Institutional Repository of Key Laboratory of Marine Environmental Corrosion and Bio-fouling, IOCAS
|Place of Conferral||中国科学院海洋研究所|
为研究典型腐蚀细菌在杀菌剂耐受条件下对金属X70管线钢的腐蚀行为，从海南省三亚市天涯镇的红塘湾（北纬 18°17′58″，东经 109°15′18″）采集了挂片44个月的碳钢921、碳钢Q345、铜合金、铝合金腐蚀试片的锈层，然后进行好氧菌和厌氧菌的分离纯化、和鉴定。从分离出来的36株细菌中选择一株典型腐蚀菌好氧假单胞菌（Pseudomonas sp.）和一株典型厌氧腐蚀细菌硫酸盐还原菌（Desulfovibrio hontreensis）为试验对象；选择腐蚀防护领域常用的四羟甲基硫酸磷（THPS）为试验用杀菌剂；选择合适的杀菌剂浓度并设置四个实验体系：无菌无杀菌剂体系，无菌含杀菌剂体系，含菌无杀菌剂体系，含菌含杀菌剂。将X70试片分别在四个体系中浸泡一定周期后，进行吸附曲线测定、腐蚀失重测试、腐蚀形貌及腐蚀产物的表征。
研究表明厌氧环境中75ppm THPS不会促进X70管线钢试片的腐蚀；Desulfovibrio hontreensis在不含杀菌剂的情况下能显著促进X70管线钢试片的腐蚀，在75 ppm（在D. hontreensis的耐受范围内）THPS存在下，与不含THPS的体系相比，D. hontreensis进一步促进了X70管线钢的腐蚀。通过吸附曲线的测定，浸泡15天以后，含菌含杀菌剂体系中细菌吸附数量大于含菌无杀菌剂体系，这说明D. hontreensis成膜能力强于含菌无杀菌剂体系。
在好氧条件下THPS对X70管线钢试片有一定的促进腐蚀作用；Pseudomonas sp.在不含杀菌剂的情况下抑制了X70管线钢试片的腐蚀，在75 ppm（在Pseudomonas sp的耐受范围内）THPS存在下，Pseudomonas sp.对X70管线钢的腐蚀行为由抑制转为促进。通过吸附曲线的测定和荧光显微镜观察，浸泡7天以后，含菌含杀菌剂体系中细菌吸附数量约为含菌无杀菌剂体系的4-5倍，Pseudomonas sp.成膜能力也远强于无杀菌剂体系。
In petroleum industry cooling, pipelines, marine equipments and water circulation systems, biocides are usually used to inhibit microbial corrosion of metal materials, but biocides can only inhibit the growth of microorganisms to a certain extent and it is difficult to completely kill them. Nowadays, the long-term use of large doses of biocides has greatly accelerated the increase of microbial resistance. When the concentration of the biocides is in the range of the microbial tolerance, the metabolic modes and biofilm-forming abilities of the microorganisms may be changed under the stimulation of the biocides. Therefore, the corrosion behavior of the metals and the corrosion mechanisms may not be the same compared with that without biocides, and research in this area is completely missing.
In order to study the corrosion behavior of X70 steel by typical corrosive bacteria under biocide stress, the rust layer samples were collected from the carbon steel 921, carbon steel Q345, copper alloy and aluminum alloy, which were immersed in seawater for 44 months in Hongtang Bay (latitude 18°17'58″ north latitude, 109°15′18″ east longitude) Tianya Town, Sanya City, Hainan Province. Bacterial cultures were enriched from the samples, and isolation, purification and identification of both aerobic bacteria and anaerobic bacteria were done. An aerobic strain of Pseudomonas sp. and a typical anaerobic corrosion bacterial strain of Desulfovibrio hontreensis which is one of the sulfate-reducing bacteria (SRB), were selected from the 36 purified strains for further studies. Tetramethylol phosphate sulfate (THPS), commonly used in the field of corrosion protection, was selected as the test biocide. Appropriate biocide concentrations were chosen and then four experimental systems were set up: sterile systems free of biocide, sterile systems containing biocide, bacterial inoculation systems free of biocide and bacterial inoculation systems containing biocide. The X70 test coupons were immersed in the four experimental systems for a certain period. For comparison of the corrosion behavior of X70 at each condition, the weight loss test, X70 morphology and characterization of corrosion products were performed.
Studies showed that 0-xx ppm alone did influence the corrosion behavior of X70 steel; D. hontreensis accelerated the corrosion of X70 steel in the absence of THPS; In the presence of 75 ppm THPS (within its tolerance range of D.hontreensis ) corrosion of X70 steel by D. hontreensis was greatly promoted in comparison with that without THPS. According to the measurement of the adsorption curve, the number of bacteria colonized on the X70 test coupons in the biocide-containing system was more than that of the bacterial system without biocide after 15 days of immersion. This clearly indicates that biofilm-forming ability of D. hontreensis was increased due to the presence of biocide.
Under aerobic conditions, THPS alone could accelerate the corrosion of X70 to some extend; Pseudomonas sp. inhibited the corrosion process of X70 in the absence of THPS; Interestingly, Pseudomonas sp. accelerated the corrosion process of X70 in the presence of 75 ppm THPS. The data of adsorption curve measurement and fluorescence microscopic observation showed that, the number of bacteria colonized on the X70 test coupons in the biocide-containing system was about 4-5 times compared with that of the biocide-free system after 7 days of immersion. Similarly to cells of D. hontreensis, the biofilm-forming ability of Pseudomonas sp. was also promoted by biocide.
Therefore/to conclude, the use of THPS can promote the biofilm forming ability of corrosive microorganisms and thus influence the corrosion behavior of metals. The mechanisms of microbiologically influenced corrosion are thus very likely altered.
|徐利婷. 细菌在杀菌剂耐受条件下对X70钢的腐蚀行为研究[D]. 中国科学院海洋研究所. 中国科学院大学,2020.|
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