کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5144379 1496863 2018 53 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Ultrasound coupled with supercritical carbon dioxide for exfoliation of graphene: Simulation and experiment
ترجمه فارسی عنوان
سونوگرافی همراه با دی اکسید کربن فوق بحرانی برای لایه برداری گرافن: شبیه سازی و آزمایش
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی (عمومی)
چکیده انگلیسی
Ultrasound coupled with supercritical CO2 has become an important method for exfoliation of graphene, but behind which a peeling mechanism is unclear. In this work, CFD simulation and experiment were both investigated to elucidate the mechanism and the effects of the process parameters on the exfoliation yield. The experiments and the CFD simulation were conducted under pressure ranging from 8 MPa to 16 MPa, the ultrasonic power ranging from 12 W to 240 W and the frequency of 20 kHz. The numerical analysis of fluid flow patterns and pressure distributions revealed that the fluid shear stress and the periodical pressure fluctuation generated by ultrasound were primary factors in exfoliating graphene. The distribution of the fluid shear stress decided the effective exfoliation area, which, in turn, affected the yield. The effective area increased from 5.339 cm3 to 8.074 cm3 with increasing ultrasonic power from 12 W to 240 W, corresponding to the yield increasing from 5.2% to 21.5%. The pressure fluctuation would cause the expansion of the interlayers of graphite. The degree of the expansion increased with the increase of the operating pressure but decreased beyond 12 MPa. Thus, the maximum yield was obtained at 12 MPa. The cavitation might be generated by ultrasound in supercritical CO2. But it is too weak to exfoliate graphite into graphene. These results provide a strategy in optimizing and scaling up the ultrasound-assisted supercritical CO2 technique for producing graphene.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Ultrasonics Sonochemistry - Volume 41, March 2018, Pages 181-188
نویسندگان
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