Controlled release of the fungicide thiram from starch–alginate–clay based formulation

In order to modify the release of thiram, a dithiocarbamate fungicide, from starch–alginate beads and to minimize the agro-environmental pollution, kaolin and bentonite have been used as adsorbent in the bead formulations. Beads of different compositions were prepared by varying the amount of kaolin and bentonite and characterizing it by Fourier transform infrared spectroscopy (FTIR), scanning electron micrograph (SEM), energy dispersion analysis (EDAX), thermogravimetry and swelling studies. Formulation characteristics like entrapment efficiency, bead size, percentage equilibrium swelling of the beads and diffusion mechanism for thiram release have been evaluated. The incorporation of kaolin and bentonite in starch–alginate beads has controlled the release profile of thiram. The release from the bentonite-based formulations was slower than from the kaolin based formulations. The release proceeded as non-Fickian diffusion.