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    MILD STEEL CORROSION INHIBITION IN 1 M HCL BY AN ALCOHOLIC EXTRACT OF SARGASSUM MUTICUM
    (Portugaliae Electrochimica Acta, 2023) Jeslina, V; Jone Kirubavathy, S; Abdulhameed, Al-Hashem; Rajendran, S; Joany, R M; Caslav, Lacnjevac
    The inhibitive effect of a seaweed (SM) alcoholic extract on MS corrosion immersed in 1 M HCl, for 30 min, was evaluated by the WL method and PPD technique. The protective film was investigated by the Vickers hardness test. WL revealed that 500 ppm SM offered 84 % IE against MS corrosion in 1 M HCl. The inhibitor molecules adsorption onto the metal surface obeyed Langmuir’s adsorption isotherm. The R2 value was very high (0.998). The PPD study showed that Ecorr slightly shifted to the anodic side. It was inferred that SM functions as a mixed type of corrosion inhibitor, since the shifts were relatively small. In SM presence, LPR value increased and Icorr decreased. Due to the blanket effect (formation of a protective film on the metallic surface, which was found to be a monolayer, blocking anodic and cathodic sites), the electrons transfer from the metal into the solution was blocked. Vickers hardness of the inhibited MS surface was lower than that of the polished one, but higher than that of the corroded one. The outcome of the study may be used in the pickling industry, where HCl is used to remove the rust from the metal surface, simultaneously not attacking it.
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    INHIBITIVE EFFECT OF AN ALCOHOLIC EXTRACT OF A SEAWEED SARGASSUM MUTICUM IN CONTROLLING CORROSION OF MILD STEEL IN 0.5 N HCL
    (International Journal of Corrosion and Scale Inhibition, 2021-10-20) Jeslina, V; Kirubavathy, S J; Al-Hashem, A; Rajendran, S; Lacnjevac, C; Joany, R M
    The inhibitive effect of an alcoholic extract of a seaweed, namely, Sargassum Muticum, in controlling corrosion of mild steel in 0.5 N HCl has been evaluated by weight loss method (immersion period 1 day) and electrochemical techniques such as polarization study and AC impedance spectra. The protective film has been investigated by AFM and Vickers Hardness test. Weight loss method reveals that 500 ppm of inhibitor offers 99% inhibition efficiency to mild steel immersed in 0.5 N HCl. The adsorption of inhibitor molecules on the metal surface follows Langmuir adsorption isotherm. The R2 value is very high, 0.998. Polarization study reveals that the corrosion potential is slightly shifted to anodic side. It is inferred that the inhibitor solution functions as mixed type corrosion inhibitor. In the presence of the inhibitor, the linear polarization resistance (LPR) increases and the corrosion current decreases. Because of the Blanket effect (formation of a protective film on the metal surface blocking the anodic sites and cathodic), electron transfer from the metal to the bulk of the solution is blocked. AC impedance spectra confirm the formation of a protective film on the metal surface. As the inhibitor concentration increases, the Rct value increases and the double layer capacitance (Cdl) decreases, the impedance increases and the phase angle increases due to the blocking effect on the metal surface. It is found to be a monolayer of protective film. The Vickers hardness of the inhibited metal surface is lower than that of polished metal but higher than that of corroded surface. The average roughness, RMS roughness and maximum peak-to-valley height of inhibited metal surface are lower than those of corroded metal surface but higher than those of polished metal surface. The outcome of the study may be used in pickling industry where HCl is used to remove rust and at the same time metal surface is protected.
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    INHIBITION OF CORROSION OF MILD STEEL BY AN ALCOHOLIC EXTRACT OF A SEAWEED SARGASSUM MUTICUM
    (Engineering Society for Corrosion, 2021-09-25) Victor David Arockiaraj, Mallika Jeslina; Suyambulingam, Jone Kirubavathy; Abdulhameed, Al-Hashem; Susai, Santhammal Rajendran; Joany, RM; Caslav, Lacnjevac
    An alcoholic extract of a sea weed Sargassum muticum has been used to control corrosion of mild steel in 0.5 N HCl. Weight loss method and Electrochemical studies have been used in this study. Weight loss study reveals that 500 ppm of the inhibitor offers 99.25 % inhibition efficiency. Polarization study reveals that the inhibitor functions as an anodic inhibitor at higher concentration. The AC impedance spectra confirm the formation of a protective film on the metal surface. Adsorption of inhibitor molecules on the metal surface follows Langmuir adsorption isotherm.
