Efficient mercury removal from aqueous solutions using carboxylated Ti₃C₂T_x MXene

Area of Science:

• Materials Science
• Environmental Science
• Nanotechnology

Background:

• Heavy metal contamination in water supplies is a critical global environmental issue.
• MXenes possess unique properties suitable for adsorbing metal ions from aqueous solutions.
• Existing MXene materials may have limitations in terms of adsorption efficiency and stability for water remediation.

Purpose of the Study:

• To develop a simple, one-step carboxylation method for Ti3C2Tx MXene.
• To enhance the stability and metal ion adsorption capabilities of Ti3C2Tx.
• To evaluate the performance of the modified MXene (COOH-Ti3C2Tx) for mercury ion removal from water.

Main Methods:

• A one-step carboxylation of Ti3C2Tx using a linear chelating agent to introduce carboxylic acid groups.
• Characterization of the modified Ti3C2Tx (COOH-Ti3C2Tx) including zeta-potential measurements.
• Adsorption experiments to assess mercury ion uptake capacity, kinetics, and leaching behavior at various pH levels.

Main Results:

• Carboxylation decreased the zeta-potential of Ti3C2Tx and improved its stability in oxygenated water.
• COOH-Ti3C2Tx exhibited significantly faster and higher mercury ion adsorption than unmodified Ti3C2Tx.
• At 50 ppm Hg2+ and pH 6, COOH-Ti3C2Tx achieved an adsorption capacity of 499.7 mg/g, removing 95% in under 1 minute with a 5-minute equilibrium time.
• Leached mercury ion concentrations were below U.S.-EPA maximum levels for both materials.

Conclusions:

• The developed carboxylation method effectively enhances MXene properties for water treatment.
• COOH-Ti3C2Tx is a highly efficient adsorbent for mercury ions, outperforming existing materials.
• This modified MXene offers a promising solution for rapid and effective removal of heavy metals from contaminated water sources.