Fe^(2+)对碳钢的微生物腐蚀作用的影响

THE INFLUENCE OF Fe^(2+) ON THE MICROBIOLOGICAL CORROSION OF CARBON STEEL

硫酸盐还原菌(SRB)对碳钢的腐蚀与其腐蚀产物FeS膜的状态有关。实验表明,当介质中的Fe^(2+)离子浓度低于50mg/L时,SRB的存在对碳钢起保护作用,其腐蚀产物膜致密,阻碍了介质与铁的作用,而且生物膜(bioilm)中的细菌数少于介质中的菌量;当介质中Fe^(2+)浓度高于50mg/L时,SRB的腐蚀产物膜厚且疏松,FeS成为腐蚀微电池的阴极,对碳钢的腐蚀起促进作用,生物膜的存在影响了杀菌剂的杀菌效能,膜越厚,杀菌效果越低。

The carbon steel corrosion induced by sulfate reducing bacteria (SRB) is attributed to the corrosion product film which is the biofilm of FeS. The test shows that, in the case of Fe2+ concentration less than 50 mg/L, the corrosion of carbon steel is inhibited since SRB live in it and the biofilm is compact so that it prevents carbon steel from reacting to the medium. Simultaneously the amount of SRB in the biofilm is less than that in the medium. In the case of Fe2+ concentration more than 50 mg/L, the biofilm is loose and porous, and FeS is the cathode of microelectric cell, which accelerates the corrosion of coupons. Moreover, the biofilm under this situation provides the bacteria with good safeguard so that it is difficult to kill the SRB in biofilm. The thicker the biofilm, the lower the effectiveness of the bactericide.