Improved film evaporator for mechanistic understanding of microwave-induced separation process

Abstract

Microwave-induced film evaporation separation process has been reported recently to separate the polar/nonpolar mixture. However, the efficiency of the separation is still too low for practical applications, which requires further enhancement via different strategies such as optimization design of evaporator structure. In addition the depth understanding of the separation mechanisms is great importance for better utilization of the microwave-induced separation process. To carry out these investigations, a novel microwave-induced falling film evaporation instrument was developed in this paper. The improvement of the enhancement effect of microwave-induced separation was observed based on the improved film evaporator. The systematic experiments on microwave-induced separation with different binary azeotropic mixtures (ethanol-ethyl acetate system and dimethyl carbonate (DMC)-H₂O system) were conducted based on the new evaporator. For the ethanol-ethyl acetate system, microwave irradiation shifted the direction of evaporation separation at higher ethanol content in the starting liquid mixture. Moreover, for DMC-H₂O system microwave-induced separation process broke through the limitations of the traditional distillation process. The results clearly demonstrated the microwave-induced evaporation separation process could be commendably applied to the separation of binary azeotrope with different dielectric properties. Effects of operating parameters are also investigated to trigger further mechanism understanding on the microwave-induced separation process.

Key words： process intensification; microwave; falling film evaporation; separation; azeotrope

Acknowledgments

The authors are grateful for financial support from the National Natural Science Foundation of China (Grant No. 21878219), the National Key Research and Development Program of China (Grant No. 2018YFB0604903), and X. Gao thanks the China Scholarship Council (CSC, No. 201706255020) for his academic visiting fellowship in the UK.NunknownN

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