Evaluation of graphene oxide-activated carbon as effective composite adsorbent toward the removal of cationic dyes: Composite preparation, characterization and adsorption parameters

Graphene oxide-activated carbon (GO-AC) composite was synthesized by a single-step mixing method via direct conjugation of m-AC particles onto GO using tetraethyl orthosilicate (TEOS) as a chemical linker. GO-AC composite was employed for the removal of methylene blue (MB) and crystal violet (CV) dyes from an aqueous solution. GO-AC composite was investigated by IR, SEM, TEM, XRD, and TGA analyses. Notably, SEM photographs and TGA data of GO-AC composite showed a rough surface morphology and a significant thermal stability, respectively, due to incorporation of m-AC. The obtained data exhibited that the removal of dyes increased clearly with high initial dye concentration, contact time, high composite dosage, and pH. Moreover, these data revealed that, composite possesses an efficient adsorption performance appeared in the maximum adsorption capacity which reached to similar to 70 and 147 mg/g for removal of CV and MB dyes, respectively, according to Langmuir isotherm. Meanwhile, the adsorption kinetics data for GO-AC composite modeled using the pseudo-second-order kinetic found to be justify the experimental data, as well. Furthermore, the GO-AC composite shows reusability performance. These results suggest that GO-AC composite is a potential costless adsorbent for the removal of organic dyes from industrial wastewater. (C) 2019 Published by Elsevier B.V.