In situ corrosion control in industrial water systems

The main objective of this study was to evaluate the efficacy of a biocide and a corrosion inhibitor against the corrosion of a circulating pipe in a cooling tower. Isothiazolone was tested as the industrial biocide. The results showed that the biocide by itself or combined with a dispersant was not efficient to control corrosion in the industrial system. Corrosion rates of 0.324 mm/year were recorded in both the presence and absence of the biocide. Corrosion control was successfully accomplished by using a corrosion inhibitor. In the latter case the maximum corrosion rate of 0.024 mm/year were obtained.     

Microstructure,morphology and physicochemical properties of nanocomposites containing hydroxyapatite/vivianite/graphene oxide for biomedical applications

Designing a nanocomposite that accumulates biocompatibility and antimicrobial behaviour is an essential requirement for biomedical applications. Hydroxyapatite (HAP), graphene oxide, and vivianite in one ternary nanocomposite with three phases and shapes led to an increase in cell viability to 97.6% ± 4 for the osteoblast cells in vitro. The obtained nanocomposites were investigated for their structural features using X-ray diffraction, while the microstructure features were analyzed using a scanning electron microscope (SEM) and a transmission electron microscope. The analysis showed a decrease in the crystal size to 13 nm, while the HAP grains reached 30 nm. The elongated shape of vivianite reached 200 nm on SEM micrographs. The monoclinic and hexagonal crystal systems of HAP and vivianite were presented in the ternary nanocomposite. The maximum roughness peak height reached 236.1 nm for the ternary nanocomposite from 203.3 nm, while the maximum height of the roughness parameter reached 440.7 nm for the di-nanocomposite of HAP/graphene oxide from 419.7 nm. The corrosion current density reached 0.004 μA/cm². The ferrous (Fe²⁺) and calcium (Ca²⁺) ions released were measured and confirmed. Therefore, the morphology of the nanocomposites affected bacterial activity. This was estimated as an inhibition zone and reached 14.5 ± 0.9 and 13.4 ± 1.1 mm for Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) after 24 h. The increase in viability and the antibacterial activity refer to the compatibility of the nanocomposite in different medical applications.     

Use of skin cell cultures for in vitro assessment of corrosion and cutaneous irritancy

Skin cell culture is one of the most promising tools for in vitro evaluation of both cutaneous irritancy and corrosion. New culture methodologies, including three-dimensional reconstruction of skin, allow the evaluation of a wide range of compounds and complex formulations. A number of tests have already been developed for the evaluation of cytotoxicity and many end-points are now currently used, including cell viability, alteration of cell growth or cell function. In recent years parameters more closely related to in vivo irritancy effects such as synthesis of inflammatory mediators and/or their release by keratinocytes after exposure to potential skin irritants have been evaluated. This paper reviews technological aspects and results of validation using skin cell culture for in vitro assessment of corrosion and skin irritancy. Advantages and limits of skin cell cultures are also presented. Current questions about the validation process of cutaneous irritation and corrosion are also considered.     

微生物抑制金属腐蚀机理的研究进展

传统金属防腐方法成本较高或者容易产生次生环境问题。微生物防腐蚀是一项新的绿色防腐技术,随着越来越多抗腐蚀微生物的发现,以及有益菌膜研究的开展,研究者们发现了微生物抑制金属腐蚀的众多机理,本文对此进行了归纳总结。微生物可以通过生物驱除、分泌腐蚀抑制剂、生成胞外多聚物、降低溶解氧、形成生物膜屏障、分泌生物表面活性剂、噬菌体控制、非生物膜屏障等过程控制和减缓金属腐蚀。金属的微生物腐蚀抑制作用通常不是由单一机制引起的,而是多种机制共同作用的结果。深入理解微生物抑制金属腐蚀的机理,有利于为减缓金属腐蚀行为提供借鉴。     

Isolation and Some Properties of Alkalophilic Bacteria Utilizing Rayon Waste

Bacillus No. C-11 which utilized rayon waste was isolated. This strain belongs to the genus Bacillus from its morphological and biochemical characteristics but grew better in alkaline media than in neutral media. Residual sugars of rayon waste were 34.7 % after 2 days cultivation, 25.5% after 4 days and 7.0% after 9 days. Yeast extract and N-source, such as polypeptone or urea stimulated the utilization of rayon waste. The long period cultivation optimum pH was about 11, and the short period cultivation optimum pH was about 9. Partially purified hemicellulase from Bacillus No. C-11 was most active at pH 7, but still active at pH 10. The stable pH for this enzyme action was in the range of 5.5 to 9, and from the hemicellulose enzymatic digest, xylose, xylobiose, xylotriose and oligosaccharides were detected.     

