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The synthesis of novel l -proline nitrate ionic liquid referred to as [Pro][NO3] (IL), was performed and the 1H, 13C NMR, and FT-IR spectroscopic techniques were used to elucidate the chemical structure. The inhibition properties of the [Pro][NO3] IL were evaluated for mild steel (MS) corrosion in 1 M HCl using gravimetric measurement, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) measurement, FT-IR spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle measurement, scanning electron microscopy (SEM), density functional theory (DFT) and Monte Carlo (MC) simulation studies. As indicated by electrochemical and weight loss techniques the tested [Pro][NO3] IL was established as an excellent mixed type high-temperature acid corrosion inhibitor for MS; the optimal temperature and concentration being 70 °C and 300 ppm, respectively. Furthermore, the contact angle measurement and surface studies revealed water-repelling property and the protecting capability, respectively of the investigated inhibitor. The electronic property of [Pro][NO3] IL has been explored using density functional theory (DFT) and the sites susceptible for electron sharing were identified through Fukui indices analysis. Furthermore, molecular dynamics simulation based on the Monte Carlo method has been employed to envisage the spontaneous adsorption of [Pro][NO3] IL on MS surface.

Herein, we reported a facile, cost efficient, synthesis of Gr@NiCu NCs nanocomposite and explored their application in supercapacitor and antibacterial applications. The Graphene sheets in the NiCu based electrode showed a high specific surface area and supports conductive networks decorated with oxygen groups, which synergistically improve charge storage capability. Furthermore, Gr@NiCu NCs contain hydrophilic oxygen groups of chemically reduced graphene oxide, which allows easy access of the electrolyte to the electrode’s pores. An electrochemical study demonstrated the highest specific capacitance of 977 Fg−1 at 10 Ag-1 and remarkable cyclic retentiveness ∼90% even after 1000 cycles. A noteworthy energy density of the Gr@NiCu NCs achieves approximately 542 KWh kg−1 and a power density of 21 kW kg−1 acquired through the CD description utilizing a current density of 10 Ag-1. The antimicrobial activity of synthesized Gr@NiCu NCs was performed against S. Aureus, E. coli, and MRSA ATCC BAA 1708, P.Aeroginosa (ATCC 27853), S.Mutans (MTCC SM 497) strains compared with ampicillin antibiotic drug. This potent antibacterial activity is attributable to the synergistic apoptosis from Cu2+ and bacteriostatic effect Ni2+ ions with graphene sheet (enhance ROS production), released from Gr@NiCu NCs.

This work demonstrates the fabrication of a highly selective ammonia (NH3) gas sensor based on Graphene/Silver–Silver Oxide/Polypyyrole (Gr/Ag–Ag2O/PPy) nanocomposite. To archive this objective, a cost-effective, room temperature mediated solution-based synthesis of Gr/Ag–Ag2O/PPy nanocomposite was exploited as an efficient performance NH3 gas sensor through combining the exceptional electrical characteristics of Graphene and sensing abilities of Ag–Ag2O/PPy. The as-synthesized nanomaterials were examined for relative DC conductivity with ammonia vapors' exposure at room temperature (25 °C) with the electrical signals' changes. The incorporation of Gr/Ag–Ag2O in PPy revealed about 40 times higher amplitude of conductivity change as compared to pristine PPy on exposure to the ammonia vapors. The reversibility response of Gr/Ag–Ag2O/PPy regarding the DC electrical conductivity with an effective variation range from 9.15 S/cm to 6.48 S/cm was observed in the ambient air on exposure to 1000 ppm of ammonia vapors. Gr/Ag–Ag2O/PPy was shown to offer a more excellent selectivity toward ammonia due to its basicity compared to different volatile organic compounds.

Graphene polyindole (Gr@PIn) nanocomposite with varying content of graphene was synthesized via an in‐situ redox polymerization doping technique. The techniques like FT‐IR, XRD, SEM, and TEM were utilized to characterize the produced nanocomposites. The produced nanocomposites were cast on LCS (low carbon steel) substrate employing NMP as a solvent, 10% epoxy as a binder, and triethylenetetramine as a curing agent. The anti‐corrosion ability of the Gr@PIn nanocomposite coatings was established by performing corrosion tests such as OCP, EIS, PDP measurements, Salt spray test, and Wettability test. Gr@PIn coating was observed as an effective anti‐corrosion coating for LCS substrate in 3.5 wt.% NaCl. The anticorrosion behavior of coating was dependent on graphene content; the higher content of graphene providing higher protection. The anticorrosion performance of Gr@PIn nanocomposite coating was also compared with that of Polyindole (PIn) coating and bare steel.

The present study aims to explore the effect of 2-nitroacridone, an antimicrobial compound, on low carbon steel (LCS) corrosion in acid solution (1 M HCl). The compound was tested at various concentrations (0.001−10 mM) and five temperatures (25, 35, 45, 55, and 65 °C) to determine the optimal concentration and temperature range for the best corrosion inhibiting effect. In evaluating the inhibition efficiency, weight loss measurement, potentiodynamic polarization measurement, electrochemical impedance spectroscopy, SEM/EDAX/AFM and DFT measurements were used. The inhibition efficiency increases with the increase in concentration and decreases with temperature. The maximum inhibition efficiency was found (94.96%) at 25 °C in the presence of 5 mM concentration of the studied compound. The various adsorption isotherms were also explored to find the best fit, which was found to obey the Langmuir adsorption isotherm. The thermodynamic parameters (Ea, Kads, ΔG°ads) have also been calculated and discussed. The potentiodynamic polarization study revealed that 2-nitroacridone behaved as a mix-type of inhibitor that predominantly inhibited the anodic reaction. Moreover, a correlation between the inhibition efficiency of the studied compound and certain molecular parameters were determined by quantum chemical computations.

Cysteine based silver-gold nanocomposite (Cys/Ag-Au NCz) was synthesized, this was followed by its characterization using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Ultraviolet-visible spectroscopy (UV-Vis), Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDAX), Thermogravimetric analysis (TGA) and Transmission electron microscopy (TEM). Cys/Ag-Au NCz was studied as novel green corrosion inhibitor for mild steel in 1M HCl solution at varying concentration and temperature using gravimetric, Potentiodynamic polarization (PDP), Electrochemical impedance spectroscopy (EIS), SEM, EDAX and FTIR. Weight loss, PDP and EIS studies confirmed Cys/Ag-Au NCz as efficient corrosion inhibitor at moderately low concentration. The maximum inhibition efficiency of 96 % was observed at 303 K at 300 ppm. Cys/Ag-Au NCz acted by affecting both anodic and cathodic processes and its adsorption on steel surface followed the Langmuir adsorption isotherm. EIS data displayed the existence of protective film at mild steel/solution interface in Cys/Ag-Au NCz inhibited system. SEM micrograph in presence of Cys/Ag-Au NCz inhibited acid solution displayed better morphology as compared to blank solution. The UV-Vis and FTIR data indicates good interaction between the Cys/Ag-Au NCz and steel surface.

