Adsorption of hexavalent chromium from aqueous solution using glucose-derived spherical activated carbon: The role of functional groups

This research explores the production of spherical activated carbon derived from glucose using the combination of a hydrothermal process followed by chemical impregnation with hydrogen peroxide (H۲O۲), citric acid (CA), and acrylic acid (AA), and pyrolysis. The adsorption performances, kinetics, and thermodynamics of the synthesized materials were compared with those of the material without chemical impregnation using batch experiments. Boehm titration and Fourier-transform infrared spectroscopy (FTIR) confirmed an increase in oxygen-containing functional groups (carboxyl, lactone, and phenol), facilitating adsorption through electrostatic interaction, reduction, and complexation. Adsorption kinetics and isotherm modeling confirmed that the process adhered to the Elovich model and the Redlich-Peterson or Langmuir isotherm, suggesting chemisorption dominance. Among the materials tested, AA-modified activated carbon (AC-AA) exhibited the highest adsorption capacity of ۲۴۴ mg/g, outperforming previously studied biochar-based adsorbents. Kinetic and thermodynamic assessments demonstrated that Cr(VI) adsorption was spontaneous (ΔG<۰), endothermic (ΔH>۰), and entropy-favored (ΔS>۰). Notably, the study elucidates the concurrent adsorption and reduction of Cr(VI) to Cr(III) at low pH, driven by electron transfer from surface functional groups. Moreover, NaOH was identified as the most effective desorption agent, underscoring the potential for material regeneration and reuse. This research highlights the potential application of glucose-based carbon spheres with functionalized surfaces as a sustainable, cost-effective solution for Cr(VI) removal in industrial wastewater treatment.

کلیدواژه ها:

Adsorption mechanism ، Functional groups ، Hexavalent chromium ، Hydrothermal synthesis ، Spherical Activated Carbon