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    CHEMINFORMATIC SCRUTINY OF SOME HETEROCYCLIC COMPOUNDS FOR THEIR CORROSION PROTECTIVE CAPABILITY
    (International Journal of Corrosion and Scale Inhibition, 2021-12-27) Ramkumar S; Nalini D; Priyanka D; Qurashi M A; Chauhan D S
    Over the last two decades, molecular modellings are capable of accurately predicting structures, energetics, reactivity, and other properties of molecules. Computational chemistry plays an important role in enabling chemists to: (i) explain and rationalize known chemistry of corrosion inhibitors and (ii) explore new or unknown chemicals applicable as corrosion inhibitors. In contrast to the traditional techniques of identifying and synthesizing new corrosion inhibitors in the wet lab, a prior dry-lab process is suggested by using cheminformatics tools. Once a correlation between the structure and activity or property is found, any number of compounds can be readily screened employing computational methodology. In the present work, the inhibitive performance of three important classes of heterocyclic compounds namely dithiazolidine, thioamidine, and thiourea derivatives have been calculated using quantum chemical methods. The three selected heterocyclic series contains nitrogen and sulphur in their chemical framework that were expected to be the main electron rich centres which act as the adsorption sites on the metal surface. The presence of aromatic ring together with electron donating substituents such as methyl and methoxy were found to enhance the adsorption characteristics of the studied heterocyclic systems. The global reactivity parameters and the local selectivity adsorption centres in each of the studied system were analyzed using theoretical parameters.
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    MACROCYCLIC COMPOUNDS AS GREEN CORROSION INHIBITORS FOR ALUMINIUM: ELECTROCHEMICAL, SURFACE AND QUANTUM CHEMICAL STUDIES
    (International Journal of Corrosion and Scale Inhibition, 2018-09-28) Ansari, K R; Ramkumar, S; Chauhan, D S; Salman, Md; Nalini, D; Srivastava, V; Quraishi, M A
    In the present work, two macrocyclic compounds namely 5,6,11,12-tetramethyl1,2,4,7,8,10 hexaazacyclododeca-4,6,10,12-tetraene-3,9-dithione (TMCD) and 5,6,11,12- tetraphenyl-1,2,4,7,8,10-hexaazacyclododeca-4,6,10,12-tetraene-3,9-dithione (TMPD) have been synthesized and for the first time reported as inhibitors against the corrosion of aluminium in 1 M hydrochloric acid. The synthesized compounds were characterized using 1H NMR and 13C NMR. The corrosion inhibition behaviour of TMCD and TMPD was studied using gravimetric measurements, electrochemical impedance spectroscopy and potentiodynamic polarization studies. The surface analysis was carried out using AFM and SEM. Theoretical studies on the adsorption behaviour of inhibitor were carried out using the Density Functional Theory method. A detailed study of the effect of temperature and the influence of immersion time is presented using weight loss technique. Potentiodynamic polarization study proves that the corrosion inhibition efficiencies of TMCD and TMPD at 400 mg L –1 concentration are 97.30% and 89.71% respectively. Both the inhibitors behaved as mixed type but exhibit cathodic predominance. The results of EIS-Nyquist plots show inductive behavior at low frequency characteristic of the electrochemical behaviour of aluminium. The increase in polarization resistance with concentration suggests the adsorption and corrosion inhibition behaviour for both TMCD and TMPD. The AFM studies reveal a considerable decrease in surface roughness in the presence of inhibitors compared to blank sample and the SEM images show a highly smooth surface of the metal sample in the presence of inhibitors. The Fukui functions, global softness and Mulliken charges reveal that the sites for electrophilic attack are the hetero atoms. The frontier molecular orbital energies, the molecular orbital energy gap and the other quantum chemical parameters corroborated the experimental observations and suggested a better performance of TMCD compared to TMPD molecule.