The aim of this chapter is to cover an outline of the basics introduction of the corrosion inhibitors. Corrosion has been faced by mankind for ages and is considered one of the major catastrophic problems. The protection of metals from corrosion is a very challenging task and a matter of enormous importance. One of the most prevalent ways of combating the internal corrosion in various industries is by utilizing corrosion inhibitors. These are the chemicals that when added in traces to the corrosive media impede the corrosion of the metals. They work by getting adsorbed onto the surface of metals that need to be protected, and in turn, protect it from further corrosion by forming a very thin film of the molecules. This film retards the interaction between metal surfaces and the corrosive environment. This minimization can be associated with the physical blockage effect, or with the impact of the inhibitor on the mechanisms and kinetics of the corresponding corrosion reactions. They are mainly distributed into the solution or dispersion, but some of the corrosion inhibitors are incorporated into the paints and coatings also. The practice of utilizing corrosion inhibitors can tackle the severity of the problem related to the corrosion. The advancement in corrosion control methods and techniques remains a topic of significant industrial and academic concern. This chapter will cover the brief outline about the corrosion inhibitors.

A terpolymer (TP) comprising of aniline (ANi), o-toluidine (OTd) and o-aminobenzoic acid (OAc), and its nanocomposite (NCs) with TiO2 nanoparticles (NPs) (TP-TiO2-NCs) were prepared through in situ...

The aim of this paper is to study the anticorrosive performance of the polymer–surfactants system comprising of mixed solutions of varying concentrations (10–700 ppm) of sodium salt of carboxymethylcellulose (NaCMC) and fixed concentration (1 ppm) of synthesized oppositely charged biodegradable cationic di-ester bonded gemini surfactants i.e., ethane-1,2-diylbis(N,N-dimethyl-N-alkylammoniumacetoxy)dichloride, referred as m-E2-m, (where m = 12, 14, 16, the number of carbon atoms in alkyl chain and E2 is the di-ester group in gemini’s spacer part), for mild steel in 1 M HCl solution. The inhibition effect of mixed NaCMC - gemini surfactant system was examined using weight loss measurement, potentiodynamic polarization (PP) measurements, electrochemical impedance (EIS) measurements, surface morphological observation by scanning electron microscopy (), and molecular dynamics simulation study. NaCMC alone was observed to offer moderate inhibition efficiency (IE) of 57.3% at 500 ppm, which was synergistically increased in the presence of very small amount of synthesized gemini surfactants. The improvement in IE was highly dependent on the surfactant tail length; the maximum improvement in IE of 90.1% was observed in presence of 16-E2-16. The adsorption of the studied systems followed Langmuir adsorption isotherm. PP result showed that all the examined systems behave as mixed type inhibitors. EIS results supported the existence of protective layer by the adsorption of inhibitor molecules on the metal surface. The formation of protective layer of studied systems on the mild steel surface was confirmed by FT-IR and SEM results. Molecular dynamics simulation was further performed to provide molecular level insights into the adsorption mechanism with the structure of studied systems. Keywords: Acid corrosion, Inhibition, Natural polymer, Gemini surfactants, Green inhibitor, Synergism, MD simulation

Polycrystalline undoped and chromium doped (2%, 4%, 6% and 8%) TiO2 nanoparticles (NPs) were synthesized using a simple acid-modified sol–gel method. Influence of chromium (Cr) doping on the microstructural, electrical, optical, and photocatalytic properties was studied using various analytical techniques viz. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), two-probe resistivity measurement and UV–visible absorption spectroscopy. Rietveld refinement of the XRD data reveals single phase, anatase crystal structure of the NPs in tetragonal symmetry with space group I41/amd. FTIR spectra demonstrate various functional groups and ensure anatase phase of all the samples. TEM images exhibit a significant change in the shape, size and morphology of the NPs on Cr incorporation in TiO2. Temperature-dependent resistivity measurements indicate the semiconducting nature of the samples and obey Arrhenius behaviour based on the mechanism of thermally activated conduction. A red shift in the UV–visible absorption spectra is noted on Cr doping, associated with the decrease in band gap from 3.1 eV for an undoped sample to 2.5 eV for an 8% Cr doped sample. Photoluminescence spectra signify that the dopant ions alter the density of oxygen vacancies that directly influence the electron–hole recombination rate. The photocatalytic performance is studied with regard to the degradation of chromophoric dyes, namely, rhodamine B and methylene blue under visible light illumination, revealing an increase in the photocatalytic activity with 82.2% and 73.4% degradation of the dyes after 120 min for the 6% Cr doped sample. This significant enhancement in the photocatalytic activity is attributed to the ease in the electron and hole separation by trapping sites produced due to Cr ions and oxygen vacancies. These observed results suggest that the Cr doped TiO2 NPs can be considered efficient photocatalysts with the advantage to tune the electronic structure and optical properties for possible applications in waste water treatment.

The anticorrosion behavior of bromelain on low carbon steel (LCS) in 1 M HCl solution was studied employing weight loss, potentiodynamic polarization measurement (PDP), electrochemical impedance spectroscopy (EIS), UV–visible spectrophotometry, and surface assessment techniques like scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) at 308–338 K. The obtained results suggest that bromelain is an excellent corrosion inhibitor and its inhibition efficiency (%η) is both concentration and temperature dependent. %η is observed to increase with an increase in bromelain concentration and an increase in electrolyte temperature. The maximum %η of 97.6% is observed at bromelain concentration of 1000 ppm at 338 K. The inhibitor adsorption on the LCS surface is in accordance with the Langmuir adsorption isotherm. As evidenced by PDP measurements, bromelain behaves as a mixed-type inhibitor and controls both anodic and cathodic processes. Adsorption free energy of the bromelain on LCS surface together with an increase in %η with the rise in temperature is suggestive of chemical adsorption. SEM micrographs show a smoother surface for inhibited LCS specimen. Analysis of variance statistically compare the difference existing between inhibition efficiencies from gravimetric, PDP and EIS technique and suggests that they are not significantly different.

