Search Results (96)

Background/Objectives: Electrolytes used in in vitro corrosion testing critically determine the behavior inferred for metallic dental implants, yet formulations and their justifications are inconsistently reported across the literature. This review compiles and compares electrolytes employed to simulate the oral cavity and the bone–implant interface, linking their chemical composition to the corrosion mechanisms they target. Methods: This structured narrative review synthesized peer-reviewed literature on simulated electrolytes used for in vitro corrosion testing of metallic dental implants and implant-related alloys. Literature was identified using database searches and targeted reference screening, with emphasis on artificial saliva formulations, physiological simulated fluids, challenge chemistries, protein-containing media, hydrodynamic conditions, and microbiological models. Relevant formulations were standardized to grams per liter and grouped according to application domain and targeted corrosion mechanisms. Results: The analysis maps electrolyte selection to corresponding corrosion modes, including uniform dissolution, pitting, crevice, galvanic, and microbiologically influenced corrosion. Consolidated composition tables highlight how pH, halide concentration, calcium–phosphate balance, proteins, gas control, and flow conditions modify passive-film stability and metal-ion release. Dental-specific gaps are identified, notably the lack of a standardized fluoride–pH matrix and limited guidance for microbiome-integrated assays. Conclusions: Aligning electrolyte formulations with the research question enhances reproducibility and mechanistic interpretation. However, current in vitro corrosion data should be interpreted cautiously because quantitative links between simulated-fluid testing and clinical outcomes such as peri-implantitis, peri-implant bone loss, and implant failure remain insufficiently established. The adoption of shared reporting standards, dynamic programmable chemistries, and interoperable datasets may improve the translational value of future corrosion studies. Full article

Juglone (5-hydroxy-1,4-naphthalenedione), a natural compound derived from walnut husks, was investigated as a sustainable dual-function antibacterial agent and corrosion inhibitor for Q235 steel in sulfate-reducing bacteria (SRB)-containing seawater. Juglone was synthesized via an improved one-pot method, and its performance was evaluated through antibacterial assays, weight loss measurements, surface characterization (SEM, XPS, XRD), and electrochemical techniques (EIS, PDP). Juglone exhibited potent antibacterial activity against Desulfovibrio sp., with a minimum inhibitory concentration (MIC) of 40 mg/L. At 20 mg/L (0.5 MIC) and 40 mg/L (1 MIC), it effectively suppressed bacterial growth and metabolism, mitigating corrosion. At 80 mg/L (2 MIC), a dual-action mechanism was observed: strong antibacterial effect combined with chemical reaction with H₂S, a corrosive SRB metabolite, forming a protective thiol-containing film on the steel surface. This reduced the corrosion current density from 3.16 × 10⁻⁵ A/cm² to 7.94 × 10⁻⁷ A/cm², achieving an inhibition efficiency of 97.5%. Juglone represents a promising green alternative to conventional toxic antibacterial agents, aligning with circular economy principles. Full article

The correlation between fouling-driven corrosion and magnetic Barkhausen noise (MBN) in AH36 naval steel was investigated under real Mediterranean seawater conditions over a 12-month immersion period. A custom-designed MBN analyzer was used to monitor four MBN parameters at monthly intervals: RMS amplitude (MBN_RMS), peak amplitude (MBN_peak), peak field position (MBN_{peak pos.}), and full width at half maximum (MBN_FWHM). Complementary characterization included pit morphology analysis, X-ray diffraction (XRD) of corrosion products, and quantitative biofouling community profiling. Three distinct MBN evolution regimes were identified, corresponding to active pitting (T₀–T₃), transitional oxide formation (T₃–T₆), and mature corrosion equilibrium (T₆–T₁₂). Over the full exposure period, MBN_RMS decreased by 50.4% and MBN_{peak pos.} increased by 83.3%, consistent with domain wall pinning at pit stress concentrations and electromagnetic shielding by paramagnetic corrosion product layers (γ-FeOOH, β-FeOOH, α-FeOOH). Pearson correlation analysis revealed near-unity relationships between MBN_RMS and maximum pit depth (r = −0.982, p < 0.01), supporting its potential use as a quantitative non-destructive indicator of corrosion severity under comparable exposure conditions. Biofouling, particularly sulfate-reducing bacteria (SRB)-dominated communities and biogenic iron sulfides (mackinawite, greigite), was identified as a statistically significant secondary correlate of MBN signal intensity (r = −0.944 vs. SRB fraction). A composite diagnostic threshold of (MBN_RMS × MBN_peak)/MBN_FWHM ≈ 0.015 effectively discriminated active pitting from passive rusting. These findings provide a physically grounded framework for multiparametric MBN analysis as a non-destructive condition monitoring tool, with the caveat that the reported correlations are descriptive and require independent validation before deployment in regulatory inspection protocols. Full article

