Sulfate-reducing Bacteria Research Articles

Indicators of the Microbial Corrosion of Steel Induced by Sulfate-Reducing Bacteria Under the Influence of Certain Drugs

Microorganisms cause microbiologically influenced corrosion, for the prevention of which bactericide inhibitors are used. The aim of the work was to study in vitro the sensitivity of SRB Desulfovibrio oryzae NUChC SRB1 to different concentrations of dimethyl sulfoxide (DMSO), and evaluate the indicators of the microbial corrosion of steel induced by this bacterium in the presence of the pharmaceutical drugs DMSO and paracetamol. The sensitivity of SRB D. oryzae to 1–100% DMSO (v/v) was studied via the dilution method in Postgate’s “C” liquid medium. The corrosion activity of D. oryzae against steel 3 was investigated under DMSO and paracetamol treatment at a final concentration of 45% (v/v) and 0.2% (w/v), respectively, according to the ability of bacteria to form a biofilm on the surface of the steel samples (via the crystal violet method) and the effect on the corrosion rate (via the gravimetric method). It was revealed that DMSO affected D. oryzae NUChC SRB1 and exhibited bactericidal properties (at a concentration range of 10–100%, v/v) and antibiofilm properties (at a concentration of 45%, v/v). Despite its antibiofilm properties confirmed by the reduction in bacterial biofilm mass, anticorrosion features were not observed in the model 35-day conditions of the microbial corrosion of steel in an anaerobic environment with bacterial sulfate reduction. Paracetamol (0.2%, w/v) did not affect biofilm formation by SRB under these conditions, and significantly contributed to an increase in the rate of the microbial corrosion of steel. The prospect of further research is to assess the effect of DMSO and paracetamol on the indicators of microbial corrosion induced by SRB under the influence of the concentrations of these compounds found in wastewater, to clarify the possible additional causes of damage to the equipment of treatment plants. Further research should also be directed at investigating the antimicrobial properties of complexes of compounds with DMSO, which should be considered as an ecological solution to the problem of microbiologically influenced corrosion prevention.

Experimental and numerical study of efficient sulfate reduction and heavy metal elimination from real acid mine drainage

Copper mine drainage typically contains large quantities of heavy metal ions and sulfate (SO4 2-) contaminants. Among various strategies for treating acid mine drainage (AMD), using anaerobic bioreactors for biological removal has proven to be particularly effective. This study aimed to assess the efficiency of sulfate-reducing bacteria (SRB) in AMD treatment. To achieve this, a semi-pilot-scale down-flow fluidized bed (DFFB) anaerobic reactor was employed to remove SO4 2– and copper (Cu), while a robust numerical model was developed to evaluate the reactor’s performance. The initial concentrations of Cu and SO4 2– in the waste stream were 20 and 3900 mg/L, respectively. At an optimal retention time of 24 h, the maximum removal efficiencies reached 98.05% for Cu and 98.38% for SO4 2-. The treatment process also increased the effluent’s alkalinity and effectively neutralized acidity, providing substantial environmental benefits. Notably, the reactor exhibited stable performance across six consecutive cycles, which can be attributed to the inclusion of activated carbon (AC) granules in the reactor bed. Consequently, the biological approach used here offers a promising, cost-effective, and environmentally sound method for AMD treatment. Finally, computational fluid dynamics (CFD) simulations were conducted to model the reactor, and their outputs showed excellent agreement with experimental data, underscoring the significant potential of this approach for large-scale industrial applications.

Intelligent antibacterial coatings based on sensitive response and periodic fast drug release for long-term defense against corrosion induced by sulfate-reducing bacteria.