Chemical oxidative polymerization of aniline (AN) and o-toluidine (OT) for the synthesis of copolymer, Poly(AN-co-OT) and its composite with TiO2 nanoparticles, Poly(AN-co-OT)/TiO2 employing ammoni...

In this research work Reduced Graphene Oxide with Nickel (II) peroxide/copper (I) Oxide (Gr@NiO2/Cu2O NCs) have been successfully synthesized through a facile, one-step green synthesis mediated through the honey. The benefit of this methodology is that both the reducing agents themselves and also the oxidized product are eco-friendly. Additionally, reduction capability to graphene oxide, the oxidized products of honey i.e. reducing sugar could also act as capping agent and stabilizer in the synthesis of Gr@NiO2/Cu2O NCs, which showed good stability as a heterogeneous catalyst. This environmentally friendly approach can open up the new possible synthesis route for the graphene based nanocomposites on industrial scale production. Moreover, In this context, herein we report, an easy and effective synthesis of substituted Schiff base derivatives through the Graphene-based (Gr@NiO2/Cu2O NCs) green heterogeneous catalyst under ligand-free conditions, which provided good to excellent yields. The catalyst was characterized by FT-IR, XRD, SEM-EDX, TEM, RAMAN, UV and DLS analysis. The thermal stability of the catalyst was assessed by TGA and DSC analysis. Shorter reaction times, low packing of catalyst and higher yields are the benefit of this novel protocol. Its activity and simple recyclability without losing catalytic activity sort this catalyst a better replacement than another catalyst.

Two ‘natural’ non-ionic surfactants namely, N-alkyl-N′-glucosylethylenediamine with formula CnH2n+1NH(CH2)2NHCO(CHOH)4CH2OH (n = 10, 12), designated as Glu (n) were prepared and identified by FT-IR and 1H NMR. Synthesized compounds were investigated for mild steel corrosion in 3.5% NaCl medium using electrochemical measurement, gravimetric measurement and surface characterization techniques like Fourier transform infra-red spectroscopy (FT-IR), atomic force microscopy (AFM) and scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDAX). The compounds act as predominantly anodic corrosion inhibitors and their inhibition efficiencies are observed to increase with increasing inhibitors’ concentrations, chain length and temperature. The adsorption of Glu (n) inhibitor on the mild steel surface in 3.5% NaCl solution followed the Langmuir adsorption isotherm. The AFM micrographs showed a reduction of surface roughness in the presence of the investigated inhibitor. SEM micrographs confirmed the existence of an adsorbed protective film on the mild steel surface. EDAX was carried out to characterize the chemical composition of the inhibitive film formed on the steel surface. Density functional theory (DFT) calculations are made to correlate the efficiencies of Glu (n) with their intrinsic molecular parameters.

Sn 1-x Co x O 2 (x = 0.00, 0.01, 0.03, 0.05) nanoparticles (NPs) of average size ∼30–40 nm were synthesized by co-precipitation method. The interaction of Co doped SnO 2 NPs with human serum albumin (HSA) and their photocatalytic and antimicrobial properties were studied. The structural analysis and morphology of Co doped SnO 2 NPs were analysed via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), high resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FT-IR). Besides the structural and morphological analysis, the interaction of Co doped SnO 2 NPs with HSA were studied by UV–vis, Circular dichroism (CD) and fluorescence spectroscopy. Fluorescence quenching results suggest that Co doped SnO 2 NPs interact with an HSA molecule through static mechanism. CD indicates that α-helicity of HSA increases due to the interaction of Co doped SnO 2 NPs. The photocatalytic activities of the NPs with increased doping concentration were evaluated through a degradation process in the presence of methylene-blue (MB) dye under UV light irradiation, which exhibited that the surface area of NPs with increased doping concentration plays a major role in improving the photocatalytic activity. The antimicrobial effect of undoped and Co-doped SnO 2 NPs was determined using agar-well diffusion method and analyzed against gram-positive bacteria ( Bacillus Cereus MC 2434). In our results, we have found that as the doping concentration increases into NPs, zone of inhibition increases, which could be ascribed to the production of ROS and large surface area of the NPs.

Organic-inorganic nanocomposites (PPy/GNS/RE3 +/DBSA) involving pyrrole (Py), graphene nano sheets (GNS), rare earth elements (RE3 + = La3 +, Sm3 +, Nd3 +) and dodecyl benzene sulfonic acid (DBSA) were synthesized via in situ chemical oxidative polymerization using FeCl3 as an oxidant. PPy/GNS/DBSA and PPy/DBSA was also synthesized by following the identical synthesis route. The resultant nanocomposites were characterized by FTIR, XRD, SEM and TEM. The synthesized nanocomposites were chemically deposited on low carbon steel specimens by solvent evaporation method using N-Methyl-2-pyrrolidone (NMP) as solvent and 10% epoxy resin (by weight) as binder. The anticorrosive nature of polymer coatings were studied in 0.1 M HCl solution by subjecting them to various corrosion tests, which includes: EIS, potentiodynamic polarization, free corrosion potential (OCP) measurement and immersion test. The surface morphology of coated samples before and after immersion was evaluated using SEM.

Candida rugosa lipase (CRL) was treated with surfactants and immobilized onto the novel formulated magnetic graphene anchored silica nanocomposite (Fe3O4/SiO2/Gr NC). For this purpose, the surface of lipase was initially coated with Triton-X 100 and cetyltrimethylammonium bromide surfactants, to stabilize enzyme in its open form and was then adsorbed onto aminated Fe3O4/SiO2/Gr NC. Glutaraldehyde (GA) was then utilized to cross-link the adsorbed lipase onto the NC. The fabricated NC and conjugated lipase was characterized by various techniques such as FT-IR, XRD, TGA, SEM, TEM, CLSM, CD and Fluorescence spectroscopy. The magnetic character of the as-synthesized NC was verified by AGM investigation. CD and fluorescence spectroscopic analysis demonstrated slight structural rearrangements in lipase upon conjugation. The surfactant stabilized immobilized lipase demonstrated significantly enhanced thermostability, tolerance to various metal ions and inhibitors. The immobilization yield obtained owing to lipase interfacial activation by Triton X 100 and CTAB was remarkably enhanced by 6-folds and 3-folds, respectively which were remarkably higher in comparison to free immobilized lipase. The fabricated nanobiocatalysts were employed to synthesise green apple flavour ester, ethyl valerate via esterification reaction. Triton X 100 stabilized immobilized lipase was a better performer in yielding green apple flavour ester, demonstrating about 90% ester yield as compared to 78% yield obtained by CTAB stabilized immobilized lipase preparation. The obtained outcomes suggested that enzyme structure was stabilized by the GA treatment if executed in the absence or in the presence of detergent, and that, in the company of detergent, a conformation of the lipase with the exposed active center to the medium provided an aggrandized catalytic performance.

