Corrosion and Dye

Cetyl trimethyl ammonium bromide (CTAB) is tested as corrosion inhibitor for carbon steel in different concentration of hydrochloric acid medium and at different temperature. Corrosion rate and Percentage Corrosion Inhibition Efficiency (PCIE) was measured by weight loss method, Electrochemical polarization and Impedance spectroscopy techniques. Surface study of corroded and blank specimens was carried out by SEM and Metallurgical Research Microscopy techniques. 100, 200, 400, 600, 800 and 1000 ppm of Cetyl trimethyl ammonium bromide was tested in different concentration of HCl solution i.e. 2.0, 1.0 and 0.1 N. It was observed that percentage corrosion inhibition efficiency increases with increase in concentration of corrosion inhibitor. Effect of temperature on percentage corrosion inhibition efficiency was also investigated. As the temperature increases percentage corrosion inhibition efficiency decreases. It is observed that percentage corrosion inhibition efficiency decreases with dilution of HCl. CTAB acts as a very good inhibitor for Carbon Steel in different hydrochloric acid medium.

Corrosion inhibition of mild steel in 0.5 M H₂SO₄ was investigated in the absence and presence of different concentrations of extract of Crossandra infudibuliformis leaves [C.I.L]. Weight loss measurements and electrochemical studies were employed. The results obtained show that the inhibition was found to increase with increasing concentration of the plant extract. The inhibitive actions of plant extract are discussed on the basis of adsorption of stable complex at the mild steel surface. Theoretical fitting of different isotherms were tested to clarify the nature of adsorption. Polarization curves revealed that C.I.L inhibitor acts as mixed type inhibitor and the inhibition efficiency up to 96.40% was obtained.

The oxidative decolourization of AMCOT Red 3BLF in aqueous medium has been studied using photo Fenton process. Fenton’s reagent (H2O/Fe3+) was used to generated hydroxyl radical (?OH). A visible light source was used to provide radiation for photo Fenton process. The experimental parameter such as pH, air, light, time and catalyst strongly influenced the dye removal rate in photo Fenton process. The result shows that the AMCOT Red 3BLF bleaches upto 70% within 4 hrs and degrades into CO2 and H2O. The proposed mechanism for the reaction of ?OH with AMCOT Red 3BLF dye molecules is summarized.

Leaf and stem extracts of Catharanthus roseus and Murraya koenigii were taken for the comparison of their corrosion inhibition efficiencies on Aluminium in hydrochloric acid solution. Weight loss and thermometric methods were employed for these investigations. 1M and 2M for weight loss and 1M and 2M concentrations of HCl solutions were taken for thermometric analysis. Inhibitor concentrations were taken 0.1%, 0.3%, 0.5% and 0.7% in these methods. Results show good agreement mutually and illustrate that the corrosion inhibition efficiency of leaf and stem extracts of Catharanthus roseus was more as compared to that of Murraya koenigii. Further, results revealed that corrosion inhibition efficiency increases with the increase in the concentration of the acid as well as those of inhibitors. Maximum efficiency was found for 2M concentration of HCl at 0.7% concentration of leaf extract of the Catharanthus roseus whereas minimum efficiency was found for 1M concentration of HCl at 0.1% concentration of stem extract of the Murraya koenigii.

In this paper, study on the electrodeposition of ZnNi/nanosilica alloy coating on carbon steel and in?uence of 5g/L nanosilica in the plating bath on some properties such as morphology, structure characteristics and corrosion resistance of the ZnNi/nanosilica coating were conducted. The results revealed that ZnNi/nanosilica composite coating contained 16.37 % Ni and 0.32 % Si. Only the phase ?Ni5Zn21 were observed in the ZnNi/nanosilica alloy coatings. The thickness of the ZnNi/nanosilica coating was 16.56 µm. The corrosion resistance on the ZnNi/nanosilica coating was evaluated by time for red rust appearing in salt fog test as 900 hours.

The effects of some organic additives to the galvanizing in amonium chloride electrolyte zinc plating baths were studied. The results show that all additives added to the plating solution shifted the potential of the zinc precipitate towards a more negative side. Additive NAP 14-90 added to the plating solution increased cathode polarization and created a coating with a wide gloss and semi-gloss range. Additives Berol 840 and o-Chlorobenzaldehyde added with NAP 14-90 improved gloss and widen the semi-gloss range. When Berol 840 and o-Chlorobenzaldehyde were added to the plating solution without NAP 14-90, the deposit distribution decreased deeply and the coating could not form at low current densities. The additives added to the plating solution changed the coating morphology. The plating samples in the solution containing the additive NAP 14-90 gived a smooth and uniform coating morphology. The sample had all three additives providing the smoothest coating morphology. The additives added to the plating solution had little effect on the plating efficiency. Additives 2 ml/L NAP 14-90 + 1 ml/L Berol 840 + 0.2 ml/L o-Chlorobenzaldehyde were selected to improve the properties of the coating and the plating process in the ammonium chloride system.

