Redox-coupled coordination strategy for xanthate detoxification via self-catalysis over a broad pH range

Area of Science:

• Environmental Chemistry
• Materials Science
• Catalysis

Background:

• Xanthate compounds are widely used in mineral flotation but pose environmental risks.
• Effective degradation strategies for sulfur-containing pollutants are crucial for industrial wastewater treatment.
• Existing methods often struggle with stability, reusability, or efficiency in neutral pH conditions.

Purpose of the Study:

• To develop a stable and efficient catalytic system for xanthate degradation.
• To investigate the mechanism of xanthate degradation using a Cu(II)/Cu(I) redox cycle on MWCNTs.
• To assess the catalyst's performance, stability, and applicability to other sulfur-containing flotation reagents.

Main Methods:

• Anchoring Cu(II)/Cu(I) onto multi-walled carbon nanotubes (MWCNTs) via wet ball milling.
• Utilizing a Cu(II)/Cu(I) redox cycle to activate hydrogen peroxide for degradation.
• Employing DFT calculations to verify adsorption mechanisms.
• Conducting degradation experiments under various conditions and assessing catalyst stability and reusability.
• Analyzing degradation products and pathways using UHPLC-MS and ECOSAR toxicity modeling.

Main Results:

• Over 90% degradation of PBX achieved under optimal conditions (pH 7.0, 12 mM H2O2, 0.1 g/L catalyst).
• Catalyst demonstrated high activity across a wide pH range (4-9) and maintained performance over five cycles with minimal copper leaching (<0.05 mg/L).
• Effective degradation of diethyl dithiophosphate (71.7% removal) and significant reduction in aquatic toxicity of degradation products were observed.

Conclusions:

• The developed Cu(II)/Cu(I)@MWCNT catalyst provides an effective and stable method for xanthate degradation via a redox-coupled mechanism.
• The catalyst shows excellent resistance to interference and broad applicability to sulfur-containing flotation reagents.
• This study offers a promising strategy for treating industrial effluents containing sulfur-based pollutants at neutral pH.