Almond gum (AG) was studied as an economically and environmentally viable corrosion inhibitor in 1 M HCl on mild steel (MS). Studies such as gravimetric, NMR, FTIR, EIS, PDP, SEM/EDAX, UV–Visible, DFT and Monte Carlo simulation were performed to assess the potency of AG as a green inhibitor. Gravimetric study was done in the temperature range 30°C–60 °C, I.E increased with increasing concentration and temperature giving significant inhibition efficiency (I.E) of 96.37% at 300 ppm at 60 °C.The adsorption of AG on MS followed Langmuir Adsorption Isotherm. Characterization by NMR and FTIR confirmed the structure of AG. UV–Visible study confirmed the existence of complex [Fe+2-AG] on inhibited MS surface. While in 1 M HCl in the presence of AG, MS showed a reduced surface roughness and better surface morphology. Obtained PDP measurements show that AG acts as a mixed type inhibitor but showing predominantly anodic effect while EIS results unveiled the formation of inhibitive layer on the MS surface. I.E calculated from the EIS, PDP showed the same trend as gravimetric. Calculated thermodynamic and activation parameters predicted strong interaction between MS surface and inhibitor. Density functional theory (DFT), condensed Fukui indices (FIs) and Monte Carlo (MC) simulation results further supported the experimental findings.

A copolymer nanocomposite Poly(aniline-co-2,3-xylidine)/ZnO [Poly(AN-co-XY)/ZnO], pure copolymer and its homopolymers namely, Poly(aniline-co-2,3-xylidine) [Poly(AN-co-XY)], Polyaniline (PANi) and Poly (2,3-xylidine) were synthesized by chemical oxidative polymerization using ammonium persulfate as an oxidant in hydrochloric acid medium. The synthesized compounds were characterized by FTIR, XRD, SEM, and TEM techniques. Saturated solutions of the synthesized compounds were made in N-methyl-2-pyrrolidone and casted on low-carbon steel specimens using 10% epoxy resin as a binder. The anticorrosion behavior of polymeric coatings was studied in 3.5 wt% NaCl solution at a temperature of 30 °C by electrochemical techniques, which include: open-circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy. Protective properties of nanocomposite coating were also evaluated at different immersion times for an extended period of 60 days. Anticorrosion properties of nanocomposite...

A copolymer of aniline (AN) and N-ethylaniline (EA), namely Poly(AN-co-EA) and its composite with ZnO nanocomposites, Poly(AN-co-EA)/ZnO were synthesized by chemical oxidative polymerization using ammonium persulphate as an oxidant. The synthesized compounds were characterized by FTIR, XRD, SEM and electrical conductivity techniques. The synthesized compounds were dissolved in N-methyl-2-pyrrolidone (NMP) and were casted on mild steel (MS) specimens using 10 % epoxy resin as a binder. The adhesion properties of the copolymer and nanocomposite coatings were also tested. The anticorrosion behaviour of coated MS was investigated in 0.1 M HCl, 5 % NaCl solution, distilled water and open atmosphere by performing immersion test, open-circuit potential measurements, potentiodynamic polarization measurements, electrochemical impedance spectroscopy and atmospheric exposure test. Surface morphology of the coated steel prior to and after 30 days immersion in corrosive solution was evaluated using SEM. The nanocomposite coating showed excellent protection against MS corrosion; the protection efficiency (PE) varied in the range of 89–96 % after 30 days of immersion. The incorporation of ZnO nanoparticles improved the anticorrosion properties of Poly(AN-co-EA) copolymer in all corrosion media subjected to investigation.

A copolymer of aniline (AN) and o-anisidine (OA), Poly(AN-co-OA) and its nanocomposite with ZnO nanoparticles, Poly(AN-co-OA)/ZnO were synthesized by chemical oxidative polymerization using ammonium persulfate as an oxidant in hydrochloric acid medium. The synthesized compounds were characterized using FTIR, XRD, SEM-EDS, TEM, and electrical conductivity techniques. The copolymer and nanocomposite were separately dissolved in N-methyl-2-pyrrolidone and were casted on low-carbon steel specimens using 10% epoxy resin as a binder. The anticorrosive properties of the coatings were studied in different corrosive environments such as 0.1 M HCl, 5% NaCl solution, and distilled water at a temperature of 30 °C by conducting corrosion tests which include immersion test, open circuit potential measurements, potentiodynamic polarization measurements, and atmospheric exposure test. The surface morphology of the coatings prior to and after one-month immersion in corrosive solution was evaluated using SEM. It was observed that the nanocomposite coating exhibited higher corrosion resistance and provided better barrier properties in comparison with copolymer coating. The presence of ZnO nanoparticles improved the anticorrosion properties of copolymer coating in all corrosive media subjected to investigation.

A soluble terpolymer of aniline (AN), 2-pyridylamine (PA) and 2,3-xylidine (XY), poly(AN-co-PA-co-XY) and its nanocomposite with ZnO nanoparticles namely, poly(AN-co-PA-co-XY)/ZnO were synthesized by chemical oxidative polymerization employing ammonium persulfate as an oxidant. Nanocomposites of homopolymers, polyaniline/ZnO, poly(XY)/ZnO and poly(PA)/ZnO were also synthesized by following similar synthesis route. FTIR, XRD and SEM techniques were used to characterize the synthesized compounds. The synthesized compounds were chemically deposited on mild steel specimens by solvent evaporation method using N-methyl-2-pyrrolidone (NMP) as solvent and 10% epoxy resin (by weight) as binder. Anticorrosive properties of homopolymer nanocomposites, terpolymer and its nanocomposite coatings were studied in 0.1 M HCl by subjecting them to various corrosion tests which includes: free corrosion potential measurement (OCP), weight loss measurements, potentiodynamic polarization, and AC impedance technique. The surface morphology of the corroded and uncorroded coated steel specimens was evaluated using SEM. The corrosion protection performance of terpolymer nanocomposite coating was compared to the terpolymer and individual homopolymers nanocomposites coatings after 30 days immersion in corrosive medium.

