超临界CO2微乳液中的超声空化与声流耦合特性及其对石墨烯片层剥离的影响规律

This project aims at the key problems of engineering thermophysics on the graphene preparation in supercritical CO2 microemulsion by ultrasonic processing. The most advanced PIV testing technology will be performed during the preparation process, and the ultrasonic cavitation and acoustic streaming coupling phenomena in supercritical CO2 microemulsion containing graphite particles will be observed and analyzed by high-resolution microscopy and high-speed CCD camera. We will demonstrate the rules how particle concentration, CO2/water ratio and fluid status parameters influence the ultrasonic cavitation & acoustic streaming coupling characteristics. The effects of hydrophobic/hydrophilic interaction on the coupling phenomena of the ultrasonic cavitation & acoustic streaming in supercritical CO2 microemulsion are to be examined. The coupling characteristics of the ultrasonic cavitation & acoustic streaming in supercritical CO2 microemulsion are to be clarified. Moreover we will focus on the phenomena such as interfacial adsorption, aggregation, molecular intercalation and the particle swelling in the different properties of supercritical CO2 microemulsion. The complex multi-phase interfacial behaviors induced by ultrasound and its influence on the different modes of exfoliation of graphite into graphene are to be identified. The collections between the production rate of graphene and the ultrasonic characteristic parameters as well as fluid status parameters are to be established. Finally, how the coupling phenomena of ultrasonic cavitation & acoustic streaming accelerate the intercalation and exfoliation of graphite into graphene in supercritical CO2 microemulsion will be investigated, and the thermalphysics mechanism of ultrasound cavitation & acoustic streaming on the intercalation and exfoliation will also be explored. The results will provide reliable experimental data and theoretical basis for the development and application of large-scale preparation of graphene.

针对超声波作用下超临界CO2微乳液中石墨烯的制备过程，采用最先进的PIV测试技术，借助高分辨显微镜和高速CCD摄像机，对含石墨颗粒的超临界CO2微乳液中超声空化与声流耦合作用现象进行在线观测和分析；寻找颗粒浓度、CO2/水比例和流体状态参数对超声空化与声流耦合特性的影响规律；探索疏水/亲水作用对含固微乳液中的超声空化和声流耦合特性的影响机理；阐明含石墨颗粒的超临界CO2微乳液中的超声空化与声流耦合特性。聚焦不同性质微乳液中石墨颗粒表面上发生的吸附、聚集、分子插层和颗粒溶胀现象，揭示超声波诱导的复杂多相界面行为特性。研究超声诱导的复杂多相界面行为对石墨烯片层的不同剥离方式的作用机制；建立超声作用特征参数和流体状态参数与石墨烯产率的关联；阐明超临界CO2微乳液中的超声空化与声流耦合效应对石墨烯片层剥离的热物理作用机制。研究结果将为石墨烯大规模制备工艺的开发应用提供可靠的实验数据和理论基础。

针对超声波作用下超临界CO2微乳液中石墨烯的制备过程，建立了可视化的超声耦合高压釜系统装置，对含石墨颗粒的超临界CO2微乳液中超声空化与声流耦合作用现象进行在线观测、实验测试和理论分析；通过改变颗粒表面特性、介质组成比例、流体介质状态参数和超声波作用参数，探索了超临界CO2微乳液中的超声空化与声流耦合特性，研究了超声诱导的复杂多相界面行为对石墨烯片层的不同剥离方式的作用机制。采用硝酸预处理天然石墨颗粒，明确了表面特性对溶剂分子吸附、插层和颗粒剥离具有重要作用。分别比较了无空化存在下的声流和有超声空化与声流耦合工况下的作用效应，提出了一种用石墨烯剥离效率来检验超声空化与声流耦合作用效应的新方法。结果表明，与无空化存在下的声流和搅拌作用相比，施加超声空化作用，超声操控超临界CO2微乳液中的石墨烯产率大大提高，明确了超声空化与声流耦合的重要作用，阐述了插层剥离、表面洗脱和反胶束界面相互作用等不同的剥离机制。针对本征石墨烯的制备存在产率低、耗时长、量产困难等技术瓶颈，将超声操控技术和超临界流体技术相结合，在国际上率先开发了超声操控超临界CO2微乳液制备本征石墨烯工艺，解决了物理剥离石墨烯的量产化关键技术，使得石墨烯制备时间少于2小时，石墨烯产率大于95%。通过该方法量产的石墨烯，已与中船集团711所合作成功应用于减振降噪隔振器中，所承担相关项目已通过中船集团公司验收。发明了超声操控微尺度声流耦合作用裁剪石墨烯量子点技术，阐明了超声裁剪石墨烯量子点的调控机理。揭示了石墨烯在超临界CO2-H2O微乳液中的界面行为，以及石墨烯促进超临界CO2 Pickering微乳液长期稳定的机理。获得了水性化环氧微乳液形成过程中超声空化与声流耦合作用特性和乳化机理，开发了超声操控超临界CO2微乳液制备水性化环氧微乳液新技术。阐述了氧化石墨烯促进本征石墨烯分散的界面行为及其促进分散的机理。研究结果将为石墨烯大规模制备工艺的开发和应用提供可靠的实验数据和理论基础。