This review examines the role of sulfate-reducing bacteria in the anaerobic degradation of hydrocarbons in marine sediments, where they contribute to the mineralization of organic matter under anoxic conditions. The metabolic diversity of these microorganisms is described, including their ability to degrade various classes of hydrocarbons such as short-chain (C₂–C₅), medium-chain (C₆–C₁₂), and long-chain (C₁₃–C₂₀₊) alkanes, alkenes, and aromatic compounds like naphthalene and phenanthrene. The primary mechanisms involved in the initial activation of these hydrocarbons—fumarate addition and carboxylation—are discussed, along with key enzymes, including alkylsuccinate synthase and benzylsuccinate synthase. Syntrophic interactions are also considered, particularly in which archaea initiate the oxidation of short-chain alkanes (e.g., ethane and butane), with sulfate-reducing bacteria serving as terminal electron acceptors via sulfate reduction. The potential application of these anaerobic processes in bioremediation strategies for oil-contaminated marine sediments is discussed. This microbially mediated degradation may offer a complementary approach to aerobic methods, particularly in oxygen-limited environments. Understanding the activity of sulfate-reducing bacteria activity is relevant to several areas: the development of remediation techniques for anoxic zones, the assessment of methane emissions from marine sediments, the management of microbiologically influenced corrosion, and potential biotechnological applications. Current research directions include the study of syntrophic microbial consortia and the exploration of bioelectrochemical systems. Full article

The corrosion behavior of pipeline steels in marine environments is strongly affected by hydrodynamic conditions and microbial activity, yet their coupled influence remains insufficiently understood. In this study, the corrosion behavior of X70 pipeline steel was systematically investigated in flowing artificial seawater over a velocity range of 0–1.5 m/s, under both sterile conditions and in the presence of Pseudomonas aeruginosa. Corrosion weight loss measurements, electrochemical techniques, and surface characterization were employed to evaluate flow-dependent corrosion evolution. The results show that flow velocity plays a dominant role in regulating corrosion behavior. Under sterile conditions, increasing flow velocity enhances mass transfer and surface renewal, leading to progressively increased corrosion severity. In the presence of P. aeruginosa, corrosion behavior exhibits a non-monotonic dependence on flow velocity. Lower flow velocities are associated with reduced corrosion rates and relatively uniform surface degradation, whereas moderate flow velocities promote localized corrosion and increased pitting severity. At higher flow velocities, strong hydrodynamic effects suppress the retention of corrosion products and microbe-associated surface layers, resulting in corrosion behavior primarily controlled by fluid flow. Overall, the results indicate that microbial presence modifies the flow–corrosion relationship of X70 steel by altering interfacial conditions under low-to-moderate flow regimes. Full article

Extracting reliable corrosion kinetic parameters from polarization curves is particularly challenging for X70 steel under the synergistic effect of microbiologically influenced corrosion (MIC) and alternating current (AC) interference, as both factors significantly distort the electrochemical response. To address this, a novel fitting strategy was developed. In this approach, the overall polarization curve is reconstructed by combining separately modeled anodic and cathodic branches. To preserve the shape of the polarization curve, a slope-consistency constraint was enforced through dynamic penalty factors that balance fitting accuracy with shape preservation during optimization, which was performed using an intelligent algorithm. The results demonstrate the robustness of the proposed strategy, demonstrating low sensitivity to initial guesses and algorithmic parameters. Evaluation confirms that accuracy is maintained even when the data density is reduced by half. Among the parameters extracted, the Tafel slopes and corrosion current density show higher reliability than others. This work provides a robust and effective tool for the kinetic analysis of complex corrosion systems involving MIC and AC. Full article