SnO2/NiO nanocomposite are prepared by using a simple cost effective and ecofriendly green soft template method followed by ultrasonication treatment further by calcination at 300 °C. The resulting nanocatalysts were characterized by X-ray diffraction (XRD), UV-Visible spectroscopy and transmission electron microscopy (TEM). The SnO2−NiO photocatalyst was made of a mesoporous network of aggregated NiO and cassiterite SnO2 nanocrystallites, the size of which was estimated to be 16.68 nm and 13.17 nm, respectively, after calcination. According to UV–visible spectroscopy, the evident energy band gap value of the SnO2−NiO photocatalyst was estimated to be 3.132 eV to be compared with those of pure SnO2, that is, 3.7 eV. Moreover, the heterostructure SnO2−NiO photocatalyst showed much higher photocatalytic activities for the degradation of methylene blue than those of individual SnO2 and NiO nanomaterials. This behaviour was rationalized in terms of better charge separation and the suppression of charge recombination in the SnO2−NiO photocatalyst because of the energy difference between the conduction band edges of SnO2 and NiO as evidenced by the band alignment determination. Finally, this mesoporous SnO2−NiO heterojunction nanocatalyst was stable and could be easily recycled several times opening new avenues for potential industrial applications.

In the 21st century evolution of microelectronics industries, consumptions of integrated circuits (IC’s) increases, so the demand of miniscule permittivity (MP) material with minimum loss factor arises in the electronics industries. Graphene embedded ZnO Nanoparticle (Gr/ZnO NCs) is synthesized and studied their dielectric properties In the studied frequency range 75 kHz to 7 MHz. In the sample Gr/ZnO NCs dielectric permittivity decrease gradually from 7.2 to 6.7 as the frequency increases, whereas dielectric permittivity of ZnO NPs shows also diminishing behavior in the range 75 to 20 as the frequency increases. In the Gr/ZnO NCs, Maxwell–Wagner polarization model explains strong interfacial polarization to presence of functionalization group and lattice defects on graphene sheet.

A biopolymer from tragacanth gum, arabinogalactan (AG), was investigated for its adsorption and corrosion inhibition traits for carbon steel corrosion in 1 M HCl. Gravimetric method, potentiodynamic polarization measurements, electrochemical impedance spectroscopy, UV–visible spectroscopy, scanning electron microscopy, and atomic force microscopy were used to judge the adsorptive nature of AG in the acid solution. The inhibition efficiency improved with an increase in AG concentration and temperature of the acid solution. Thermodynamic and activation parameters (ΔGads, Ea, ΔH, and ΔS) were also calculated and discussed. The adsorption of AG favored Langmuir adsorption isotherm. The results of corrosion tests confirmed that AG could serve as an efficient green corrosion inhibitor for the carbon steel in 1 M HCl, yielding high efficiency and a low risk of environmental pollution. Theoretical quantum chemical and Monte Carlo simulation studies corroborated the experimental results.

Lagerstroemia speciosa leaf extract (LSLE) was examined as corrosion mitigating agent against mild steel in 1 M HCl. The extract was characterized by GC–MS and FTIR. Weight loss (WL), potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), SEM- EDX, AFM, UV–Vis spectroscopy and DFT studies were performed to examine corrosion mitigation performance of LSLE. As revealed by WL the extract was above 94% efficient at the concentration of 500 ppm and 333 K. Adsorption of LSLE on mild steel surface is spontaneous and follows Langmuir isotherm model. Mixed type inhibition with anodic predominance was revealed by PDP results. EIS data revealed the formation of inhibitive film on metal surface by the active groups of the extract. SEM and AFM show a better morphological image and reduced surface roughness in the presence of LSLE. UV–Vis results indicate Fe-LSLE complex formation during corrosion reaction. DFT has been conducted to correlate the inhibition efficiency with the molecular structure of active species present in the extract. Quantum parameters and Molecular dynamic simulation helps in correlating the molecular structure and adsorption strength with inhibition efficiency. ANOVA statistical test was conducted to compare the inhibition efficiencies obtained by using different techniques and the data reveals that they are significantly not different.

The adsorption and corrosion inhibition behaviors of polyethylene glycol (PEG) alone and in the presence of surfactants sodium dodecyl benzene sulfonate and cetyltrimethyl ammonium bromide on mild steel in 0.1 M H2SO4 in temperature range of 30-60 °C was investigated using weight loss method, solvent analysis of iron ions, scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDAX), atomic force microscopy (AFM) and determination of kinetic/thermodynamic parameters. The inhibition efficiency (IE) of PEG increased with increasing concentration showing a maximum IE of 86.91% at 30 °C at 25 ppm but decreased with increasing temperature. Inhibiting action of PEG is synergistically enhanced on addition of small amount of surfactants. Surface morphology of the corroded mild steel specimen as evaluated by SEM, EDAX and AFM confirmed the existence of an adsorbed protective film on the mild steel surface. The calculated thermodynamic/kinetic parameters reveal that adsorption process is spontaneous and obey Langmuir adsorption isotherm.

A soluble terpolymer from 2-pyridylamine (2PA), aniline (AN) and 2,3-xylidine (XY), poly (2PA-co-AN-co-XY) was synthesized by chemical oxidative polymerization using ammonium persulfate as an oxidant in hydrochloride aqueous medium. The two copolymers, poly (AN-co-XY) and poly (2PA-co-AN) were also synthesized by following identical synthesis route. The resultant terpolymer and copolymers were characterized by Fourier transform infrared (FTIR) and 1 H NMR spectroscopy. The terpolymer and copolymers were chemically deposited on mild steel specimens using N-methyl-2-pyrrolidone (NMP) as solvent via solution evaporation method. The anticorrosive properties of terpolymer and copolymers coatings was investigated in major corrosive environments such as 0.1 M HCl, 5% NaCl solution, artificial seawater, distilled water and open atmosphere by conducting various corrosion tests which include: immersion test, open circuit potential measurements, potentiodynamic polarization measurements, and atmospheric exposure test. The corrosion performance of terpolymer and copolymers coatings was also compared separately with polyaniline (PANi) homopolymer coating. The surface morphology of terpolymer and copolymers coatings was evaluated using scanning electron microscopy (SEM). The synthesized terpolymer exhibited excellent protection against mild steel corrosion; the protection efficiency being in the range of 93–96% after 30 days of immersion. The corrosion performance of individual copolymers was found inferior than the terpolymer. However, the performance of copolymer poly (2AN-co-XY) was found better than copolymer poly (2PA-co-AN).

