C1018 Carbon Steel Research Articles

Evaluation of thiocarbohydrazide derivative as corrosion inhibitor for C1018 carbon steel in 3.5% NaCl + 500ppm HAc solution: Electrochemical, SEM, FTIR and computational studies

N'-((E)-3-phenylallylidene)hydrazinethiocarbohydrazide (PHCT) was synthesized, purified, characterized and assessed for its inhibitive property against the sweet corrosion of C1018 carbon steel in CO2-saturated 3.5 % NaCl + 500 ppm HAc solution at 25 and 60 °C. At 50 ppm and 25 °C, electrochemical impedance spectroscopy (EIS) confirmed that the presence of PHCT in the electric double layer fortified the hydrophobicity of the region and mitigated rate of charge transfer. Potentiodynamic polarization (PP) measurements at 25 °C showed that PHCT is a mixed-type inhibitor, which could reduce corrosion rate from 24.32 mpy in blank to 0.67 mpy at 50 ppm dosage and deliver 97.24 % inhibition efficiency. PHCT adsorbs, principally, using its NH2, C = S and C = C functional groups, based on FTIR characterization. Computational modeling using the FMO and MEP analyses confirmed that PHCT exhibits higher electron donating than electron accepting power and interacts with the metal surface through nitrogen and sulfur atoms. Scanning electron microscopy (SEM) confirmed the ability of PHCT to protect the steel surface from localized pitting corrosion. Although increasing the temperature up to 60 °C diminished the efficiency of PHCT, the inhibitor was able to provide up to 92 % efficiency.

Surface roughness influence on extracellular electron microbiologically influenced corrosion of C1018 carbon steel by Desulfovibrio ferrophilus IS5 biofilm

Carbon steel microbiologically influenced corrosion (MIC) by sulfate reducing bacteria (SRB) is known to occur via extracellular electron transfer (EET). A higher biofilm sessile cell count leads to more electrons being harvested for sulfate reduction by SRB in energy production. Metal surface roughness can impact the severity of MIC by SRB because of varied biofilm attachment. C1018 carbon steel coupons (1.2 cm2 top working surface) polished to 36 grit (4.06 μm roughness which is relatively rough) and 600 grit (0.13 μm) were incubated in enriched artificial seawater inoculated with highly corrosive Desulfovibrio ferrophilus IS5 at 28 ℃ for 7 d and 30 d. It was found that after 7 d of SRB incubation, 36 grit coupons had a 11% higher sessile cell count at (2.0 ± 0.17) × 108 cells/cm2, 52% higher weight loss at 22.4 ± 5.9 mg/cm2 (1.48 ± 0.39 mm/a uniform corrosion rate), and 18% higher maximum pit depth at 53 μm compared with 600 grit coupons. However, after 30 d, the differences diminished. Electrochemical tests with transient information supported the weight loss data trends. This work suggests that a rougher surface facilitates initial biofilm establishment but provides no long-term advantage for increased biofilm growth.

Conductive magnetic nanowires accelerated electron transfer between C1020 carbon steel and Desulfovibrio vulgaris biofilm

Microbial biofilms are behind microbiologically influenced corrosion (MIC). Sessile cells in biofilms are many times more concentrated volumetrically than planktonic cells in the bulk fluids, thus providing locally high concentrations of chemicals. More importantly, “electroactive” sessile cells in biofilms are capable of utilizing extracellularly supplied electrons (e.g., from elemental Fe) for intracellular reduction of an oxidant such as sulfate in energy metabolism. MIC directly caused by anaerobic biofilms is classified into two main types based on their mechanisms: extracellular electron transfer MIC (EET-MIC) and metabolite MIC (M-MIC). Sulfate-reducing bacteria (SRB) are notorious for their corrosivity. They can cause EET-MIC in carbon steel, but they can also secrete biogenic H2S to corrode other metals such as Cu directly via M-MIC. This study investigated the use of conductive magnetic nanowires as electron mediators to accelerate and thus identify EET-MIC of C1020 by Desulfovibrio vulgaris. The presence of 40 ppm (w/w) nanowires in ATCC 1249 culture medium at 37 °C resulted in 45 % higher weight loss and 57 % deeper corrosion pits after 7-day incubation. Electrochemical tests using linear polarization resistance and potentiodynamic polarization supported the weight loss data trend. These findings suggest that conductive magnetic nanowires can be employed to identify EET-MIC. The use of insoluble 2 μm long nanowires proved that the extracellular section of the electron transfer process is a bottleneck in SRB MIC of carbon steel.

