Physico-chemical properties of carbohydrate polymer coatings for slow release urea industry

Abstract

It has been estimated that 20-70% of the used urea escapes to the environment which not only harms the environment but also reduces the urea efficiency. The urea performance can be enhanced by applying the coatings and controlling the nutrients release. For this purpose, different organic and inorganic materials are being used in urea coating industry. Most of them are either expensive or unfriendly to the environment and remind us to work on their alternatives. Being cheap and eco-friendly materials, the modified starches may also be used as a potential coating material for slow release urea. Therefore, in this study, cassava starch was reacted and modified with urea and di-sodium tetraborate. The resulting starchy solution was used to coat the urea granules of 3.45 mm size. The FTIR spectroscopy was used to study the reaction mechanism. The coated and uncoated urea was further characterized for surface morphology, coating hardness and dissolution rate. The SEM images revealed that the surface of the coated urea was denser and smoother as compared with the uncoated urea. The coated surfaces were also found uniform, hard, compact and water resistant. The overall nutrients release time of the coated urea was 3 times higher when compared with uncoated urea. It was concluded that the surface hardness of coated urea strongly depends on the coating composition and thickness.