The Poly(pyrrole-co-o-toluidine), (PY/OT) copolymer was prepared by chemically oxidative polymerization of pyrrole (Py) and o-toluidine (OT) in HCl aqueous medium. The copolymer was characterised by using Fourier Transform Infrared Spectroscopy (FTIR) technique. The coating of PY/OT copolymer on 8-Hydroxyquinoline sulphonic acid (HQSA) pretreated mild steel surface was chemically deposited using N-methyl-2-pyrrolidone (NMP) as the solvent. The corrosion performance of the PY/OT copolymer coating on steel, both scribed and unscribed samples, was studied by conducting immersion tests and electrochemical tests which include free corrosion potential measurements and potentiodynamic polarization measurements. The above tests were conducted in different corrosive media which include 0.1 M HCl, 5% NaCl solution, artificial seawater and distilled water. The performance of coating in open atmosphere was also evaluated by conducting atmospheric exposure test. The results of different studies indicate that PY/OT copolymer coating may be considered as potential coating material for corrosion protection of mild steel in the above corrosive medium.

A material evaluation study has been carried out to determine corrosion behavior of a commercial polyurethane coating system (Souplethane 5) in the marine environment. The coating system is solvent free, two-component polyurethane protective coating. The performance of the coating on steel and rebar concrete was evaluated by conducting different types of tests which include atmospheric exposure, immersion in 5% sodium chloride solution, exposure to splash zone in seawater, salt fog, sabkha soil burial, and electrochemical tests, which include potentiodynamic polarization and AC impedance measurements. Uncoated, coated, and coated scribed specimens were used in each study. In general, the coating showed good corrosion resistance in marine environment. However, the coated samples, when subjected to break under applied compressive load, showed partial or complete detachment from the substrate, e.g., steel and rebar concrete. This appears to be the major drawback of the coating while applying on steel and concrete structures.

This article describes the results of an investigation concerning the failure of the back wall riser tube of a high pressure boiler in a SWCC dual purpose power/water cogeneration plant. The failure occurred in one tube (facing furnace) which contained eight ruptured openings covering a length of approximately 1.8 m. The tube material was carbon steel (SA 210A1). The cause of the failure was determined by on-site visual inspection of the boiler and detailed macro and micro examinations of inner and outer scales on the tube. The in situ non-destructive testing of selected boiler riser tubes was carried out using boroscope and ultrasonic test (UT). The composition of the tube material and fire and water-side scale deposits were analyzed by energy dispersive x-ray (EDX) and inductively coupled plasma (ICP) techniques. The cause of the failure of the riser boiler tube appears to be caustic attack. The inside brown scale that developed during service resulted in overheating, wall thinning due to caustic corrosion, and the associated ruptures of the tube in areas of high stress. The escaping steam eroded the outer surface of the tube resulting in heavy loss of metal around the rupture points (punch). Recommendations are given to prevent/minimize such failures.

A soluble copolymer from aniline and o-toluidine [poly(aniline-co-o-toluidine)] was synthesized by chemical oxidative copolymerization using ammonium persulphate as an oxidant in hydrochloride aqueous medium. The resultant copolymer was characterized by Fourier Transform Infrared (FTIR) spectroscopy and chemically deposited on mild steel specimens using N-methyl-2-pyrrolidone (NMP) as solvent via solution evaporation method. The anticorrosive properties of copolymer coating was investigated in major corrosive environments, such as 0.1 M HCl, 5% NaCl solution, artificial seawater, distilled water and open atmosphere by conducting various corrosion tests which include: immersion test, open circuit potential (OCP) measurements, potentiodynamic polarization measurements and atmospheric exposure test. The corrosion performance of copolymer coating was also compared separately with polyaniline (PANi) and poly(o-toluidine) (POT) homopolymer coatings. The surface morphologies of polymer coatings were evaluated using scanning electron microscopy (SEM). The synthesized copolymer exhibited excellent protection against mild steel corrosion; the protection efficiency being in the range of 78–94% after 30 days of immersion. The corrosion performance of copolymer in 5% NaCl and artificial seawater was comparable, which was only marginally better than in 0.1 M HCl. In general, the performance of copolymer coating was found to be better than that of homopolymer coatings.

The soluble copolymers, poly (aniline-co-o-toluidine) and poly (pyrrole-co-o-toluidine) were synthesized by chemical oxidative copolymerization using ammonium persulphate as an oxidant in hydrochloride aqueous medium and characterized by FTIR spectroscopy. The polymers were dissolved in N-methyl-2-pyrrolidone and casted by solution evaporation on to the metallic substrate. The corrosion performance of the poly (aniline-co-o-toluidine) and poly (pyrrole-co-o-toluidine) coatings on carbon steel was studied by conducting immersion tests and electrochemical tests which include free corrosion potential measurements and potentiodynamic polarization measurements. The tests were conducted in 0.1 M HCl and 5% NaCl solution. The performance of coating in open atmosphere was also evaluated by conducting atmospheric exposure test. The surface morphology of the copolymer coatings were studied by scanning electron microscopy (SEM). The anticorrosive properties of copolymer coatings were also compared with polyaniline and poly (o-toluidine) coatings. In general the performance of poly (aniline-co-o toluidine) copolymer was found better than poly (pyrrole-co-o-toluidine) and homopolymer.

Uniform corrosion, localized corrosion (pitting and crevice corrosion), cavitation, stress corrosion cracking, corrosion and mechanical fatigue, galvanic corrosion, dealloying, etc., are the common types of corrosion by which materials in desalination plants are subject to deterioration. Carbon steel, austenitic stainless steels, cupronickel alloys and titanium are prevalent materials in a modern day desalination plant. However, the majority of the failures in multistage flash (MSF) and seawater reverse osmosis (SWRO) plants have been attributed to localized attack. Localized attack in the form of pitting and/or crevice corrosion arise due to stagnation of chloride containing water, CO2 attack, presence of internal stresses, weld defect, foreign material carryover, mismatch of the material, etc. Flash chamber, pipelines, pumps, valves, heat exchanger, demister, storage tanks, intake system and power generating ancillary units may be affected by local attack. Right selection of material, skillful control o...

