Search Results (32)

Reinforced concrete durability depends on a passive oxide film protecting embedded steel, sustained by high-alkalinity pore solutions. Cracking fundamentally alters transport, allowing rapid chloride and carbon dioxide ingress, which undermines passivity and accelerates corrosion. Self-healing concrete technologies aim to autonomously restore transport barriers and reestablish electrochemical stability. This review critically synthesizes evidence on healing effectiveness for corrosion mitigation through a dual framework of barrier restoration and interface stabilization, integrating depth-resolved chloride profiles with electrochemical performance indices. Critically, visual crack closure proves an unreliable indicator of corrosion protection. Healing mechanisms exhibit characteristic spatial signatures: autogenous and microbial approaches preferentially seal surface zones with diminishing effectiveness at reinforcement depth, while encapsulated low-viscosity polymers achieve greater depth continuity. However, electrochemical recovery consistently lags transport recovery, with healed specimens achieving only partial restoration of intact corrosion resistance. Recovery effectiveness depends on crack geometry, moisture conditions, and healing mechanism characteristics, with systems performing effectively only within narrow, condition-specific windows. Effective corrosion protection requires coordinated barrier and interface strategies targeting both bulk transport and steel surface chemistry. The path forward demands rigorous field validation emphasizing electrochemical outcomes over appearance metrics, long-term durability assessment, and performance-based verification frameworks to enable predictable service life extension. Full article

Microbiologically Influenced Corrosion (MIC) significantly endangers steel infrastructure, particularly in marine and buried environments, causing considerable economic and environmental damage. Sulphate-reducing bacteria (SRB) are primary supporters of MIC, accelerating iron corrosion through hydrogen sulfide production. Conventional mitigation strategies, including protective coatings and cathodic protection, often face challenges such as limited effectiveness against SRB and the aggressiveness of saltwater corrosion. This study explores a novel approach by directly introducing zinc oxide (ZnO) nanoparticles into the microbial medium to inhibit SRB activity and reduce MIC. Iron metal coupons were immersed in seawater under three conditions: control (seawater only), seawater with SRB, and SRB with ZnO nanoparticles. These coupons were used as electrodes in microbial fuel cells to obtain real-time voltage readings. At the same time, corrosion was evaluated using cyclic voltammetry (CV), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), mass loss, and pH measurements. Results demonstrate that ZnO nanoparticles significantly inhibited SRB growth, as confirmed by the antibiotic susceptibility test (ABST). It was revealed that the corrosion rate increased by 21.3% in the presence of SRB compared to the control, whereas the ZnO-added electrode showed a 21.7% reduction in corrosion rate relative to the control. SEM showed prominent corrosive products on SRB-exposed coupons. ZnO-added coupons exhibited a protective layer with grass-like whisker structures, and EDX results confirmed reduced sulfur and iron sulfide deposits, indicating suppressed SRB metabolic activity. ABST confirmed ZnO’s antimicrobial properties by producing clear inhibition zones. ZnO nanoparticles offer the dual benefits of antimicrobial activity and corrosion resistance by forming protective self-coatings and inhibiting microbial growth, making them a scalable and eco-friendly alternative to traditional corrosion inhibitors. This application can significantly extend the lifespan of iron structures, particularly in environments prone to microbial corrosion, demonstrating the potential of nanomaterials in combating microbiologically influenced corrosion (MIC). Full article

