Adsorptive Removal of Selected Anionic and Cationic Dyes by Using Graphitic Carbon Material Prepared from Edible Sugar: A Study of Kinetics and Isotherms.

Graphitic carbon-like material (GCM) derived from edible sugar under a nitrogen environment was applied as an adsorbent for the removal of anionic and cationic dyes (methyl orange, MO) and methylene blue (MB) from wastewater. The physico-chemical characterization of GCM was analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The plate-like morphology with an average size of 50-100 nm was measured from the SEM images. The measured BET 'surface area and pore volume were 574 m2/g and 0.248 cm3/g, respectively with pore diameter (d), 1.8 47 (< 2 nm) indicates that the GCM classified as a microporous. The effects of dosage, pH, contact time and concentration on the adsorption of MB and MO onto GCM were studied to unveil the adsorption process. The experimental isotherm data concurred with the Langmuir isotherm model (R2 = 0.990) for MB, while the MO isotherm data concurred with Freundlich model (R2 = 0.995). The maximum adsorption capacity achieved from the Langmuir isotherm equation at 25 °C was 38.75 and 43.48 mg/g for MB and MO, respectively, which indicates that GCM is a suitable adsorbent for the adsorption of both anionic and cationic dyes. The kinetic study demonstrated that the adsorption of both dyes onto GCM was the pseudo-second-order diffusion kinetics. The thermodynamic parameters reveal the adsorption of both dyes was endothermic spontaneous through chemical interactions. The GCM was found to be a potential adsorbent for the removal of MB and MO from an aqueous solution.