Abstract
The present work reports the use of venturi-based hydrodynamic cavitation reactor for the preparation of stable submicron emulsions. Different types of cavitating devices such as circular venturi and slit venturi have been used in this study. Effect of different operating parameters such as inlet pressure and number of passes of the emulsion through the cavitating zone on the droplet size and the stability of emulsion has been investigated. Emulsion of coconut oil in water has been chosen as the model system. Two types of emulsifying agents, namely, Tween 80 and Span 80, were used for the preparation of the emulsions, and the effect of emulsifying agent volume fraction on the emulsion droplet size has been illustrated. Zetasizer has been used to measure the droplet size and distribution of internal phase of emulsion. It has been established that the inlet pressure affects the droplet size of emulsion favorably due to the enhanced cavitational intensity with increasing inlet pressures. Among the two types of venturi investigated in the work, slit venturi showed pronounced effect on droplet size reduction as compared to the circular venturi with the requirement of lower number of passes for the formation of stable emulsion. The present work has, for the first time, illustrated the enhanced effectiveness of hydrodynamic cavitation-based emulsification approach for the preparation of stable emulsions with controlled droplet size distribution illustrating the dependency on the type of the cavitating device.
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