Microbiologically influenced corrosion (MIC) represents a critical challenge to the integrity of pipelines, piping, and metal structures in offshore environments, directly affecting the safety and operational costs of companies in the energy sector. However, conventional control methods, such as the use of chemical inhibitors, raise environmental and economic concerns. To face this problem, a biosurfactant produced by Pseudomonas cepacia CCT 6659 was tested as a biocorrosion inhibiting agent on carbon steel specimens immersed in seawater. For this purpose, static and dynamic conditions were simulated using different concentrations of the biosurfactant. Furthermore, analyses were performed using Scanning Electron Microscopy paired with Energy Dispersive Spectroscopy (SEM/EDS) to visualize the morphology of the biofilm and its chemical components. Laboratory tests indicated that the biosurfactant formulated in a 1:5 (v/v) ratio reduced the mass loss of test specimens (119.72 ± 2.64 g/m²) by no less than 57.3% compared to the control (280.28 ± 4.58 g/m²). Under dynamic conditions, the 1:2 (v/v) formulation showed greater protection, being able to reduce specimen corrosion (578.87 ± 7.01 g/m²) by 69.6% compared to the control (1901.41 ± 13.53 g/m²). SEM/EDS analyses revealed changes in surface composition and a reduction in corrosive elements associated with sulfur in the formed biofilms, which may be associated with a decrease in sulfate-reducing bacteria (SRB) activity, suggesting microbial inhibition by the biosurfactant. The results obtained in this study highlight the biosurfactant as a viable and ecological alternative to synthetic inhibitors, with potential application in the protection of metal structures exposed to corrosive environments in offshore energy systems, promoting greater durability, sustainability, and less environmental impact. Full article

Microbial extracellular polymeric substances (EPSs) are emerging as sustainable alternatives to conventional corrosion inhibitors due to their eco-friendly nature, biodegradability, and functional versatility. Secreted by diverse microorganisms including bacteria, fungi, archaea, and algae, EPSs are composed mainly of polysaccharides, proteins, lipids, and nucleic acids. These biopolymers, chiefly polysaccharides and proteins, are accountable for surface corrosion prevention through biofilm formation, allowing microbial survival and promoting their environmental adaptation. Usually, EPS-mediated corrosion inhibitions can take place via different mechanisms: protective film formation, metal ions chelation, electrochemical property alteration, and synergy with inorganic inhibitors. Even though efficacious EPS corrosion prevention has been demonstrated in several former studies, the application of such microbial inhibitors remains, so far, a controversial topic due to the variability in their composition and compatibility toward diverse metal surfaces. Thus, this review outlines the microbial origins, biochemical properties, and inhibition mechanisms of EPSs, emphasizing their advantages and challenges in industrial applications. Advances in synthetic biology, nanotechnology, and machine learning are also highlighted and could provide new opportunities to enhance EPS production and functionality. Therefore, the adoption of EPS-based corrosion inhibitors represents a promising strategy for environmentally sustainable corrosion control. Full article

Microorganisms take an active part in the processes of microbiologically influenced corrosion, which is protected against by using bactericides—often toxic compounds—with inhibitory properties. There are many studies of eco-friendly “green” biocides/inhibitors, in particular those based on microbial metabolites. Indicators for the processes of microbial corrosion of steel 3 induced by the sulfate-reducing bacteria Desulfovibrio oryzae NUChC SRB2 under the influence of the strains Bacillus velezensis NUChC C2b and Streptomyces gardneri ChNPU F3 have not been investigated, which was the aim of this study. The agar well diffusion method (to determine the antibacterial properties of the supernatants) was used, along with the crystal violet (to determine the biomass of the biofilm on the steel) and gravimetric methods (to determine the corrosion rate). A moderate adhesiveness to steel 3 was established for D. oryzae due to its biofilm-forming ability. The presence of a supernatant on cultures of S. gardneri, B. velezensis and their mixture (2:1) did not reduce the biofilm-forming properties of D. oryzae. Compared to the control, a decrease in the corrosion rate was recorded for the variant of the mixture of the studied bacterial culture supernatants. This indicates the potential of this mixture for use in corrosion protection in environments with sulfate-reducing bacteria, which requires further research. Full article

This study investigates the formation of a protective layer on a 5083 aluminum alloy surface induced by microorganisms from salt marsh. The influence of the initial surface roughness was examined to identify optimal conditions for maximum coverage and thickness of the protective layer. As two opposing effects are suspected, where high surface roughness enhances bacterial adhesion but reduces the resistance to abiotic corrosion, various degrees of roughness were tested. Using electrochemical experiments (OCP measurement, 1/Rp determination, and pitting sensitivity), SEM/TEM observation and EDX characterization, a compromise was found on the initial roughness to obtain a thick protective layer through good bacterial adhesion while minimizing abiotic corrosion. The optimal roughness, achieved through 240-grit grinding, facilitates a uniform distribution of microorganisms and the development of a dense, evenly thick protective layer that significantly enhances the alloy’s resistance to pitting corrosion. The passivity domain doubled when comparing the electrochemical behavior of electrodes immersed in the presence of microbial activity to those immersed without it. Full article

