Nordenström Andreas, Boulanger Nicolas, Iakunkov Artem, Baburin Igor, Klechikov Alexey, Vorobiev Alexei, Talyzin Alexandr V
Department of Physics, Umeå University, S-90187 Umeå, Sweden.
Theoretische Chemie, Technische Universitat Dresden, Bergstraße 66b, 01062 Dresden, Germany.
J Phys Chem C Nanomater Interfaces. 2021 Apr 1;125(12):6877-6885. doi: 10.1021/acs.jpcc.1c00327. Epub 2021 Mar 23.
Intercalation of dyes into thin multilayered graphene oxide (GO) films was studied by neutron reflectivity and X-ray diffraction. Methylene blue (MB) penetrates the interlayer space of GO in ethanol solution and remains intercalated after the solvent evaporation, as revealed by the expansion of the interlayer lattice and change in chemical composition. The sorption of MB by thin GO films is found to be significantly stronger compared to the sorption of Crystal violet (CV) and Rose bengal (RB). This effect is attributed to the difference in the geometrical shape of planar MB and essentially nonflat CV and RB molecules. Graphite oxides and restacked GO films are found to exhibit different methylene blue (MB) sorptions. MB sorption by precursor graphite oxide and thin spin-coated films of GO is significantly stronger compared to freestanding micrometer-thick membranes prepared by vacuum filtration. Nevertheless, the sorption capacity of GO membranes is sufficient to remove a significant part of the MB from diluted solutions tested for permeation in several earlier studies. High sorption capacity results in strong modification of the GO structure, which is likely to affect permeation properties of GO membranes. Therefore, MB is not suitable for testing size exclusion effects in the permeation of GO membranes. It is not only hydration or solvation diameter but also the exact geometrical shape of molecules that needs to be taken into account considering size effects for penetration of molecules between GO layers in membrane applications.
通过中子反射率和X射线衍射研究了染料插入多层氧化石墨烯（GO）薄膜的情况。亚甲基蓝（MB）在乙醇溶液中渗透到GO的层间空间，并且在溶剂蒸发后仍保持插层状态，这通过层间晶格的膨胀和化学成分的变化得以揭示。发现与结晶紫（CV）和孟加拉玫瑰红（RB）相比，薄的GO薄膜对MB的吸附要强得多。这种效应归因于平面MB与基本上非平面的CV和RB分子在几何形状上的差异。发现氧化石墨和重新堆叠的GO薄膜表现出不同的亚甲基蓝（MB）吸附情况。与通过真空过滤制备的独立微米厚膜相比，前驱体氧化石墨和GO的薄旋涂膜对MB的吸附要强得多。然而，GO膜的吸附能力足以从早期几项研究中测试渗透的稀释溶液中去除相当一部分MB。高吸附能力导致GO结构的强烈改性，这可能会影响GO膜的渗透性能。因此，MB不适用于测试GO膜渗透中的尺寸排阻效应。在考虑膜应用中分子穿透GO层之间的尺寸效应时，不仅需要考虑水合或溶剂化直径，还需要考虑分子的确切几何形状。
