Stockbridge School of Agriculture, University of Massachusetts , Amherst, Massachusetts 01003, United States.
Environ Sci Technol. 2014;48(1):331-9. doi: 10.1021/es403873r. Epub 2013 Dec 23.
Surfactant mediated exfoliation of multilayer graphene and its effects on phenanthrene adsorption were investigated using a passive dosing technique. In the absence of surfactant (sodium cholate, NaC), multilayer graphene had higher adsorption capacity for phenanthrene than carbon nanotube and graphite due to the higher surface area and micropore volume. The observed desorption hysteresis is likely caused by the formation of closed interstitial spaces through folding and rearrangement of graphene sheets. In the presence of NaC (both 100 and 8000 mg/L), phenanthrene adsorption on graphene was decreased due to the direct competition of NaC molecules on the graphene surface. With the aid of sonication, multilayer graphene sheets were exfoliated by NaC, leading to better dispersion. The degree of dispersion depended on the graphene-NaC ratio in aqueous solution rather than critical micelle concentration of NaC, and the good dispersion occurred after reaching adsorption saturation of NaC molecules on graphene sheets. In addition, exfoliation weakened the competition between phenanthrene and NaC and enhanced the adsorption capacity of graphene for phenanthrene due to exposed new sites. The findings on exfoliation of graphene sheets and related adsorption properties highlight not only the potential applications of multilayer graphene as efficient adsorbent but also its possible environmental risk.
采用被动投加技术研究了表面活性剂介导的多层石墨烯的剥落及其对菲吸附的影响。在没有表面活性剂（胆酸钠，NaC）的情况下，由于更高的表面积和微孔体积，多层石墨烯对菲的吸附容量高于碳纳米管和石墨。观察到的解吸滞后可能是由于石墨烯片折叠和重排形成封闭的间隙空间所致。在存在 NaC（100 和 8000 mg/L）的情况下，由于 NaC 分子在石墨烯表面的直接竞争，石墨烯对菲的吸附减少。在超声的辅助下，多层石墨烯片被 NaC 剥落，导致更好的分散。分散程度取决于水溶液中石墨烯-NaC 的比例，而不是 NaC 的临界胶束浓度，并且在达到石墨烯片上 NaC 分子的吸附饱和后，良好的分散发生。此外，由于暴露了新的吸附位，剥落削弱了菲和 NaC 之间的竞争，增强了石墨烯对菲的吸附能力。关于石墨烯片剥落及其相关吸附性能的研究结果不仅突出了多层石墨烯作为高效吸附剂的潜在应用，还突出了其可能的环境风险。
