Efficient removal of Pb(II) ions from aqueous solution by modified red mud

Area of Science:

• Environmental Chemistry
• Materials Science
• Water Treatment

Background:

• Red mud, a byproduct of alumina production, presents significant disposal challenges.
• Heavy metal contamination, particularly lead (Pb(II)), poses severe risks to aquatic ecosystems and human health.
• Effective and economical methods for removing heavy metals from industrial wastewater are urgently needed.

Purpose of the Study:

• To develop a modified red mud material for efficient adsorption of lead ions from aqueous solutions.
• To investigate the structural and chemical changes in red mud after modification.
• To evaluate the adsorption capacity and mechanism of the modified red mud for Pb(II) ions.

Main Methods:

• Hydrothermal modification of red mud using colloidal silica and sodium hydroxide.
• Adsorption experiments to determine Pb(II) removal efficiency.
• Kinetic and isotherm modeling (pseudo-first-order, pseudo-second-order, Langmuir, Dubinin-Radushkevich).
• Material characterization using XRD, FTIR, XPS, and SEM-EDS.

Main Results:

• Formation of a zeolite structure in the modified red mud.
• A significant increase in Pb(II) adsorption capacity, approximately 10 times higher than the original red mud.
• Saturated adsorption capacity reached 551.11 mg/g for Pb(II).
• Adsorption mechanism involves monolayer physical adsorption, ion exchange, and precipitation, forming PbCO3 and Pb3(CO3)2(OH)2.

Conclusions:

• Hydrothermal modification effectively transforms red mud into a high-performance adsorbent for lead ions.
• The modified red mud demonstrates excellent efficiency and capacity for Pb(II) removal.
• This material presents a sustainable and promising solution for treating heavy metal-contaminated wastewater.