• Journal of Electrochemical Science and Technology
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• v.9 no.3
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• pp.238-249
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• 2018

The impact of methanol extract of Chaenomeles sinensis (C. sinensis) leaves on acid corrosion of low carbon steel was assessed by gravimetric and electrochemical methods. Phytochemical characterization by total phenolic content (TPC), and total flavonoids content (TFC) of the extract was performed. The TPC and TFC concentrations were identified as 193.50 and 40.55 mg/g. Efficiency increased remarkably in the presence of inhibitor and found as concentration dependent. A maximum inhibition efficiency of 93.19% was achieved using 2000 ppm of the C. sinensis inhibitor. Impedance and surface morphology analysis by SEM and AFM revealed that the anticorrosive activity results from the protective film of phytochemical components of C. sinensis extract adsorbed on the metal surface.

• Corrosion Science and Technology
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• v.19 no.2
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• pp.82-88
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• 2020

This work examined the corrosion protection performance of benzoate loaded hydrotalcite/graphene oxide (HT/GO-BZ) for carbon steel. HT/GO-BZ was fabricated by the co-precipitation method and characterized by infrared spectroscopy, X-ray diffraction, and scanning electronic microscopy. The corrosion inhibition action of HT/GO-BZ on carbon steel in 0.1 M NaCl solution was evaluated by electrochemical measurements. The benzoate content in HT/GO-BZ was determined by UV-Vis spectroscopy. Subsequently, the effect of HT/GO-BZ on the corrosion resistance of the water-based epoxy coating was investigated by the salt spray test. The obtained results demonstrated the intercalation of benzoate and GO in the hydrotalcite structure. The benzoate content in HT/GO-BZ was about 16%. The polarization curves of the carbon steel electrode revealed anodic corrosion inhibition activity of HT/GO-BZ and the inhibition efficiency was about 95.2% at a concentration of 3g/L. The GO present in HT/GO-BZ enhanced the inhibition effect of HT-BZ. The presence of HT/GO-BZ improved the corrosion resistance of the waterborne epoxy coating.

• Journal of the Korean Chemical Society
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• v.59 no.2
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• pp.125-131
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• 2015

Inhibition effects of histidine (His), methionine (Met) on the corrosion of nickel were investigated in deaerated 0.5 M HCl and 0.5 M $H_2SO_4$ solution. All the inhibition efficiency for the nickel corrosion depended on the anodic inhibition. Amino acid adsorption process on nickel surface in the solution of HCl can be explained by modified Langmuir isotherm, however, in the solution of $H_2SO_4$ by Temkin logarithmic isotherm due to the interaction between the adsorbed molecules. The molecule of histidine dissolved in HCl-solution were physically adsorbed due to the electrostatic interaction between the surface of {$Ni-Cl^-$} and the {$-NH{_3}^+$} and {$-NH^+=$} of His. However the other cases of adsorption in this investigation can be explained by chemical adsorption between the empty d-orbital of Ni and the lone pair of electron in His and Met.

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.6
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• pp.349-353
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• 2003

The physiological characteristics of cultures of very high cell mass (e.g. 10g cell mass/L), termed“ultrahigh cell density cultures”is reviewed. A close relationship was found between the length of the optical path (OP) in flat-plate reactors and the optimal cell density of the culture as well as its areal (g m$\^$-2/ day$\^$-1/) productivity. Cell-growth inhibition (GI) unfolds as culture density surpasses a certain threshold. If it is constantly relieved, a 1.0cm OP reactor could produce ca. 50% more than reactors with longer OP, e.g. 5 or 10cm. This unique effect, discovered by Hu et al. [3], is explained in terms of the relationships between the frequency of the light-dark cycle (L-D cycle), cells undergo in their travel between the light and dark volumes in the reactor, and the turnover time of the photosynthetic center (PC). In long OP reactors (5cm and above) the L-D cycle time may be orders of magnitude longer than the PC turnover time, resulting in a light regime in which the cells are exposed along the L-D cycle, to long, wasteful dark periods. In contrast, in reactors with an OP of ca. 1.0 cm, the L-D cycle frequency approaches the PC turnover time resulting in a significant reduction of the wasteful dark exposure time, thereby inducing a surge in photosynthetic efficiency. Presently, the major difficulty in mass cultivation of ultrahigh-density culture (UHDC) concerns cell growth inhibition in the culture, the exact nature of which is awaiting detailed investigation.

• Corrosion Science and Technology
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• v.4 no.3
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• pp.89-94
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• 2005

This paper presents the results of a study that was undertaken to optimize the ratio of the components of a new multi-component inhibitor blend composed of orthophosphate/ phosphonates/ acrylate copolymer/ isothiazolone. The effects of newly developed inhibitor on carbon steel dissolution in synthetic cooling water were studied through weight loss tests, electrochemical tests, scale tests, and micro-organism tests. The obtained results were compared to blank (uninhibited specimen) and showed that developed inhibitor revealed very good corrosion, scale, and micro-organism inhibition simultaneously. All measurements indicated that the efficiency of the blended mixture exceeded 90 %. The inhibitive effects arose from formation of protective films which might contain calcium phosphate, calcium phosphonate, and iron oxide. The nature of protective films formed on the carbon steel was studied by scanning electron microscopy (SEM) and auger electron spe ctroscopy (AES). Inhibitor used in this study appeared to have better performance for scale inhibition due to their superior crystal modification effect and excellent calcium carbonate scale inhibition properties. The effect of inhibitor on microorganisms was evaluated through minimum inhibitory concentration (MIC) test. All kinds of micro-organisms used in this study were inhibited under 78ppm concentration of inhibitor.