High-strength low-alloy (HSLA) steels in marine environments suffer from microbiologically influenced corrosion (MIC) and hydrogen-assisted degradation. This study investigates the synergistic effects of sulfate-reducing bacterial biofilms, mechanical stress, and seawater chemistry on HSLA AH36 steel using electrochemical, microstructural, and magnetic Barkhausen noise (MBN) monitoring. Under multiparametric exposure (80% yield strength tensile stress, Desulfovibrio vulgaris, 28 days), biotic samples exhibited sustained 1.88× corrosion acceleration despite 86% sulfate depletion. Magnetic Barkhausen noise RMS amplitude (MBN_RMS) peaked at day 7 (612 ± 38 mV/mm) at pit depths of only 20–50 μm, detecting subsurface hydrogen damage before macroscopic failure. Quantitative correlations (R² ≥ 0.99) between MBN_RMS and cumulative mass loss revealed distinctive linear relationships in abiotic conditions and nonlinear cubic polynomials in biotic conditions, providing a non-destructive signature diagnostic of hydrogen-assisted MIC. Directional anisotropy analysis (parallel vs. perpendicular fields) showed that hydrogen-induced damage produces isotropic magnetic signatures (anisotropy ratio: 1.27 → 1.15), enabling discrimination between hydrogen embrittlement and stress-controlled degradation. The integration of portable MBN measurements with electrochemical monitoring establishes a quantitative framework for real-time structural health assessment and predictive maintenance of HSLA steels in maritime applications. Full article

Corrosion remains one of the major contemporary technological challenges, causing significant economic, environmental, and operational impacts on industrial systems. Although it is a spontaneous process inherent to metals and their alloys, its progression can be significantly mitigated by appropriate protection strategies. Traditionally, synthetic inhibitors have been widely used; however, their toxicity, environmental persistence, and increasing regulatory restrictions have prompted a search for greener alternatives. Biosurfactants stand out as promising green anticorrosive agents, acting through the formation of adsorbed films, reduction in wettability, modification of the metal–medium interface, and, in some cases, antimicrobial effects that inhibit the formation of corrosive biofilms. This review presents an integrated analysis of the main corrosion mechanisms, including uniform, localized, galvanic, and microbiologically influenced corrosion, with an emphasis on critical industrial environments such as the maritime, petrochemical, energy, and infrastructure sectors. Additionally, the main classes of biosurfactants are discussed, along with their key physical and chemical characteristics, including critical micelle concentration, thermal and saline stability, adsorption capacity, and their mechanisms of action in mitigating corrosion. Finally, the article summarizes the advances of the last decade, highlighting experimental studies, emerging applications, and technological trends that consolidate biosurfactants as viable, efficient, and environmentally safe alternatives for industrial corrosion protection. Full article

Microbiologically influenced corrosion induced by sulfate-reducing bacteria (SRB) poses a significant threat to shale gas pipeline integrity. This study investigates an integrated control strategy combining the biocide glutaraldehyde with denitrifying bacteria (DNB) to synergistically inhibit SRB activity and corrosion. The efficacy and mechanisms were systematically evaluated using electrochemical measurements (EIS, LPR), weight-loss analysis, surface characterization (SEM, maximum pit depth), and microbial community profiling (16S rDNA sequencing). Compared to the SRB-inoculated system, the combined treatment reduced the average corrosion rate of L245 steel by 44.2% (to 0.01608 mm/a) and the maximum pit depth by 84.3% (to 1.53 μm). EIS results further confirmed the superior inhibition effect, showing the largest capacitive arc diameter and the highest polarization resistance in the combined system. Microbial community analysis indicated a substantial decline in SRB abundance from 62.7% (day 1) to 11.9% (day 14). This synergistic strategy presents an effective and more sustainable approach by reducing chemical dosage and leveraging the bio-competitive exclusion by DNB. Full article

