Dynamics of controlled release of chlorpyrifos from swelling and eroding biopolymeric microspheres of calcium alginate and starch

In the present study biopolymer microspheres of sodium alginate and starch were prepared by employing CaCl2 as a crosslinker. A series of such microspheres of different compositions were prepared by varying the amounts of sodium alginate, starch and CaCl2 in the feed mixture. The prepared microspheres were loaded with an insecticide, chlorpyrifos, and both the native (unloaded) and loaded microspheres were characterized by FTIR and SEM techniques to gain insights into the structural and morphological features of the beads. The swelling experiments were performed for different compositions of beads at varying pH and temperature of the release medium. The swelling and erosion controlled release of insecticide was investigated for 8 days taking bidistilled water as a release medium. The release experiments were carried out under the static and varying experimental conditions and the data obtained were fitted to Ficks equation to evaluate diffusion co-efficient of insecticide. The results were further analyzed by Ficks power law equation, and the possible mechanisms of the insecticide release were suggested. In order to demonstrate the possible applicability of the present release system to natural agricultural fields the soil-pot experiments were designed and release profiles were studied. (C) 2008 Elsevier Ltd. All rights reserved.