天然海水中NaN_3对316L不锈钢表面微生物膜催化阴极氧还原的影响

利用荧光显微观察技术选择临界使用浓度的NaN3,分别在O2及N2气氛下采用循环伏安及电化学阻抗技术研究其氧还原过程的电化学行为。结果表明,不锈钢表面的生物膜能够加大还原峰电流密度值,当使用临界浓度的NaN3处理不锈钢试样后,还原峰值明显减小,且峰电位均负移。微生物膜能够促进电子传递给最终电子受体O2,同时降低不锈钢材料发生腐蚀的可能性。由此推测,天然海水中,316L不锈钢表面微生物膜改变了传统阴极氧还原的电子传递途径,即加速了O2作为最终电子受体的电子传递过程,催化了O2的还原;同时,还能够抑制不锈钢材料的腐蚀。

Influence of NaN3 on Cathodic Oxygen Reduction Induced by Microbe-assisted Catalysis on Surface of 316LSS in Seawater

The influence of sodium azide NaN₃ on cathodic oxygen reduction induced by microbe-assisted catalysis on the surface of 316LSS in seawater was studied in order to reveal the possible use of sodium azide (NaN₃) as an agent to inhibit the activity of cytochrome c oxidase in microbial respiration. For such action, the adopted critical concentration of NaN₃ was evaluated by fluorescence microscopic technology, and cyclic voltammograms and AC impedance were used to study the variations of electrochemical properties of the electrodes in seawater aerated with oxygen and nitrogen atmosphere respectively. Results showed that biofilm on the surface of the stainless steel could increase the intensity of reduction peak current density; however, it decreased obviously when stainless steel samples were disposed with NaN₃, meanwhile, the peak potentials shifted negatively. According to the results of AC impedance, microbial respiration could directly promote the transfer of electrons to the final electron acceptor (oxygen); simultaneously reduce the tendency to corrosion of the stainless steel. It was suggested that the microbial adhesion on 316L stainless steel could change the traditional way of electron transfer of cathodic oxygen reduction in natural seawater, accelerating the transfer of electron to oxygen and finally catalyzing the reduction of oxygen.