Lanthanum hydroxide engineered sewage sludge biochar for efficient phosphate elimination: Mechanism interpretation...

Area of Science:

• Environmental Chemistry
• Materials Science
• Water Treatment

Background:

• Sewage sludge is a growing environmental concern, requiring sustainable management strategies.
• Phosphate pollution in aquatic environments leads to eutrophication.
• Developing cost-effective and efficient adsorbents for phosphate removal is crucial.

Purpose of the Study:

• To synthesize and characterize lanthanum hydroxide-engineered sewage sludge biochar (La-SSBC) for efficient phosphate removal.
• To investigate the adsorption capacity and stability of La-SSBC under various conditions.
• To elucidate the underlying phosphate adsorption mechanism of La-SSBC.

Main Methods:

• Synthesis of La-SSBC from sewage sludge biochar.
• Phosphate adsorption experiments in aqueous solutions.
• Adsorption performance evaluation under varying pH, co-existing anions, and recycling conditions.
• Characterization using various physicochemical techniques.
• Statistical physics modeling and adsorption energy calculations.

Main Results:

• La-SSBC exhibited a high phosphate adsorption capacity of 312.55 mg P/g at 20 °C.
• The adsorbent demonstrated stable performance across a wide pH range and in the presence of competing anions.
• Recycling experiments confirmed the adsorbent's durability.
• A unique double-layered adsorption mechanism involving functional groups and cation release was identified.

Conclusions:

• La-SSBC is a highly efficient and stable adsorbent for phosphate removal from aqueous solutions.
• The study reveals a novel double-layered adsorption mechanism, advancing the understanding of phosphate-biochar interactions.
• This approach offers a sustainable solution for simultaneous sewage sludge valorization and phosphate remediation.