• Corrosion Science and Technology
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• v.18 no.6
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• pp.243-252
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• 2019

The pitting corrosion and inhibition studies of AZ31B magnesium alloy were investigated in the alkaline solution (pH12) with chloride and inhibitors. The corrosion behavior of passive film with/without Cl^- in the alkaline electrolyte were conducted by polarization curve and immersion tests in the presence of various additives (inhibitors) to clarify the inhibition efficiency of pitting corrosion at higher potential region. Critical concentration of pitting corrosion for Mg alloy was evaluated with 0.005 M NaCl in 0.01 M NaOH on the anodic polarization behavior. Critical pitting of AZ31B Mg alloy in 0.01 M NaOH is a function of chlorides; E_pit = - 1.36 - 0.2 log [Cl^-]. When the Sodium Benzoate (SB) was only used as an inhibitor, a few metastable pits developed on the Mg surface by an immersion test despite no pitting corrosion on the polarization curve meaning that adsorption of SB on the surface is insufficient protection from pitting corrosion in the presence of chloride. The role of SB and Sodium Dodecylbenzenesulfonate (SDBS) inhibitors for the Mg alloy surface in the presence of chloride was suppressed from pitting corrosion to co-adsorb on the Mg alloy surface with strong formation of passive film preventing pitting corrosion.

• Journal of the Korean Chemical Society
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• v.55 no.2
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• pp.268-278
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• 2011

Corrosion of aluminum in 0.1 M HCl solution in the absence and presence of ${\beta}$-blocker inhibitors (atenolol, propranolol, timolol and nadolol) was investigated using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The inhibition efficiency increased with inhibitor concentration and decreased with rise of temperature. Potentiodynamic polarization curves revealed that they acted as cathodic inhibitors. Some thermodynamic parameters were calculated and discussed. All inhibitors were adsorbed on Al surface obeying Frumkin isotherm. All EIS tests exhibited one capacitive loop which indicates that the corrosion reaction is controlled by charge transfer process. The inhibition efficiencies of all test methods were in good agreement.

• Journal of Electrochemical Science and Technology
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• v.10 no.1
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• pp.29-36
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• 2019

Corrosion inhibition by synthesised ligand, 2-acetylpyridine 4-ethyl-3-thiosemicarbazone (HAcETSc) and its tin(IV) complex, dichlorobutyltin(IV) 2-acetylpyridine 4-ethyl-3-thiosemicarbazone ($Sn(HAcETSc)BuCl_2$) on mild steel in 1 M hydrochloric acid (HCl) was studied using weight loss measurement, potentiodynamic polarisation, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). The inhibition efficiency increases by increasing the inhibitor concentrations. The polarisation study showed that both synthesised compounds were mixed type inhibitors. The electrochemical impedance study showed that the presence of inhibitors caused the charge transfer resistance to increase as the concentration of inhibitors increased. The adsorption of these compounds on mild steel surface was found to obey Langmuir's adsorption isotherm with the free energy of adsorption ${\Delta}G{^o}_{ads}$ of -3.7 kJ/mol and -7.7 kJ/mol for ligand and complex respectively, indicating physisorption interaction between the inhibitors and 1 M HCl solution.

• Corrosion Science and Technology
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• v.22 no.1
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• pp.1-9
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• 2023

This work studied the inhibitory effect of the combination of benzoate-intercalated hydrotalcite (HT-BZ) and Ce³⁺-loaded clay (Clay-Ce) on carbon steel (CS). HT-BZ was prepared by the co-precipitation method and Clay-Ce was fabricated by a cation exchange reaction. HT-BZ and Clay-Ce were assessed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) coupled with zeta potential measurement. Electrochemical measurements coupled with scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX) were used for studying the inhibitory action of the mixture of HT-BZ and Clay-Ce on steel electrodes immersed in 0.1 M NaCl. For comparison, the inhibitory effect of HT-BZ or Clay-Ce alone was also evaluated. The results showed that HT-BZ combined with Clay-Ce provided synergistic inhibition of the CS substrate. The mixture of 0.5 g/L HT-BZ + 0.5 g/L Clay-Ce provided 93.5% inhibition efficiency. The protective mechanism of the HT-BZ + Clay-Ce mixture consisted of the reaction of released BZ and Ce³⁺ and the deposition of HT-BZ and Clay-Ce structures on the CS substrate.

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.549-554
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• 2002

Recently, interest in hygiene has been arouse in the health care field. Consequently, Filters with antibacterial agent applied to improve air quality by sterilizing bacteria, fungi, etc. We actually installed antibacterial air filter containing 2.5wt%Ag zeolite on the air intake route to air-conditioner in passenger cu, and evaluated filter's performance on antibacterial effect. By the microbe liquid spattering method, we found that the antibacterial air filter has notably sufficient antibacterial efficiency against standard strains and wild type strains. Antibacterial effect was observed at whole area of filter media by zone of inhibition test. The evaluation of microbe quantity was conducted through mixing dilution plate culture method. In comparison with ordinary filter, the amount of germs attached on antibacterial air filters was larger. The amount of germs attached on ordinary filters was very small since ordinary filters contained less dust. In comparison in antibacterial air filter with thickness, the amount of germs attached on 9mm filter was smaller than that of on 6mm filter. i.e. thicker filter, superior efficiency.