Session: Undergraduate Research Posters: Nanochemistry:

Graphene oxide (GO) is widely used as an adsorbent for organic dyes because of its high surface area and dispersibility. Several studies have investigated the interaction of GO with Methylene blue (MB), a model organic dye used in assessing the adsorptive efficacy of materials. Although such studies establish that MB molecules actively adsorb onto the GO nanosheets, these have limited elucidations on how the adsorptive interactions of the molecular species of MB, primarily monomers, dimers, and higher-order aggregates, vary. It is largely presumed that these species interact with GO in an analogous manner. This study shows that although monomers and dimers evince similar adsorptive characteristics with GO, the adsorptive behavior of higher-order aggregates differs from them. Spectroscopic insights demonstrate preferential adsorption of monomers and dimers at certain GO concentrations, and vice-versa. This preferential adsorption also depends on the lateral dimensions of GO nanosheets. Subsequently, this disparity is linked with the inherent difference in the interaction of these molecular species with GO—while the monomers and dimers interact through London dispersion and electrostatic forces, the higher-order aggregates primarily interact through π-π interactions. Such chemo-physical insights shall facilitate a better understanding of the fundamental interfacial sciences between GO and organic dyes.

Aqueous Methylene blue (MB) primarily constitutes two molecular species—monomers and dimers (blue-colored). In the presence of Graphene oxide (GO), these molecular species either adsorb onto the GO surface (orange-colored), aggregate to form higher-order aggregates (red-colored), or remain unadsorbed. The degree of adsorption and aggregation of MB species on GO depends on the GO concentration and nanosheet dimensions, as shown in this work. Results evince a higher degree of aggregation at lower GO concentrations and with larger GO nanosheet dimensions. On the other hand, higher GO concentrations and smaller nanosheet dimensions foster preferential adsorption of monomers and dimers over higher-order aggregation.

Aqueous Methylene blue (MB) primarily constitutes two molecular species—monomers and dimers (blue-colored). In the presence of Graphene oxide (GO), these molecular species either adsorb onto the GO surface (orange-colored), aggregate to form higher-order aggregates (red-colored), or remain unadsorbed. The degree of adsorption and aggregation of MB species on GO depends on the GO concentration and nanosheet dimensions, as shown in this work. Results evince a higher degree of aggregation at lower GO concentrations and with larger GO nanosheet dimensions. On the other hand, higher GO concentrations and smaller nanosheet dimensions foster preferential adsorption of monomers and dimers over higher-order aggregation.

Kabeer Jasuja

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