Microbial corrosion has significant implications for the economy, environment, and human safety worldwide. Photocatalytic antibacterial technology, owing to its advantages in environmental protection, broad-spectrum, and efficient sterilization, presents a compelling alternative to traditional antibacterial strategies for microbial corrosion protection. In recent years, photocatalytic quantum dot materials have garnered considerable attention in this field due to their unique quantum effects. This article provides a brief overview of the quantum effects associated with quantum dot materials, reviews the classification and preparation methods of these photocatalytic quantum dots, and elucidates their inhibitory effects and mechanisms against microbial corrosion. Finally, this article summarizes unresolved issues and prospects for the future development of quantum dots in the realm of microbial corrosion protection. Full article

Microbially influenced corrosion poses a significant threat to the integrity and longevity of carbon steel infrastructure, particularly in environments conducive to biofilm formation by thiosulfate-reducing bacteria (TRB) to carbon steel. This study explores the potential of Portulaca oleracea, an edible plant species, as a dual-action biocide and green corrosion inhibitor for mitigating MIC adhesion. Through a comprehensive suite of experimental and analytical techniques, including electrochemical analysis, microbial analysis, gravimetric methods, and surface characterization, the efficacy of Portulaca oleracea extract is evaluated for its ability to inhibit TRB growth and biofilm formation while concurrently providing corrosion protection to carbon steel substrates. The electrochemical analyses reveal the extract’s capacity with the anodic reaction inhibition achieving 80%, thereby reducing the overall corrosion rate of carbon steel in the presence of TRB biofilms. Complementary microbial analyses, such as viable cell counting using test kits, elucidate the biocidal action of the extract, effectively suppressing TRB growth and biofilm development, with the presence of 20 ppm of the extract reducing bacterial growth. Surface characterization techniques provide insights into the adsorption behavior of the extract’s constituents on the carbon steel surface, forming a protective film that mitigates corrosion and biofilm adhesion. The adsorption of the extract at the interface between mild steel and the formation water adheres to Langmuir isotherm. Overall, the biocorrosion issue we are addressing in this work is crucial for ensuring the sustainability and efficiency of equipment, pipelines, and other metal-based systems. Full article

Drinking water distribution systems (DWDSs) may be contaminated to various degrees when different microorganisms attach to the pipe walls. Understanding the characteristics of biofilms on pipe walls can help prevent and control microbial contamination in DWDSs. The biofilm formation, interspecific interactions, and chlorine resistance of 10 dual-species biofilms in polyethylene (PE) and cast iron (CI) pipes were investigated in this paper. The biofilm biomass (heterotrophic bacterial plate count and crystal violet) of dual species in CI pipes is significantly higher than that in PE pipes, but the biofilm activity in CI pipes is significantly lower than that in PE pipes. The interspecific interaction of Sphingomonas-containing group presented synergistic or neutral relationship in PE pipes, whereas the interspecific interaction of the Acidovorax-containing group showed a competitive relationship in CI pipes. Although interspecific relationships may help bacteria resist chlorine, the chlorine resistance was more reliant on dual-species groups and pipe materials. In CI pipes, the Microbacterium containing biofilm groups showed better chlorine resistance, whereas in PE pipes, most biofilm groups with Bacillus exhibited better chlorine resistance. The biofilm groups with more extracellular polymeric substance (EPS) secretion showed stronger chlorine resistance. The biofilm in the PE pipe is mainly protected by EPS, while both EPS and corrosion products shield the biofilms within CI pipe. These results supported that dual-species biofilms are affected by pipe materials and interspecific interactions and provided some ideas for microbial control in two typical pipe materials. Full article

