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Öğe Application of polymer composites and nanocomposites as corrosion inhibitors(Nova Science Publishers, Inc., 2016) Umoren, Saviour A.; Solomon, Moses M.Corrosion commonly defined as the deterioration of a material (usually a metal) or its properties because of a reaction with its environment is a global problem. NACE International, The Corrosion Society, estimates that global corrosion costs can be about 3-5% of GDP or GNP. Methods commonly adopted to combat corrosion include coatings and linings, cathodic protection, materials selection and corrosion inhibitors. Corrosion inhibitors are chemicals that, when present in very low concentrations, retard corrosion. Corrosion inhibitors form a layer over the metallic substrate and protect the metal from corrosion, thereby enhancing the life of the metal. Polymers, both naturally occurring and synthetic have been tested for metal corrosion inhibitors as replacement for the toxic inorganic and organic corrosion inhibitors. Interest in polymers stems from their availability, cost effectiveness, and eco-friendliness in addition to the inherent stability and multiple adsorption centers. However, it is found that most polymer materials studied are moderate corrosion inhibitors. Several attempts such as copolymerizing, addition of substances that exert synergistic effect, cross linking, blending, and most recently incorporation of inorganic substances in nano size into the polymer matrix have been made to improve the inhibition ability of polymers. Composites are materials consisting of two or more chemically distinct constituents on a minutescale, having a distinct interface separating them, and with properties which cannot be obtained by any constituent working individually. The production of composite materials is either by ex-situ or in-situ formation through chemical synthesis although electrochemical method had been used recently. The application of polymer composites and nanocomposites as anticorrosion materials have shown promising results and are believed to form metal chelate which could barricade metal surfaces from corrosive agents. In this chapter, the application of polymer composites and nanocomposites as corrosion inhibitors for different metal substrates in different corrosive media is explored. © 2017 Nova Science Publishers, Inc.Öğe Assessment of the corrosion behaviour of untreated and chemically treated pure magnesium in simulated body fluid(Taylor & Francis Ltd, 2022) Gerengi, Hüsnü; Cabrini, Marina; Solomon, Moses M.; Kaya, ErtuğrulThe corrosion behaviour of pure Mg in simulated body fluid (SBF) and the effect of chemical treatment on the corrosion resistance property were investigated using DEIS (dynamic electrochemical impedance spectroscopy), EIS (electrochemical impedance spectroscopy), PDP (potentiodynamic polarization), SEM (scanning electron microscopy), AFM (atomic force microscope), and pH measurement techniques for 30 h. NaOH or H2O2 were utilized for the chemical treatment. The DEIS was used for the first time in the investigation of Mg corrosion in SBF. Results obtained disclosed that the chemical treatment benefitted the anticorrosion property immensely. Results from both the electrochemical and surface analysis techniques are consistent.Öğe Carboxymethyl Cellulose/Silver Nanoparticles Composite: Synthesis, Characterization and Application as a Benign Corrosion Inhibitor for St37 Steel in 15% H2SO4 Medium(Amer Chemical Soc, 2017) Solomon, Moses M.; Gerengi, Hüsnü; Umoren, Saviour A.This study has been designed to boost the inhibition efficiency and stability of carboxymethyl cellulose (CMC) and this objective has been achieved by incorporating silver nanoparticles (AgNPs) generated in situ by reduction of AgNO3 using natural honey into CMC matrix. Characterization of CMC/AgNPs composite was done using transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectroscopy, ultraviolet visible spectroscopy (UV-vis), scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDS). Weight loss, electrochemical (dynamic electrochemical impedance spectroscopy, electrochemical impedance spectroscopy, and potentiodynamic polarization) supported by surface assessment (SEM, atomic force microscope, and FTIR) techniques are deployed for the anticorrosion studies of CMC/AgNPs on St37 specimen in 15% H2SO4 medium. CMC/AgNPs performs better than CMC. At 25 degrees C, optimum inhibition efficiency of 93.94% is afforded by 1000 ppm of CMC/AgNPs from DEIS method. Inhibition efficiency of 96.37% has been achieved from weight loss method at 60 degrees C. CMC/AgNPs is found to retard both the anodic and cathodic reactions and the adsorption is explained using Langmuir adsorption isotherm. AFM and SEM graphics reveal smoother surface for St37 sample in the acid solution containing inhibitor than inthe solution without the inhibiting agent. FTIR and EDS results show that CMC/AgNPs molecules were adsorbed on the metal surface.