Pitting corrosion caused by sulfate-reducing bacteria (SRB) significantly shortens the lifespan of metallic pipelines. Antibacterial coatings containing S2--responsive drug-loaded nanocontainers represent a promising method to mitigate SRB corrosion. However, the challenge of balancing rapid bactericide release with continuous antibacterial effect limits their practical application. In this study, a S2- and pH dual-responsive periodic drug release system was developed based on raspberry-like mesoporous silica intelligent nanocontainers (BAC-RMSNs@Cu-BTA) loaded with bactericide benzalkonium chloride (BAC) and blocked by copper-benzotriazole nano valves (Cu-BTA). When S2- concentration exceeded 0.5mM or pH fell below 6.3, the intelligent nanocontainers accelerated drug release. Under simultaneous S2- and pH stimulation, the drug release rate was increased by 91%, compared to isolated S2- stimulation. The sustained release duration exceeded 384h, which was more than twice that of existing S2--responsive nanocontainers. The reversible dissociation-complexation transition of Cu-BTA nano valves and the adsorption effect of the raspberry structure facilitated an inhibition of drug release after the stimulation disappeared, thereby enabling cyclic drug release and extending the antibacterial duration. The epoxy coating embedded with BAC-RMSNs@Cu-BTA showed excellent repeatable sterilization, long-term antibacterial adhesion and corrosion medium barrier ability in the SRB environment. Based on active intelligent sterilization and passive physical barrier effects, the composite coating's resistance to SRB corrosion in the simulated internal environment of pipelines was 14.6 times that of coating containing BAC-RMSNs. This study aims to provide valuable insights for the design of innovative long-acting antibacterial coatings.

Facile and green synthesis of Ag/Cu bimetallic nanoparticles using waste banana peel extract for effective corrosion inhibition of mixed sulfate-reducing bacteria.

Microbiologically induced corrosion (MIC) is widespread in the oilfield industry, and new environmentally friendly materials are urgently needed to inhibit MIC with the increasing environmental requirements and microbial resistance problems. The synthesis method and cost of the materials are important factors that must be considered in the production and application. In this study, Ag/Cu bimetallic nanoparticles (BNPs) were synthesized by eco-friendly and sustainable method using waste banana peel extract (BPE) as a green reducing. The antibacterial and corrosion inhibition properties of Ag/Cu BNPs were investigated by using the enriched mixed strains containing sulfate-reducing bacteria (SRB) as model bacteria. The results of electron microscopy showed that the prepared BNPs exhibited spherical structure with about 19.0nm in size. The synthesized nanoparticles significantly inhibited the growth of mixed strains by antimicrobial experiments with minimum inhibitory concentration (MIC) value of 9.38μg/mL. The addition of Ag/Cu BNPs (9.38μg/mL) inhibited the corrosion of X65 carbon steel induced by the mixed strains with 77.9% compared to the untreated condition. Correspondingly, the number of sessile SRB cells in the solution containing Ag/Cu BNPs (9.38μg/mL) after 28 days of immersion decreased by 5-log compared with the treatment group without nanomaterials (1.1×108cells/cm2). Furthermore, the observation of the surface morphology and strains cellular microstructure of carbon steel treated with nanoparticle materials illustrated that the corrosion inhibition mechanism mainly includes destroying cell structure, affecting metabolic activities and inhibiting biofilm formation. The environmentally friendly nanoparticle materials prepared in this study have great potential in the safe and clean production of oil fields.

Identifying Bacteria Responsible for Non-Sulphate-Based Hydrogen Sulphide Production in Aquaculture.

The unintended microbiological production of hydrogen sulphide (H2S) poses a significant challenge in engineered systems, including sewage treatment plants, landfills and aquaculture systems. Although sulphur-rich amino acids and other substrates conducive to non-sulphate-based H2S production are frequently present, the capacity and potential of various microorganisms to perform sulphate-free H2S production remain unclear. In this study, we identify the identity, activity and genomic characteristics of bacteria that degrade cysteine to produce H2S in anaerobic enrichment bioreactors seeded with material from aquaculture systems. Our comparison with canonical sulphate-reducing bacteria reveals that both sulphur sources contribute to microbial H2S production, with cysteine facilitating a more rapid process compared to sulphate. 16S rRNA amplicon sequencing and metagenomic analysis identified four bacterial families-Dethiosulfatibacteraceae, Fusobacteriaceae, Vibrionaceae and Desulfovibrionaceae-as central to non-sulphate H2S production. Metagenome- and metatranscriptome-assembled genomes elucidated the primary cysteine degradation pathway mediated by cysteine desulphidase cyuA and indicated that some bacteria may also utilise cysteine as a carbon source in sulphate-based H2S production.