N‐(4‐Chloromethylbenzyl)‐N, N‐dimethyldodecan‐1‐aminium Chloride: A Quaternary Ammonium Surfactant as Corrosion Inhibitor

AbstractThis study used a quaternary surfactant, N‐(4‐Chloromethylbenzyl)‐N, N‐dimethyldodecan‐1‐aminium chloride (CMBDAC), as an excellent corrosion inhibitor of C1018 carbon steel (C1018 CS) in harsh 15 % HCl acidizing condition. CMBDAC was synthesized with an excellent yield and characterized by NMR, FTIR, and TGA. Gravimetric weight loss (WL), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) studies were employed to measure the efficacy of CMBDAC. At a relatively low concentration of 15 ppm, CMBDAC surpassed 90 % inhibition efficiency, with a maximum inhibition efficiency of 99.25 % being reached just for 50 ppm of CMBDAC. The inhibitor showed an efficacy of 96.16 % even at a temperature of 60 °C via the WL technique, showing potential to be used as a high‐temperature corrosion inhibitor. The adsorption isotherm study revealed that CMBDAC followed Langmuir adsorption isotherm. The Gibbs free energy of adsorption ( was calculated to be −40.43 kJ mol−1, indicating that CMBDAC was adsorbed via chemisorption. A very high value (1.68×105 L mol−1) of equilibrium constant ( ) suggested very strong adsorption of the inhibitor. PDP study disclosed that CMBDAC acted as a mixed‐type inhibitor. SEM‐EDX study demonstrated the adsorption of CMBDAC on the C1018 surface. Different DFT‐optimized parameters have been discussed in detail to support the superb inhibitory action indicated by CMBDAC.

Corrosion mitigation of carbon steel using triazole Mannich base derivatives: Correlation of electrochemical studies with quantum chemical calculations

The study investigated the corrosion-inhibitory properties of three synthetic triazole Mannich bases on C1018 carbon steel using various electrochemical techniques. The inhibitors, namely 4-amino-2-[(4-methylpiperazin-1-yl)methyl]-5-(pyridin-4-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (4MPT), 4-amino-2-[(piperidin-1-yl)methyl]-5-(pyridin-4-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (PPT) and 4-amino-2-[(morpholin-4-yl)methyl]-5-(pyridin-4-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (MPT), demonstrated the high inhibition efficiencies of 92.8%, 93.3% and 92.6%, respectively, and adhered to the Langmuir adsorption isotherm. The inhibitors also functioned as mixed-type inhibitors and improved the protective layer on the metal surface. The study also utilized scanning electron microscopy - energy dispersive x-ray (SEM-EDX) analysis to examine the surface morphology of the uninhibited and inhibited carbon steel specimens. Furthermore, density functional theory (DFT) was utilized for theoretical calculations, which corroborated with experimental measurements.

Surface and interfacial properties of poly(methyldiallylammonium chloride): Effect of hydrophobic pendant and synergism (KI) on corrosion of C1018CS in 15% HCl

BackgroundIn the current investigation, a dicationic surfactant made of poly(methyldiallylammonium chloride) (PMDAAC) was tested for its ability to suppress corrosion of C1018 carbon steel (C1018 CS) in a 15% HCl (acidizing) solution. MethodsWeight loss, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), linear polarization resistance (LPR), scanning electron spectroscopy (SEM), energy dispersive X-ray (EDX), atomic force microscope (AFM), and density functional theory (DFT). Significant findingsWeight loss tests show that PMDAAC has no significant inhibitory potential for the C1018CS/15% HCl system, as seen by its inhibition efficiency (IE) of 76.57% at 50 ppm concentration. However, adding 5 mM KI significantly increases the% IE of PMDAAC from 76.57% to 95.26% at the same concentration. A similar trend in the boost of% IE of PMDAAC from 85.33% to 99.28% and 83.28% to 98.42% was observed through PDP and EIS studies, respectively. PDP study showed that the current density (icorr) values kept decreasing with increasing PMDAAC concentration. PMDAAC behaves as a mixed- and interface-type inhibitor, being able to retard the progress of both anodic and cathodic reactions. EIS analysis showed that the values of charge transfer resistance (Rct) kept increasing with increasing inhibitor concentration. The adsorption isotherm study suggests that PMDAAC becomes effective by adsorbing on the C1018 CS surface, and its adsorption follows the Langmuir isotherm. A high value of 6.37 × 105 L mol-1 corresponds to the equilibrium constant for the adsorption process (Kads), indicating very strong adsorption of PMDAAC onto C1018 CS. PMDAAC was found to chemisorb onto the metal surface, as confirmed by the Gibbs free energy of adsorption (ΔGads∘) found to be – 43.76 kJ mol−1. The adsorption of PMDAAC on the C1018CS surface was confirmed by SEM and EDX studies. The improvement in surface morphology and alteration in elemental alignment in the presence of PMDAAC demonstrate the adsorption mode of corrosion mitigation. Lastly, the interaction of PMDAAC and its constituting components were described using the DFT method.

