engleski

Comparison of batch and microreactor emulsification process – two phase system oil - water

Up to this day emulsions that include two or more liquid phases are found in almost all kinds of industries ranging from food to environmental. Most common emulsification processes are carried out in classical batch reactors with capabilities of mixing two or more phases at high stirring rates. Besides batch reactors, over the last 20 years, microreactor technology has provided excellent results in fields of chemical and pharmaceutical industry, biotechnology, medicine and also food industry. This research is therefore focused on comparison of the batch and microreactor emulsification process of the two phase oil-water system. Experiments were conducted using two emulsifiers –Tween 20 and polyethylene glycol 2000 (PEG 2000) in a two phase system comprising of 30 % oil and 70 % water (v/v). For batch experiments, IKA RW20 overhead stirrer, equipped with 5 cm diameter emulsifying disc stirrer, was used at 2 rotational speeds: 1000 min-1 and 1400 min-1, with a total mixing time of 7 minutes. For microreactor experiments, Micronit teardrop micromixer microreactor was used with microchannel width of 240 μm, height of 150 μm and length of 53.3 mm), at 5 different combinations of oil and water flows: i) 30 µL min-1 oil and 90 µL min-1 water ; ii) 40 µL min-1 oil and 100 µL min-1 water ; iii) 50 µL min-1 oil and 110 µL min-1 water ; iv) 70 µL min-1 oil and 130 µL min-1 water and v) 90 µL min-1 oil and 150 µL min-1 water. After emulsification, formed emulsions were photographed under a microscope at magnification 4x (BTC Type LCD-35, Bresser, Germany), and the micrographs were analyzed using the ImageJ software v.1.8.0 (NIH, Maryland, USA), with the results expressed as Feret diameter (minimal, maximal and average). Based on the obtained results, batch experiments resulted in emulsions with lower minimal Feret diameter, but with much larger differences in minimal and maximal droplet sizes and larger span of droplet sizes. In microreactor experiments, the obtained average droplet size was larger compared to the batch experiments, but the differences between minimal and maximal droplet sizes were lower. This leads to a conclusion that, when uniform particle size of the emulsions is a priority, regardless of the required size, microreactor emulsification shows better results. However, if smaller droplet diameter emulsions are required, but with low uniformity, the batch process is more adequate.

emulsification ; batch ; microreactor ; oli-water system

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