Microscopic analysis of the destruction of passive film on stainless steel caused by sulfide in simulated cooling water

Abstract Sulfide often appears in circulating cooling water due to the presence of sulfate reducing bacteria and could affect corrosion behavior of cooling pipe metals such as stainless steel. Scanning Kelvin probe and scanning electrochemical microscope measurements, combined with electrochemical testing, were used to investigate the micro-electrochemical information of passive film and analyzed the influence of sulfide in simulated cooling water on corrosion resistance of stainless steel. Results showed that the presence of sulfide in water caused a negative shift in surface potential of stainless steel, an increase in surface potential difference, and an increase in local response current on the surface, resulting in a current peak that gradually increased over time. The analysis results of passive film composition showed that the presence of sulfide caused increase in the ratio of Fe/Cr and OH−/O2−, as well as the content of Cr(OH)3 and Fe(OH)3 in passive film, whereas caused a decrease of Cr2O3 content, and led to the formation of FeS2 in the passive film. These changes in the composition of the passive film made it easier for active sites to appear on the surface of stainless steel and enhanced the conductivity of the passive film and significantly reducing its protective performance.

Climatic variability as a principal driver of primary production in the southernmost subalpine Rocky Mountain lake

ABSTRACT Mountain lakes are sensitive indicators of anthropogenically driven global change, with lake sediment records documenting increased primary production during the twentieth century. Atmospheric nutrient deposition and warming have been attributed to changes in other Western mountain lakes, however, the intensity of these drivers varies. We analyzed a sediment core representing a 270-year record from Santa Fe Lake, New Mexico, to constrain the southern margin of Rocky Mountain lakes and quantify patterns of change in lake biogeochemistry, production, and diatoms since 1750. Lake sediments were dated using 210Pb and analyzed for carbon (C), nitrogen (N), stable isotopes (δ13C, δ15N), diatoms, and phototrophic pigments. The abundance of cyanobacteria, purple sulfur-reducing bacteria, and diatom pigments were elevated during the stable conditions of the Little Ice Age; these phototrophic groups declined in the late 1800s and reached a minimum by 1950. From 1950 to 2020, sediments recorded an increased abundance of cryptophyte, diatom, and chlorophyte groups. The C and N (percentage dry mass) increased after 1950, whereas δ15N and δ13C values declined. Changes since the mid-twentieth century are contemporaneous with warming trends in the Southwest and modest deposition of atmospheric N. Our findings highlight the geographic variability of mountain lake responses to changing environmental conditions.

Behavior and Mechanisms of Antimony Precipitation from Wastewater by Sulfate-Reducing Bacteria Desulfovibrio desulfuricans

The development of the non-ferrous metal industry is generating increasingly large quantities of wastewater containing heavy metals (e.g., Sb). The precipitation of heavy metals by microorganisms involves complex mechanisms that require further investigation to optimize bioremediation technologies. In this study, we employed a sulfate-reducing bacteria (SRB) strain Desulfovibrio desulfuricans CSU_dl to treat the antimony (Sb)-containing wastewater; the behavior of Sb and mechanisms underlying precipitation were investigated by characterizing the precipitates. The results showed that the abiotic factors constraining SRB bacterial growth greatly affect Sb forms and precipitation. For instance, Sb precipitation maximumly occurred at pH 6 and 7, or C:N ratio of 10:1 and 40:3 for Sb(III) and Sb(V), respectively, resulting in a maximum Sb removal rate of 94%. Interestingly, we found that substantial antimonate and antimonite were adsorbed on the SRB cell surface, indicating that cell surface is a critical reaction site of Sb transformation and precipitation. Sb was adsorbed to the cell surface by C-C and C=O groups, and was further precipitated by forming Sb2S3 and Sb2S5 or was coprecipitated with the P-containing group. Partial Sb(V) reduction was also observed on the SRB cell surface. These results provided a deep insight into the Sb bio-transformation and were an advancement with respect to understanding bioremediation of Sb-contaminated wastewater.

Microbial Corrosion of Copper Under Conditions Simulating Deep Radioactive Waste Disposal.

This paper presents the results of microbial corrosion tests on M0-grade copper under conditions simulating a geological repository for radioactive waste at the Yeniseisky site (Krasnoyarsk Krai, Russia). The work used a microbial community sampled from a depth of 450 m and stimulated with glucose, hydrogen and sulfate under anaerobic conditions. It was shown that the maximum corrosion rate, reaching 9.8 µm/y, was achieved with the addition of sulfate (1 g/L) with the participation of microorganisms from the families Desulfomicrobiaceae, Desulfovibrionaceae and Desulfuromonadaceae. It was noted that the most important factor leading to copper corrosion was the accumulation of hydrogen sulfide during the activation of sulfate-reducing microorganisms of the genera Desulfomicrobium, Desulfovibrio and Desulfuromonas. During the development of the microbial community under these conditions, the content of copper can have a significant toxic effect at a concentration of more than 250 mg/L.

