Removal of arsenic from aqueous solution using a surface-functionalized magnetic biochar derived from Chlorella

Area of Science:

• Environmental Science
• Materials Science
• Chemistry

Background:

• Arsenic contamination in water poses significant health risks.
• Effective remediation of inorganic arsenic(III) remains a challenge.
• Development of advanced materials for heavy metal removal is crucial.

Purpose of the Study:

• To design and synthesize magnetic biochar microspheres (Fe3O4/BC-α-MnOOH@A) for efficient arsenic(III) remediation.
• To investigate the combined redox and adsorption mechanisms for arsenic removal.
• To evaluate the performance and stability of the developed material in various water matrices.

Main Methods:

• Solvothermal decomposition to synthesize Fe3O4 nanoparticles using Chlorella biomass.
• Functionalization with α-MnOOH and sodium alginate (SA) for enhanced As(III) interaction.
• Characterization using SEM, XRD, FTIR, Raman, and XPS.
• Adsorption experiments to determine removal efficiency, kinetics, and stability.

Main Results:

• Fe3O4/BC-α-MnOOH@A microspheres demonstrated rapid adsorption kinetics, reaching equilibrium in 2 hours.
• Achieved 99.6% As(III) removal at pH 7, significantly outperforming control materials.
• Effective performance across a wide pH range (3-10) with minimal impact from common co-existing ions.
• High As(III) uptake capacity (2.91-2.94 mg g⁻¹) in drinking water, tap water, and seawater.
• Good stability over four adsorption-desorption cycles with low Fe/Mn leaching.

Conclusions:

• The Fe3O4/BC-α-MnOOH@A microspheres represent a multifunctional and regenerable material for arsenic(III) remediation.
• The material effectively combines redox and adsorption processes for enhanced arsenic removal.
• This approach offers a scalable and promising solution for treating arsenic-contaminated water.