This article describes the results of an investigation concerning with the failure of a pipe which was carrying oil from the control oil unit to the steam turbine control valves servomotor. The failure was in the form of a crack, propagating horizontally along the pipe. The crack initiated on the outside of the pipe. The cause of the failure was investigated by conducting visual examination, detailed macro and microstructural examinations and determining the composition of material from the failed pipe. The composition of the pipe material was analyzed by atomic absorption spectrometer. The failure of the oil pipe was attributed to stress corrosion cracking. The pipe material is A312 TP 304L. Recommendation to minimize such failures includes coating the pipe to prevent contact with chloride from the surrounding marine environment.

This study deals with the investigations concerning with the suitability of coated steel piping system as an economically viable alternative to costly stainless steel piping for high pressure seawater reverse osmosis (SWRO) application. The piping system selected for investigation is a carbon steel piping coated internally and externally with thermoplastic coating (coating powder Plascoat PPA 571). The performance of thermoplastic coating was investigated by conducting SWRO pilot plant test, salt spray test, mechanical tests and testing of the coating under crevices (both in pilot plant and laboratory), and for leachable organics and inorganics (both in laboratory and pilot plant test). The testing of coating in the pilot plant resulted in the formation of some blisters on the internal surface of the pipes. The blisters were broken causing the corrosion of underneath steel. The coating showed a poor resistance to salt fog test. In general, the coating performed satisfactorily under the crevices but showed blistering on either side of the test panels. The adhesive strength of the coating was found to be poor; however, it showed good flexibility. The results of chemical analysis did not show the leaching of organic or inorganic pollutants from the coating.

The work presented in this paper deals with the performance evaluation of some fusion-bonded epoxy (FBE) coatings under water transmission line conditions. The work is aimed to evaluate corrosion–erosion behavior of selected FBE coatings in different product waters under simulated water transmission line conditions to find applications in sections of water transmission lines which are subjected to high flow, water hammer or turbulence. Three different FBE coatings, namely, Scotchkote 206 N, NAP-GARD 7–2500, and RESICOAT R4 Blue were considered for the studies. The studies were carried out in treated SWRO (seawater reverse osmosis) permeate and treated and untreated MSF (multistage flash) product water. To generate data about the erosion–corrosion resistance of the coatings under pipelines operating conditions, coated steel panels of fixed dimension were subjected to jet impingement test (JIT). ac impedance tests were carried out on the coated steel samples obtained after subjecting to JIT. The tests were carried out to evaluate qualitatively water uptake by the coatings. Adhesion test was carried out to assess the adhesive strength of the coatings. The monitoring of total organic carbon (TOC) in the test media, before and after subjecting of JIT, was also carried out. The extent of formation of TOC in the test media is indicative of the possible degradation/leaching of coatings under severe JIT conditions. All the three coatings subjected to JIT did not show any impingement damage, loss of adhesion, blistering damage or color changes, thus reflecting their excellent corrosion–erosion property. The effect of residual chlorine concentration on the corrosion–erosion property of the coatings appears to be insignificant. The results of ac impedance showed very high initial impedance for all the three coatings giving them excellent ratings. However, the performances of Scotchkote 206 N and NAP-GARD 7–2500 in treated SWRO permeate was found to be affected after 10 months immersion. The results of TOC monitoring indicated the presence of some organic compounds in the test media possibly due to the degradation/leaching of coatings under severe JIT conditions. The residual chlorine concentration in the test media appears to influence the formation of TOC. Therefore, further studies are needed to establish the safety of the coating from health point of view.

This article describes the results of an investigation concerning the failure of economizer tubes of a high-pressure boiler in a dual-purpose power/water cogeneration plant. The failure was observed in the form of rupturing of one tube and a macrohole or pinhole in another tube. The boiler had an operating period of 116,123 h since its inception. For approximately the first 100,000 h, the fuel for the boiler was crude oil, which was replaced by Bunker C oil. The boiler tube is fabricated from carbon steel SA 210A1. The location of the failure was determined by on-site visual inspection of the boiler. Detailed macro- and microexaminations of inner and outer scales on the tube were begun to determine the cause of the rupture. The composition of the fire- and waterside scale and ash deposited on the outer surface of the tubes was analyzed by energy-dispersive x-ray (EDX) technique. The reduction percentage of wall thickness of the tube facing inside and outside the furnace was calculated. The cause of the failure of the economizer tube appears to be H2SO4 dew-point corrosion. The relatively low temperature of feedwater lowered the tube metal temperature and promoted the condensation of H2SO4. The external deposits on the tubes, as a result of bunker oil firing, further helped to lower the tube metal temperature, thus promoting H2SO4 condensation over the deposit and subsequent corrosion of the tube wall. Recommendations are given to prevent/minimize such failures.

The work presented in this paper deals with the investigations on the effect of heavy metal ions, e.g., Cu and Ni, on the localized corrosion behavior of carbon steel and SS 316L under different experimental conditions. The important experimental conditions which include the nature of aqueous medium, metal ion concentration, temperature, pH and flow condition have been taken into account. Immersion tests of 1, 6 and 12 month duration were carried out to determine the effect of metal ions on the corrosion rate of steels. Electrochemical technique like free corrosion potential measurements, has been carried out to investigate the role heavy metal ions on the corrosion behavior of carbon steel and SS 316L. The effect of heavy metal ions on the corrosion behavior of carbon steel is quite pronounced and follows interesting trends. The results of immersion tests in distilled water under both static and dynamic conditions show a decrease in the corrosion rates of carbon steel in presence of higher concentrations of metal ions. In seawater, the corrosion rate of carbon steel is affected significantly only at 100 ppm of metal ion concentration. Under different experimental conditions the corrosion rate of 316L is unaffected in presence of metal ions. The results of immersion tests find support from free corrosion potential measurements. Under controlled laboratory conditions, there is no evidence of localized attack in presence of different concentration of metal ions.