Biofouling and microbiologically influenced corrosion (MIC) pose profound allied threats, both visible and invisible, across global industrial and societal infrastructures, encompassing both stationary and mobile systems, such as maritime shipping, aquaculture, offshore and onshore energy platforms, desalination and wastewater treatment and distribution systems [...] Full article

Many industrial sectors are concerned about microbiological contamination and the associated risk of microbiologically influenced corrosion (MIC). This applies in particular to the transmission and storage of fuels in the refining industry. Exceeding a certain level of these contaminants poses a serious risk to fuel quality and can cause storage and pipeline infrastructure corrosion. This situation requires an urgent evaluation of microorganism levels in the fuel to avert such detrimental consequences. Diesel fuels containing biofuel additives are particularly susceptible to these phenomena. Traditional detection methods are limited by low sensitivity, high costs, and long turnaround times, making them unsuitable for quick, on-site, and real-time detection and monitoring. A novel approach involves the application of microwave dielectric testing to quantify microbial load in diesel fuel. Microwave dielectric spectroscopy offers a non-destructive, label-free solution, providing rapid information on microorganism presence. Combined with chemometric techniques, it effectively estimates total microorganism counts in diesel fuel. Measurement in the X-band range (8.2–12.4 GHz) takes a few seconds. Calibration with known bacterial and fungal concentrations (10³ to 10⁷ CFU/mL) and principal component analysis (PCA) of the spectroscopic data allow for clear differentiation of contamination levels, categorizing them from acceptable to hazardous. The sensitivity limit of the proposed method corresponds to a bacterial concentration of 10³ CFU/mL. Full article

The process of bacterial reproduction on surfaces conducive to growth forms colonies, which are defined as physical bodies with functional and environmental effects. This phenomenon can be conceptualized as transforming biological processes into physical phenomena. Large bacterial multicellular aggregates can be conceptualized as physical entities, produced by “colonial organisms”, thereby transforming physics into biology. The formation of colonies requires surfaces, typically hydrogels or liquid–air interfaces, but also hard solid surfaces. Bacterial cell layers also contribute to the production of surfaces. Within a typical 3D-shaped, frequently domed colony, a variety of microcompartments form at the intersections of gradients that diffuse from its aerial and surface limits, leading to cellular functional diversity. This heterogeneity can lead to physical changes and fractures in the colony material, leading to the formation of fluid microchannels. The second primary type of colony is the 2D-shaped form that spreads over larger surfaces and is known as a biofilm. These physical structures possess significant water content, which is retained by a bacterial-excreted exopolymer. Biofilms are structurally organized as multilayer structures that can expand in the space through the lateral slippage of a more fluid overlayer on top of the surface-attached layer. The dissemination of biofilms may entail the integration of additional bacterial colonies, thereby giving rise to complex biofilms. The physical occupancy of microenvironments by colonies created on surfaces of higher organisms or on environmental surfaces exerts a significant influence on fluid mechanics and the functioning of organisms and ecosystems. In addition, colonies also contribute to the pathology of industrial constructions and devices, often leading to microbiologically influenced electrochemical corrosion, which results in material degradation. Full article