Öğe Chemical, Electrochemical, and Surface Morphological Studies of the Corrosion Behavior of the AZ31 Alloy in Simulated Body Fluid: Effect of NaOH and H2O2 Surface Pretreatments on the Corrosion Resistance Property(Amer Chemical Soc, 2022) Gerengi, Hüsnü; Cabrini, Marina; Solomon, Moses M.; Kaya, Ertuğrul; Gritti, Luca; Yola, Mehmet LutfiMagnesium and its alloys have attracted attention for biomedical implant materials in dental and orthopedic applications because of their biodegradability and similar properties to human bones. The very high rate of degradation in the physiological systems is, however, a major setback to their utilization. Chemical modification is one of the approaches adopted to enhance the corrosion resistance property of Mg and its alloys. In this work, NaOH and H2O2 were used as a pretreatment procedure to improve the corrosion resistance of the AZ31 Mg alloy in simulated body fluid (SBF). Advanced techniques such as dynamic electrochemical impedance spectroscopy (dynamic-EIS), atomic force microscopy, and optical profilometry were used in addition to the classical mass loss, hydrogen evolution, EIS, and polarization techniques to study the corrosion resistance property of the alloy in SBF for 30 h. Results obtained show that the surface treatment significantly enhanced the corrosion resistance property of the alloy. From dynamic-EIS at 30 h, the charge transfer resistance of the untreated AZ31 Mg alloy is 432.6 omega cm(2), whereas 822.7 and 2617.3 omega cm(2) are recorded for NaOH-and H2O2-treated surfaces, respectively. H2O2 is a better treatment reagent than NaOH. The mechanism of corrosion of both untreated and treated samples in the studied corrosive medium has been discussed.Öğe A comparative analysis of the corrosion characteristics of electro-galvanized steel coated with epoxy zinc-free and zinc-rich coatings in 5% NaCl(Taylor & Francis Ltd, 2022) Gerengi, Hüsnü; Solomon, Moses M.; Maraşlı, Muhammed; Kohen, Beni B.Anchor elements and pad hooks are used to attach large or small parts made of Glass Fiber Reinforced Concrete (GFRC) panels to the main structure of a building. The protection of these metallic parts is important to avoid corrosion. This work aims to compare the protection ability of normal epoxy and zinc-rich coatings (96% Zn) against chloride-induced corrosion of GFRC electrogalvanized pad hooks. The ASTM B117 salt spray test methods supported by SEM and EDAX surface analysis were adopted. The influence of surface treatment on coating thickness and performance was also considered. The results obtained show that the normal epoxy coatings are unsuitable for the studied pad hooks. Corrosion progressed under the coatings. Surface pre-treatment has a significant effect on the thickness of coatings. The average thickness of a two-coats untreated, sandblasted, and wire brushed pad hook zinc-rich coated layer is 39.27 mu m, 117.8 mu m, and 228.2 mu m. The sandblasted pad hooks coated with zinc-rich coatings exhibit high corrosion resistance after the salt spray test. The EDAX results reveal that the surface products on the sandblasted zinc-rich coatings were devoid of the main substrate components, namely Fe, Si, and Mn but consisted of 2.43 wt.% O, 0.53 wt.% Cl, and 96.49 wt.% Zn. The absence of these elements implies no corrosion and effective corrosion prevention by zinc-rich coatings. Visual observation and SEM images corroborate the EDAX results. However, the thickness of the sand-blasted zinc-rich coated surface increased from 117.8 mu m to 306.2 mu m due to the formation of ZnO. Zinc-rich coatings are recommended for the protection of GFRC electrogalvanized hooks and elements.Öğe Corrosion characteristics of plasma spray, arc spray, high velocity oxygen fuel, and diamond jet coated 30MnB5 boron alloyed steel in 3.5 wt.