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

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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.

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  1. 1.

    Stefanidis G D, Muñoz A N, Sturm G S J, Stankiewicz A. A helicopter view of microwave application to chemical processes: Reactions, separations, and equipment concepts. Reviews in Chemical Engineering, 2014, 30(3): 233–259

  2. 2.

    Gao X, Li X, Zhang J, Sun J, Li H. Influence of a microwave irradiation field on vapor-liquid equilibrium. Chemical Engineering Science, 2013, 90: 213–220

  3. 3.

    Stankiewicz A I, Moulin J A. Process intensification: Transforming chemical engineering. Chemical Engineering Progress, 2000, 96(1): 22–34

  4. 4.

    Perreux L, Loupy A. A tentative rationalization of microwave effects in organic synthesis according to the reaction medium, and mechanistic considerations. Tetrahedron, 2001, 57(45): 9199–9223

  5. 5.

    Komorowska-Durka M, van Houten R, Stefanidis G D. Application of microwave heating to pervaporation: A case study for separation of ethanol-water mixtures. Chemical Engineering and Processing: Process Intensification, 2014, 81: 35–10

  6. 6.

    Kappe C O. Controlled microwave heating in modern organic synthesis. Angewandte Chemie International Edition, 2004, 43(46): 6250–6284

  7. 7.

    Wang W, Liu Z, Sun J, Ma Q, Zhang Y. Experimental study on the heating effects of microwave discharge caused by metals. AIChE Journal. American Institute of Chemical Engineers, 2012, 58(12): 3852–3857

  8. 8.

    Chen F, Du X, Zu Y, Yang L, Wang F. Microwave-assisted method for distillation and dual extraction in obtaining essential oil, proanthocyanidins and polysaccharides by one-pot process from Cinnamomi Cortex. Separation and Purification Technology, 2016, 164: 1–11

  9. 9.

    Constant T, Moyne C, Perré P. Drying with internal heat generation: Theoretical aspects and application to microwave heating. AIChE Journal. American Institute of Chemical Engineers, 1996, 42(2): 359–368

  10. 10.

    Wang W, Chen G. Freeze drying with dielectric-material-assisted microwave heating. AIChE Journal. American Institute of Chemical Engineers, 2007, 53(12): 3077–3088

  11. 11.

    Appleton T J, Colder R I, Kingman S W, Lowndes I S, Read A G. Microwave technology for energy-efficient processing of waste. Applied Energy, 2005, 81(1): 85–113

  12. 12.

    Lupinska A. IR technique for studies of microwave assisted drying. Drying Technology, 2007, 25(4): 569–574

  13. 13.

    Salomatov A V, Salomatov V V. Thermal regime of slotted channel with moving incompressible liquid under microwave conditions. Journal of Engineering Thermophysics, 2017, 26(3): 359–365

  14. 14.

    Man A, Shahidan R. Microwave-assisted chemical reactions. Journal of Macromolecular Science, Part A. Pure and Applied Chemistry, 2007, 44(6): 651–657

  15. 15.

    Chandrasekaran S, Ramanathan S, Basak T. Microwave material processing—A review. AIChE Journal. American Institute of Chemical Engineers, 2012, 58(2): 330–363

  16. 16.

    Thostenson E T, Chou T W. Microwave processing: Fundamentals and applications. Composites Part A. Applied Science and Manufacturing, 1999, 30(9): 1055–1071

  17. 17.

    Werth K, Lutze P, Kiss A A, Stankiewicz A I, Stefanidis G D, Górak A. A systematic investigation of microwave-assisted reactive distillation: Influence of microwaves on separation and reaction. Chemical Engineering and Processing: Process Intensification, 2015, 93: 87–97

  18. 18.

    Li H, Cui J, Liu J, Li X, Gao X. Mechanism of the effects of microwave irradiation on the relative volatility of binary mixtures. AIChE Journal. American Institute of Chemical Engineers, 2017, 63 (4): 1328–1337

  19. 19.

    Gao X, Liu X, Li X, Zhang J, Yang Y, Li H. Continuous microwave-assisted reactive distillation column: Pilot-scale experiments and model validation. Chemical Engineering Science, 2018, 31(186): 251–264

  20. 20.

    Li H, Liu J, Li X, Gao X. Microwave-induced polar/nonpolar mixture separation performance in a film evaporation process. AIChE Journal. American Institute of Chemical Engineers, 2019, 65 (2): 745–754

  21. 21.

    Link G, Ramopoulos V. Simple analytical approach for industrial microwave applicator design. Chemical Engineering and Processing: Process Intensification, 2018, 125: 334–342

  22. 22.

    Estel L, Poux M, Benamara N, Polaert I. Continuous flow-microwave reactor: Where are we? Chemical Engineering and Processing: Process Intensification, 2017, 113: 56–64

  23. 23.

    Gabriel C, Gabriel S, Grant E H, Halstead B, Mingos D. Dielectric parameters relevant to microwave dielectric heating. Chemical Society Reviews, 1998, 27(3): 213–224

  24. 24.

    Ogunniran O, Binner E R, Sklavounos A H, Robinson J P. Enhancing evaporative mass transfer and steam stripping using microwave heating. Chemical Engineering Science, 2017, 165: 147–153

  25. 25.

    Niu X F, Du K, Xiao F. Experimental study on ammonia-water falling film absorption in external magnetic fields. International Journal of Refrigeration, 2010, 33(4): 686–694

  26. 26.

    Ortega J, Pena J A, De Anonso C. Isobaric vapor-liquid equilibria of ethyl acetate + ethanol mixtures at 760 ± 0.5 mmHg. Journal of Chemical & Engineering Data, 1986, 31(3): 339–342

  27. 27.

    Chen M, Han G, Guo P, Xiao Z. Solute diffusion flux under microwave enhancement. Journal of Engineering Thermophysics, 2008, 29(11): 1950–1952

  28. 28.

    Won W, Feng X, Lawless D. Separation of dimethyl carbonate/methanol/water mixtures by pervaporation using crosslinked chitosan membranes. Separation and Purification Technology, 2003, 31(2): 129–140

  29. 29.

    Camy S, Pic J S, Badens E, Condoret J S. Fluid phase equilibria of the reacting mixture in the dimethyl carbonate synthesis from supercritical CO2. Journal of Supercritical Fluids, 2003, 25(1): 19–32

  30. 30.

    Horsley L H. Azeotropic Data-III. Advances in Chemistry, 1973, (116): 1–628

  31. 31.

    Walrafen G E. Raman spectral studies of water structure. Journal of Chemical Physics, 1964, 40(11): 3249–3256

  32. 32.

    Kryachko E S. Ab initio studies of the conformations of water hexamer: Modelling the penta-coordinated hydrogen-bonded pattern in liquid water. Chemical Physics Letters, 1999, 314(3–4): 353–363

  33. 33.

    Roy S, Humoud M S, Intrchom W, Mitra S. Microwave-induced desalination via direct contact membrane distillation. ACS Sustainable Chemistry & Engineering, 2017, 6(1): 626–632

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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.

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Correspondence to Hong Li.

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Gao, X., Shu, D., Li, X. et al. Improved film evaporator for mechanistic understanding of microwave-induced separation process. Front. Chem. Sci. Eng. 13, 759–771 (2019). https://doi.org/10.1007/s11705-019-1816-1

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  • process intensification
  • microwave
  • falling film evaporation
  • separation
  • azeotrope