This paper describes the investigation of a corrosion failure of bottom plates on an aboveground tank used for the storage of potable water. The tank was internally inspected for the first time after six years of service. Paint blisters and rust spots were observed on the bottom plates and first to third course shell plates. Sand blasting and repainting of the bottom plates and first course shell plates was to be used as a remedial measure. However, during the sand blasting, holes and deep pitting were observed on the bottom plates. On-site visual inspection, magnetic flux leakage (MFL) inspection, ultrasonic testing (UT), and evaluation of the external cathodic protection (CP) system were used in the failure analysis. The corrosion products were analyzed using energy-dispersive X-ray analysis (EDAX). The failure is attributed to the ingress of water and its impoundment under the tank bottom along the periphery inside the ring wall and failure of water side epoxy coating. Various measures to prevent such failures in the future are recommended.

This article presents the results of an investigation on the corrosion of flash chamber floor plates in a multistage flash (MSF) desalination plant. In an MSF plant, desalinated water is produced by flashing deaerated seawater in successive flash chambers under reduced pressure. The flash chamber floor plates were made of carbon steel with AISI type 317L stainless steel (UNS S31703) internal cladding. The thickness of the carbon steel and cladding was 8.5 and 3 mm, respectively. Approximately four years after the plant was commissioned, indications of corrosion processes, in the form of numerous red-colored spots, were noticed on the floor plates.

Reverse osmosis (RO) water constitutes about 22% of total desalinated water produced in the world. The rest of the desalinated water is almost entirely from thermal distillation, such as multistage flash (MSF) evaporation and multi-effect desalination (MED) techniques. The RO permeate is more corrosive than water produced by thermal distillation due to its high dissolved salts (TDS) level, particularly chlorides. As the RO water is transported through cementitious or polymer lined pipelines, steel components like pumps, valves and pipes are likely to corrode, if proper material selection is not made. Not much information is available regarding the corrosion behavior of RO water towards the metallic materials particularly steels which forms the bulk of constructional materials. A study has been conducted to investigate the corrosion behavior of some structural materials which include carbon steel 1018, electroless nickel plated carbon steel 1018 ENP, austenitic stainless steel AISI 304, and martensitic stainless steels AISI 410, AISI 420 and AISI 431 in RO water. These materials have been the main constructional materials used in metallic components of pipelines in Saudi Arabia. Studies have been carried out under dynamic conditions (impingement under flow), static conditions (crevice formers) and in presence of an inhibitor (phosphate) using a dynamic test loop. High chromium steels (>15% Cr) appear to provide good resistance where as low chromium steels (

The aluminide and CeO2 and La2O3 containing aluminide coatings on carbon steel have been prepared by a pack cementation process. The influence of CeO2 and La2O3 additions on the oxidation rates of aluminide coatings has been investigated. The performance of coatings was studied by measuring oxidation kinetics, metallography, SEM and X‐ray diffraction analysis techniques. The oxidation‐resistance of coated carbon steel is discussed on the basis of a decrease in oxidation rates as well as adherence of oxide scales. The oxidation rates of carbon steel and aluminide coatings were markedly reduced in the presence of CeO2 and La2O3 in the temperature range of 700‐900°C. The oxidation rates were significantly affected by the morphology of oxide scales. In the case where the structure of oxides scales was not seriously disrupted due to decarburisation, the oxidation rates were significantly reduced.

The interaction of different metal oxides such as Co3O4, NiO, Al2O3, Cr2O3, Fe2O3 and SiO2 with Na2SO4 at a temperature of 1100 and 1200 K in flowing oxygen has been studied. The thermogravimetric studies for each system were carried out as a function of Na2SO4 in the mixture. The presence of different constituents in the reaction products were identified by X-ray diffraction analysis and the morphologies of the reaction products were characterized using metallography and scanning electron microscopy (SEM). The formation of products was also investigated by thermodynamic computation of free energies of the reactions and the study of relevant equilibrium phase diagrams. The soluble species in the aqueous solutions of the reaction products were determined quantitatively using atomic absorption spectrophotometry. The high temperature interaction products usually contain a 3-phase structure namely, Na2O·M2O x , M2O x and metal sulphide and/or metal sulphate. The formation of Na2O·M2O x depends upon the solid state solubility of metal oxide in the molten salt at high temperatures. Under limited solubility conditions Na2O·M2O x is invariably formed, but as soon as this condition is relaxed the oxide. M2O x , precipitates and forms a separate phase.

The emeraldine base (EB) was synthesized by chemically oxidative polymerization using ammonium persulphate as an oxidant in hydrochloride aqueous medium. The polymer was chemically deposited on mild steel specimens using tetra methyl urea (TMU) as solvent through solvent evaporation method. The coating of polypyrrole (PPy) on carbon steel was deposited by chemical polymerization. A bi-layered polymer coating comprising of inner coat of PPy with top coat of EB (PPy/EB) was also deposited on mild steel following identical procedure. The deposited EB, PPy and PPy/EB coatings were characterized by Fourier Transform Infrared (FTIR) Spectroscopy and Scanning Electron Microscopy (SEM). The anticorrosive properties of single and bi-layered coatings was investigated in major corrosive environments such as 0.1 M HCl, 5% NaCl solution, artificial seawater, distilled water, tap water and open atmosphere by conducting various corrosion tests which include: immersion test, open circuit potential measurements, potentiodynamic polarization measurements, and atmospheric exposure test. The results of immersion tests showed that the PPy/EB coating gave best protection in all media under investigation, the protection efficiency being in the range of 72 to 79% after 30 days of immersion. The result of OCP measurements showed significant positive shift in the corrosion potential for single as well as bi-layered coatings in all corrosive medium under investigation; the bi-layered coating showing more positive corrosion potential. The potentiodynamic polarization studies also confirmed lower corrosion rates for PPy/EB coating than the single polymer coatings.

The work presented in this paper deals with the investigations on the effect of Cu and Ni on the corrosion behavior of carbon steel under different experimental conditions. Electrochemical techniques like potentiodynamic polarization, linear polarization resistance and AC impedance have been used to investigate the effect of Cu and Ni on the corrosion behavior of carbon steel. The important experimental conditions which include the nature of aqueous medium, metal ion concentration and pH have been taken into account. The instantaneous corrosion parameters as computed by potentiodynamic polarization, linear polarization resistance and AC impedance show an increase in corrosion rates of carbon steel with increasing Cu and Ni concentrations. However, the corrosion parameter as computed by AC impedance for an extended period of one month follows an interesting trend. The presence of Cu and Ni in the aqueous medium produces almost identical effect on the corrosion behavior of carbon steel. The microscopic examination of the test samples, under controlled laboratory conditions, did not show the evidence of localized attack on carbon steel in presence of different concentrations of Cu and Ni.