Adsorption characteristics of acrylonitrile, p-toluenesulfonic acid, 1-naphthalenesulfonic acid and methyl blue on graphene in aqueous solutions

In order to explore the potential of graphene (G) in removal of hazardous chemicals in waste water, chemically reduced graphene oxide was employed as the adsorbent and the adsorption characteristics of graphene toward acrylonitrile (AN), p-toluenesulfonic acid (p-TA), 1-naphthalenesulfonic acid (1-NA) and methyl blue (MB) were evaluated under laboratory conditions. The results showed that the organic chemicals with larger molecule size and more benzene rings possessed a higher adsorption speed and a higher maximum adsorption capacity on G. The maximum adsorption capacities of p-TA, 1-NA and MB on G are ∼1.43 g/g G, ∼1.46 g/g G and ∼1.52 g/g G at 30 °C, respectively, which are the highest values of p-TA, 1-NA or MB adsorption on different kinds of today's nanomaterials. Under the maximum adsorption capacity, the absorption quantity of MB on G was dependent on the initial concentration of MB, and higher temperature could facilitate the adsorption process. The G efficiency remains almost constant during the first five cycles of the adsorption–desorption process. In addition, the fluorescence spectra implied that the adsorption of MB on G was a π–π stacking adsorption process. In conclusion, the G could serve as a promising adsorbent for the removal of chemicals containing benzene rings in waste water.

The maximum adsorption capacity of methyl blue (MB) on graphene (G) is ∼1.52 g/g G at 30 °C, which are the highest values of MB adsorption on different kinds of today's nanomaterials. The absorption quantity of MB on G was dependent on the initial concentration of MB, the negative ΔG° indicated that the adsorption was a spontaneous process and higher temperature could facilitate the adsorption process. The fluorescence spectra implied that the adsorption of MB on G was a π–π stacking adsorption process.Figure optionsDownload as PowerPoint slideHighlights
► The maximum adsorption capacity of methyl blue (MB) on graphene (G) is ∼1.52 g/g G.
► The negative ΔG° indicated that the adsorption was a spontaneous process.
► The adsorption of MB on G was a π–π stacking adsorption process.