Nanocomposite complex ZnO in combination with a triazoloazepinium derivative for inhibition of microbial steel corrosion

We have established the possibility of using ZnO nanoparticles to inhibit microbial corrosion with simultaneous inhibition of growth and sulfate-reducing activity of bacteria of the corrosive active group. The search for ways to increase the antibacterial and anticorrosive effect of ZnO nanoparticles makes it possible to combine them with substances, in particular, inhibitors-biocides of microbial steel corrosion. The nanocomposite complex of ZnO nanoparticles and cationic heterocyclic compound (triazoloazepinium derivative) was studied as a biocide and inhibitor of microbial corrosion on steel. The component concentrations are 3 mg/mL and 1 mg/mL accordingly. The experiments were carried out by using a microbiological and corrosion control methods. It has been established that the proposed nanocomposite complex affects the number of bacteria in the plankton and biofilm. In its presence, there is a complete inhibition of the growth of sulfate-reducing bacteria (the most aggressive component of the microbial community) in plankton. Also, the number of denitrifying bacteria and iron-reducing bacteria in plankton decreases by 3 and 4 orders, respectively. The biofilm formed in the presence of the nanocomposite in the culture medium is less dense in terms of the number of bacterial cells of the sulfidogenic community.

Effects of Medium and Flow Rate on the Film-Forming Structures of B10 Cu-Ni Alloys and Their Resistance to Corrosion Caused by Sulfate-Reducing Bacteria

The effects of medium and flow rate on the film-forming structures of B10 Cu-Ni alloys and their resistance to corrosion caused by sulfate-reducing bacteria are investigated in this article. Combined with a predicted cloud map of pipeline corrosion area and a particle motion trajectory map obtained using Computational Fluid Dynamics (CFD), the growth law of alloy passivation films was analyzed and the pitting process of sulfate-reducing bacteria (SRB) on passivation films was revealed. The results show that the film formation effect is best when the stream of water in the film-forming environment is filtered seawater with a flow rate of 0.8 m/s, which consists of a uniform and dense gray-brown passivated film layer with the strongest resistance to SRB corrosion. When the flow rate is 0 m/s, the clay particles in the seawater cover the surface of the passivation film, hindering the contact of oxygen with the substrate and inhibiting the growth of the passivation film. When the stream of water in the film-forming environment is seawater with a flow rate of 3 m/s, the surface of the substrate shows obvious scouring marks, which is favorable for the enrichment of SRB and further accelerates the pitting corrosion of the substrate. Cl− has a significant influence on the formation of passivation films on B10 Cu-Ni alloys. When the filming medium is deionized water, the B10 Cu-Ni alloy does not form a complete passivation film at all flow rates.

Biogeochemistry of peat deposits of the Holocene section of the Vydrinsky bog (southern Baikal region)

