Urea release rate from a scoop of coated pure urea beads: Unified extreme analysis

Urea release from a scoop of coated beads in a given volume of a well stirred liquid has been investigated analytically and experimentally. A method for determining the fractional cumulative release and fractional release rate curves for the scoop without knowing particle number and radii is presented. The representative D/Kb for a scoop of urea beads spray coated with ethyl cellulose is near 3.5 × 10−8 cm2/s, and that with cellulose acetate phthalate is near 7 × 10−8 cm2/s.