% NaCl solution(Walter De Gruyter Gmbh, 2022) Güney, Bekir; Dilay, Yusuf; Solomon, Moses M.; Gerengi, Hüsnü; Özkan, Adem; Yıldız, Mesut30MnB5 boron alloyed steel surface is coated using different coating techniques, namely 60(Ni-15Cr-4.4Si-3.5Fe-3.2B 0.7C)-40(WC 12Co) metallic powder plasma spray, Fe-28Cr-5C-1Mn alloy wire arc spray, WC-10Co-4Cr (thick) powder high velocity oxy-fuel (HVOF), and WC-10Co-4Cr (fine) diamond jet HVOF. The microstructure of the crude steel sample consists of ferrite and pearlite matrices and iron carbide structures. The intermediate binders are well bonded to the substrate for all coated surfaces. The arc spray coated surface shows the formation of lamellae. The cross-section of HVOF and diamond jet HVOF coated surfaces indicates the formation of WC, W2C Cr, and W parent matrix carbide structures. The corrosion characteristic of the coated steel has been investigated in 3.5 wt.% NaCl solution using electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDAX) techniques. The results reveal that the steel corroded in the medium despite the coatings. However, the extent of corrosion varies. HVOF coated sample demonstrated the highest corrosion resistance while arc spray coated sample exhibited the least. EDAX mapping reveals that the elements in the coatings corroded in the order of their standard electrode potential (SEP). Higher corrosion resistance of HVOF coated sample is linked to the low SEP of tungsten.Öğe Corrosion response of ultra-high strength steels used for automotive applications(Iop Publishing Ltd, 2019) Gerengi, Hüsnü; Şen, Nuri; Uygur, İlyas; Solomon, Moses M.The corrosion resistance properties of two ultra-high strength steels, Docol 1200 and 1400 were studied in 3.5 wt% NaCl solution using chemical and electrochemical techniques supported by surface characterization techniques namely scanning electron microscope (SEM), energy dispersive spectroscopy (EDX), atomic force microscope (AFM), and optical profilometer. The mechanical properties of both Docol 1200 and Docol 1400 uncorroded and corroded were determined by tensile test. Results obtained reveal that the two alloys exhibit similar mechanical properties. Corrosion has effect on the mechanical properties of the alloys. Corrosion studies reveal that both Docol 1200 and 1400 are prone to corrosion in NaCl environment. A corrosion rate of 30.6 mpy and 49.6 mpy was recorded for a Docol 1200 at 25 degrees C and 60 degrees C, respectively. For Docol 1400, the corrosion rate obtained at 25 degrees C and 60 degrees C was 32.7 mpy and 52.4 mpy, respectively. Docol 1200 is adjudged to exhibit superior corrosion resistance property than Docol 1400. The optical profilometric results disclose that Docol 1200 and Docol 1400 suffered pitting corrosion in NaCl solution. Pitting corrosion was more severe with Docol 1400 than 1200.Öğe Effect of surface treatment on the bioactivity and electrochemical behavior of magnesium alloys in simulated body fluid(Wiley-V C H Verlag Gmbh, 2017) Sasikumar, Y.; Solomon, Moses M.; Olasunkanmi, Lukman O.; Ebenso, EnoThe effect of surface treatment using NaOH or H2O2 on the bioactivity and corrosion behavior of AZX310, AZ91D, AM50, and AZ31 Mg alloys in simulated body fluid (SBF) has been studied with the aid of surface morphological assessment, in vitro characterization, and electrochemical measurements. The influence of immersion time on the behavior of the treated alloys in SBF was also investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirmed successful surface modification upon treatment of alloy surface with NaOH and H2O2. XRD and SEM analyses also revealed that surface modification enhances formation and growth of hydroxyapatite (HA). Formation of HA layer on the alloy surface was further confirmed by Fourier transform infrared spectroscopy analysis. In vitro immersion test reveals that pH of SBF solution containing treated alloys is lower than that containing untreated alloy. However, pH increases with immersion time. Results from weight loss and electrochemical measurements indicate that treated alloys possess higher corrosion resistance in SBF than the untreated ones. H2O2 treated alloys demonstrated greater corrosion resistance in SBF than NaOH treated alloys.