Silica-coated calcium pectinate formulations for controlling carbendazim release: water and soil release studies

Abstract

This study aims to encapsulate the fungicide carbendazim using a biodegradable polymer (pectin). First, we have obtained calcium pectinate beads (CPG-Carb) by ionotropic gelation using calcium ions as a crosslinking agent. These beads were then coated with silica starting from tetraethoxysilane (TEOS), by a sol-gel process to form hybrid beads (CPG-Carb-SG). The morphology, composition and structure of both beads were characterized and the controlled release assays of the fungicide were studied in both water and soil columns. The encapsulation efficiency for CPG-Carb was slightly higher (75%) compared to CPG-Carb-SG (67%) due to carbendazim loss during the impregnation and condensation steps. The release rate in water and soil columns was about 4 times lower for CPG-Carb-SG than CPG-Carb demonstrating the efficiency of the silica coating to delay the release of carbendazim. Moreover, the release of CPG-Carb-SG is due to the erosion of the silica layer during the first two weeks. After this period, the silica layer was degraded, and the release is then controlled by the swelling of the organic part of the bead as observed for CPG-Carb. Finally, the biodegradability of the pectin, and the release profile make such systems promising candidates for sustained and economical pesticide delivery systems.

Keywords:

• Pectin
• silica coating
• controlled release
• pesticides

Acknowledgements

We acknowledge the DIVVA platform (AgroSup Dijon, Université Bourgogne Franche Comté) for the various physico-chemical characterizations performed in this work. We also acknowledge Marie-Laure Léonard and Jean-Marc Dachicourt (ESIREM, UBFC) for their valuable technical support on TGA and SEM experiments.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.