Deciphering Mn(II)/peroxymonosulfate system with nitrilotriacetic acid to degrade antibiotics: Roles of Mn species and interference of protein-like DOM

Area of Science:

• Environmental Chemistry
• Water Treatment Technologies
• Aquaculture Science

Background:

• Aquaculture wastewater contains significant antibiotic residues, such as florfenicol (FF).
• The impact of coexisting protein-like dissolved organic matter (DOM) on FF degradation in wastewater is not well understood.
• Efficient removal of FF is crucial for mitigating environmental contamination and antibiotic resistance.

Purpose of the Study:

• To develop an efficient advanced oxidation process (AOP) for florfenicol (FF) degradation in aquaculture wastewater.
• To investigate the role of protein-like dissolved organic matter (DOM) in interfering with FF removal.
• To elucidate the degradation pathways and mechanisms of FF under the established AOP.

Main Methods:

• An advanced oxidation process (AOP) was established using Mn(II), nitrilotriacetic acid (NTA), and peroxymonosulfate (PMS).
• Electrochemical measurements and density functional theory (DFT) calculations were employed to study the interaction between DOM components and the AOP system.
• Degradation pathways were analyzed to understand the transformation of FF and its toxicity reduction.

Main Results:

• The Mn(II)/NTA/PMS system achieved (97.38±1.02)% FF removal within 20 min, primarily driven by the Mn(V)=O species.
• Protein-like amino acids, especially poly lysine, tryptophan, and methionine, inhibited FF degradation by competing for PMS and being preferentially oxidized.
• Primary degradation pathways included defluorination, dechlorination, and aromatic ring hydroxylation, leading to reduced toxicity.

Conclusions:

• The developed Mn(II)/NTA/PMS AOP is a sustainable strategy for removing florfenicol (FF) from aquaculture wastewater.
• Mn(V)=O is the key active species for FF degradation, while •OH, •SO4-, and 1O2 play minor roles.
• Protein-like DOM significantly interferes with FF degradation by competing for reaction sites and influencing the oxidation pathways.