中性厌氧环境中硫酸盐还原菌导致锌的腐蚀行为研究

Investigation of zinc corrosion by sulfate-reducing bacteria in a neutral anaerobic environment

以锌为研究对象,使用表面表征方法和电化学测试,研究了一个培养周期内硫酸盐还原菌(Sulfatereducing bacteria,SRB)Desulfovibrio vulgaris(D.vulgaris)引起锌(Zn)试样腐蚀行为的影响。实验结果表明,SRB导致Zn试样发生了严重的均匀腐蚀和点蚀。浸泡7天后,SRB体系中的Zn试样平均失重为32.2 mg/cm^2,是无菌培养基中试样平均失重的42倍,腐蚀产物主要为ZnS。生物膜和腐蚀产物膜的累积在培养初期可以减缓金属基体与溶液界面的电子传输过程,导致腐蚀速率减缓。培养中后期,由于生物膜和腐蚀产物膜的阻隔作用,导致混合膜层底部有机碳源缺乏,SRB转向Zn获取自身所需电子,表现为腐蚀速率上升。

In this work,we investigated Zn corrosion by Desulfovibrio vulgaris(D.vulgaris),a type of sulfate-reducing bacteria(SRB),by surface characterizations and electrochemical measurement.The experimental data indicated that the minimum inhibitory concentration(MIC)of Zn by the SRB increased the corrosion rate during a 7-day incubation period,with both uniform and pitting corrosions evident on the coupons.After 7 days of immersion,the presence of D.vulgaris caused a weight loss in the Zn of 32.2 mg/cm^2,which was 42 times larger than that occurring in sterile medium.The corrosion product was ZnS.In the initial stage of incubation,the accumulation of biofilms and corrosion-product films reduced the electron transfer between the metal and solution interface,resulting in a decreased MIC.In the middle and late stages of incubation,biofilms and corrosion-product films formed on the coupons,which resulted in carbon-source starvation.As such,SRB sessile cells were forced to use elemental zinc as a substitute for lactate as the electron donor to achieve sulfate reduction,thereby leading to a more severe MIC.