Öğe Electrochemical and morphological assessments of inhibition level of 8-hydroxylquinoline for AA2024-T4 alloy in 3.5% NaCl solution(Taylor & Francis Ltd, 2018) Gerengi, Hüsnü; Solomon, Moses M.; Kurtay, Mine; Bereket, Gözen; Gökşen, Kadir; Yıldız, Mesut; Kaya, ErtuğrulThe corrosion inhibition of AA2024-T4 in 3.5% NaCl solution by 8-hydroxylquinoline (8-HQ) was investigated by potentiodynamic polarisation (PDP), electrochemical impedance spectroscopy and dynamic electrochemical impedance spectroscopy. Experimental results were supported with scanning electron microscopy (SEM), atomic force microscopy and Fourier transform-infrared (FTIR) spectroscopy analysis. It was found that 8-HQ molecules adsorbed on the alloy surface and protected it against corrosion. SEM, energy dispersive spectroscopy, and FTIR results confirm the adsorption of 8-HQ molecules on AA2024-T4. The inhibition efficiency of 8-HQ is found to increase with increase in concentration and the highest concentration studied (0.05 M) offered corrosion inhibition efficiency of 84%. PDP results show that 8-HQ acts as mixed type inhibitor in the studied medium.Öğe Enhanced corrosion inhibition effect of chitosan for St37 in 15% H2SO4 environment by silver nanoparticles(Elsevier Science Bv, 2017) Solomon, Moses M.; Gerengi, Hüsnü; Kaya, Tuğçe; Umoren, Saviour A.The inhibitive performance of chitosan and silver nanoparticles - chitosan (AgNPs-Chi) composite towards St37 steel corrosion in 15% H2SO4 solution was studied using weight loss and electrochemical techniques in addition to surface morphological examination. Results obtained show that chitosan could fairly protect St37 steel surface by 45%. Inhibition efficiency above 94% has been achieved with AgNPs-Chi composite. AgNPs-Chi composite performs better at longer immersion time and elevated temperature. AgNPs-Chi retards both anodic and cathodic redox reactions. The mode of adsorption of AgNPs-Chi onto St37 surface has been described using Langmuir adsorption isotherm. Surface screening results ascertain the adsorption of AgNPs-Chi molecules on St37 surface. (C) 2017 Elsevier B.V. All rights reserved.Öğe An evaluation of the anticorrosion effect of ethylene glycol for AA7075-T6 alloy in 3.5% NaCl solution(Elsevier Sci Ltd, 2018) Gerengi, Hüsnü; Solomon, Moses M.; Kaya, Ertuğrul; Bağcı, Fatma E.; Abai, Ekaette J.The corrosion behaviour of AA7075-T6 aluminum alloy in 3.5% NaCl devoid of and containing various amounts of ethylene glycol (EG) has been examined by DEIS (dynamic electrochemical spectroscopy), PDP (Potentiodynamic polarization), SEM (scanning electron microscope), EDAX (energy dispersive X-ray spectroscopy), and AFM (atomic force microscope). AA7075-T6 alloy specimen corroded significantly in 3.5% NaCl solution. In 3.5% NaCl containing EG, the alloy is protected but the extent of protection is a function of immersion duration and concentration of EG. EG affects both the anodic and cathodic corrosion reactions according to PDP results. The adsorption of EG molecules onto AA7075-T6 surface follow Langmuir adsorption isotherm model. The Delta G(ads)(0) value calculated for the adsorption process reveals that physisorption is the prevailing mechanism. SEM and AFM pictures support the experimental results and EDAX results confirm the presence of EG molecules on AA7075-T6 surface.Öğe Evaluation of the corrosion inhibiting efficacy of a newly synthesized nitrone against St37 steel corrosion in acidic medium: Experimental and theoretical approaches(Elsevier Science Bv, 2018) Gerengi, Hüsnü; Solomon, Moses M.; Öztürk, Serkan; Yıldırım, Ayhan; Gece, Gökhan; Kaya, ErtuğrulA novel amphiphilic nitrone, N-phenyl-1-(4-((11-(pyridin-1-ium-1yl) undecanoyl) oxy)phenyl)methanimine oxide bromide (NP-1-4-11-PUOPMOB) has been synthesized from a fatty acid derivative as a starting material. Structural characterization of the new compound has been realized by spectroscopic techniques (FTIR, H-1 NMR, and C-13 NMR). The corrosion inhibition effect of the compound for St37 steel corrosion in 1 M HCl medium has been investigated using experimental (weight loss, electrochemical impedance spectroscopy, potentiodynamic polarization, dynamic electrochemical impedance spectroscopy) and theoretical approaches complemented by surface morphological examination using energy dispersive X-ray spectroscopy, scanning electron microscope, and atomic force spectroscopy. Results from both chemical and electrochemical techniques reveal that the presence of the nitrone in the acid solution impedes St37 steel corrosion. The inhibition efficiency obtained at 125 ppm and 150 ppm concentrations for all methods is found to be over 90%. NP-1-4-11-PUOPMOB behaves as a mixed type corrosion inhibitor according to the potentiodynamic polarization studies. The adsorption of NP-1-4-11-PUOPMOB molecules onto the metal surface follows Langmuir adsorption isotherm and the calculated K-ads (equilibrium constant of the adsorption process) value reflects strong interaction. There is evidence of NP-1-4-11-PUOPMOB adsorption on the metal surface from SEM, EDAX, and AFM studies. Experimental and theoretical results are in good agreement.