Microbial corrosion is the deterioration of materials associated with microorganisms in environments, especially in oil- and gas-dominated sectors. It has been widely reported to cause great losses to industrial facilities such as drainage systems, sewage structures, food-processing equipment, and oil and gas facilities. Generally, bacteria, viruses, and other microorganisms are the most important microorganisms associated with microbial corrosion. The destructive nature of these microorganisms differs based on the kind of bacteria involved in the corrosion mechanism. Amongst the microorganisms related to microbial corrosion, sulfate-reducing bacteria (SRB) is reported to be the most common harmful bacteria. The detailed mechanistic explanations relating to the corrosion of pipelines by sulfate-reducing bacteria are discussed. The mechanism of microbial corrosion in pipelines showing the formation of pitting corrosion and cathodic depolarization is also reported. The current review provides theoretical information for the control and protection of pipelines caused by microbial corrosion and how new eco-friendly protection methods could be explored. Full article

Lacquered brass objects are widely present in scientific and technical heritage collections. Localized atmospheric corrosion occurs on the metal when the coating fails to play its protective role. Although lacquered brass objects are not necessarily endangered by this phenomenon, the presence of dark, unpleasant corrosion spots alters the surface appearance, affecting the readability of the objects. Conservators are therefore frequently asked to clean these surfaces. We hereby present the results of a study conducted in the framework of the CleanLaB (Cleaning of Lacquered Brass) project at the Haute Ecole Arc of Neuchâtel for the cleaning of lacquered brass. This work investigates the effects of several gelled cleaning systems applied on artificially aged, lacquered brass samples to remove the corrosion products without affecting the integrity of the coating. The performance of complexing agents commonly used in conservation was compared on lacquered brass mock-ups coated with shellac resin by means of multiple non-invasive characterization and imaging techniques. The tests included conventional complexing agents like sodium citrate and disodium ethylenediaminetetraacetic acid, as well as a bio-originated system based on deferoxamine, a microbial metal chelator investigated as a green alternative in cleaning formulations. Full article

In contrast to “frank” pathogens, like Salmonella entrocolitica, Shigella dysenteriae, and Vibrio cholerae, that always have a probability of disease, “opportunistic” pathogens are organisms that cause an infectious disease in a host with a weakened immune system and rarely in a healthy host. Historically, drinking water treatment has focused on control of frank pathogens, particularly those from human or animal sources (like Giardia lamblia, Cryptosporidium parvum, or Hepatitis A virus), but in recent years outbreaks from drinking water have increasingly been due to opportunistic pathogens. Characteristics of opportunistic pathogens that make them problematic for water treatment include: (1) they are normally present in aquatic environments, (2) they grow in biofilms that protect the bacteria from disinfectants, and (3) under appropriate conditions in drinking water systems (e.g., warm water, stagnation, low disinfectant levels, etc.), these bacteria can amplify to levels that can pose a public health risk. The three most common opportunistic pathogens in drinking water systems are Legionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa. This report focuses on these organisms to provide information on their public health risk, occurrence in drinking water systems, susceptibility to various disinfectants, and other operational practices (like flushing and cleaning of pipes and storage tanks). In addition, information is provided on a group of nine other opportunistic pathogens that are less commonly found in drinking water systems, including Aeromonas hydrophila, Klebsiella pneumoniae, Serratia marcescens, Burkholderia pseudomallei, Acinetobacter baumannii, Stenotrophomonas maltophilia, Arcobacter butzleri, and several free-living amoebae including Naegleria fowleri and species of Acanthamoeba. The public health risk for these microbes in drinking water is still unclear, but in most cases, efforts to manage Legionella, mycobacteria, and Pseudomonas risks will also be effective for these other opportunistic pathogens. The approach to managing opportunistic pathogens in drinking water supplies focuses on controlling the growth of these organisms. Many of these microbes are normal inhabitants in biofilms in water, so the attention is less on eliminating these organisms from entering the system and more on managing their occurrence and concentrations in the pipe network. With anticipated warming trends associated with climate change, the factors that drive the growth of opportunistic pathogens in drinking water systems will likely increase. It is important, therefore, to evaluate treatment barriers and management activities for control of opportunistic pathogen risks. Controls for primary treatment, particularly for turbidity management and disinfection, should be reviewed to ensure adequacy for opportunistic pathogen control. However, the major focus for the utility’s opportunistic pathogen risk reduction plan is the management of biological activity and biofilms in the distribution system. Factors that influence the growth of microbes (primarily in biofilms) in the distribution system include, temperature, disinfectant type and concentration, nutrient levels (measured as AOC or BDOC), stagnation, flushing of pipes and cleaning of storage tank sediments, and corrosion control. Pressure management and distribution system integrity are also important to the microbial quality of water but are related more to the intrusion of contaminants into the distribution system rather than directly related to microbial growth. Summarizing the identified risk from drinking water, the availability and quality of disinfection data for treatment, and guidelines or standards for control showed that adequate information is best available for management of L. pneumophila. For L. pneumophila, the risk for this organism has been clearly established from drinking water, cases have increased worldwide, and it is one of the most identified causes of drinking water outbreaks. Water management best practices (e.g., maintenance of a disinfectant residual throughout the distribution system, flushing and cleaning of sediments in pipelines and storage tanks, among others) have been shown to be effective for control of L. pneumophila in water supplies. In addition, there are well documented management guidelines available for the control of the organism in drinking water distribution systems. By comparison, management of risks for Mycobacteria from water are less clear than for L. pneumophila. Treatment of M. avium is difficult due to its resistance to disinfection, the tendency to form clumps, and attachment to surfaces in biofilms. Additionally, there are no guidelines for management of M. avium in drinking water, and one risk assessment study suggested a low risk of infection. The role of tap water in the transmission of the other opportunistic pathogens is less clear and, in many cases, actions to manage L. pneumophila (e.g., maintenance of a disinfectant residual, flushing, cleaning of storage tanks, etc.) will also be beneficial in helping to manage these organisms as well. Full article

