspensions of zinc oxide suitable for fortification of fertilizers, with particle size in the range of micron to nano.
2. Obtain the toxicological data for soil suspension of the same zinc oxide particles

Outcome of the Research

1. Humic Acid: Better stability of zinc oxide nanoparticles was observed with humic acid as the dispersant compared to starch.
2. BSA as an Additive: Addition of BSA enhanced the stability of ZnO dispersion by restricting the size of the agglomerates. Best stability results were obtained with BSA, but BSA being costly, this method is not cost-effective for adoption in manufacturing.
3. PAA: Addition of PAA to the dispersion decreased dispersion stability to a certain extent; however, it helped to improve the flowability of the slurry, which is important for the spraying of the slurry in field application.
4. Sonication: From all the above experiments conducted, it can safely be concluded that the best and most cost-effective method for high-volume manufacturing applications for stability of Sigma Aldrich ZnO aqueous solution is sonication. Multiple probe-type sonicators can be used at various locations inside the storage vessel and operated in pulse mode to improve the dispersion stability. Sonication must be performed in-situ just before spraying the suspension onto fertilizer granules in order to obtain maximum stability, and hence, uniform coating.

It was recommended that this process be implemented on a pilot scale for validation prior to implementation in volume production.