Öğe Experimental and Quantum Chemical Evaluation of 8-Hydroxyquinoline as a Corrosion Inhibitor for Copper in 0.1 M HCl(Amer Chemical Soc, 2016) Gerengi, Hüsnü; Mielniczek, Michal; Gece, Gökhan; Solomon, Moses M.The corrosion inhibition properties of 8-hydroxyquinoline (8-HQ) in 0.1 M HCl for copper have been investigated by using experimental (electrochemical impedance spectroscopy (EIS), dynamic electrochemical impedance spectroscopy (DEIS), and potentiodynamic polarization) and theoretical methods complemented by surface morphological examination with the aid of scanning electron microscopy (SEM) and electron dispersive X-ray spectroscopy (EDAX). Results obtained from all of these applied techniques are in agreement and demonstrate that 8-HQ inhibited copper corrosion in 0.1 M HCl solution significantly and the inhibition efficiency varies directly with 8-HQ concentration. Potentiodynamic polarization results show that 8-HQ behaved like a cathodic-type inhibitor in the studied system. EDAX results reveal that 8-HQ is most stable and effective at 10 h of immersion time. Inhibition of Cu corrosion by 8-HQ is due to electrostatic interaction between the Cu surface and salt of 8-HQ according to the Delta G(ads)(0) value and FTIR results. E-HOMO, E-LUMO, and Delta E values support the proposed physisorption mechanism. SEM and EDAX results confirm the adsorption of 8-HQ molecules on a Cu surface.Öğe Exploration of Dextran for Application as Corrosion Inhibitor for Steel in Strong Acid Environment: Effect of Molecular Weight, Modification, and Temperature on Efficiency(Amer Chemical Soc, 2018) Solomon, Moses M.; Umoren, Saviour A.; Obot, Ime B.; Sorour, Ahmad A.; Gerengi, HüsnüThe possibility of utilizing dextran as a green corrosion inhibitor for steel in strong acid environment was explore using weight loss, electrochemical (electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM), potentiodynamic polarization (PDP), and linear polarization (LPR)) supported with surface analysis via scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) techniques. The effect of molecular weight, temperature, and modification on the inhibition efficiency of dextran was also studied. Results from all the applied techniques reveal that dextran exhibit moderate anticorrosion property toward St37-2 steel dissolution in 15% H2SO4 solution. Dextran with molecular weight of 100 000-200 000 g/mol (Dex 1) exhibited the highest inhibition efficiency of 51.38% at 25 degrees C. Based on PDP results, dextran behaved as a mixed type corrosion inhibitor. Inhibition efficiency of dextran varies inversely with molecular weight but directly with temperature. Two modification approaches, namely incorporation of silver nanoparticles (AgNPs) into dextran matrices and combination with 1 mM KI were adopted to enhance the inhibition efficiency of dextran and the approaches proved effective. The protective capability of Dex 1 has been upgraded from 51.38% to 86.82% by infusion of AgNPs and to 94.21% by combination with KI at 25 degrees C. Results from the study on the effect of temperature reveals that Dex 1 + KI mixture could synergistically offer 99.4% protection to St37-2 steel in 15% H2SO4 environment at 60 degrees C. Surface analysis results confirm the presence of additives molecules on the studied metal surface. XPS results disclose that AgNPs are in oxide form while iodide ions are in the form of triiodide and pentaiodide ions on the metal surface. Modified dextran is a promising candidate for application as corrosion inhibitor in acid induced corrosive environment.