| dc.description.abstract | Eucalyptus Globulus oil with high pest control property is a powerful material for green
pesticide. Eucalyptol (1,8-cineole) is known as the main active ingredient in E. Globulus
oil, have strong insect repellent properties. Nanoemulsion system is a best carrier system
to overcome several drawbacks of essential oil in biopesticide including low aqueous
solubility, susceptibility to volatilization, photodegradation and instability when storing
over a period of time. However, the stability of nanoemulsions is quite fluctuated over
time that can affect the pesticidal property of products. Therefore, this research was
conducted to investigate the stability of eucalyptus essential oil in nanoemulsion system
over time and the effect of some factors including storage temperature, the addition of
co-surfactant and the co-existence of E. Globulus oil and Neem oil on the stability of the
system. These findings suggested that 4oC is the best storage condition which can
minimize the effect of some main destabilization mechanism such as coalescence and
Ostwald ripening up to 60 days. The obtained results from the study of co-surfactant on
the stability of the system showed that 1.6% of sorbitan monooleate (Span 80) is an
appropriate concentration which makes the system stable during 60 days and retains
7601 mg/L Eucalyptol in the system after 90 days, higher than that in the system without
the addition of Span 80. Higher concentration of Span 80, at 2% and 2.7%, made the
system become broad in size distribution only after 15 days while phase separation was
observed at 4% of Span 80 after preparation. Regarding the co-existence of Neem oil
and E.Globulus oil, a complex interaction between them in nanoemulsion system was
observed. Oil was encapsulated at maximum level (18%) in the formulations consist of
20% of Neem oil. At higher percentage of Neem oil (50% and 62.5%), the oil loading
capacity of the system decrease to 14% and 12%, respectively. | en_US |
