Formulation of a natural biocide based on lavandin essential oil by emulsification using modified starches

The formulation of lavandin essential oil as an emulsion for agrochemical applications has been studied. Four different biodegradable and non-toxic n-octenyl succinic anhydride (OSA)-modified starches have been tested as surfactants for this purpose. The results obtained with these surfactants have been compared with emulsions prepared with synthetic non-ionic surfactants (span20 and tween20). Furthermore the adsorption equilibrium of the OSA-modified starches on lavandin oil droplets has been studied because is of crucial importance for the formation and stabilization of emulsions. Results demonstrate that stable emulsions could be prepared with all types of OSA-modified starches tested in this work. Obtained oil droplet sizes were in the range 0.5–1.4 μm, and approximately 80% of the oil remained stabilized in the emulsion after 50 days of storage at 5 °C. The starch surface loads were very high, in some cases of up to 370 mg/m2, which correspond to a very thick adsorbed multilayer. It has been shown that for this application OSA-modified starches present similar surfactant capabilities as synthetic non-ionic surfactants. The results of this study show that OSA-modified starches can be used as effective surfactant agents for the formulation of natural biocides.

A formulation of lavandin essential oil as an O/W emulsion for application as natural biocide in agriculture has been developed. Biodegradable OSA-modified starches have been used as surfactants. The emulsions have been characterized and compared to emulsions obtained using commercial non-ionic surfactants.Figure optionsDownload as PowerPoint slide