Enhancing Cr(vi) removal performance of Ti₃C₂T through structural modification by using a spray freezing method

Area of Science:

• Materials Science
• Environmental Science
• Nanotechnology

Background:

• MXenes, particularly Ti₃C₂T_z, are promising adsorbents.
• Structural modification is key to enhancing MXene performance.
• Hexavalent chromium (Cr(VI)) poses significant environmental and health risks.

Purpose of the Study:

• To structurally modify Ti₃C₂T_z using spray freezing.
• To prepare and characterize spherical and flaky Ti₃C₂T_z nanomaterials.
• To investigate the Cr(VI) adsorption performance of the modified Ti₃C₂T_z structures.

Main Methods:

• Spray freezing technique for structural modification of Ti₃C₂T_z.
• Preparation of flaky Ti₃C₂T_z at 3 mg mL^-1 and spherical Ti₃C₂T_z at 6 mg mL^-1.
• Characterization of specific surface area and morphology of the nanomaterials.

Main Results:

• Flaky Ti₃C₂T_z (8-10 μm, 17.81 m² g^-1) exhibited a maximum adsorption capacity of 928 mg g^-1.
• Spherical Ti₃C₂T_z (1-4 μm, 17.07 m² g^-1) achieved a maximum adsorption capacity of 626 mg g^-1.
• Adsorption capacity decreased with increasing pH (optimal at pH 2) and increased with Cr(VI) concentration.

Conclusions:

• Spray freezing enables facile structural modification of Ti₃C₂T_z for enhanced Cr(VI) adsorption.
• Flaky Ti₃C₂T_z offers significantly higher Cr(VI) adsorption capacity and faster kinetics (3 min) than spherical forms.
• Adsorption follows Langmuir model, indicating monolayer chemisorption, driven by reductive and electrostatic interactions.