Amino-triggered micro acidity promotes phosphate release from hydroxyapatite and uranium autunite formation

Area of Science:

• Environmental Science and Engineering
• Materials Science
• Inorganic Chemistry

Background:

• Uranium(VI) (U(VI)) contamination in leachate from uranium tailings poses significant environmental risks.
• Existing remediation methods often lack efficiency, stability, or environmental friendliness.
• Development of advanced materials is crucial for effective U(VI) removal from contaminated water sources.

Purpose of the Study:

• To synthesize and characterize a novel composite material, APTES/ATP@HAP, for efficient U(VI) removal.
• To systematically investigate the adsorption efficacy and mechanism of U(VI) extraction using the prepared composite.
• To evaluate the material's performance in actual wastewater and its recyclability.

Main Methods:

• Modification of attapulgite (ATP) with 3-aminopropyltriethoxysilane (APTES) to create APTES/ATP.
• Loading of hydroxyapatite (HAP) onto the modified ATP to form the APTES/ATP@HAP composite.
• Systematic adsorption experiments to determine optimal conditions (pH, temperature, time) and assess U(VI) removal capacity and mechanism.

Main Results:

• The APTES/ATP@HAP composite exhibited a maximum U(VI) adsorption capacity of 2128.72 mg·g⁻¹, significantly higher than unmodified HAP or ATP.
• The material achieved 99.11% U(VI) removal from actual wastewater at a dosage of 0.8 g·L⁻¹.
• High removal efficiency (99.06%) was maintained after five recycling cycles, demonstrating excellent stability and reusability.

Conclusions:

• APTES/ATP@HAP is a highly effective and stable adsorbent for U(VI) removal from contaminated water.
• The study elucidated the mechanism involving amino-triggered micro-acidity promoting autunite formation for U(VI) immobilization.
• This work presents a promising green and efficient composite material for addressing uranium contamination in industrial wastewater.