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Ultrasonic treatment of glassy carbon for nanoparticle preparation

机译：纳米粒子制备玻璃碳的超声波处理

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Glassy carbon particles (millimetric or micrometric sizes) dispersions in water were treated by ultrasound at 20 kHz, either in a cylindrical reactor, or in a "Rosette" type reactor, for various time lengths ranging from 3 h to 10 h. Further separations sedimentation allowed obtaining few nanoparticles of glassy carbon in the supernatant (diameter <200 nm). Thought the yield of nanoparticle increased together with the sonication time at high power, it tended to be nil after sonication in the cylindrical reactor. The sonication of glassy carbon micrometric particles in water using "Rosette" instead of cylindrical reactor, allowed preparing at highest yield (1-2 wt%), stable suspensions of carbon nanoparticles, easily separated from the sedimented particles. Both sediment and supernatant separated by decantation of the sonicated dispersions were characterized by laser granulometry, scanning electron microscopy, X-ray microanalysis, and Raman and infrared spectroscopies. Their multiscale organization was investigated by transmission electron microscopy as a function of the sonication time. For sonication longer than 10 h, these nanoparticles from supernatant (diameter <50 nm) are aggregated. Their structures are more disordered than the sediment particles showing typical nanometer-sized aromatic layer arrangement of glassy carbon, with closed mesopores (diameter similar to 3 nm). Sonication time longer than 5 h has induced not only a strong amorphization (subnanometric and disoriented aromatic layer) but also a loss of the mesoporous network nanostructure. These multi-scale organizational changes took place because of both cavitation and shocks between particles, mainly at the particle surface. The sonication in water has induced also chemical effects, leading to an increase in the oxygen content of the irradiated material together with the sonication time. (C) 2016 Elsevier B.V. All rights reserved.
机译：通过在圆柱形反应器中以20kHz，或在“玫瑰丝”型反应器中，通过超声处理水中的玻璃碳颗粒（毫米或微米尺寸）分散体，或者在“玫瑰丝”反应器中，各种时间长度为3小时至10小时。进一步的分离沉降允许在上清液中获得少量纳米颗粒（直径<200nm）。认为纳米粒子的产量随着高功率的超声处理时间而增加，在圆柱形反应器中超声处理后往往是零。使用“玫瑰花”而不是圆柱形反应器的玻璃状碳微米粒子的超声处理，而不是圆柱形反应器，允许以最高产率（1-2重量％），稳定的碳纳米粒子悬浮液，容易与沉积的颗粒分离。通过激光粒度，扫描电子显微镜，X射线微分析和拉曼和红外光谱，以通过倾析分离的沉积物和上清液。通过透射电子显微镜作为超声处理时间的函数来研究其多尺度组织。对于长于10小时的超声处理，这些纳米颗粒来自上清液（直径<50nm）。聚集。它们的结构比显示玻璃碳的典型纳米型芳族层布置的沉积物颗粒更紊乱，封闭的封闭的凹陷（直径与3nm类似）。超声时间超过5小时，不仅诱导了强烈的混合物（亚域计量和迷失方向的芳族层），而且诱导了介孔网络纳米结构的损失。由于颗粒之间的空穴和冲击，主要在颗粒表面处发生这些多种组织变化。水中的超声处理也诱导化学效果，导致辐照材料的氧含量与超声处理时间一起增加。 （c）2016年Elsevier B.v.保留所有权利。

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