Surface Fe^IV═O Induced Highly Selective Phenol Polymerization via Proton-Coupled Electron Transfer

Area of Science:

• Environmental Chemistry
• Materials Science
• Polymer Chemistry

Background:

• Organic polymerization is a sustainable method for water decontamination and resource recovery.
• Traditional electron transfer processes lack the selectivity needed for efficient pollutant removal.

Purpose of the Study:

• To demonstrate the use of surface high-valent iron-oxo species (≡FeIV═O) on nanoscale zerovalent iron (nZVI) for selective organic polymerization.
• To investigate the mechanism and efficiency of phenol recovery via proton-coupled electron transfer (PCET).

Main Methods:

• Characterization of surface high-valent iron-oxo species on nZVI.
• Utilizing PCET pathway for phenol transformation and polymerization.
• Kinetic analysis using para-substituted phenolic compounds and a dual descriptor model (pKa and vertical ionization potential).
• Testing performance in continuous-flow operations with real phenol wastewater.

Main Results:

• Achieved high polymeric selectivity of 92.6% and average molecular weight of 3231 g mol⁻¹ for phenol polymers.
• Demonstrated superior selectivity compared to traditional electron transfer systems (below 77.0%).
• Identified hydrogen bonding between ≡FeIV═O and phenol as a key facilitator.
• Validated a dual descriptor model for predicting polymerization kinetics.
• Showcased effective phenol removal from real wastewater in continuous-flow operations.

Conclusions:

• Surface high-valent iron-oxo species on nZVI enable highly selective organic polymerization via PCET.
• This method offers a sustainable and efficient strategy for phenol recovery and water decontamination.
• The findings highlight the potential of ≡FeIV═O in resource utilization and advanced water treatment.