Process optimization and stability of d-limonene-in-water nanoemulsions prepared by ultrasonic emulsification using response surface methodology
Journal
Ultrasonics Sonochemistry
Journal Volume
19
Journal Issue
1
Pages
192-197
Date Issued
2012
Author(s)
Li P.-H.
Abstract
d-limonene in water nanoemulsion was prepared by ultrasonic emulsification using mixed surfactants of sorbitane trioleate and polyoxyethylene (20) oleyl ether. Investigation using response surface methodology revealed that 10% d-limonene nanoemulsions formed at S0 ratio (d-limonene concentration to mixed surfactant concentration) 0.6-0.7 and applied power 18 W for 120 s had droplet size below 100 nm. The zeta potential of the nanoemulsion was approximately -20 mV at original pH 6.4, closed to zero around pH 4.0, and around -30 mV at pH 12.0. The main destabilization mechanism of the systems is Ostwald ripening. The ripening rate at 25 ¢XC (0.39 m3 s -1 ¡Ñ 1029) was lower than that at 4 ¢XC (1.44 m3 s-1 ¡Ñ 1029), which was in agreement with the Lifshitz-Slezov-Wagner (LSW) theory. Despite of Ostwald ripening, the droplet size of d-limonene nanoemulsion remained stable after 8 weeks of storage. ? 2011 Elsevier B.V. All rights reserved.
Subjects
d-limonene
Nanoemulsions
Ostwald ripening
Response surface methodology
Ultrasonic emulsification
SDGs
Type
journal article