A Highly Efficient Graphene-Based Material for the Removal of Cationic Dyes from Aqueous Solutions

Graphene materials and their derivatives have shown promising capabilities in removing anionic and cationic dyes from wastewater. The present study aims at the synthesis of graphene-based material with a high specific surface area and evaluates its use as an adsorbent for removing toluidine blue and methyl violet from aqueous solutions. The physicochemical characterization of the adsorbent before and after dye adsorption is made by XRD, Raman spectroscopy, SEM, TEM, nitrogen physisorption, TG-DTA, and XPS. The influence of the solution's pH, contact time, dye concentration, and temperature on the adsorption efficiency is investigated. The adsorbent demonstrated high adsorption capacity towards toluidine blue (265.2 mg.g^-1) and methyl violet (200.4 mg.g^-1) dyes from water. The adsorption process for both dyes follows the Langmuir model and involves physical rather than chemical interactions. Kinetic parameters were also determined. The adsorption of the studied cationic dyes can be attributed to a combination of mechanisms, including electrostatic interactions, hydrogen bonding, and π-π interactions between the dye molecules and the aromatic structure of reduced graphene oxide. The findings in the present work highlight the possibilities for enhancing graphene-based materials' adsorption capabilities.