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    STUDY OF BIO-SYNTHESISED TRANSITION NANO METAL OXIDES DISPERSED POLYESTER COMPOSITES AS ENHANCED PROTECTORS FOR MILD STEEL IN 0.5 M H2SO4 MEDIUM-A GREEN APPROACH
    (Taylor & Francis Online, 2018-06-12) Nusrath Unnisa, C; Nirmala Devi, G; Selvaraj, Mohana Roopan; Subramanian, Chitra
    A facile, efficient and eco-friendly synthesis of transition nano metal oxides like zinc oxide (ZnO), copper oxide (CuO), tin oxide (SnO) from Persea americana. Mill was executed followed by ex-situ polymerization favoring poly (glycerol succinate) (PGS)/nano metal oxide composite for the first time. The incorporation of nanofillers was confirmed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction spectrometer (XRD), Scanning electron microscopy (SEM) and Energy dispersive spectroscopy (EDS). As a comparative approach, the extent of metal dissolution was evaluated in presence of precursor as well as nano dispersed forms for various concentrations (10, 50, 100, 500, 1000 ppm) under the cluster of electrochemical and non-electrochemical techniques. Enhanced inhibition efficiency of 97% was observed in the case of CuO dispersion which was additionally supported by XRD particle size determination. The increase in charge transfer resistance (Rct) and a decrease in corrosion current (Icorr) elicited from electrochemical measurements strictly proved the role of metal – oxide nanoparticles. Further, the mode of inhibitor was found to be predominantly cathodic.
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    MACROCYCLIC COMPOUNDS AS GREEN CORROSION INHIBITORS FOR ALUMINIUM: ELECTROCHEMICAL, SURFACE AND QUANTUM CHEMICAL STUDIES
    (International Journal of Corrosion and Scale Inhibition, 2018-09-28) Ansari, K R; Ramkumar, S; Chauhan, D S; Salman, MD; Nalini, D; Srivastava, V; Quraishi, M A
    In the present work, two macrocyclic compounds namely 5,6,11,12-tetramethyl1,2,4,7,8,10 hexaazacyclododeca-4,6,10,12-tetraene-3,9-dithione (TMCD) and 5,6,11,12- tetraphenyl-1,2,4,7,8,10-hexaazacyclododeca-4,6,10,12-tetraene-3,9-dithione (TMPD) have been synthesized and for the first time reported as inhibitors against the corrosion of aluminium in 1 M hydrochloric acid. The synthesized compounds were characterized using 1H NMR and 13C NMR. The corrosion inhibition behaviour of TMCD and TMPD was studied using gravimetric measurements, electrochemical impedance spectroscopy and potentiodynamic polarization studies. The surface analysis was carried out using AFM and SEM. Theoretical studies on the adsorption behaviour of inhibitor were carried out using the Density Functional Theory method. A detailed study of the effect of temperature and the influence of immersion time is presented using weight loss technique. Potentiodynamic polarization study proves that the corrosion inhibition efficiencies of TMCD and TMPD at 400 mg L –1 concentration are 97.30% and 89.71% respectively. Both the inhibitors behaved as mixed type but exhibit cathodic predominance. The results of EIS-Nyquist plots show inductive behavior at low frequency characteristic of the electrochemical behaviour of aluminium. The increase in polarization resistance with concentration suggests the adsorption and corrosion inhibition behaviour for both TMCD and TMPD. The AFM studies reveal a considerable decrease in surface roughness in the presence of inhibitors compared to blank sample and the SEM images show a highly smooth surface of the metal sample in the presence of inhibitors. The Fukui functions, global softness and Mulliken charges reveal that the sites for electrophilic attack are the hetero atoms. The frontier molecular orbital energies, the molecular orbital energy gap and the other quantum
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    STUDY ON THE INHIBITION OF MILD STEEL CORROSION BY BENZOISOXAZOLE AND BENZOPYRAZOLE DERIVATIVES IN H2SO4 MEDIUM (Article pdf)
    (Portugaliae Electrochimica Acta, 2010-06-24) Parameswari, K; Rekha, S; Chitra, S; Kayalvizhy, E
    Four heterocyclic compounds, namely 4- phenyl-5-acetyl/carbethoxy-3-methyl-6- hydroxyl-6-methyl-4,5,6,7-tetrahydro-2,1-benzoisoxazole and benzopyrazole (BIS1, BP1and BIS2, BP2), were synthesized and their influence on the inhibition of corrosion of mild steel in 1 M H2SO4 was investigated by means of weight loss, potentiodynamic polarization, electrochemical impedance (EIS) and scanning electron microscopy (SEM). The values of activation energy and free energy of adsorption of these compounds were also calculated. Adsorption obeys Langmuir adsorption isotherm. The IE of the compounds was found to vary with concentration and temperature. Synergistic effect was also investigated for the four compounds at 0.05 mM concentration by weight loss method in 1 M H2SO4 medium in presence of KI, KBr and KCl. Results obtained revealed that all the four compounds performed excellently as a corrosion inhibitor for mild steel in 1 M H2S04 and their efficiency attains more than 90% at 0.6 mM at 298 K. Polarisation studies showed them to be mixed type inhibitors.
