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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 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 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 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 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.Öğe Synergistic corrosion inhibition effect of 1-ethyl-1-methylpyrrolidinium tetrafluoroborate and iodide ions for low carbon steel in HCl solution(Taylor & Francis Ltd, 2016) Gerengi, Hüsnü; Uğraş, Halil İbrahim; Solomon, Moses M.; Umoren, Saviour A.; Kurtay, Mine; Atar, NecipInvestigation into the corrosion inhibition of low carbon steel in 0.1-M HCl solution by 1-ethyl-1-methylpyrrolidinium (EMTFB) and the effect of KI addition on the inhibition efficiency was carried out using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy and surface analysis (scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDAX)) techniques. Results show that EMTFB suppresses low carbon steel dissolution in the corrosive environment. Inhibition efficiency increased with the increase in EMTFB concentration. Addition of iodide ions to EMTFB raises inhibition efficiency from 75 to 98%. PDP results indicate that EMTFB affects majorly anodic reactions while EMTFB + KI act as cathodic-type inhibitor. The adsorption of EMTFB onto low carbon steel surface is by physical adsorption mechanism and follows Langmuir adsorption isotherm model. SEM and EDAX results confirm the adsorption of EMTFB alone and in combination with KI onto the steel surface.Öğe Synergistic corrosion inhibition effect of metal cations and mixtures of organic compounds: A Review(Elsevier Sci Ltd, 2017) Umoren, Saviour A.; Solomon, Moses M.The devastating effect of corrosion on the structural integrity of metals surfaces has been of great concern for some time. However, the challenge is to develop a benign and cost effective inhibitor that is highly effective. Addition of substances that exert synergistic influence and blending of different metals inhibitors had been employed. This review article delineates the effect of addition of metals cations and blending on the inhibition efficiency of metals corrosion inhibitors. The mechanisms proposed for the synergistic inhibition resulting from either addition of metals cations or blending are also discuss based on reported experimental data. (C) 2016 Elsevier Ltd. All rights reserved.Öğe Synergistic inhibition of St37 steel corrosion in 15% H2SO4 solution by chitosan and iodide ion additives(Springer, 2017) Solomon, Moses M.; Gerengi, Hüsnü; Kaya, Tuğçe; Kaya, Ertuğrul; Umoren, Saviour A.The inhibiting ability of chitosan alone and in combination with KI for St37 steel in 15% H2SO4 solution has been studied using potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), dynamic electrochemical impedance spectroscopy(DEIS), and weight loss (WL) complemented by surface morphological examination with the aid of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The effect of immersion time on inhibition efficiency has been examined for 15 h and the influence of temperature studied over the temperature range of 25-60 A degrees C. Results obtained from all the applied methods portray chitosan as a moderate inhibitor for St37 steel in the studied acid environment. Addition of KI is found to remarkably enhance the inhibition efficiency of the polymer above 92%. DEIS results show that the adsorbed chitosan-KI film on the metal surface is more stable at longer immersion time and performs more effectively. The inhibition efficiency of chitosan decreases with increasing temperature, while that of the chitosan-iodide combination increases with a rise in temperature reaching an optimum value of 99.72% at 60 A degrees C. PDP results show that both chitosan and chitosan + KI behave as a mixed type inhibitor. A calculated synergism parameter confirms that the improved performance of chitosan is due to a synergistic effect. EDS results confirm the adsorption of inhibitor molecules on the metal surface.Öğe Synthesis and Characterization of Cyclic Cationic Polymer and its Anti-corrosion Property for Low Carbon Steel in 15% HCl Solution(Esg, 2017) Haladu, Shamsuddeen A.; Umoren, Saviour A.; Ali, Shaikh A.; Solomon, Moses M.A new cyclic cationic polymer (CCP) bearing bis-3-phosphorylpropyl pendants was synthesized using chain-growth polymerization technique with ammonium persulphate (APS) as initiator. The synthesized polymer was characterized using FTIR, H-1 NMR and C-13 NMR techniques. The corrosion inhibition performance evaluation of the newly synthesized polymer for low carbon steel in 15% HCl was carried out using weight loss measurements at 25 - 60 degrees C, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) and linear polarization resistance (LPR) techniques. The effect of addition of small amounts (5 mM) of ZnCl2 and KI on the corrosion inhibition performance of CCP was also assessed. Results obtained indicate that CCP acts as an inhibitor for low carbon steel corrosion in the aggressive acid environment. Inhibition efficiency increased slightly with increasing CCP concentration. Also, inhibition efficiency was found to decrease with increase in temperature. Addition of ZnCl2 and KI to CCP has profound effect on the corrosion inhibition performance, which was more pronounced with KI compared to ZnCl2. Corrosion protection efficiency followed the trend CCP + KI > CCP + ZnCl2 > CCP. The enhanced corrosion inhibition of CCP on addition of ZnCl2 and KI is due to synergistic effect as confirmed from the calculated synergistic parameter which was found to be greater than unity. Inhibition of low carbon steel corrosion in 15% HCl occurs by virtue of physical adsorption of CCP onto the steel surface which can be approximated by Langmuir adsorption isotherm model. The SEM/EDS images confirm the adsorption of CCP to form protective film on the low carbon steel surface.