Drilling cores from peat deposits of the Vydrinsky bog with a thickness of 4.4 m and an age of 13,100 cal. years, composed of lowland, transitional and high-moor types of peat, were studied in detail. The processes of post-sedimentary transformations of swamp sediments during early diagenesis are considered, the distribution of elements, the formation of authigenic minerals and the chemical composition of swamp waters are studied. The destruction of organic matter begins already in the upper intervals of peat at the early stages of diagenesis. Pyrograms do not have clearly defined high-temperature peaks, “rudiments” of the macromolecular structure of kerogen, which indicates a low degree of transformation of peat organic matter. A high number of organotrophic, ammonifying, nitrifying, phosphate-mobilizing microorganisms, a small number of Fe- and Mn-oxidizing microorganisms, and sulfate-reducing bacteria were revealed. The presence of organotrophic microorganisms throughout the section indicates that the biogeochemical processes of the carbon cycle cover the entire thickness of the peat deposit. A small amount of S (II) indicates a low intensity of sulfate reduction processes. Lowland peat is characterized by high contents of Si, Al, Fe, Ca, Sr, Ba, Zr, La and anomalous contents of Cu, Zn, which is a consequence of the formation of the bog under conditions of rich mineral nutrition. In the ash part of the transitional peat, a decrease in the contents of Si, Fe, Sr, Br, K Si, Ca, Ba, Cu, Zn and La is noted, which reflects the gradual weakening of the connection of the peat deposit with the underlying rocks. In the near-surface horizon of high-moor peat, there is an increase in the contents of K, Mn, Zn, Hg, Pb and As, which is associated with an increase in atmospheric dust and anthropogenic impact on the bog ecosystem in the 20th and 21st centuries. Bog waters of low-lying peat are characterized by high contents of the main ions, Al, Fe, Mn, Sr, while transitional peat is characterized by a decrease in DOC, SO42–, HCO3–, Al, Fe, Ni, Ca, Mg. The oligotrophic strata is characterized by the development of Fe oxides and hydroxides, the presence of vivianite is noted for transitional peats, and the eutrophic part of the peat deposit includes rhodochrosite and sulfides of Fe, Cu, and Zn.

From Structure to Function: Analysis of the First Monomeric Pyridoxal-5'-Phosphate-Dependent Transaminase from the Bacterium Desulfobacula toluolica.

The first monomeric pyridoxal-5'-phosphate (PLP)-dependent transaminase from a marine, aromatic-compound-degrading, sulfate-reducing bacterium Desulfobacula toluolica Tol2, has been studied using structural, kinetic, and spectral methods. The monomeric organization of the transaminase was confirmed by both gel filtration and crystallography. The PLP-dependent transaminase is of the fold type IV and deaminates D-alanine and (R)-phenylethylamine in half-reactions. The enzyme shows high stereoselectivity; no deamination of L-amino acids and (S)-phenylethylamine is detected. Structural analysis and subsequent mutagenesis led to the conclusion that the monomeric architecture of the enzyme is the only one possible and sufficient for stereoselectivity and PLP binding, but not for the overall double-substrate transamination reaction and the stability of the holo form with the reduced cofactor-pyridoxamine-5'-phosphate. These results extend the structural university of the PLP fold type IV enzymes and demonstrate the need for deeper analysis of the sequence-structure-function relationships in the transaminases.

A Novel G-C3N4 Modified Biogenic Mackinawite Mediated by SRB for Boosting Highly Efficient Adsorption and Catalytic Degradation of Antibiotics in Photo-Fenton Process.

FeS-based nanomaterials are widely used in Fenton-like reaction of antibiotics degradation. However, the problems of poor stability and low reusability limit the catalytic efficiency. Herein, the study ingeniously introduced the g-C3N4 into FeS to synthesize g-C3N4@biogenic FeS (CN-BF-1) nanocomposite with strong interaction of iron ions and "N-pots" by the mediation of sulfate reducing bacteria (SRB). Results indicated the g-C3N4 accelerated SRB metabolism and improved the mineralization and stability of FeS to well-crystallized mackinawite. The CN-BF-1 can efficiently adsorb and degrade antibiotics compared with FeS and g-C3N4, and bear a broad pH range which further proved the increase of stability. The toxicity studies showed ciprofloxacin (CIP) degradation solution hardly caused ecotoxicity and induced antibiotic resistance genes, while CN-BF-1 can be regenerated by SRB in this solution with chemical and enzymatic reduction of Fe(III)-mud to achieve efficient CIP degradation (99.9%). Finally, the mechanism part showed that CN-BF-1 can activate H2O2 to form 1O2 and •OH which played the main roles in the catalysis process. The work paves the way for a novel approach to intensify iron-based photo-Fenton system in sustainable remediation of antibiotic wastewater, upon which the high-efficiency removal and non-toxic degradation solution of antibiotic contamination are expected.

On the function of TRAP substrate-binding proteins: the isethionate-specific binding protein IseP.

