气体扩散电极体系的电化学消毒

以自制活性炭/聚四氟乙烯(PTFE)气体扩散电极在无隔膜体系发生H2O2进行电化学消毒的系统研究,探讨了膜电极中PTFE质量分数WPTFE对氧气电还原特性的影响,研究了膜电极中载铂量WPt和造孔剂含量WNH4HCO3、外部操作条件pH值、氧气流速、溶液含盐量和电流密度对杀菌效率的影响.结果表明,WPTFE对H2O2的产率有明显的影响:产H2O2的峰电流先是随着WPTFE的增加而增大,然后减小.当WPTFE=50%时,峰电流最高.杀菌效果随着载铂量的提高而改善,WPt增加到4‰,杀菌效果和WPt=3‰时的杀菌效果基本相当.适量造孔剂的添加有效地改善了杀菌效果.杀菌效率随着pH值的下降迅速提高;该体系pH值适用范围较广:当原水细菌总数为106cfu.ml-1,pH=3—10,以载铂量WPt=3‰的气体扩散电极作为阴极进行电解,30 min后杀菌效率均能达到80%以上.在一定范围内增加氧气流速对H2O2的产生及杀菌效率的变化无太大影响.一方面,高的氧气流速增大了水的电阻,增加了杀菌能耗,提高了气体扩散电极体系杀菌的运行成本;另一方面,高的氧气流速在一定程度上缩短了处理时间,降低了设备投资.含盐量的增加使杀菌能耗减小,因此本电化学杀菌体系更加适合于高含盐量的水.杀菌效率随电流的升高而增加,但电流较大时,杀菌效率增加幅度较小.电流密度控制在6.6 mA.cm-2较为适宜.

THE ELECTROCHEMICAL DISINFECTION USING THE GAS DIFFUSION ELECTRODE SYSTEM

Study was performed on the electrochemical disinfection with H_2O_2 produced at the gas diffusion electrode (GDE) prepared from active carbon/ poly-tetrafluoroethylene(PTFE)in the non-membrane cell.The effect of PTFE mass fraction W_(PTFE) the reduction of oxygen at GDE was investigated.Additionally,the effect of Pt load W_(Pt), and the pore-forming agent content in GDE, operating such as pH value, oxygen flow rate Q_(o_2), salt content and current density on the disinfection were also investigated.The experimental results showed that W_(PTFE) had a significant effect on the generation of H_2O_2;its peak current first increased with W_(PTFE), then decreased, and reached the highest at W_(PTFE) of 50%.The disinfection improved with increasing Pt load, but its efficiency at W_(Pt) of 3% was equivalent to that at W_(Pt),of 4%.Addition of the pore-forming agent in the appropriate amount significantly improved the disinfection, lower pH value resulted in rapid rise of the disinfection efficiency.