Frankica Kapor

Corrosion inhibition of carbon steel in the near neutral media by blends of tannin and calcium gluconate

The efficiency of tannin/calcium gluconate blends, as corrosion inhibitors for carbon steel in near neutral water media, heva been studied.Synrgistic behaviour of two components blend of different concentrations has been demonstrated in solutions prepared with distilled and a tap water. The anodic character of the inhibitor was recognised by the shift of corrosion potential to more positive values and a decrease of the passivation current on potentiodynamic polarisation curves. The cathodic inhibition was also recognised by slowing down the cathodic current of the polarisation run.Soluble iron tannate chelate has been observed as a dark blue flux flowing down from the metal surface into solution of tannin in the tap water, resulting in a corrosion process. Tannin decreased the pH of tap water.Calcium gluconate added in tannin solutions increases the pH maintaining it in the near neutral region enabling the precipitation of a low soluble protctive iron tannate and metal gluconate.

Corrosion Inhibition of Carbon Steel by Blends of Gluconate/Benzoate at Temperatures Up to 60°C

The inhibition of carbon steel in solutions of mixtures of calcium- and zinc-gluconate with sodium benzoate was investigated in the temperature range from 25° to 60°C, under atmospheric conditions in stagnant solutions prepared with the tap water. The efficiency and the mechanism of inhibition were estimated by potentiodynamic polarization measurements. The influence of the concentration and the ratio of gluconate/benzoate on the anodic reaction and an observed cathodic effect, indicating slowing down the oxygen reduction process, relevant to the concentration of zinc ions, have been demonstrated. The performed inhibition of carbon steel, as shown by polarization data, may be attributed to the adsorption of gluconate along with benzoate or/and to the formation of a low soluble iron gluconate complex on the metal surface. The inhibition is enhanced by the cathodic polarization mechanism resulting in the precipitation of a zinc hydroxide film, due to the local cathodic gradient of hydroxyl ions. Gluconates act also as sequestring agents preventing a deposition of calcium carbonate from hard waters. Results obtained by electrochemical measurements were confirmed by immersion tests, and could be of interest for the application in cooling water treatement systems, and for the injection water in oil and gas recovery. Investigated compounds are environmentally acceptable being non-toxic and non-polluting.

Inhibition properties and adsorption behavior of olive leaf extract on N80 carbon steel in CO2-saturated brine solution

Abstract The inhibition effect of olive leaf extract on corrosion of carbon steel in brine solutions saturated with CO2 was investigated at 25 °C and 65 °C by means of Tafel polarization, weight loss measurements and Fourier transform infrared spectroscopy. The experimental results reveal that the olive leaf extract has a good inhibition effect on the carbon steel in CO2-saturated brine solution at both temperatures. Tafel polarization investigations revealed that olive leaf extract acted as a mixed inhibitor showing anodic and cathodic behavior. The adsorption of olive leaf extract on carbon steel surface obeyed the Langmuir adsorption isotherm. The adsorption thermodynamic parameters indicated the physisorption of olive leaf extract on carbon steel surface was a spontaneous and exothermic process with an increase in entropy. Fourier transform infrared spectroscopy spectra showed types of bonding for olive leaf extract on the carbon steel surface.

Olive Leaf Extract as a Corrosion Inhibitor of Carbon Steel in CO2-Saturated Chloride– Carbonate Solution

In the present study corrosion inhibition of carbon steel in CO2-saturated chloride– carbonate solution by the olive leaf extract has been researched. For that purpose the electrochemical and spectrophotometric techniques such as potentiodynamic polarization, electrochemical impedance spectroscopy and Fourier transform infrared spectroscopy were employed. Both electrochemical techniques, potentiodynamic polarization and electrochemical impedance spectroscopy, demonstrate that olive leaf extract inhibits the carbon steel corrosion in CO2-saturated chloride–carbonate solution. It was determined that the inhibition efficiency increases with increasing concentration of the olive leaf extract. The olive leaf extract achieves high corrosion efficiency as a mixed type inhibitor, with a prevailing influence on the anode process. Recorded electrochemical impedance spectra in the presence of the extract show the presence of the inhibitor film on the steel surface. This is further confirmed by the recording in Fourier transform infrared spectroscopy spectrum.