Anticorrosion performance of 1–benzylimidazole and synergistic iodide additives on C1018 carbon steel in 15% HCl solution

Acidizing, an industrial practice to enhance petroleum recovery, causes one of the most severe corrosion attacks on carbon steel drilling pipelines. Identifying highly efficient inhibitors to ameliorate this phenomenon is important for the petroleum industry. Here, the performance of 1–benzylimidazole (BZM) as a corrosion inhibitor for C1018 carbon steel in 15% HCl was investigated using electrochemical, weight loss and surface characterization techniques. Results from electrochemical techniques (electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM), linear polarization resistance (LPR) and potentiodynamic polarization (PDP)) agree that BZM performs efficiently by providing inhibition efficiency up to 75% at 25 °C with 1200 ppm concentration. The addition of 5 mM KI significantly enhances BZM efficiency to 93% at 25 °C. BZM alone is a mixed–type corrosion inhibitor with slightly anodic behavior. The addition of KI transforms the BZM inhibition mechanism more cathodically. However, the BZM + KI efficiency decreases to 60% at 60 °C. Surface characterization by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) confirm that BZM uses its nitrogen and phenyl groups to adsorb on the steel surface, forming a thin film which mitigates localized corrosion.

Investigation into the adsorption and inhibition properties of sodium octanoate against CO2 corrosion of C1018 carbon steel under static and hydrodynamic conditions

Sodium octanoate (Na-oct), a simple, naturally-abundant, cheap and low-toxic organic molecule has been investigated for its adsorption and inhibition properties against the CO2 corrosion of C1018 carbon steel in 3.5 % NaCl under static (0 rpm) and hydrodynamic conditions (1000 rpm). At open circuit potential (OCP) under static condition, a Langmuir-type adsorption of Na-oct modified the dielectric property of the steel-solution interface by lowering double layer capacitance and increasing resistance to charge transfer, based on electrochemical impedance spectroscopy (EIS) analysis. Under this condition, potentiodynamic polarization (PDP) analysis showed that Na-oct adsorbed more preferentially on anodic sites of steel surface and impacted ∼96 % inhibition efficiency. Hydrodynamic condition at 1000 rpm caused a Langmuir and Temkin adsorption mechanism and diminished the Na-oct efficiency to ∼86 %. FTIR characterization revealed that the inhibitor adsorption was enabled by its COO– functional group. Computational modeling, using DFT and MDS, confirmed the experimental findings.

Investigation of some new triazole derivatives for inhibiting the acid corrosion of C1018 carbon steel: Correlation of electrochemical studies with quantum chemical calculations

Iron and alloys of iron are commonly used in industries for various purposes. Despite their toughness, they are prone to corrosion. A common way to protect metallic components from corrosion is the use of pyridine inhibitors. Hence, two new triazole derivatives, ethyl{[5-(pyridin-4-yl)-4H-1,2,4-triazol-3-yl]sulfanyl}acetate (EPT) and 2-({[5-(pyridin-4-yl)-4H-1,2,4-triazol-3-yl]sulfanyl}methyl)-1H-benzimidazole (PTB) have been synthesised and the formation of compounds were confirmed by spectral data. The inhibition efficacy of both the inhibitors on C1018 metal in 1 M HCl were examined by electrochemical techniques. The results proved the anticorrosive ability of EPT and PTB with inhibition efficiency of 92% and 94%, respectively. Meanwhile, current density decreased from 1330 µA/cm2 to 106 µA/cm2 for EPT and 79.5 µA/cm2 for PTB with an increase in inhibitor concentration. Further, both of the triazole derivatives behaved as mixed type inhibitors through the Langmuir adsorption mechanism. Surface morphological analysis gave further proof for the higher adsorbing ability of these triazole derivatives on the metallic surface. The above experimental investigations were validated by performing quantum chemical calculations. The results of theoretical methods indicated the effectiveness of EPT and PTB for protecting the metal from acid corrosion.

