D-氨基酸对不同钢材混合菌腐蚀行为的影响

Effect of D-amino Acids on Corrosion Behavior of Different Steels due to Mixed Bacteria

研究了杀菌剂与D-氨基酸对20#碳钢、N80钢以及P110钢在硫酸盐还原菌(SRB)+铁氧化菌(IOB)混合菌腐蚀过程中的影响作用,利用失重与电化学测量以及扫描电镜(SEM)对腐蚀形貌分析等初步探索了D-氨基酸的杀菌缓蚀增强机理。无杀菌剂组中P110发生严重腐蚀(0.278 mm/a),20#与N80腐蚀速率较低(为0.149、0.148 mm/a),所有试样表面有均匀且致密的生物膜以及腐蚀产物堆积;有杀菌剂组中三种钢材腐蚀程度减缓,腐蚀产物膜发生龟裂、剥离,其中Ca、Mg、P以及S含量明显减少。在添加杀菌剂溶液中浸泡14 d后,三种钢材的腐蚀速率明显降低。有无杀菌剂下,三种钢材耐蚀性由优到差排序均为N80>20#>P110。SRB和IOB混合菌的腐蚀机制可能是由于SRB通过自身代谢将基体Fe氧化为Fe^(2+),Fe^(2+)又被IOB进一步氧化为Fe^(3+)且IOB为SRB提供环境条件形成了协同作用。D-氨基酸和杀菌剂通过调控细菌基因表达、破坏细胞结构、氧浓差环境等方式有效的抑制微生物腐蚀(MIC)行为。三种钢材由于C、Cu等元素含量不同,使得三种钢材在无菌条件下腐蚀速率有所差异。

The effect of biocide and D-amino acid on the corrosion behavior of 20#carbon steel,N80 steel and P110 steel in the media of SRB+IOB mixed bacteria,was comparatively assessed by using weight loss method,electrochemical measurements and SEM.In the tests without biocide,P110 suffered from severe corrosion with weight loss of 0.278 mm/a,while weight loss of 20#and N80 were 0.149 and 0.148 mm/a respectively,while uniform and dense biofilms with deposited corrosion products formed on the surface of all the steels;in the tests with biocide,the corrosion of the three steels slowed down,it is found that the formed rust scales on the surface of steels with significantly lower content of Ca Mg,P,and S,but with cracks and spallation steels.The electrochemical measurement results also revealed that the corrosion rate of three steels was significantly reduced when they were immersed for 14 d in the corrosive media with addition of biocides.The corrosion mechanism of SRB and IOB mixed bacteria is probably due to that SRB oxidizes Fe to Fe^(2+)through its own metabolism,and Fe^(2+)is further oxidized by IOB to Fe^(3+),and IOB provides environmental conditions for SRB so as to form a synergistic effect.It is proposed that D-amino acids and biocide effectively inhibit MIC behavior by regulating the bacterial gene expression and destroys the cell structure,as well as the oxygen concentration difference environment.Due to the different content of C,Cu and others,the corrosion rate of the three steels may be different under the sterile conditions.