Corrosion and Dye

Corrosion is one of the most damaging and costly naturally occurring events seen today. The most common kinds of corrosion result from electrochemical reactions. It can be prevented if the metal is coated with something which does not allow moisture and oxygen to react with it. It can be controlled by either alloying or by anti rust solutions. The naturally occurring plant products are eco-friendly, compatible, nonpolluting, less toxic, easily available, biodegradable and economic to be used as corrosion inhibitor.Euphorbia caducifolia has been selected to study its corrosion inhibition efficiency. It is easily available in any season. It is native to Thar Desert of India and located on rocky terrain, hills. It is used for treatment of bleeding wound, cutaneous eruption, urinary problems, kidney stones, rheumatic pain, bronchitis, jaundice, diabities, stomach pain, hernia etc. It is also called “Thor” and “Danda-thor”. It contains caudicifolin) norcycloartane type triterpene, cyclocaducinol, triterpenes euphol, tirucallol and cycloartenol. Corrosion inhibition efficiency of arial parts of Euphorbia caducifolia was studied for aluminium in HCl. Maximum inhibition efficiency was found 99.47% in 1N HCl acid with 0.8% leaf corrosion inhibitor whereas it was 94.21% for stem and 90.51% for flower with same concentration of inhibitor i.e. 0.8%. Inhibition efficiency was studied in different concentration of acid (1N, 1.5N, 2N and 2.5N) with different concentration of inhibitor (0.2%, 0.4%, 0.6% and 0.8%). Weight loss and thermometric methods were used. Inhibition efficiency was found to be increase with increase in concentration of inhibitor and decrease with increase in acid strength.

The corrosion behavior of copper-nickel alloy in the presence of two organic inhibitors that belong to the pyrazole derivatives namely 1,5-dimethyl-1H-pyrazol-3-yl)methylamine and 1,3-Dimethyl-1H-pyrazol-4-yl)acetic acid has been investigated in natural sea water. Weight-loss measurements, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were applied to analyze the effect of the organic compounds on the corrosion inhibition of copper-nickel alloy. Polarization studies showed that these inhibitors were found to act as mixed type for alloy in chloride solution. It suppresses the cathodic and anodic reactions rates and it renders the open circuit potential to more noble directions. Measurements of values of charge transfer resistance (Rct) and the double layer capacity (Cdl) have been carried out. Accelerated leaching studies revealed that the inhibitors control the dissolution of copper and nickel in the alloy.

The corrosion and synergistic inhibition behaviour of mild steel in H2SO4 (pH=1) in the presence of 2 mercapto Benzidazol (MBI), 2 Mercapto Benzithiazol (MBT) and 2 Mercapto 5 Methylbenzimidazol (MMBI) and potassium chloride (KCl), potassium Bromide (KBr) and potassium iodide (KI) was investigated using weight loss measurements, potentiodynamic polarization measurements and electrochemical impedance measurements. The inhibition efficiency has been found to increase with inhibitor concentration. All the three inhibitors function through adsorption followed Langmuir isotherm and made contribution with physical adsorption. It has been found the addition of potassium halides enhanced the inhibition action and the maximum enhancement has been obtained in case of the KI compared to other halides for each inhibitor. The inhibition system composed by 500 ppm MBT and 700 ppm KI offered maximum corrosion protection (~96%). On the other hand, it was found that the inhibiting effect of MBI, MBT and MMBI decreased with exposure period and temperature of the corrosion medium. The potentiodynamic results showed that these compounds suppressed both cathodic and anodic processes; preferentially acting on cathodic areas. The presence of these inhibiting species decreased the double layer capacitance and increased the charge transfer resistance, derived from Nyquist plots obtained from impedance studies. The comparative FTIR studies between pure compound and respective metal surface product indicated the presence of inhibitor in the metal surface product obtained after exposure in inhibited solutions. SEM analysis suggested that the metal had been protected from the aggressive corrosion because of the addition of the inhibitors on the surface.

The extraction from the agricultural waste like coconut shell using sulfuric acid and the identification of furfural in the extract treated as corrosion inhibitor. Extracted furfural was characterized by Fourier Transform Infra-Red (FTIR) spectroscopy and High Performance Liquid Chromatography (HPLC). The inhibition efficiency of extracted furfural was studied on the corrosion of mild steel in 0.5M H2SO4 with different concentrations by weight loss method and Tafel plot techniques. The inhibition efficiency increases with also increase in the extract concentration. The effect of temperature on corrosion behavior was also studied over the temperature range of 30–45°C. The results indicate that the inhibition efficiency increases with increase in concentration of inhibitor and decreases with rise in temperature. Electrochemical polarization (Tafel plot) data explores the mixed mode of inhibition. The extracted Furfural follow Langmuir adsorption isotherm. Adsorption mechanism involves both physisorption and chemisorptions. The surface study of inhibited mild steel was performed by scanning electron microscopy (SEM).

