Formulation of oil-in-water emulsions for pesticide applications: impact of surfactant type and concentration on physical stability

• Published in: Environmental science and pollution research international Vol. 25; no. 22; pp. 21742 - 21751
• Main Authors: Feng, Jianguo, Chen, Qicheng, Wu, Xuemin, Jafari, Seid Mahdi, McClements, David Julian
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-08-2018; Springer Nature B.V
• Subjects: Agricultural industry; Agrochemicals; Aquatic Pollution; Aromatic hydrocarbons; Atmospheric Protection/Air Quality Control/Air Pollution; Castor oil; Castor Oil - analogs & derivatives; Castor Oil - chemistry; Cyhalothrin; Deionization; Earth and Environmental Science; Ecotoxicology; Emulsification; Emulsions; Emulsions - chemistry; Environment; Environmental Chemistry; Environmental Health; Environmental science; Insecticides; Light scattering; Nitriles - chemistry; Pesticide application; Pesticides; Pesticides - chemistry; Polyoxyethylene; Pyrethrins - chemistry; Research Article; Stability; Surface-Active Agents - chemistry; Surfactants; System effectiveness; Waste Water Technology; Water - chemistry; Water Management; Water Pollution Control; HLB value; Surfactant; Pesticide emulsions; Physical stability
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-018-2183-z

Oil-in-water (O/W) emulsions can be utilized as effective pesticide delivery systems in the agricultural industry. In this study, the effects of hydrophile-lipophile balance (HLB), concentration, and location of surfactants on the formation and physical stability of O/W emulsions suitable for pesticide applications was investigated using dynamic light scattering and vertical laser profiling. A non-polar pesticide (lambda-cyhalothrin) was used as a model. The pesticide emulsion with the highest stability was obtained using a commercial non-ionic surfactant (polyoxyethylene castor oil ether, EL-20) with a required HLB value of 10.5. Emulsion stability increased as the surfactant concentration was increased from 2 to 6%, which was attributed to the formation of smaller oil droplets during emulsification. Emulsions prepared with the surfactant initially in the oil phase were more stable than those prepared with it initially in the aqueous phase. The optimum formulation of the pesticide emulsion was determined as follows: 5% lambda-cyhalothrin (active ingredient) and 6% EL-20 (surfactant) dissolved in 5% S-200 (aromatic hydrocarbon, as oil phase), then deionized water up to 100%, which met the quality indicators set by the FAO standards. The present study is expected to provide useful information to improve the stability of pesticide emulsions for commercial applications.