Synthesis of polymeric surfactant containing bis-cationic motifs as a highly efficient acid corrosion inhibitor for C1018 carbon steel

Synthesis of polymeric surfactant containing bis-cationic motifs as a highly efficient acid corrosion inhibitor for C1018 carbon steel

Synthesis of polymeric surfactant containing bis-cationic motifs as a highly efficient acid corrosion inhibitor for C1018 carbon steel

The present study described synthesizing and characterizing a poly(methyldiallylammonium chloride)-based surfactant containing bis-cationic motifs (9) through a series of reactions. It was evaluated as a corrosion inhibitor for C1018 CS in 1 M HCl.

Corrosion Inhibition of Rumex vesicarius Mediated Chitosan-AgNPs Composite for C1018 CS in CO2-Saturated 3.5% NaCl Medium under Static and Hydrodynamic Conditions

Rumex vesicarius (RVE) mediated chitosan–AgNPs composite was produced in situ by using an aqueous extract of Rumex vesicarius leaves as the reducing agent to reduce Ag+ to Ag0. The synthesized composite was evaluated as a sweet (CO2) corrosion inhibitor (CI) for C1018 carbon steel (CS) in 3.5 wt% NaCl solution under static and hydrodynamic conditions. The corrosion inhibitive performance was evaluated using electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR), and potentiodynamic polarization (PDP) techniques, as well as scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDAX), and atomic force microscopy (AFM) on corroded C1018 CS without and with additives. The effect of concentration, immersion time, temperature, and rotation speed on the CI performance of the composite was also investigated. The corrosion inhibitive effect increased with increasing composite dosage, with the highest inhibition efficiency (IE) acquired at the maximum composite dosage of 0.3%. Beyond this concentration, the IE decline with increasing concentration. Furthermore, IE was found to increase with immersion time and decline with a temperature rise from 25 to 40 °C, with the optimum temperature of 60 °C found to accelerate corrosion without and with RVE-mediated Chi–AgNPs composite. Under high shear stress, the Chi–AgNPs composite exhibits moderate corrosion inhibition under hydrodynamic conditions. The surface analysis results validate the formation of a protective covering due to composite adsorption on the CS surface. The RVE-mediated chitosan–AgNPs composite could be recommended as a CI for C1018 CS in sweet (CO2) corrosion environments at ambient temperature.

Mapping Surface Corrosion Damages of C1018 Carbon Steel When Exposed to High Temperature Environment

Mapping Surface Corrosion Damages of C1018 Carbon Steel When Exposed to High Temperature Environment

Mitigation of carbon steel biocorrosion using a green biocide enhanced by a nature-mimicking anti-biofilm peptide in a flow loop

Biocorrosion, also called microbiologically influenced corrosion (MIC), is a common operational threat to many industrial processes. It threatens carbon steel, stainless steel and many other metals. In the bioprocessing industry, reactor vessels in biomass processing and bioleaching are prone to MIC. MIC is caused by biofilms. The formation and morphology of biofilms can be impacted by fluid flow. Fluid velocity affects biocide distribution and MIC. Thus, assessing the efficacy of a biocide for the mitigation of MIC under flow condition is desired before a field trial. In this work, a benchtop closed flow loop bioreactor design was used to investigate the biocide mitigation of MIC of C1018 carbon steel at 25 °C for 7 days using enriched artificial seawater. An oilfield biofilm consortium was analyzed using metagenomics. The biofilm consortium was grown anaerobically in the flow loop which had a holding vessel for the culture medium and a chamber to hold C1018 carbon steel coupons. Peptide A (codename) was a chemically synthesized cyclic 14-mer (cys-ser-val-pro-tyr-asp-tyr-asn-trp-tyr-ser-asn-trp-cys) with its core 12-mer sequence originated from a biofilm dispersing protein secreted by a sea anemone which possesses a biofilm-free exterior. It was used as a biocide enhancer. The combination of 50 ppm (w/w) THPS (tetrakis hydroxymethyl phosphonium sulfate) biocide + 100 nM (180 ppb by mass) Peptide A resulted in extra 1-log reduction in the sulfate reducing bacteria (SRB) sessile cell count and the acid producing bacteria (APB) sessile cell count compared to 50 ppm THPS alone treatment. Furthermore, with the enhancement of 100 nM Peptide A, extra 44% reduction in weight loss and 36% abatement in corrosion pit depth were achieved compared to 50 ppm THPS alone treatment.Graphical

