Adsorption of Brilliant Blue and Malachite Green by Nano‐graphene Exfoliated from Waste Batteries

Abstract

Waste graphite rods from waste batteries, acting as a source of graphite, were electrochemically exfoliated to synthesize graphene. Mesoporous graphene with a pore size of 14.81 Å and a surface area of 710.396 m2g−1 was chosen for adsorptive studies involving toxic dyes, Brilliant Blue (BB) and Malachite Green (MG), by varying the graphene dosage, contact period, temperature, pH, and the concentration of the dye solution. The maximum adsorption capacities reported were 120 mg gBB−1 and 342 mg gMG−1, with dye removal rates of BB and MG greater than 99 and 98 %, respectively. Adsorption occurred as multilayer, following the Freundlich isotherm model, and the pseudo‐second‐order kinetic model fitted best, indicating chemisorption. Thermodynamic studies reveal an exothermic, spontaneous, and chemical adsorption.