Robust cellulose-based composite adsorption membrane for heavy metal removal.

Area of Science:

• Materials Science
• Environmental Science
• Chemical Engineering

Background:

• Adsorptive membranes are effective for heavy metal removal but suffer from instability and low binding affinity.
• Existing membranes struggle with long-term aqueous stability and broad-spectrum heavy metal adsorption.
• Scalable filtration systems require robust membranes with high adsorption capacity.

Purpose of the Study:

• To develop a novel adsorptive membrane with enhanced stability and high heavy metal adsorption capacity.
• To utilize a reactive layer-by-layer (LBL) assembly method for creating stable, covalently bonded active layers.
• To demonstrate the membrane's efficiency in removing multiple heavy metal ions from contaminated water.

Main Methods:

• Synthesized stable, covalently bonded polyelectrolyte active layers on regenerated cellulose support membranes using a reactive LBL assembly.
• Characterized the LBL assembled layers using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS).
• Evaluated the membrane's adsorption capacity, stability, flux, and regeneration efficiency for heavy metal ions (Cu, Pb, Cd).

Main Results:

• The covalently bonded LBL membrane exhibited superior long-term aqueous stability compared to electrostatically bonded membranes.
• Achieved a maximum adsorption capacity of up to 194 mg/g for heavy metal ions.
• Demonstrated efficient removal of multiple heavy metal ions (Cu, Pb, Cd) with tunable water flux and easy regeneration.
• Showed enhanced adsorption at lower heavy metal concentrations and higher pH.

Conclusions:

• The developed covalently bonded adsorptive membrane offers a stable and efficient solution for heavy metal water purification.
• The reactive LBL assembly method provides a pathway to create robust membranes with tunable properties for water treatment.
• This technology has the potential to extend membrane lifetime and improve the efficiency of removing multiple heavy metals.