title: Evaluation of a novel rotor-stator design for emulsification and the impact on chemical reactions
Creators: name: Harvey, Daniel
Publisher: name: University of Liverpool Repository
Year: 2014

description: The work described in this thesis aims to present results regarding the exploration, validation and use of a novel rotor-stator type mixing equipment employing controlled deformation dynamic mixing (CDDM) technology in creating sub-micron emulsions for use in chemical reactions. Emulsification is the process by which one immiscible liquid (e.g. oil) is finely dispersed throughout another immiscible liquid (e.g. water) and stabilised, commonly through the addition of a surface active agent or emulsifier to the system. Specific focus was given to the emulsification of plant oils (such as sunflower seed oil) as a way of improving their available reactive surface area. The addition of emulsifiers in this case was used to sufficiently reduce the interfacial tensions, allowing for greater droplet break-up, and provide adequate emulsion stability. Further testing of these emulsions was performed within biphasic saponification and transesterification reactions, such as those commonly employed in the production of soap and biodiesel. It was hypothesised that by reducing the dispersed oil phase droplet size in the presence of an emulsifier, and thus increasing the surface area to volume ratio, reaction rates could be manipulated. Testing of this hypothesis showed that despite the presence of surfactant and, in the case of the transesterification reaction, water, the use of sub-micron oil droplets caused a decrease in the overall reaction time (time spent at reaction temperature and under agitation). In support of this work, high-throughput formulation (HT) and design of experiment (DoE) software was adopted to allow a quick and efficient way of screening which emulsification parameters had the greatest impact on the size of the droplets when emulsifying oil. For this work a standard emulsion containing silicone oil and Sodium Lauryl Ether Sulfate (SLES) was used. Following the identification of the optimum emulsification parameter set, work focused on the scaling up from small scale (50g) to pilot plant scale mixing devices (10kg – 300kg/hour) in order to formulate large quantities of emulsion. It was shown that the HT screening and DoE was sufficiently robust to predict emulsification parameters at scale. For an emulsion system of silicone oil and SLES, the formulation parameters that created an emulsion with the smallest droplet size using the high-throughput platform, also produced an emulsion with the smallest droplet size using the new pilot plant scale Ultra Mixing and Processing Facility (UMPF) fitted with CDDM technology. In order to characterise the emulsions created, laser diffraction measurements were used throughout this work (Malvern Mastersizer X &amp; 2000) and “side by side” emulsification experiments were carried out using commercially available fluid processing units. Utilising either a rotor-stator type inline mixer (high shear Silverson 150/250MS mixer) or a high pressure valve type homogeniser (M-110S Microfluidizer Processor, Small Volume) the emulsions produced and processed on the respective equipment were compared with those produced via the CDDM in order to assess its capabilities and performance against two of the leading mixers available.