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Showing 10 results for Inhibitor

Dehghanian C., Saremi M., Mohammadi Sabet M.,
Volume 2, Issue 1 (3-2005)
Abstract

The synergistic behavior of molybdate and phosphate ions in mitigating the corrosion of mild steel in simulated cooling water was evaluated performing potentiodynamic polarization and impedance spectroscopy tests. Phosphate and molybdate showed a synergistic effect on corrosion inhibition of steel in simulated cooling water. The observed reduction in anodic and cathodic current densities could be the consequence of incorporation of both phosphate and molybdate ions in forming a protective layer on the surface. The charge transfer resistance of the protective layer formed on steel surface was much greater in presence of both ions in solution than that when each inhibitor used alone.
A. Khavasfar1,, M. H. Moayed2, M. M. Attar3,
Volume 4, Issue 3 (12-2007)
Abstract

Abstract: The performance of an Imidazoline based commercial corrosion inhibitor in CO2 corrosion of a gas-well tubing steel was studied by employing Electrochemical Impedance Spectroscopy (EIS) technique. Inhibitor performance was investigated by means of its efficiency at various concentration and also its behavior at various exposure time. EIS results showed that inhibitor interaction to the electrode surface obeys Lungmuir adsorption isotherm. Interpretation of some parameters such as Rct, Rpf, Cdl, and Cpf associated to the equivalent circuit fitted to the experimental rsults showed that not only inhibitor efficiency and surface coverage improve by increasing in inhibitor concentration in the solution but also at constant inhibitor concentration both surface coverage and efficiency improve with exposure time and reach to their highest value after 4 hours.
C. Dehghanian, Y. Mirabolfathi Nejad,
Volume 5, Issue 1 (3-2008)
Abstract

Abstract: Despite having a number of advantages, reinforced concrete can suffer rebar corrosion in high–chloride media, resulting in failure of reinforced concrete structures. In this research the corrosion inhibition capability of the mixture of calcium and ammonium nitrate of steel rebar corrosion was investigated in the simulated concrete pore solution. Cyclic polarization and Electrochemical Impedance Spectroscopy (EIS) techniques were applied on steel concrete pore solution containing 2 weight percent sodium chloride (NaCl). Results show that such mixtures had higher inhibition efficiency than calcium nitrate alone. The optimum concentration of the inhibitor mixture was determined to be 45 mgr/lit.
M. Vishnudevan,
Volume 9, Issue 4 (12-2012)
Abstract

Corrosion behavior of mild steel in chloride contaminated alkaline solution has been studied for the period up to 100days. Saturated Calcium hydroxide solution was used as alkaline solution and 0.5M NaCl solution was used to accelerate mild steel corrosion. The Charge transfer resistance Rct, Current density Icorr and inhibition efficiency values were obtained from tafel polarization and electrochemical impedance spectroscopic technique for sodium nitrite, sodium citrate and sodium benzoate mixed inhibitors. The results were compared with nitrite inhibitive system. The combination of nitrite inhibitor along with benzoate and citrate inhibitors enhanced the durability of mild steel through formation of nanosized -Fe2O3 film on steel suface even in presence of high chloride contamination. The results obtained from gravimetric method proved that the 100 days exposure of mild steel in nitrite with citrate, nitrite with citrate and benzoate mixed inhibitors showed the maximum inhibition efficiency of 98% in comparison with nitrite inhibitive system alone (41.5%). The maximum corrosion resistance performance of these mixed inhibitors system was due to the formation of thick layer of nano : Fe2O3 fibrous film on steel surface.
N. Kumpawat, A. Chaturvedi, R. K. Upadhyay,
Volume 10, Issue 4 (12-2013)
Abstract

Weight loss technique has been used to study the corrosion inhibition efficiency of tin in HNO3 solution by using the leaves and stem extract of different varieties of Holy Basil viz. ocimum basilicum (EB), ocimum cannum (EC) and ocimum sanctum (ES). The results show that all the varieties under study are good corrosion inhibitors, among which leaves extract of EB is the most effective. Corrosion inhibition efficiency increases with increasing concentration of inhibitor and it also increases with increasing concentration of HNO3 solution. Inhibition efficiency was found maximum up to 95.83% for tin in 3.0 M HNO3 solution, with 0.6% leaves extract whereas it was 81.25% in same concentration of HNO3 solution for stem extract
J. Dahdele, I. Danaee, G. H. Rashed, M. Rashvandavei,
Volume 12, Issue 2 (6-2015)
Abstract

The inhibition behavior of N,N′-bis(2,4,6-trihydroxyacetophenone)-propandiimine (THAPP) as an environmentally friendly Salen Ligand on the corrosion inhibition of mild steel was studied in alkaline solution (pH=10) containing 3% NaCl. Measurements were carried out using electrochemical and surface techniques. The experimental results suggested that this compound was an effective corrosion inhibitor for mild steel and the protection efficiency was increased with the increase in inhibitor concentration. Polarization curves indicated that this organic compound was a mixed-type inhibitor. Adsorption on the mild steel surface follows the Langmuir isotherm model. Activation parameters and thermodynamic adsorption parameters of the corrosion process such as E a , ΔH, ΔS, K ads , and ΔG ads were calculated by the obtained corrosion currents at different temperatures
J. Odusote, O. Ajayi,
Volume 13, Issue 3 (9-2016)
Abstract

