Corrosion and Dye

The corrosion inhibition of mild steel in 1.0 M HCl solution was investigated using Hexamethylene tetramine (hexamine) as a corrosion inhibitor by using different techniques i.e. weight loss method, potentiodynamic polarization and Electrochemical Impedance Spectroscopic (EIS) at 35.0o C. Further, the surface study of corroded specimen was carried out by inverted trinocular metallurgical research microscopy. It was observed that the percentage corrosion inhibition efficiency increases with increase in the concentration of inhibitor. The maximum percentage corrosion inhibition efficiency was 93.0 % at a concentration of 800 ppm. Impedance study shows the increases in Rct value with increase in the concentration of inhibitor. Potentiodynamic polarization studies showed that Hexamine behave as mixed type of corrosion inhibitor. Results obtained from corrosion experiments shows that Hexamine is a very good corrosion inhibitor for mild steel in 1.0 M HCl.

Four new cationic surfactants based on sulphonamide were synthesized. Their chemical structures were confirmed using, FTIR, H NMR spectroscopic analyses. The surface active properties of the synthesized surfactants were calculated from surface tension measurements at different temperatures .The performance of these surfactants as corrosion inhibitors for X-65 type carbon steel in oil wells formation water under H2S environment was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The obtained results showed that the percentage inhibition efficiency (?%) was increased by increasing the inhibitor concentration until the critical micelle concentration (CMC) reached. Also, it was found that inhibition efficiency was increased by increasing both molecular size of the surfactant and introducing ethylene oxide units in the surfactant molecule. The data obtained from (EIS) was analyzed to model the corrosion inhibition process through equivalent circuit. Finally, the nature of the protective film formed on carbon steel surface was examined by SEM and EDX techniques.

An aqueous extract of Allamanda Blanchetti (AB) has been prepared as a corrosion inhibitor to control the rate of corrosion. This compound has been investigated as corrosion inhibitor at room temperature for preventing mild steel corrosion in Sulphuric acid and Hydrochloric acid medium by weight loss method and by adsorption isotherm. The result showed that the corrosion inhibition efficiency of this aqueous extract of AB was found to vary with different acid concentration. Also, it was found that the corrosion inhibition behavior of AB is greater in 2M H2SO4 than 2M HCl. So AB can be used has a good inhibitor for preventing mild steel material. The surface analysis study confirms the corrosion of the mild steel and its inhibition by the inhibitor Allamanda Blanchetti.

The effect of some natural product extracts (Punica Granatum Peel PG, Solenostemma Argel SA, Olibanum O, Datura Seeds DS and Datura Leaves DL) on the corrosion behavior of mild steel in 1.0M HCl was studied by electrochemical techniques (open–circuit potential, linear polarization resistance and Tafel plots polarization). It is clear, these extracts give inhibition in both anodic and cathodic slopes in Tafel polarization, that indicate these inhibitors used as mixed-type inhibitor. The thermodynamic adsorption isotherm was studied and falls into Langmuir isotherm indicating physisorption isotherm behavior. In addition, the surface morphology of mild steel samples without and with the inhibitors was examined using scanning electron microscopy.

