Cooperative Spin Alignment Enhances Selective Singlet Oxygen Generation in Wastewater Pre-Oxidation System.

Area of Science:

• Environmental Chemistry
• Materials Science
• Catalysis

Background:

• Selective oxidation is crucial for wastewater pretreatment to improve biodegradability.
• Controlling peroxymonosulfate (PMS) activation at the molecular level for selective oxidation remains a challenge.
• Existing methods lack precise control over the activation pathway, limiting efficiency and selectivity.

Purpose of the Study:

• To develop a catalyst enabling molecular control over PMS activation for selective nonradical oxidation.
• To investigate the role of second-shell coordination in catalyst design for enhanced PMS activation.
• To demonstrate the practical application of the developed catalyst in wastewater pretreatment.

Main Methods:

• Synthesis of a Fe-N4 catalyst with second-shell boron coordination (FeN4/B) via supramolecular self-assembly.
• Characterization of the catalyst's electronic structure and coordination environment.
• Evaluation of PMS activation pathways, singlet oxygen selectivity, and catalytic activity for pollutant degradation.

Main Results:

• The FeN4/B catalyst achieved high singlet oxygen (¹O₂) selectivity (≥96%) and efficient PMS conversion (98%).
• Demonstrated rapid degradation of 15 biotoxic pollutants within 10 minutes and stable performance under various water conditions.
• A hydrogel-immobilized module operated continuously for 168 hours, increasing effluent biodegradability and reducing treatment costs.

Conclusions:

• Second-shell boron coordination in Fe-N4 catalysts enables precise control over PMS activation via cooperative spin alignment.
• The FeN4/B catalyst offers a highly selective and efficient route for wastewater pretreatment, generating singlet oxygen.
• This approach provides a practical, economically viable solution for enhancing water treatment processes.