Lanthanum-loaded biochar-based alginate hydrogels for efficient phosphate adsorption from wastewater

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Phosphate pollution poses a significant threat to aquatic ecosystems.
• Developing efficient and selective adsorbents for phosphate removal is crucial.

Purpose of the Study:

• To fabricate and characterize a lanthanum-loaded biochar-based alginate hydrogel (La@SA@BC) for phosphate adsorption.
• To evaluate the adsorption capacity, efficiency, and mechanism of the La@SA@BC hydrogel.

Main Methods:

• Fabrication of La@SA@BC hydrogel at an optimal 1:1 mass ratio.
• Phosphate adsorption experiments to determine capacity and efficiency under varying conditions (pH, competing ions).
• Characterization of hydrogel morphology, composition, and functional groups using techniques like SEM and FTIR.
• Kinetic analysis to elucidate the adsorption mechanism.

Main Results:

• Maximum phosphate adsorption capacity of 56.5 mg/g achieved at 0.9 g/L adsorbent dosage.
• 90% phosphate removal efficiency at pH 3 with minimal reduction (<10%) in the presence of competing ions.
• Pseudo-second-order model fit (R² = 0.95) indicating chemisorption as the dominant mechanism.
• Characterization confirmed a rough, folded surface structure with internal cavities and uniform lanthanum distribution.

Conclusions:

• La@SA@BC hydrogel exhibits high selectivity, robust ion tolerance, and strong adsorption capacity for phosphate.
• Multiple adsorption mechanisms including electrostatic interactions, ligand exchange, precipitation, and pore filling contribute to phosphate removal.
• La@SA@BC hydrogel is a promising candidate for remediating phosphate-contaminated water.