The corrosion inhibition and adsorption process of D - Tryptophan (DT)on mild steel in 2 HCl was studied by means of chemical (weight loss), electrochemical and quantum chemical techniques. The inhibition efficiency increases with decreasing temperature and increasing concentration of inhibitor. It has been determined that the adsorption of DT on mild steel obeys the Temkin adsorption isotherm at all studied temperatures with negative values of ?Goads, suggesting a stable and a spontaneous inhibition process. In potentiodynamic polarization, the curves shifted towards lower current density in the presence of the DT with well-defined Tafel regions suggesting that the inhibitor retard the corrosion process without changing the mechanism of the corrosion process; and exhibit cathodic and anodic polarization (mixed type inhibitor) because the change in Ecorr is less than 85 vM/SCE with respect to the blank. Corrosion current density was calculated by extrapolation of the linear parts of these curves to the corresponding corrosion potential; and corrosion potential (Ecorr), corrosion current densities (icorr), anodic Tafel slope (?a), cathodicTafel slope (?b) were determined with maximum value of inhibition efficiency for 5 x 10-4 M concentration of the inhibitor at 303 K was 78.4%. From Nyquist plot of electrochemical impedance spectroscopy, values of polarization resistance (Rp) increased with increasing inhibitor concentration whereas double layer capacitance (Cdl) decreased indicating a decrease in local dielectric constant or an increase in thickness of electric double layer suggesting that the inhibitor function by forming a protective layer at the metal surface. Quantum chemical calculations were performed using Density Functional Theory (DFT) with the help of complete geometry optimization for theoretical calculations of EHOMO, ELUMO, and energy gap (?E). Inhibition efficiency increases with increasing EHOMO indicating that the molecule has tendency to donate electrons to the mild steel with low energy empty molecular orbital; whereas low value of ELUMO suggests that the molecule easily accepts electrons from mild steel.

Bipolar plates (BPs) are a key component of Proton Exchange Membrane (PEM) Fuel Cells with multifunctional character. They uniformly distribute fuel gas and air, conduct electrical current from cell to cell, remove heat from the active area, and prevent leakage of gases and coolant. Bi-Polar Plates also significantly contributes to the volume, weight and cost of Proton Exchange Membrane Fuel Cell stacks. Hence, there are vigorous efforts worldwide to find suitable materials for Bi-Polar Plates. The materials include non-porous graphite, coated metallic sheets, polymer composites, etc. This paper reviews various types of materials, in use and proposed, for Bi-Polar Plates and critically examines their physical and chemical properties.

In the present study, anticorrosive action of the arecanut seed extract on the surface of copper in both 0.5 M HCl and 0.5 M NaOH systems was screened by weight loss and electrochemical methods. The protection efficiency of the inhibitor is directly proportional to its concentration and inversely proportional to copper immersion time and solution temperature. The copper corrosion inhibition process is related to adsorption of arecanut seed extract constituents on the copper surface and which is associated with Langmuir adsorption model. Morphological variations on the metal surface in unprotected and protected conditions were screened by scanning electron microscopy technique.

Uniform sizedTiO₂ nanoparticleswere synthesized using the sol-gel method, and the resultant powdered TiO₂ samples was heated at 500^oC air atmosphere.  Samples characterized by the XRD, FTIR, TGA and SEM and the photocatalytic degradation of Rose bengal using TiO₂ nanoparticles havebeen tested under UV light irradiation at 352nm (Long Wavelength). The rate of degradation of Rose bengalwas monitored by measuring the decrease in the absorbance value. Experimental parameters, such as the amount of catalyst loading, dye and H₂O₂ concentrations and Fenton’s reagent was tested against the degradation rate. The degradation efficiency of the synthesized nanoparticles was tested against commercially available TiO₂ (Degussa P-25).

The inhibition effect of turmeric extract on Cu corrosion in 0.5N HCl acid has been studied by impedance, Polarisation, Cyclic-Voltametry and FTIR techniques between the 303K to 333 K. The inhibition efficiency increased with the concentration of turmeric extract. The corrosion rate increased with the increase in temperature and it redused when the extract is mearged in solution. The adsorption of extract on metal surface is obeying Langmur’s and Temkin’s isotherm. The thermodynamic data and results of other technique found that the rate of corrosion is redused.

Novel surfactants based on sunflower oil and monoethanlamine were tested as inhibitors for the corrosion of steel in CO2-saturated 1% NaCl solution by Potentiodynamic polarization measurements and linear polarization resistance corrosion rate (LPR bubble test) at 50 oC. Inhibition efficiency increased with increase in the concentration of the studied compounds. Results show that the order of inhibition efficiency is II> I> III > IV >V. The adsorption of the inhibitors on the steel surface obeys Langmuir model and was physisorption.