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    INHIBITIVE EFFECT OF AN ALCOHOLIC EXTRACT OF A SEAWEED SARGASSUM MUTICUM IN CONTROLLING CORROSION OF MILD STEEL IN 0.5 N HCL
    (International Journal of Corrosion and Scale Inhibition, 2021-10-20) Jeslina, V; Kirubavathy, S J; Al-Hashem, A; Rajendran, S; Lacnjevac, C; Joany, R.M.
    The inhibitive effect of an alcoholic extract of a seaweed, namely, Sargassum Muticum, in controlling corrosion of mild steel in 0.5 N HCl has been evaluated by weight loss method (immersion period 1 day) and electrochemical techniques such as polarization study and AC impedance spectra. The protective film has been investigated by AFM and Vickers Hardness test. Weight loss method reveals that 500 ppm of inhibitor offers 99% inhibition efficiency to mild steel immersed in 0.5 N HCl. The adsorption of inhibitor molecules on the metal surface follows Langmuir adsorption isotherm. The R 2 value is very high, 0.998. Polarization study reveals that the corrosion potential is slightly shifted to anodic side. It is inferred that the inhibitor solution functions as mixed type corrosion inhibitor. In the presence of the inhibitor, the linear polarization resistance (LPR) increases and the corrosion current decreases. Because of the Blanket effect (formation of a protective film on the metal surface blocking the anodic sites and cathodic), electron transfer from the metal to the bulk of the solution is blocked. AC impedance spectra confirm the formation of a protective film on the metal surface. As the inhibitor concentration increases, the Rct value increases and the double layer capacitance (Cdl) decreases, the impedance increases and the phase angle increases due to the blocking effect on the metal surface. It is found to be a monolayer of protective film. The Vickers hardness of the inhibited metal surface is lower than that of polished metal but higher than that of corroded surface. The average roughness, RMS roughness and maximum peak-to-valley height of inhibited metal surface are lower than those of corroded metal surface but higher than those of polished metal surface. The outcome of the study may be used in pickling industry where HCl is used to remove rust and at the same time metal surface is protected.
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    INHIBITION OF CORROSION OF MILD STEEL BY AN ALCOHOLIC EXTRACT OF A SEAWEED SARGASSUM MUTICUM
    (Zastita Materijala, 2021) Victor David Arockiaraj, Mallika Jeslina; Suyambulingam, Jone Kirubavathy; Abdulhameed, Al-Hashem; Susai, Santhammal Rajendran; Joany, RM; Caslav, Lacnjevac
    An alcoholic extract of a sea weed Sargassum muticum has been used to control corrosion of mild steel in 0.5 N HCl. Weight loss method and Electrochemical studies have been used in this study. Weight loss study reveals that 500 ppm of the inhibitor offers 99.25 % inhibition efficiency. Polarization study reveals that the inhibitor functions as an anodic inhibitor at higher concentration. The AC impedance spectra confirm the formation of a protective film on the metal surface. Adsorption of inhibitor molecules on the metal surface follows Langmuir adsorption isotherm