The IR and HPLC analysis of bougainvillea flower extract revealed that it contains nitrogenous compounds, a novel betaxanthin, methyl (derivative of arginine betaxanthin) on the basis of UV-Vis spectra and mass spectrometric characteristics, as well as by comparison with literature data, which to the best of our knowledge has not been reported in bougainvillea flower extract. bougainvillea flower extract was the major betacyanin pigment present although methylated arginine betaxanthin, a novel betaxanthin hitherto not observed naturally and betalamic acid were also present. The identified compounds were then evaluated for anti-corrosive properties by the cyclic-voltammeter and potentiometer method.

The effect of polyvinyl alcohol (PVA) having molecular weight 16,000u in alkaline non-cyanide zinc plating bath on the characteristics of zinc plating process has been investigated. The SEM images indicated that zinc particles produced in plating bath were either in block form if plating bath without PVA or in slice form if plating bath with PVA. The size of zinc particles depended on PVA concentrations in plating bath. If the content of PVA in plating bath increased, the zinc grain size reduced. Hull Cell tests also illustrated that surface of zinc deposition improved for plating bath with PVA. Semi-bright scope of zinc plated coating expanded if the PVA concentration in plating bath grew. However, bright scope did not appear in all samples from plating bath with various concentrations of PVA. It was reasonable due to PVA playing a role as primary additive for zinc plating as other authors confirmed. Interestingly, cathodic polarizations were increased in presence of PVA. Throwing power increases significantly with increasing PVA concentration.

Corrosion is a natural destructive process, in which metal loss their properties through unwanted chemical or electrochemical attack by its environment, in this process metals revert back to their natural and lower energy state which is more stable than the pure state of metals, it showed that corrosion is a reverse chemical process of extraction of metals. In the refining process, energy is added to the ore to produce the pure metal. Aluminium is one of the most important metals on the earth which is widely used for different kind of activities. Generally aluminium metal exists in the forms of their oxide and it has high corrosion resistance to atmosphere and pure water but it is corroded adversely in presence of acidic environment.The corrosion inhibition of aluminium by Euphorbia Neriifolia linn in different solution of sulphuric acid was investigated by using weight less and thermometer method at 301K temperature. The findings of the study shows that the inhibition inefficiency was maximum (93.11%) for highest concentration (0.7%) of stem extract in lowest strength of sulphuric (1N) and inhibition efficiency was minimum (74.82 %) for lowest concentration of flower extract (0.1%) in 3N sulphuric acid and the study showed that the inhibition efficiency increases with increase in the concentration of extract of plant in H2SO4 solution. The study shows that extract of Euphorbia Neriifolia linn is an efficient natural corrosion inhibitor in acidic medium and the stem extract is better inhibitor than leaves and flower extract of the plant.

The corrosion resistance of trivalent chrome conversion coatings on electroplated zinc is studied and compared with that of hexavalent chrome conversion coatings in salt spray testing conditions. The trivalent chrome conversion coatings and hexavalent chrome conversion coatings were unstable at pH 3. All samples had more than 5 % of the surface area covered with white rust after 24 hours of salt fog exposure. The corrosion resistance of the samples is as follows: TM 3108 ~ SP 25 > 747 at pH 6.5. The highest resistance obtained on the TM 3108 with white rust appeared after 400 hours of salt fog exposure. All of the hexavalent chrome conversion coatings and trivalent chrome conversion coatings had corrosion current densities (1.26×10-7 ÷ 1.82×10-7 A/cm2) much smaller than corrosion current density of the zinc electrodeposited sample (7.7×10-6 A/cm2). The compositions of corrosion products of sample surfaces after exposure were investigated. The results of analysis by means of X-ray diffraction showed that the corrosion products formed on zinc coatings, trivalent and hexavalent CCCs in atmospheric conditions of Hanoi had the distinctions specialty of the humid tropical climates. Zinc sulfate hydroxide hydrate Zn4SO4(OH)6.H2O; Zinc carbonate hydroxide hydrate Zn4CO3(OH)6.H2O; Simonkolleite Zn5(OH)8Cl2.H2O; Chromium Sulfate Cr2(SO4)3; Zinc chloride sulfate hydroxide hydrat Zn12(OH)15(SO4)3Cl3.H2O; Eskolaite Cr2O3 had been identified. The presence of SO2 resulted in the formation of Zinc sulfate hydroxide hydrate Zn4SO4(OH)6.H2O. After 5 years of exposure in atmospheric conditions, the hexavalent CCCs on zinc coatings had show the best corrosion resistance and the least corrosion products. The corrosion resistance of the samples decreased in the order: 747 > SP25 ~ TM 3108 > Zn.