Multi-edged molybdenite achieved by thermal modification for enhancing Pb(II) adsorption in aqueous solutions

Area of Science:

• Materials Science
• Environmental Science
• Chemistry

Background:

• Molybdenite is a mineral with potential for adsorbing heavy metals.
• Lead (II) (Pb(II)) contamination in aqueous solutions poses significant environmental and health risks.
• Effective and economical methods for removing Pb(II) are crucial.

Purpose of the Study:

• To investigate the effect of thermal modification on molybdenite's Pb(II) adsorption capacity.
• To understand the underlying mechanisms responsible for enhanced Pb(II) adsorption.
• To explore the potential of modified molybdenite as an adsorbent for Pb(II) removal.

Main Methods:

• Thermal modification of molybdenite at 300°C, 400°C, and 500°C.
• Surface characterization using contact angle measurements and atomic force microscopy (AFM).
• Adsorption experiments to quantify Pb(II) uptake.
• Analysis of chemical interactions using X-ray photoelectron spectroscopy (XPS).

Main Results:

• Molybdenite modified at 400°C exhibited the highest Pb(II) adsorption capacity (147.846 mg/g), approximately 10 times that of natural molybdenite.
• Thermal modification increased edge defects and surface wettability (hydrophilicity) of molybdenite.
• XPS analysis confirmed strong chemical adsorption between Pb(II) and sulfur (S) elements on the molybdenite surface.
• AFM studies indicated that Pb(II) interaction with sulfur atoms at molybdenite's triangular edges is key to enhanced adsorption.

Conclusions:

• Thermal modification, particularly at 400°C, is an effective strategy to significantly enhance molybdenite's Pb(II) adsorption.
• The enhanced adsorption is attributed to increased edge defects and specific chemical interactions between Pb(II) and sulfur atoms.
• Modified molybdenite shows promise as a cost-effective adsorbent for removing lead from contaminated water.