Jatropha curcas leaves extract was tested as a green corrosion inhibitor for mild steel in aqueous hydrochloric acid solution using gravimetric and thermometric techniques. The results reveal that the inhibition efficiency vary with concentration of the leaf extract and the time of immersion. Maximum inhibition efficiency was found to be 95.92% in 2M HCl with 0.5 g/l concentration of the extract in gravimetric method, while 87.04% was obtained in thermometric method. The inhibiting effect was attributed to the presence of alkaloids, flavonoids, saponins, tannins and phenol in the extract. The adsorption processes of the Jatropha curcas leaves extract onto the mild steel is consistent with the assumptions of Langmuir isotherm model and also found to be spontaneous. From the results, a physical adsorption mechanism is proposed for the adsorption of Jatropha curcas leaves extract onto mild steel surface.


A. Ehsani, S Bodaghi, H Mohammad Shiri, H Mostaanzadeh, M Hadi,
Volume 13, Issue 3 (9-2016)
Abstract

In this study, an  organic compound  inhibitor, namely N-benzyl-N-(4-chlorophenyl)-1H-tetrazole-5-amine (NBTA), was synthesized and the role of this inhibitor for corrosion protection of stainless steel (SS) exposed to 0.5 M H2SO4 was investigated using electrochemical, and quantum analysis. By taking advantage of potentiodynamic polarization, the inhibitory action of NBTA was found to be mainly mixed type with dominant anodic inhibition. The effectiveness of the inhibitor was also indicated using electrochemical impedance spectroscopy (EIS). Moreover, to provide further insight into the mechanism of inhibition, quantum chemical calculations of the inhibitor were performed. The adsorption of NBTA onto the SS surface followed the Langmuir adsorption model with the free energy of adsorption ΔG0ads of of -7.88 kJ mol-1. Quantum chemical calculations were employed to give further insight into the mechanism of inhibition action of NBTA.


M. Shahraki, S. M. Habibi-Khorassani, M. Noroozifar, Z. Yavari, M. Darijani, M. Dehdab,
Volume 14, Issue 4 (12-2017)
Abstract

The inhibition performances of nafcillin (III), methicillin (II) and penicillin G (I) on the corrosion of copper in HCl was studied and tested by weight loss, Tafel polarization, SEM, UV-vis spectrophotometry, molecular dynamics method and quantum chemical calculations. Polarization curves indicated that the studied inhibitors act as mixed-type inhibitors. The values of inhibition efficiency and surface coverage were found to follow the order: Blank ads, indicated that the adsorption of three inhibitors was a spontaneous process. The SEM micrographs confirmed the protection of copper in a 1 M HCl solution by penicillin G, nafcillin, and methicillin. The shape of the UV/vis spectra of inhibitors in the presence of the immersion of Cu showed a strong support to the possibility of the chemisorbed layer formation on Cu surface by nafcillin (between nafcillin and Copper) and physisorption between penicillin and methicillin with copper. DFT calculations were performed to provide further insight into the inhibition efficiencies which were determined experimentally. Molecular dynamics (MD) simulations were applied to find the most stable configuration and adsorption energies of penicillin G, nafcillin and methicillin molecules on Cu (110) surface. The interaction energy followed the order: nafcillin (III)> methicillin (II)> penicillin G (I), which confirmed that nafcillin has the strongest interaction with the metal surface. The obtained results from experimental and theoretical methods were in reasonable agreement.
 

R. Ubaid, S. Saroj Kumar, S. Hemalatha,
Volume 15, Issue 3 (9-2018)
Abstract

Drug resistant pathogenic microbes have been causing serious health issues resulting in the substantial increase of death rates and morbidity paving the way for nanoparticles to be utilized as antimicrobial agents. This study was performed to evaluate the effectiveness of CuNPs on the growth of drug resistant clinical isolates of Streptococcus pyogenes, Enterococcus faecium and Enterococcus faecalis. Minimum inhibitory concentration of CuNPs against Streptococcus pyogenes, Enterococcus faecium and Enterococcus faecalis was found to be 1.25. 1.25 and 0.625 mg/ml and minimum bactericidal concentration against the same isolates was found to be 2.5, 2.5 and 5 mg/ml respectively. The ratio of MBC/MIC, referred to as tolerance level, was calculated for all the isolates which signifies the bactericidal or bacteriostatic effect of any antimicrobial agent. For Streptococcus pyogenes and Enterococcus faecium, the tolerance level was 2 while as for Enterococcus faecalis, it was 8. Antibiotic susceptibility results were calculated which showed that the isolates were resistant to Ampicillin (10 µg), Amoxycillin (30 µg) and Aztreonam (30 µg). Susceptibility results were followed by calculating multiple antibiotic resistance indices (MARI). MARI is an important tool which gives an idea about the bacterial resistance in a given population. For all the three isolates, MARI results were equivalent to 1 because of their resistance towards all the three antibiotics used. Antimicrobial activity through well-plate method was carried out and inhibitory effect of CuNPs on biofilm formation was evaluated.
 


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