A Comparative Study on the Adsorption of Eriochrome Black T Dye from Aqueous Solution on Graphene and Acid-Modified Graphene

In this study, the adsorption behavior of Eriochrome Black T (EBT) on graphene (G) and acid-modified graphene (AMG) was investigated. Surface of the graphene was modified by acid treatment. Surface and structural characterization of the adsorbents were conducted using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) surface area analysis. The effect of influential adsorption parameters (pH, contact time, and initial concentration) on the adsorption of EBT onto G and AMG were examined in batch experiments. Adsorption behavior of EBT on the surfaces of G and AMG was evaluated by applying different isotherm models (Langmuir, Freundlich, and Redlich–Peterson) on equilibrium data. The adsorption kinetics was studied by using pseudo-first-order and pseudo-second-order model. Adsorption followed the pseudo-second-order rate kinetics. The maximum removal of EBT was found to be 95 and 80% by G and AMG, respectively, at pH 2, adsorbent dosage of 10 mg, contact time of 3 h, and initial dye concentration of 10 mg/L. The maximum adsorption capacities were 102.04 and 70.42 mg/g for G and AMG, respectively. It was found that acid modification of graphene has an adverse effect on the adsorption of EBT.