Binding Of Two Cationic Compounds With Graphene Oxide: Comparative Analysis And Observation Of Synergetic Effect

The present paper reports on the results of the joint interaction of two organic cationic compounds of different structure and nature, namely bisquaternary ammonium decamethoxinum (Dec) with flexible dication and methylene blue (MB) with heterocyclic planar cation, with graphene oxide (GO) in aqueous dispersion. The qualitative differences in the 3D structures of GO modified in binary (GO+Dec), (GO+MB) and ternary (GO+Dec+MB) systems were observed and described on the basis of the UV-vis spectral analysis of the systems. On mixing the components of the binary (GO+Dec) system, a rather rapid gelation of GO dispersion was observed. The appearance of binary (GO+MB) system showed dependence on GO to MB ratio: at low GO content, MB -induced coagulation of GO to tiny bluish flakes took place followed by their sedimentation with time while at high GO content, the GO complexes with MB preserved solubility in water. The result of the joint addition of both Dec and MB to GO dispersion differed qualitatively from the above results of action of individual components. On creation of the (GO+Dec+MB) ternary system rapid flocculation of all components of the system was observed resulting in the formation of dark residue surfacing over the purified decolorized liquid. UV-vis spectra of the liquid phase showed suppression of the lines of all components or their complexes practically to the baseline. The compression of (GO+Dec+MB) composite to flocs is explained by the matching of the size of MB cation to that of Dec dication linker, which provides tight filling of the gaps between GO sheets. The observed flocculation effect in the (GO+Dec+MB) system may be of practical interest in the development of nanocomposite and sorption materials. Information on the features of GO interactions with organic cations differing in structure may be useful for advances in drug delivery problem.