Efficient adsorptive removal of Co²⁺ from aqueous solution using graphene oxide

Area of Science:

• Materials Science
• Environmental Chemistry
• Nanotechnology

Background:

• Graphene oxide (GO) is a promising material for water remediation.
• Cobalt ion contamination poses environmental and health risks.
• Understanding adsorption mechanisms is crucial for developing effective water treatment technologies.

Purpose of the Study:

• To synthesize graphene oxide (GO) for cobalt ion removal.
• To investigate the adsorption kinetics, thermodynamics, and mechanism of cobalt ions onto GO.
• To explore the potential of GO as an adsorbent for aqueous contaminant removal.

Main Methods:

• Graphene oxide synthesis via improved Hummers method.
• Characterization using SEM, TEM, Raman, FT-IR, TG, N2 sorption-desorption, and potentiometric titrations.
• Adsorption studies analyzed using pseudo-second-order kinetics and Langmuir models.
• Mechanism investigation using X-ray absorption spectroscopy (XANES, EXAFS), FT-IR, and XPS.

Main Results:

• Synthesized GO exhibits high surface area (93.7 m²/g) and abundant oxygen functional groups.
• Maximum sorption capacity of 93.7 mg/g for Co²⁺, following pseudo-second-order kinetics and Langmuir isotherm.
• Adsorption is a chemisorption and endothermic process with selectivity for Co²⁺ > Sr²⁺ > Cs⁺.
• Coordination and electrostatic interactions involving oxygen functional groups are the primary adsorption mechanisms.

Conclusions:

• Graphene oxide is a highly effective adsorbent for cobalt ion removal from aqueous solutions.
• The study elucidates the adsorption mechanism, involving coordination and electrostatic interactions.
• GO demonstrates significant potential for the removal of hazardous nuclides in water treatment applications.