Arsenic adsorption by different Fe-enriched biochars conditioned with sulfuric acid

Area of Science:

• Environmental Science
• Materials Science
• Water Treatment

Background:

• Arsenic contamination in water poses significant environmental and health risks.
• Biochar is a promising adsorbent, but its efficiency for arsenic removal can be limited.
• Iron modification can enhance the adsorption properties of biochar.

Purpose of the Study:

• To synthesize and characterize iron-modified biochar for arsenic(V) removal.
• To evaluate the adsorption capacity of modified biochar under varying pH and ionic strength.
• To investigate the effect of sulfuric acid concentration on iron modification and adsorption performance.

Main Methods:

• Biochar was modified with ferric chloride and sulfuric acid before pyrolysis at 600 °C.
• Fe-modified biochar (50FBC and 72FBC) was characterized and analyzed.
• Arsenic(V) adsorption capacity was evaluated across different pH levels and ionic strengths.

Main Results:

• Maximum As(V) adsorption capacities were 10.33 mg g^-1 for 50FBC and 15.61 mg g^-1 for 72FBC.
• Adsorption capacity increased 5.0 and 7.8 times compared to pristine biochar.
• Higher sulfuric acid concentration (72%) resulted in superior arsenic adsorption, particularly under neutral to alkaline conditions (pH 7.0–10.0).

Conclusions:

• Fe-modified biochar, especially 72FBC, demonstrates enhanced As(V) adsorption capabilities.
• Increased iron content and functional groups on the biochar surface contribute to improved adsorption.
• Fe-modified biochar shows potential as an effective and environmentally friendly adsorbent for arsenic removal from contaminated water over a broad pH range.