Bacteria evolve mechanisms to compete for limited resources and survive in new niches. Here we study the mechanism of isethionate import from the sulfate-reducing bacterium Oleidesulfovibrio alaskensis. The catabolism of isethionate by Desulfovibrio species has been implicated in human disease, due to hydrogen sulfide production, and has potential for industrial applications. O. alaskensis employs a tripartite ATP-independent periplasmic (TRAP) transporter (OaIsePQM) to import isethionate, which relies on the substrate-binding protein (OaIseP) to scavenge isethionate and deliver it to the membrane transporter component (OaIseQM) for import into the cell. We determined the binding affinity of isethionate to OaIseP by isothermal titration calorimetry, KD = 0.95 µM (68% CI = 0.6-1.4 µM), which is weaker compared with other TRAP substrate-binding proteins. The X-ray crystal structures of OaIseP in the ligand-free and isethionate-bound forms were obtained and showed that in the presence of isethionate, OaIseP adopts a closed conformation whereby two domains of the protein fold over the substrate. We serendipitously discovered two crystal forms with sulfonate-containing buffers (HEPES and MES) bound in the isethionate-binding site. However, these do not evoke domain closure, presumably because of the larger ligand size. Together, our data elucidate the molecular details of how a TRAP substrate-binding protein binds a sulfonate-containing substrate, rather than a typical carboxylate-containing substrate. These results may inform future antibiotic development to target TRAP transporters and provide insights into protein engineering of TRAP transporter substrate-binding proteins.

Dual anaerobic reactor model to study biofilm and microbiologically influenced corrosion interactions on carbon steel

Continual challenges due to microbial corrosion are faced by the maritime, offshore renewable and energy sectors. Understanding the biofilm and microbiologically influenced corrosion interaction is hindered by the lack of robust and reproducible physical models that reflect operating environments. A novel dual anaerobic biofilm reactor, using a complex microbial consortium sampled from marine littoral sediment, allowed the electrochemical performance of UNS G10180 carbon steel to be studied simultaneously in anaerobic abiotic and biotic artificial seawater. Critically, DNA extraction and 16S rRNA amplicon sequencing demonstrated the principal biofilm activity was due to electroactive bacteria, specifically sulfate-reducing and iron-reducing bacteria.

Co-occurrence of direct and indirect extracellular electron transfer mechanisms during electroactive respiration in a dissimilatory sulfate reducing bacterium.

Understanding the extracellular electron transfer mechanisms of electroactive bacteria could help determine their potential in microbial fuel cells (MFCs) and their microbial syntrophy with redox-active minerals in natural environments. However, the mechanisms of extracellular electron transfer to electrodes by sulfate-reducing bacteria (SRB) remain underexplored. Here, we utilized double-chamber MFCs with carbon cloth electrodes to investigate the extracellular electron transfer mechanisms of Desulfovibrio vulgaris Hildenborough (DvH), a model SRB, under varying lactate and sulfate concentrations using different DvH mutants. Our MFC setup indicated that DvH can harvest electrons from lactate at the anode and transfer them to cathode, where DvH could further utilize these electrons. Patterns in current production compared with variations of electron donor/acceptor ratios in the anode and cathode suggested that attachment of DvH to the electrode and biofilm density were critical for effective electricity generation. Electron microscopy analysis of DvH biofilms indicated DvH utilized filaments that resemble pili to attach to electrodes and facilitate extracellular electron transfer from cell to cell and to the electrode. Proteomics profiling indicated that DvH adapted to electroactive respiration by presenting more pili- and flagellar-related proteins. The mutant with a deletion of the major pilus-producing gene yielded less voltage and far less attachment to both anodic and catholic electrodes, suggesting the importance of pili in extracellular electron transfer. The mutant with a deficiency in biofilm formation, however, did not eliminate current production indicating the existence of indirect extracellular electron transfer. Untargeted metabolomics profiling showed flavin-based metabolites, potential electron shuttles.IMPORTANCEWe explored the application of Desulfovibrio vulgaris Hildenborough in microbial fuel cells (MFCs) and investigated its potential extracellular electron transfer (EET) mechanism. We also conducted untargeted proteomics and metabolomics profiling, offering insights into how DvH adapts metabolically to different electron donors and acceptors. An understanding of the EET mechanism and metabolic flexibility of DvH holds promise for future uses including bioremediation or enhancing efficacy in MFCs for wastewater treatment applications.

