Self-assembled graphene aerogels for removal of methylene blue and copper from aqueous solutions

Low stability and difficulty of separation are detrimental to use of graphene oxide (GO) to remove organic and inorganic contaminants. In this work, different amounts of ascorbic acid (AA) have been attempted to prepare three -dimensional (3D) graphene aerogels (GA) followed by freeze -dried (GA -F) or oven-dried (GA -O). Graphene aerogels were successfully synthesized and performance of contaminant removal as a function of AA concentrations has been investigated by using methylene blue (MB) and copper (Cu) as precursors. The batch sorption results revealed that MB and Cu removal capacity decreased with AA concentrations for freeze -dried 3D graphene aerogels, and increased with AA concentrations for oven -dried graphene aerogels. Among them, freeze -dried graphene aerogels can be used as a high -efficiency adsorbent to adsorb MB and Cu, the adsorption quantity can reach 87.30 mg g-1 and 70.37 mg g-1, the removal rates are 95.1% and 91.5%, respectively. The performance of aerogels before and after adsorption of contaminants were analyzed by characterization results. The hierarchical porous structure tends to calla with higher AA concentrations. The characterization analysis of MB and Cu - spent graphene aerogels revealed that sorption may invoke electrostatic attraction, ion exchange, surface complexation and ������ - ������ stacking mechanisms. Thus, the 3D graphene aerogels obtained by freeze -dried in this experiment provide a new thinking for the effective removal of MB and Cu from aqueous solutions.