Öğe Gum Arabic-silver nanoparticles composite as a green anticorrosive formulation for steel corrosion in strong acid media(Elsevier Sci Ltd, 2018) Solomon, Moses M.; Gerengi, Hüsnü; Umoren, Saviour A.; Essien, Nsikak B.; Essien, Uduak B.; Kaya, ErtuğrulA green anticorrosive composite (GA-AgNPs) has been formulated for steel in 15% HCl and 15% H2SO4 media. Characterization of GA-AgNPs is achieved via FTIR, UV-vis, EDAX, and SEM. Gravimetric, electrochemical (EIS, EFM, DEIS, & TP), and surface assessment (SEM, EDAX, AFM, & XPS) techniques have been deployed in the anticorrosion studies. Results from all applied methods potray GA-AgNPs as effective anticorrosive agent. Inhibition is by adsorption mechanism and follows Langmuir isotherm. GA-AgNPs acts as mixed type inhibitor in 15% H2SO4 solution but as anodic type in 15% HCl solution. Results from surface techniques confirm adsorption of GA-AgNPs molecules on specimen surface. Oxides, hydroxides, carbonates, and sulphates (H2SO4 medium) or chlorides (HCl medium) are the corrosion products in the free corrodent according to XPS results. In the presence of composite, both ionic and neutral forms of GA-AgNPS are adsorbed. AgNPs are present on the surface in the form: Ag degrees, Ag2O, and AgO.Öğe Improved Performance of 1-Ethyl-3-Methylimidazolium Tetrafluoroborate at Steel/HCl Interface by Iodide Ions(Springer International Publishing, 2018) Gerengi, Hüsnü; Solomon, Moses M.; Umoren, Saviour A.; Uğraş, H. İbrahim; Yıldız, Mesut; Slepski, PawelThe corrosion and corrosion inhibition of St37 steel in 0.1 M HCl solution by 1-ethyl-3-methylimidazolium tetrafluoroborate (EMITFB) and the effect of addition of KI on the inhibitive performance of EMITFB have been examined by electrochemical [electrochemical impedance spectroscopy, potentiodynamic polarization, and dynamic electrochemical impedance spectroscopy (DEIS)] and surface examination [scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS)] techniques. Results show that EMITFB could only afford the protection of St37 steel in HCl medium on an average scale. The highest studied concentration of EMITFB (4 mM) affords optimum inhibition efficiency of 78.86% from DEIS method. Addition of iodide ions to EMITFB has beneficial effect on the inhibition efficiency; 86.10% has been achieved by addition of 1 mM KI to 4 mM EMITFB. Adsorption of EMITFB molecules onto the metal surface is via physical adsorption mechanism and follows El Awady et al. kinetic/thermodynamic adsorption isotherm model. SEM and EDS results confirm the improvement of corrosion inhibiting ability of EMITFB by iodide ions. EMITFB and EMITFB + KI behave as mixed-type corrosion inhibitor in the studied environment. © 2018, Springer International Publishing AG, part of Springer Nature.Öğe Influence of 1-butyl-1-methylpiperidinium tetrafluoroborate on St37 steel dissolution behavior in HCl environment(Taylor & Francis Inc, 2018) Yıldız, Mesut; Gerengi, Hüsnü; Solomon, Moses M.; Kaya, Ertuğrul; Umoren, Saviour A.The efficacy of 1-butyl-1-methylpiperidinium tetrafluoroborate (BMPTFB) in retarding St37 steel corrosion in HCl environment has been examined using potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), dynamic-EIS (DEIS), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) techniques. Results from all applied methods reveal that BMPTFB is effective in suppressing St37 dissolution in the studied corrosive medium. Inhibition efficiency of 88% has been achieved by 4mM BMPTFB. From DEIS results, BMPTFB is found to perform better as corrosion inhibitor at longer immersion time. The charge transfer resistance of the metal is raised in the presence of 4mM BMPTFB from 378 to 744 cm(2) at 1h and further increased to 867 cm(2) at 4h. BMPTFB, according to PDP result behaves as mixed-type corrosion inhibitor. Corrosion inhibition by BMPTFB is via adsorption which can best be explained using El-Awady kinetic/thermodynamic adsorption isotherm. K-ads and values indicate that physisorption is the mechanism of adsorption of BMPTFB molecules onto St37 surface. The presence of BMPTFB molecules on St37 surface has been verified by SEM and FTIR.