Functional rGO aerogel as a potential adsorbent for removing hazardous hexavalent chromium: adsorption performance and mechanism

A novel functional rGO aerogel was synthesized by a facile hydrothermal method. In this process, graphene oxide (GO) was used as the precursor and oxidant to synthesize the aerogels. Ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) and pyrrole monomer (reducing agent) were selected to use as hole scavenger and nitrogen sources. The obtained EDTA-2Na/polypyrrole (Ppy)/rGO aerogel (EPGA) has a high adsorption capacity for Cr(VI) anions, and the maximum adsorption capacity reached 361 mg/g at 298 K at pH of 2. In addition, EPGA exhibited a good ability to selectively remove Cr(VI) anions under the effect of coexisting ions (Cl-, NO3-, SO42-, PO43-, Ni+, Cu2+, Zn2+, and Cd2+) and good regeneration ability. The kinetics process and adsorption isotherm can be fitted well with the pseudo-second-order kinetic model and Freundlich isotherm model, respectively. The removal mechanism involved electrostatic interaction, reduction, ion exchange, and chelation process. This work provides a simple and environmentally friendly synthetic route for EPGA, which will be a potential candidate for efficient removal Cr(VI) anions from industrial wastewater.