Experimental and theoretical investigation of a new triazole derivative for the corrosion inhibition of carbon steel in acid medium

A new triazole derivative, (E)-4-(4-(dimethylamino)benzylideneamino)-5-(pyridin-4-yl)-2H-1,2,4-triazole-3(4H)-thione (DPT), was synthesized and characterized using spectral data. The electrochemical experimental techniques were utilized to evaluate the inhibition efficiency (IE) of DPT for the corrosion of C1018 carbon steel. The studies revealed that, DPT is highly efficient with IE value 90% at 250 ppm. Further, the addition of DPT resulted in the decrease of cathodic as well as anodic current densities which is the indication of mixed-type inhibition. Also, the studies inferred the Langmuir model for DPT-metal adsorption. The surface morphological studies of C1018 carbon steel with and without DPT was investigated using SEM, EDX, and XPS, which indicated the strong adsorption of metal-DPT. Monte-Carlo simulation and Density functional theory approaches had been employed for correlating the structure of DPT and its corrosion inhibition ability. The high IE values of DPT observed in experimental studies were in agreement with the theoretical studies, and hence DPT acts as good inhibitor for the corrosion of C1018 steel.

Efficiency of a pyrimidine derivative for the corrosion inhibition of C1018 carbon steel in aqueous acidic medium: Experimental and theoretical approach

The insoluble nature of many organic compounds restricts their application for the corrosion inhibition of metals in an aqueous acidic medium. To overcome this drawback, a new pyrimidine derivative, 5-acetyl-4-[4-(dimethylamino)phenyl]-6-methyl-3,4-dihydropyrimidin-2(1H)-one (ADP), has been designed and synthesized. Various electrochemical and theoretical methods were employed to evaluate the inhibition performance of ADP for the corrosion of C1018 carbon steel in aqueous 1.0 M HCl. The inhibition efficiency was 88.9% for 750 ppm of ADP. Tafel polarization curves revealed mixed-type inhibition of ADP. The current density was reduced with inhibitor ADP from 1110 to 123 μA/cm2 at 750 ppm. Electrochemical impedance spectral data showed increased polarization resistance from 12.6 to 84.3 Ώ/cm2 with the inhibitor concentration, increasing inhibition efficacy. The adsorption data of ADP fit appropriately to the Langmuir isotherm model. The surface analysis showed the development of the protective organic film that surrounded the defects that can shield chloride attack, hence preventing metal corrosion. Density functional theory and molecular dynamics simulation methods perfectly correlated with experimental inhibition performance.

Experimental and Theoretical Study to Understand the Adsorption Process of p‐Anisidine and 4‐Nitroaniline for the Dissolution of C38 Carbon Steel in 1M HCl

AbstractIn this work, we investigated the addition effect of two organic compounds namely; p‐anisidine (P1) and 4‐nitroaniline (P2) against corrosion of C38 steel in an acidic medium HCl 1 M. We opted for these inhibitors belonging to the aniline family which is characterized by their solubility, their low cost, and their use as corrosion inhibitors in acidic environments. The concentration effect of the two products P1 and P2 either by stationary or by transiency measurements appears a significant decrease in the corrosion rate, and that the inhibition efficiency IE% reaches a value of 88.55 % and 84 % for a concentration of 1 mM respectively of P1 and P2. The thermodynamic parameters taken from the electrochemical impedance curves indicate that the tested inhibitors are adsorbed on the metal surface by a mixed mechanism (physical‐chemisorption), because the free adsorption energy of P1 and P2 is respectively equal to −38.02 Kj.mol−1 and −37.56 Kj.mol−1, and they are subjected to the Langmuir isotherm. The temperature effect lets to determine the activation energy (Ea) from the Arrhenius equation; however, the values of Ea indicate the adsorption of organic compounds on the metal surface. Scanning electron microscopy (SEM) suggested that the products tested could effectively block acid attack on metal surfaces. In parallel to experimental approach, theoretical one based on theoretical function density (DFT) calculation and Monte Carlo (MC) simulation is considered to investigate in depth the inhibition behavior of studied compounds.

Food-grade D-limonene enhanced a green biocide in the mitigation of carbon steel biocorrosion by a mixed-culture biofilm consortium.