Öğe A newly synthesized ionic liquid as an effective corrosion inhibitor for carbon steel in HCl medium: A combined experimental and computational studies(Elsevier, 2021) Ozturk, Serkan; Gerengi, Husnu; Solomon, Moses M.; Gece, Gokhan; Yildirim, Ayhan; Yildiz, MesutSurfactants present exciting adsorption chemistry due to their dual nature, i.e the present of the hydrophobic and hydrophilic parts in their structures. However, the inhibition performance of surfactants is influenced by their chemical structure as well as the nature of the electrolyte. In acidic media, high concentration of tri-cationic surfactants is required for effective surface protection. Herein, we report the synthesis of a novel tri-cationic surfactant containing three quaternized nitrogen atoms and its corrosion inhibitive effect for carbon steel in 1 M aqueous HCl medium. The molecular structure of the surfactant was elucidated by 1H NMR and C-13 NMR spectroscopic techniques and its anti-corrosion activity was investigated by electrochemical impedance spectroscopy, potentiodynamic polarization and dynamic electrochemical impedance spectroscopy methods. The results obtained from the corrosion studies show that the synthesized surfactant is quite effective against the low carbon steel corrosion and at low inhibitor concentration. The inhibition efficiency obtained at 5 mg/L concentration is above 90%, showing that the anti-corrosion effect of the synthesized surfactant on the metal surface is strong even at low inhibitor concentration. Moreover, some physicochemical parameters namely, the critical micelle concentration, surface tension, micelle formation free energy, and emulsion stability have been calculated and used to explain the correlation with the corrosion inhibition mechanism. Additionally, to support the results from the electrochemical measurements, surface morphological examination using energy dispersive Xray spectroscopy (EDAX) and scanning electron microscope (SEM) methods have been performed. The EDAX and SEM results prove the adsorption of the tri-cationic surfactant molecule on the metal surface. The adsorption followed the Langmuir adsorption isotherm and calculated Kads (equilibrium constant of the adsorption process) value reflects strong interaction. More so, density functional theory (DFT) results corroborate the experimental results. The synthesized tri-cationic surfactant is a potential candidate for the formulation of acid corrosion inhibitor for acid cleaning applications.Öğe Performance Evaluation of a Chitosan/Silver Nanoparticles Composite on St37 Steel Corrosion in a 15% HCl Solution(Amer Chemical Soc, 2017) Solomon, Moses M.; Gerengi, Hüsnü; Kaya, Tuğçe; Umoren, Saviour A.A chitosan/silver nanoparticles (AgNPs/chitosan) composite has been prepared in situ using natural honey as the reducing and capping agent, and its effectiveness as an inhibitor for St37 steel in 15% HCI solution was assessed using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), dynamic electrochemical impedance spectroscopy (DEIS), and weight loss (WL) methods complemented with surface morphological examination with the aid of energy dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). AgNPs/chitosan was characterized using Fourier transformed infrared (FTIR), EDS, and SEM. The results obtained show that AgNPs/chitosan is an effective cathodic type inhibitor particularly at higher temperature and protects the metal surface by formation of a protective film. SEM, AFM, and EDS confirm the formation of an adsorbed film. The adsorption followed the Temkin adsorption isotherm; as such, the thermodynamic and kinetic parameters governing the adsorption were calculated and discussed. The values of the free energy of adsorption suggest that a mixed adsorption mechanism characterized the adsorption of AgNPs/chitosan molecules at lower temperature while chemisorption defined the adsorption process at higher temperature.Öğe Polypropylene (PP)/Starch-Based Biocomposites and Bionanocomposites(wiley, 2017) Umoren, Saviour A.; Solomon, Moses M.The vision of replacing conventional plastics which are derived from non-renew- able sources with bioplastics of natural origin is essential to eco-system preserva- tion and a secure future. This century has witnessed an increase in the production and utilization of biocomposites and bionanocomposites. Various methods of preparation and characterization of polypropylene/starch-based biocomposites and bionano composites are discussed in this chapter. Application of PP/starch- based biocomposites and bionanocomposites in biomedical, packaging, automo- tive, military, coating, fire retardant, aerospace, and optical sectors are also covered. The recycling and lifetime studies conducted on PP/starch-based biocomposites and bionanocomposites are equally highlighted. © 2018 by World Scientific Publishing Europe Ltd. All rights reserved.
