Controlled Release by Solvent Diffusion

Solution This solution is a routine application of Eq. 19.1-5 the only problem 

The large value of P results from a very large partition coefficient. 

Example 19.1-2 Bollworm pheromones You have been using 1.0-mm-diameter microcapsules filled with a saturated solution of the pheromone gossyplure, for the pink bollworm. When the capsules contain excess solid pheromone, they attract bollworm moths into insecticide-loaded traps for 27 days. 

You are considering trying to increase the catch by using the same mass of pheromone in an equal mass of 50- J,m microcapsules that have the same thin wall thickness (i.e., the same Pjl). How long will the smaller microcapsules last  

Solution Because the wall of the microcapsules is thin and all other properties are unchanged, the gossyplure flux per area out of the capsules is constant. However, the surface area per mass of the 50 pm capsules is larger. In particular, if the microcapsules have about the same density independent of their size, then 

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