Evaluation of critical parameters for preparation of stable clove oil nanoemulsion

In this work, the effects of various factors, including the ultrasonic duty cycle and intensity of ultrasonic irradiation, ultrasonication and clove oil content in production of clove oil nanoemulsion were investigated. In preparation of nanoemulsion Tween (R) 80/Span (R) 80 as nonionic surfactants via ultrasonic emulsification method was used. The average droplets size of clove oil nanoemulsion decreased with an increase in duty cycle; whereas pulsed ultrasound with proper intervals was more efficient than continuous ultrasonication. In order to replace the use of organic solvent and increase the dispersity of active ingredient, suitable emulsifiers were used. The nanopesticides made by ultrasound at optimum formula conditions were defined at ultrasonication time of 300 s, surfactants concentration of 5 wt%, hydrophilic-lipophilic balance number of 9, duty cycle 0.75% and ultrasonic intensity 208 W/cm(2). The stability of droplets size of nanoemulsions for duration of 6 months was evaluated. Stable nanoemulsion clove oil with 10 wt% of clove oil content was formulated at optimum conditions with average droplets size around 43 nm at the beginning and after 6 months nanoemulsions re-sized and it was around 100 nm. A stable nanoemulsion of clove oil in water with suitable droplets size as a nanopesticide was prepared. (C) 2015 The Authors. Published by Elsevier B.V. on behalf of King Saud University.