Catalyst regeneration and the retention of high catalytic activity are still the critical issues in environmental application. A novel fluidized gas-liquid-solid electrochemical reactor was developed to simultaneously remove chlorinated pollutants and in situ regenerate the spent catalyst. Activated carbon modified with palladium catalyst （AC-Pd） was prepared for electrochemical dechlorination. For the 4-chlorophenol wastewater of initial concentration 200 mg· L^- 1, the removal efficiency could nearly reach 100% in less than 30 rain. Catalytic activity of AC-Pd catalyst was preserved effectively even in consecutive cycling run without special regeneration. OH radicals, generated by electrochemical reaction, played a critical role in self-regeneration of AC-Pd. High catalytic activity of spent AC-Pd catalyst provided an attractive alternative in wastewater treatment.
The most reactive hydroxyl radical (°OH) was generated by electrochemical approach with safe water as the complete atom source. The direct evidence for °OH formation was obtained by electron spin resonance method. The powerful °OH electrochemically generated could effectively degrade organic pollutants and reduce the toxicity of wastewater. Electrochemical disinfection by °OH was considerably efficient even without the aid of active chlorine. Bacteria inactivation of 99.99% was achieved for contact time of 30 min and current density of 5 mA·cm-2. In comparison with active chlorine, °OH is rather attractive as a promising environmentally benign disinfectant and opens a new route for microbial inactivation.
