Pb(II) adsorption mechanism and capability from aqueous solution using red mud modified by chitosan

Area of Science:

• Environmental Chemistry
• Materials Science

Background:

• Industrial byproducts like red mud pose disposal challenges.
• Lead (Pb(II)) contamination in aqueous solutions is a significant environmental concern.

Purpose of the Study:

• To investigate the efficacy of chitosan-modified red mud (RM/CS) as an adsorbent for Pb(II) removal.
• To analyze the adsorption kinetics and mechanisms of Pb(II) onto RM/CS.
• To determine the maximum adsorption capacity of RM/CS for Pb(II).

Main Methods:

• Red mud was modified with chitosan to create RM/CS.
• Batch adsorption experiments were conducted to study Pb(II) removal.
• Adsorption kinetics were analyzed using pseudo-first-order, pseudo-second-order, and intra-diffusion models.
• Surface area analysis and characterization of adsorption mechanisms were performed.

Main Results:

• RM/CS exhibited a >50% increase in surface area compared to raw red mud.
• Pb(II) adsorption kinetics followed the intra-diffusion model, indicating multiple removal mechanisms.
• The interaction with surface carbonate groups was identified as a key mechanism at equilibrium.
• The maximum adsorption capacity of RM/CS for Pb(II) reached approximately 209 mg/g.

Conclusions:

• Chitosan-modified red mud (RM/CS) is a highly effective adsorbent for Pb(II) removal.
• The enhanced surface area and specific surface interactions contribute to its high adsorptive capacity.
• RM/CS presents a viable and efficient solution for treating lead-contaminated water.