A novel graphene oxide-dicationic ionic liquid composite for Cr(VI) adsorption from aqueous solutions

Area of Science:

• Materials Science
• Environmental Chemistry
• Nanotechnology

Background:

• Graphene oxide (GO) is a versatile nanomaterial with potential applications in water treatment.
• Dicationic ionic liquids (DILs) offer unique properties for material modification and adsorption.
• Hexavalent chromium (Cr(VI)) is a toxic pollutant requiring efficient removal from industrial wastewater.

Purpose of the Study:

• To synthesize and characterize a novel graphene oxide-dicationic ionic liquid composite (GO-DIL).
• To evaluate the efficiency of GO-DIL for Cr(VI) adsorption from aqueous solutions.
• To investigate the adsorption mechanism, kinetics, and thermodynamics of Cr(VI) removal by GO-DIL.

Main Methods:

• Graphene oxide was modified with a dicationic ionic liquid, [C4(MIM)2]Cl2, to form GO-DIL.
• Material characterization using SEM, BET, FTIR, and XPS.
• Batch adsorption experiments were conducted to determine optimal conditions (pH, time) and adsorption capacity.

Main Results:

• GO-DIL composite exhibited excellent Cr(VI) adsorption performance, reaching equilibrium in 40 minutes at pH 3.
• The maximum theoretical adsorption capacity (q_m) was 271.08 mg g⁻¹, with capacity remaining high (>228.00 mg g⁻¹) after five cycles.
• Adsorption followed pseudo-first-order kinetics and the Langmuir model, indicating a spontaneous, endothermic process driven by electrostatic attraction and Cr(VI) reduction to Cr(III).

Conclusions:

• The novel GO-DIL composite is a highly effective adsorbent for Cr(VI) removal.
• Electrostatic interactions and the reduction of Cr(VI) to Cr(III) are key mechanisms in the adsorption process.
• GO-DIL shows significant potential for the remediation of heavy metal-contaminated wastewater.