Activating persulfate by Fe⁰ coupling with weak magnetic field: performance and mechanism

Area of Science:

• Environmental Chemistry
• Advanced Oxidation Processes
• Water Treatment Technologies

Background:

• Persulfate (PS) activation is crucial for degrading persistent organic pollutants.
• Iron-based catalysts (Fe(0)) are widely studied for PS activation.
• Weak magnetic fields (WMF) offer a novel approach to enhance catalytic processes.

Purpose of the Study:

• To investigate the synergistic effect of WMF and Fe(0) on PS activation for contaminant degradation.
• To evaluate the efficiency of the WMF-Fe(0)/PS system in removing dyes and aromatic compounds.
• To elucidate the mechanism behind WMF-enhanced Fe(0)/PS oxidation.

Main Methods:

• Batch experiments were conducted to assess contaminant removal rates under varying conditions (pH, Fe(0) dosage, PS dosage).
• Degradation of Orange G (OG) and other organic contaminants (caffeine, 4-nitrophenol, etc.) was monitored.
• Sulfate radical identification and quantification were performed to understand the degradation pathways.

Main Results:

• The WMF-Fe(0)/PS process demonstrated a 5.4-28.2 fold enhancement in OG removal compared to Fe(0)/PS alone.
• WMF significantly improved decolorization and mineralization rates of OG and other contaminants (2.1-11.1 fold enhancement).
• Sulfate radical was identified as the primary oxidant, with WMF accelerating Fe(0) corrosion and Fe(2+) release.

Conclusions:

• WMF synergistically enhances the Fe(0)/PS catalytic system for efficient organic contaminant degradation.
• The enhanced performance is attributed to accelerated Fe(0) corrosion, increased Fe(2+) release, and subsequent higher sulfate radical production.
• WMF-Fe(0)/PS is a promising, cost-effective, and environmentally friendly advanced oxidation technology.