Phase inversion temperature emulsification: from batch to continuous process

Abstract

Emulsion systems are encountered in many everyday products such as milk, agrochemicals or shampoo. This thesis presents an attempt to create an experimental set-up working in continuous flow to produce monodispersed food-grade oil nanoemulsions (< 0.1 µm in diameter) with a low-energy emulsification method. Preparation of O / W nano-emulsions with formulation Soya bean oil / Brij 97 / Water was performed using the phase inversion temperature (PIT) emulsification method with 2 different techniques.

The first technique was the emulsification in batch where the pre-emulsion was heated to its hydrophilic-lipophilic balance (HLB) temperature and then quickly cooled down to room temperature. The appearance of the resultant emulsions varied from unstable white to stable transparent. Cooling rate seemed to be a critical parameter to obtain transparent nanoemulsions. Reproducible results were difficult to obtain since a good temperature control was not achieved with the batch set-up.

Requirements for the conception of the second technique, e.g. the continuous emulsification rig, were deduced from the results of the batch experiments. The designed set-up continuously pumped the emulsion premix through a pipe immersed into a heating bath at the HLB temperature and then through a cooling micro-heat exchanger. In order to obtain small average size, narrow size distribution and transparency special attention needed to be paid to the heating treatment.

The nanoemulsions prepared with the PIT method showed a good stability over time. For instance, a fresh nanoemulsion made with 10 % (w / w) of soya bean oil in the continuous set-up displayed an average droplet size of 21 nm. A month and a half later, this average size had increased only 5 nm. The average size and polydispersity index of the emulsions obtained using both techniques were similar. The continuous device allowed the preparation of emulsions more rapidly and in a more reproducible way than the batch set-up.

Date of Award	1 Apr 2010
Original language	English
Awarding Institution	University of Bath
Supervisor	Tom Arnot (Supervisor) & Pawel Plucinski (Supervisor)