Carbon dots (CDs) have recently emerged as a novel class of eco-friendly and multifunctional corrosion inhibitors owing to their nanoscale dimensions, tunable surface functionalities, and sustainable synthesis pathways. This review summarizes the latest progress in CD-based inhibitors, focusing on synthesis methods, applications, and inhibition mechanisms. Various strategies—including hydrothermal/solvothermal treatment, microwave irradiation, pyrolysis, electrochemical synthesis, and chemical oxidation—have been employed to obtain CDs with tailored size, heteroatom doping, and surface groups, thereby enhancing their inhibition efficiency. CDs have demonstrated remarkable applicability across diverse corrosive environments, including acidic, neutral chloride, CO₂-saturated, microbiologically influenced, and alkaline systems, often achieving inhibition efficiencies exceeding 90%. Mechanistically, their performance arises from strong adsorption and compact film formation, heteroatom-induced electronic modulation, suppression of anodic and cathodic reactions, and synergistic effects of particle size and structural configuration. Compared with conventional inhibitors, CDs offer higher efficiency, environmental compatibility, and multifunctionality. Despite significant progress, challenges remain regarding precise structural control, scalability of synthesis, and deeper mechanistic understanding. The effectiveness of CDs inhibitors is highly dependent on factors such as pH, temperature, inhibitor concentration, and exposure time, which should be tailored for specific applications to maximize performance. Future research should focus on integrating sustainable synthesis with rational heteroatom engineering and advanced characterization to achieve long-term, cost-effective, and environmentally benign corrosion protection solutions. Compared to earlier reviews, this review discusses the emerging trends in the field of CDs as corrosion inhibitors. Full article

Conventional petroleum-based protective coatings release high levels of volatile organic compounds (VOCs) and contribute to resource depletion, urging the development of environmentally responsible alternatives. Among the bio-based candidates, microalgae and Cyanobacteriophyta have recently gained attention for their ability to produce diverse biopolymers and pigments with intrinsic protective functionalities. However, existing literature has focused mainly on algal biofuels and general biopolymers, leaving a major gap in understanding their application as sustainable coating materials. This review addresses that gap by providing the first integrated assessment of algae-based protective coatings. It begins by defining abiotic and biotic surface degradation mechanisms, including microbiologically influenced corrosion, to establish performance benchmarks. The review then synthesizes recent findings on key algal components, including alginate, extracellular polymeric substances (EPS), and phycocyanin, linking biochemical composition to functional performance, techno-economic feasibility, and industrial scalability. It evaluates their roles in adhesion strength, UV stability, corrosion resistance, and antifouling activity. Reported performance metrics include adhesion strengths of 2.5–3.8 MPa, UV retention above 85% after 2000 h, and corrosion rate reductions of up to 40% compared with polyurethane systems. Furthermore, this study introduces the concept of carbon-negative, multifunctional coatings that simultaneously protect infrastructure and mitigate environmental impacts through CO₂ sequestration and pollutant degradation. Challenges involving biomass variability, processing costs (>USD 500/ton), and regulatory barriers are critically discussed, with proposed solutions through hybrid cultivation and biorefinery integration. By bridging materials science, environmental engineering, and sustainability frameworks, this review establishes a foundation for transforming algae-based coatings from laboratory research to scalable, industrially viable technologies. Full article

Lake Salda in Türkiye serves as a valuable Earth analog for studies of the properties of Mars due to its mineralogical and microbiological similarities to Jezero Crater on Mars. This study investigated the role of sulfate-reducing bacteria (SRB) enrichment culture isolated from Lake Salda on the microbiologically influenced corrosion (MIC) of an aluminum alloy (AA7075) using electrochemical, microbiological, molecular, and spectroscopic methods. Potentiodynamic polarization (PDP) tests confirmed SRB-enriched biofilm significantly accelerated corrosion. Fourier Transformed Infrared Spectroscopy (FTIR) further distinguished the control and biotic surfaces, showing the replacement of a 980 cm⁻¹ polysaccharide band with a 1075 cm⁻¹ cyclic polysaccharide vibration in SRB-colonized coupons. This spectral transition reflects biofilm maturation and EPS accumulation, providing molecular evidence for SRB-driven MIC. Molecular analysis identified Proteobacteria and Firmicutes as dominant phyla, and Desulfofustis limnaeus was detected in Lake Salda for the first time. Moreover, benthic foraminifera and ostracods were observed, some with morphological anomalies. These results provide mechanistic insight into the biochemical and electrochemical interactions driving SRB-induced corrosion, highlighting Lake Salda’s importance for studying microbial–material interactions in extreme environments. Full article