Studies on the formation of bifenthrin oil-in-water nano-emulsions prepared with mixed surfactants

The formation of oil-in-water (O/W) nano-emulsions suitable for pesticidal application has been studied in water/mixture of non-ionic surfactant (C12E3) and anion surfactant (MAPK)/oil (bifenthrin dissolved in dimethylbenzene) systems. The nano-emulsions with constant oil concentration were prepared by using high-energy emulsification methods. Effects of surfactant ratio and total surfactant concentration on the mean droplet size and size distribution of the emulsions were measured by dynamic light scattering. The stability of nano-emulsions prepared with different surfactant ratios of MAPK and C12E3 was tested by two methods: by measuring the change in droplet size as a function of time using dynamic light scattering and by multiple light scattering. The results showed the data acquired by the short-term scan using multiple light scattering technique corresponded with the droplet size variations measured by dynamic light scattering. The optimum concentration and mixing ratio of the two surfactants for the bifenthrin oil-in-water nano-emulsion was 10 wt% and 6:4 (MAPK to C12E3) and the quality indicators of this nano-emulsion were up to standard according to FAO standards.

Effects of surfactant ratio on droplet size and poly-dispersity index of nano-emulsions and Turbiscan LAb spectra showing delta backscattering (%) as a function of sample height (0–42 mm) and time (from 0:04 to 2:00 d) for nano-emulsions prepared with different mixing ratios of MAPK and C12E3.Figure optionsDownload as PowerPoint slideHighlights
► Oil-in-water nano-emulsions suitable for pesticidal application were prepared using anion–nonionic mixed surfactants.
► Figure out the relationship between the mixing ratio, total surfactant concentration and the stability of nano-emulsions.
► Droplet size variations of emulsions prepared with different mixing ratios of MAPK and C12E3 were tested by two methods.
► Data acquired by the multiple light scattering technique accorded with the result measured by dynamic light scattering.
► Multiple light scattering technique could be used for quickly estimating the droplet size variations of nano-emulsions.