The effect of ampicillin and amoxicillin on the corrosion of copper in 0.1 M HCl was evaluated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. The results of polarization studies indicate that the investigated drugs are mixed type inhibitors. It was observed that inhibition efficiency increased with increasing drug concentrations and decreased with raising temperature. Thermodynamic activation and adsorption parameters were calculated and discussed. Adsorption of these drugs on the copper surface was found to follow Langmuir adsorption isotherm. The experimental results are supported by the theoretical data.

Anticorrosion activity of Pluchea dioscoridis (L) extract (PDE) as a corrosion inhibitor for mild steel in 1M HCl has been investigated using mass loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM). The mass loss results show that PDE is an excellent corrosion inhibitor. The inhibition efficiency increases with increasing the temperature from 25 to 45oC, reaching a maximum value of 82 % at the highest concentration of 300 ppm at the temperature of 45oC. Polarization measurements demonstrate that the PDE acts as a mixed type inhibitor. Nyquist plot illustrates that on increasing PDE concentration, the charge transfer increases and the double layer capacitance decreases. The adsorption of PDE on mild steel obeys Temkin adsorption isotherm. SEM studies confirm the adsorption of PDE on mild steel surface.

The influence of a natural extract of fenugreek on the corrosion of steel in 10 ppm NaCl and 35 ppm Al2(SO4)3 has been studied by weight loss, polarization and EIS measurements. Results obtained show that the natural substance inhibits the corrosion process. It acts on the cathodic domain without modifying the reduction mechanism. The inhibition efficiency increases with fenugreek concentration to attain 75 % at extract of 0.6 g/L of fenugreek at temperatures between 303 and 333K. The effect of temperature on the corrosion behaviour of steel indicated that inhibition efficiency is temperature dependent. The activation energy of adsorption is determined.

The effect of the addition of safflower extract on the corrosion of ?-brass in nitric acid done by chemical method (WL), electrochemical method "electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and electrochemical frequency modulation (EFM) technique". The efficiency of inhibition rise with increment the concentration inhibitor, but diminishes with expanding the temperature. The adsorption of safflower on the ?-metal surface takes as Temkin adsorption isotherm. Impact of the temperature on the consumption of metal in one molar nitric corrosive was additionally mulled over. Potentiodynamic polarization studies demonstrated that safflower concentrates is blended sort inhibitor and the outcomes got from the systems are in great understanding.

The effect of novel corrosion inhibitors, new class of substituted benzotriazoles namely N-[(benzylidene hydrazino)-propyl]- benzotriazole(BPBT) and N-[(4-oxo-2-phenyl-1,3-thiazolidineimino)-propyl]-benzotriazole (OPBT) were synthesised and their inhibition behaviour on Cu-Ni alloy in natural sea water were investigated by the weight-loss method, potentiodynamic polarisation and electrochemical impedance studies. Polarization measurements showed that the organic compounds investigated are mixed type inhibitors, inhibiting the corrosion of Cu-Ni alloy by blocking the active sites of the metal surface. They decrease the anodic reaction rate more strongly than the cathodic reaction rate and render the open circuit potential of Cu-Ni alloy more positive in natural sea water. Changes in the impedance parameters (charge transfer resistance (Rct) and double layer capacitance (Cdl)) are related to adsorption of organic inhibitors on the metal surface, leading to the formation of a protective film. Solution analysis revealed the decrease in dissolution of both copper and nickel in the presence of benzotriazole derivatives. The morphology of the Cu-Ni alloy after corrosion in the presence and absence of the benzotriazole derivatives was examined using scanning electron microscopy (SEM). All studies clearly show that the substituted benzotriazoles inhibits the corrosion of Cu-Ni alloy in natural seawater and the value of inhibition efficiency increases with increasing concentration of inhibitors.

Ziziphus Spina Christi Extract (ZSCE) was tested as corrosion inhibitor for aluminum in 0.5 M HCl using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) measurements. Surface morphology was tested using scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDX). The effect of temperature on the corrosion behavior of Al in 0.5 M HCl with and without different concentrations of plant extract was studied at temperatures of 298 and 318 K. Inhibition efficiency of 85.7% was achieved with 500 ppm ZSCE at 298 K. It is evident from the results obtained that ZSCE inhibits the corrosion in 0.5 M HCl through adsorption process following Langmuir adsorption isotherm. The inhibition efficiency increased with increase in extract concentration but decreased with raising temperatures. The mixed mode of action exhibited by the extract was confirmed by the polarization studies while SEM analysis substantiated the formation of protective layer over the Al surface. The values of inhibition efficiency obtained from different techniques are in good agreement.