Facile one-pot preparation of nitrogen-doped ultra-light graphene oxide aerogel and its prominent adsorption performance of Cr(VI)

Abstract

A novel nitrogen-doped ultra-light graphene oxide (GO) aerogel with three-dimensional (3D) network structure is used for removing of Cr(VI) from aqueous solution, which is fabricated by a facile one step hydrothermal self-assembly process and an environmentally friendly freeze-drying technique. GO and organic amine are used as the precursors to synthesize the aerogels, in which pyrrole and Tetraethylenetetramine (TEPA) are introduced as nitrogen sources to obtain the amino functional groups, meanwhile, they also play the roles as cross-linking agents to control the assembly of GO sheets in the 3D structure. The obtained TEPA/polypyrrole/GO aerogel (TPGA) has a high adsorption capacity for Cr(VI) anions (up to 408.48 mg/g) at an optimal pH of 2.0. The kinetics process of Cr(VI) adsorption on TPGA can be fitted well with the pseudo-second-order kinetic model. The mechanism of adsorption is analyzed by intraparticle diffusion and external film diffusion models, which indicates that the overall rate of Cr(VI) adsorption process is influenced by multi-steps. The isotherm and thermodynamic studies confirms that adsorption of Cr(VI) on TPGA is a spontaneous and endothermic process in the monolayer adsorption pattern. Furthermore, the prepared TPGA exhibits a good regeneration ability and satisfactory recovery for Cr(VI) anions in practical water samples. This work provides a simple and environmentally friendly method to synthesize the nitrogen-doped GO aerogel, which show a great potential and promise for practical application in the field of waste water treatment.