Enhanced Electrochemical Dehalogenation via Direct Electron Transfer on Pd/Ti₄O₇ Flow Cathode

Area of Science:

• Environmental Chemistry
• Materials Science
• Electrochemistry

Background:

• Persistent halogenated organic pollutants pose environmental risks.
• Conventional water treatment methods face challenges like limited mass transfer and high energy consumption.
• Electrochemical dehalogenation offers a promising alternative for pollutant removal.

Purpose of the Study:

• To develop a self-separating flow cathode system for efficient electrochemical dehalogenation.
• To investigate the performance of palladium-loaded Ti4O7 microparticles (Pd/Ti4O7) in removing pollutants.
• To assess the system's efficiency, energy demand, and applicability to real-world wastewater.

Main Methods:

• Fabrication of a self-separating flow cathode using Pd/Ti4O7 microparticles and a porous Ti filter.
• Optimization of palladium loading for enhanced catalytic activity.
• Testing the system's efficiency in dechlorinating diclofenac (DCF) and other chlorinated pollutants.
• Analysis of the dehalogenation pathway (Direct Electron Transfer vs. hydrogen-mediated reduction).

Main Results:

• The Pd/Ti4O7 system demonstrated significantly faster DCF dechlorination compared to controls.
• Optimized Pd loading (0.5 wt%) enhanced dechlorination rates by 93- and 13-fold.
• The system effectively removed 99% of DCF from municipal wastewater in 7 minutes at a low energy cost.
• Direct electron transfer was identified as the dominant dehalogenation pathway, ensuring resistance to water matrix interferences.

Conclusions:

• Pd/Ti4O7 self-separating flow cathodes represent a robust and scalable platform for electrochemical dehalogenation.
• The technology offers efficient and energy-saving removal of halogenated organic pollutants from water.
• Further research is needed to address material costs and long-term life-cycle impacts for practical implementation.