`Evaluation of the antimicrobial corrosion properties of electropolymerized poly(aniline-co-o-toluidine) films on carbon steel surfaces

Microbiologically influenced corrosion (MIC) can lead to structural weakening and shortened service life of carbon steel, resulting in serious economic losses and safety hazards. In particular, sulfate-reducing bacteria (SRB) produce hydrogen sulfide and sulfide during their growth and metabolism, which accelerates the corrosion of carbon steel. Thin films of poly(aniline-co-o-toluidine) (PA-co-POT) were electrodeposited on the surface of carbon steel using cyclic voltammetry in an electrolyte consisting of oxalic acid, aniline and o-toluidine monomers. The mechanical properties of the polymer films were analyzed by a micro-Vickers hardness tester. The corrosion resistance of the polymer films was evaluated by an electrochemical corrosion test and immersion test of the polymer films in a solution containing SRB and 3.5% NaCl. The results showed that PA-co-POT films have superior SRB corrosion resistance than single polymer films. The corrosion rate of PA-co-POT film was 0.0171mm/year, and the protection efficiency was 83% after 14 days of immersion in solution. In addition, due to the antibacterial properties of the PA-co-POT film, the adhesion of bacteria on its surface is significantly reduced, and local corrosion is also effectively inhibited. This study demonstrates the potential of electropolymerized aniline derivative copolymer films in preventing MIC of carbon steel and provides valuable insights for the development of new corrosion protection materials.

Preparation of Composite Materials with Slow-Release Biocides and Solidifying Agents for Remediation of Acid Pollution in Coal Gangue

The processes of coal mining and washing generate a substantial amount of coal gangue. During prolonged outdoor storage, this waste can lead to both direct and indirect environmental pollution, as well as geological hazards. Recent research has indicated that the redox processes of coal gangue are regulated by microorganisms. Techniques such as the application of biocides and the facilitation of microbial interactions have proven effective in controlling the acidic pollution of coal gangue in the short term. However, conventional doping methods that couple sulfate-reducing bacteria with biocides face challenges, including a short effective duration and poor stability. To address these issues, this study utilized corn straw biochar as a microbial attachment material and incorporated water-retaining agents as slow-release biocide carriers, resulting in the development of an environmentally friendly microbial remediation material. This study selected 0.6 g of biochar produced from the pyrolysis of corn straw at 700 °C to immobilize sulfate-reducing bacteria. Additionally, 0.6 g of polyacrylamide was used to prepare a slow-release bactericide with 100 mL of a sodium dodecyl sulfate solution at a concentration of 50 mg·L−1. The composite remediation material successfully raises the pH of weathered coal gangue leachate from 4.32 to 6.88. Its addition notably reduces the sulfate ion concentration in the weathered coal gangue, with sulfate content decreasing by 86.45%. Additionally, the composite material effectively lowers the salinity of the weathered coal gangue. The composite immobilizes heavy metal ions within the weathered coal gangue, achieving an approximate removal rate of 80% over 30 days. Following the introduction of the composite material, significant changes were observed in the dominant microbial communities and population abundances on the surface of the coal gangue. The composite demonstrated the ability to rapidly, sustainably, and effectively remediate the acidification pollution associated with coal gangue.

The Role of the Bactericidal Mechanism of Copper Elements and Its Effect on the Corrosion Resistance of Steel.

In this paper, two kinds of copper-containing steels with copper contents of 2.31 and 6.01 wt.% were designed. By comparing with commercial Q355, the bactericidal properties of copper in seawater containing sulfate-reducing bacteria (SRB) and its influence on the corrosion process of steel were revealed. The corrosion rate, morphology of products, and bactericidal action of copper were tracked by scanning electron microscopy, X-ray diffraction, confocal microscopy, and electrochemical analysis techniques. It was found that the resistance of copper-containing steel to bacterial corrosion was obviously better than that of non-copper-containing steel. At 28 days, the weight loss rates in the SRB environment for 0Ni2Cu6 samples increased by merely 5.43%, which was nearly half that of Q355 of 9.75%. Cu-containing steels exhibited potent antibacterial action, with the ε-Cu phase altering the corrosion byproduct composition from brittle flakes to robust particles and inhibiting the production of H2S. The killed bacteria adhered to the surface of the steel and slowed down the corrosion of the steel. The confocal laser scanning microscope and electrochemical experiments showed that a dense CuFeO4 film formed on the substrate, impeding corrosive ion penetration, and an upsurge in Cu content markedly enhanced the material's anti-corrosion and antimicrobial attributes.