不同生态系统对湘西洛塔降雨量及岩溶效应的影响

采用雨量器、滤膜法、CO2气体监测管法、标准试片对湘西洛塔不同生态系统降雨量、泥沙量、土壤CO2浓度、溶蚀速度进行了研究。结果表明:森林生态系统降雨量高于灌丛生态系统,观测第一年高6.84mm,第二年高218.08mm,且时间趋向均匀;灌丛生态系统水土流失严重,其泥沙含量是森林生态系统的1.53倍,土壤侵蚀为强度,而森林生态系统为微度;不同深度土壤CO2浓度在森林和灌丛生态系统中具有相同的变化趋势,在春季、秋季、冬季随土层加深而增大,在夏季,随土层加深先减少后增大,但季节变化动态略有差异,森林生态系统不同深度、不同季节土壤CO2浓度均大于灌丛生态系统;从全年土壤CO2浓度对比来看,10、20、40cm处,森林生态系统分别是灌丛生态系统的1.66、1.59和1.90倍;不同深度上,溶蚀速度在森林和灌丛生态系统具有相同的变化趋势,15cm处均大于地面,从同一深度来看,森林生态系统溶蚀速度均大于灌丛生态系统,地面、15cm处溶蚀速度分别是灌丛生态系统的1.11倍、2.57倍,说明森林生态系统具有较好的岩溶效应。     

Instrumental analysis of microbiologically influenced corrosion

Appropriate application of techniques for detection andmonitoring of microbiologically influenced corrosion isessential for understanding the mechanistic nature of theinteractions and for obtaining control methods. This paperreviews techniques and methods applied tomicrobiologically influenced corrosion in recent years.The techniques presented in this paper includeelectrochemical noise measurement, concentric electrodes,scanning vibrating electrode mapping, electrochemicalimpedance spectroscopy, atomic force microscopy,confocal laser microscopy, Fourier transform infraredspectroscopy, x-ray photoelectron spectroscopy, Augerelectron spectroscopy, extended x-ray absorption finestructure and utilization of piezoelectric materials. Thesetechniques are reviewed regarding the heterogeneouscharacteristics of microbial consortia and their possibleinfluences on metal substrata. We hope this review willmotivate application and combination of new techniquesfor practical detection and on-line monitoring of theimpact of biofilms on engineering alloys.     

氯盐型融雪剂的环境影响及其替代材料研发进展

传统氯盐型融雪剂对环境的负面影响日益凸显,亟需研发价格低廉、环境影响较弱、融雪效果良好的环境友好型融雪替代材料。论文综述了现有氯盐型融雪剂应用现状,及其对土壤环境、水环境、植物和交通基础设施等的影响机理,并详细阐述了非氯型和混合型融雪剂替代材料的研发状况与应用成效。针对目前替代融雪材料开发和应用中所存在的问题,提出了环境友好融雪剂的研制发展方向以及减轻其环境危害行之有效的对策。     

Bulk phase resource ratio alters carbon steel corrosion rates and endogenously produced extracellular electron transfer mediators in a sulfate-reducing biofilm

Desulfovibrio alaskensis G20 biofilms were cultivated on 316 steel, 1018 steel, or borosilicate glass under steady-state conditions in electron-acceptor limiting (EAL) and electron-donor limiting (EDL) conditions with lactate and sulfate in a defined medium. Increased corrosion was observed on 1018 steel under EDL conditions compared to 316 steel, and biofilms on 1018 carbon steel under the EDL condition had at least twofold higher corrosion rates compared to the EAL condition. Protecting the 1018 metal coupon from biofilm colonization significantly reduced corrosion, suggesting that the corrosion mechanism was enhanced through attachment between the material and the biofilm. Metabolomic mass spectrometry analyses demonstrated an increase in a flavin-like molecule under the 1018 EDL condition and sulfonates under the 1018 EAL condition. These data indicate the importance of S-cycling under the EAL condition, and that the EDL is associated with increased biocorrosion via indirect extracellular electron transfer mediated by endogenously produced flavin-like molecules.