Phase-Mediated Heavy Metal Adsorption from Aqueous Solutions Using Two-Dimensional Layered MoS₂

Area of Science:

• Materials Science
• Environmental Science
• Nanotechnology

Background:

• Understanding inorganic material phases is crucial for effective heavy metal removal.
• Material structure significantly influences adsorption properties.
• Molybdenum disulfide (MoS₂) exists in metallic (1T) and semiconducting (2H) phases with distinct characteristics.

Purpose of the Study:

• To investigate the adsorption behaviors of lead (Pb(II)) and copper (Cu(II)) on different phases of MoS₂.
• To compare the heavy metal removal efficiency of 1T-MoS₂ and 2H-MoS₂.
• To provide insights into the application of MoS₂-based adsorbents for environmental remediation.

Main Methods:

• Theoretical calculations (computational studies) to determine adsorption energies and complex stability.
• Experimental synthesis of two-dimensional (2D) MoS₂ nanosheets with 1T and 2H phases via hydrothermal reaction.
• Adsorption experiments to quantify heavy metal removal capacities and kinetics.

Main Results:

• Computational results indicated more stable Pb(II) and Cu(II) complex formation on 1T-MoS₂ due to lower adsorption energy.
• Synthesized 1T-MoS₂ exhibited significantly higher adsorption capacities for Pb(II) (147.09 mg/g) and Cu(II) (82.13 mg/g) compared to 2H-MoS₂ (64.16 and 50.74 mg/g, respectively) at 298 K.
• 1T-MoS₂ demonstrated ultrafast adsorption kinetics and superior anti-interference activity against other cations.

Conclusions:

• The metallic 1T phase of MoS₂ is more effective for heavy metal removal than the semiconducting 2H phase.
• Active sulfur sites on MoS₂ are essential for heavy metal adsorption.
• This study guides the development and application of MoS₂-based adsorbents in environmental remediation.