Smart self-healing coatings offer a revolutionary approach to mitigating metal corrosion, a problem with significant economic and environmental impacts. Divided into intrinsic and extrinsic types, these coatings autonomously rectify the damage. Intrinsic variants utilize reversible bonds to achieve ongoing repair, while extrinsic ones incorporate micro/nanocontainers that activate upon environmental triggers to mend micro-cracks, their efficacy dictated by the encapsulated healing agents’ volume. This review dissects the rapidly evolving sector of stimuli-responsive self-healing coatings, emphasizing the progress in micro/nano container technology. It discusses the synthesis and encapsulation processes of different micro/nanocontainers and charts the transition from single to multistimulus-responsive systems, which enhances the coatings’ sensitivity and functionality. The addition of multifunctional traits such as self-reporting and anti-microbial actions further broadens their industrial applicability. The review provides a succinct overview of the field’s current state and future potential, envisioning a paradigm shift in corrosion protection through advanced smart coatings. Full article

Low-modulus β-type Ti-45Nb alloy is a promising implant material due to its good mechanical biocompatibility, non-toxicity, and outstanding corrosion resistance. Its excellent chemical stability brings new challenges to chemical surface modification treatments, which are indispensable for both osteogenesis and antibacterial performance. Coatings containing metal ions as anti-microbial agents can be an effective way to reduce implant-associated infections caused by bacterial biofilm. Gallium ion (Ga³⁺) has the potential to reduce bacterial viability and biofilm formation on implant surfaces. In this study, a novel two-step process has been proposed for Ga³⁺ incorporation in hydroxyapatite (HAP) to develop bioactive and antibacterial surfaces on Ti-45Nb alloy. For the generation of bioactive surface states, HAP electrodeposition was conducted, followed by wet chemical immersion treatments in gallium nitrate (1 mM). Different buffers such as phosphate, sodium bicarbonate, ammonium acetate, and citrate were added to the solution to maintain a pH value in the range of 6.5–6.9. Coating morphology and HAP phases were retained after treatment with gallium nitrate, and Ga³⁺ ion presence on the surface up to 1 wt.% was confirmed. Combining Ga and HAP shows great promise to enable the local delivery of Ga³⁺ ions and consequent antibacterial protection during bone regeneration, without using growth factors or antibiotics. Full article

Microbially influenced concrete corrosion (MICC) causes substantial financial losses to modern societies. Concrete corrosion with various environmental factors has been studied extensively over several decades. With the enhancement of public awareness on the environmental and economic impacts of microbial corrosion, MICC draws increasingly public attention. In this review, the roles of various microbial communities on MICC and corresponding protective measures against MICC are described. Also, the current status and research methodology of MICC are discussed. Thus, this review aims at providing insight into MICC and its mechanisms as well as the development of protection possibilities. Full article