Microbiologically influenced corrosion (MIC), or microbial biocorrosion, is caused directly by microbial metabolic activities/products or induced by microbial biofilm's damage of a protective film that exposes a solid surface to a pre-existing corrosive environment. MIC causes billions of dollars of losses in various industrial processes, especially in oil and gas and water utilities. The mitigation of problematic industrial microbes typically relies on biocides whose discharges can cause environmental problems. Thus, more effective biocide applications are desired to minimize environmental impact. D-Limonene, a citrus peel oil, generally regarded as safe (GRAS), was used to enhance the popular biodegradable tetrakis hydroxymethyl phosphonium sulfate (THPS) biocide. An oilfield mixed-culture biofilm was grown anaerobically in enriched artificial seawater containing C1018 carbon steel coupons for 7days at 37°C. One hundred ppm (w/w) D-limonene reduced general heterotrophic bacteria (GHB) and acid-producing bacteria (APB) effectively, leading to 5.4-log and 6.0-log reductions in sessile GHB and APB cell counts, respectively, compared to no treatment control. The combination of 100ppm D-limonene + 100ppm THPS achieved extra 1.0-log SRB, 0.6-log GHB and 0.5-log APB reductions in sessile cell counts, which led to extra 58% reduction in microbial corrosion mass loss (1.2 vs. 0.5mg/cm2) and extra 30% reductions in maximum pit depth (11.5 vs. 8.1µm), compared to 100ppm THPS-only treatment. Linear polarization resistance and potentiodynamic polarization (PDP) corrosion data supported mass loss and pitting data. Mixed-culture biofilms on carbon steel coupons after 7day incubation at 37°C showing enhanced biocide treatment outcome using D-limonene + THPS: A no treatment, B 100ppm D-limonene, C 100ppm THPS, D 100ppm D-limonene + 100ppm THPS.

Evaluation of trehalase as an enhancer for a green biocide in the mitigation of Desulfovibrio vulgaris biocorrosion of carbon steel.

Trehalase can biocatalyze the conversion of trehalose to glucose. It is an enzyme that plays an important role in biofilm formation. Thus, trehalase has been patented as a chemical for preventing and treating biofilms. Sulfate-reducing bacteria (SRB) biofilms are often found responsible for biocorrosion, also known as microbiologically infuenced corrosion (MIC), especially in the oil and gas industries and in water utilities. The MIC treatment process typically requires biocide treatment of biofilms, sometimes together with scrubbing. Owing to environmental concerns, a lower biocide dosage is desired in the treatment process. In this work, trehalase was tested as a green biocide enhancer to enhance tetrakis hydroxymethyl phosphonium sulfate (THPS) in the prevention of Desulfovibrio vulgaris MIC of C1018 carbon steel in ATCC 1249 culture medium at 37°C. THPS is one of the most popular industrial biocides owing to its broad-spectrum efficacy and green chemical status. After 7days of incubation in 50mL anaerobic vials containing 40mL culture medium at pH 7.0, the sessile cell counts indicated that 50ppm (w/w) THPS + 30ppm (w/w) trehalase led to an extra 5.7-fold sessile cell reduction when compared with the 50ppm THPS alone treatment. As a consequence, the combination treatment also resulted in an extra 54% in pit depth reduction and 30% in weight loss reduction when compared with the 50ppm THPS alone treatment (with 9.0μm and 1.0mg/cm2). The biofilm images corroborated the decreased sessile cell count and pitting corrosion.

Efficacy of glutaraldehyde enhancement by D-limonene in the mitigation of biocorrosion of carbon steel by an oilfield biofilm consortium.

Microbiologically influenced corrosion (MIC) is one of the major corrosion threats in the oil and gas industry. It is caused by environmental biofilms. Glutaraldehyde is a popular green biocide for mitigating biofilms and MIC. This work investigated the efficacy of glutaraldehyde enhancement by food-grade green chemical D-limonene in the biofilm prevention and MIC mitigation using a mixed-culture oilfield biofilm consortium. After 7 days ofincubation at 37°C in enriched artificial seawater in 125mL anaerobic vials, the 100ppm (w/w) glutaraldehyde + 200ppm D-limonene combination treatment reduced the sessile cell counts on C1018 carbon steel coupons by 2.1-log, 1.7-log, and 2.3-log for sulfate reducing bacteria, acid producing bacteria, and general heterotrophic bacteria, respectively in comparison with the untreated control. The treatment achieved 68% weight loss reduction and 78% pit depth reduction. The 100ppm glutaraldehyde + 200ppm D-limonene combination treatment was found more effective in biofilm prevention and MIC mitigation than glutaraldehyde and D-limonene used individually. Electrochemical tests corroborated weight loss and pit depth data trends.