Corrosion of carbon steel in formic acid as an organic pollutant under the influence of concentration cell

The presence of contaminants in water even in small amounts can cause considerablecorrosion damages of metals. This is due to free corrosion effect or the formation ofconcentration cell of pollutants resulting in a galvanic effect. The current work was devotedto study the effect of formic acid (CH2O2) as an organic pollutant on the corrosion rate ofcarbon steel under different operating conditions. It includes an investigation of galvaniccorrosion caused by the establishment of concentration cell of formic acid under differentoperating conditions. The ranges of operating parameters were formic acid concentration of10-4 - 10-5 M and temperature of 32 - 50 °C. The results showed that increasing formic acidconcentration to 10-4 M leads to an increase in the corrosion rate by up to 7.6 times that inthe water of 0.1N NaCl. In addition, the corrosion rate in each terminal in concentrationcell also increased by up to 2.3 times. Pumping of air in formic acid solution led to aconsiderable increase in the corrosion rates and enhances the concentration cell effectwhich increases the galvanic currents. High increase of corrosion rate was noticed bypumping the air at high temperature reaching up to 4 times depending on temperature. Ingeneral, the galvanic currents were high initially and decreased with time due to theformation of corrosion product layer. The increase in temperature from 25 to 50 oC causedan increase in the galvanic corrosion rate reached up to 2 times in formic acid solution. Inaddition, the galvanic currents were noticed to decrease with temperature while thecorrosion rate of each terminal was increased.

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Corrosion of Carbon Steel in Oxygen and NaCl Concentration Cells: the Influence of Solution Temperature and Aeration

Iraqi Journal of Chemical and Petroleum Engineering ◽

10.31699/ijcpe.2019.3.7 ◽

2019 ◽

Vol 20 (3) ◽

pp. 49-57

Author(s):

Muayad F. Hamad ◽

Huda D. Abdul Kader ◽

Hussein A. Alabdly ◽

Basim O. Hasan ◽

Israa S. M. Ali

Keyword(s):

Carbon Steel ◽

Corrosion Rate ◽

Galvanic Corrosion ◽

Operating Conditions ◽

Solution Temperature ◽

Concentration Cell ◽

Noticeable Increase ◽

Nacl Concentration ◽

Increasing Temperature ◽

Concentration Cells

Corrosion rate tests were carried out on carbon steel under concentration cells conditions of oxygen and sodium chloride. The effect of aeration in one compartment on the corrosion rate of both coupled metals was determined. In addition, the effects of time and temperatures on the corrosion rate of both coupled metals and galvanic currents between them were investigated. Corrosion potentials for the whole range of operating conditions under concentration cell conditions were also studied. The results showed that under aeration condition, the formation of concentration cell caused a considerable corrosion rate of the Carbon steel specimens coupled in different concentrations of O2 and NaCl due to the galvanic effect. Aerating one compartment caused a noticeable increase in the corrosion rate of the coupled specimen in the other compartment due to the galvanic effect. Increasing temperature caused unstable trends in the free and galvanic corrosion potentials. Increasing the temperature led to an increase in the corrosion rate for both metals.

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Galvanic corrosion of carbon steel under concentration cell formation in MgCl2 solution as an inorganic pollutant and the effect of flow velocity

Corrosion Reviews ◽

10.1515/corrrev-2019-0092 ◽

2020 ◽

Vol 38 (3) ◽

pp. 287-298

Author(s):

Marwa E.M. Ali ◽

Basim O. Hasan

Keyword(s):

Carbon Steel ◽

Corrosion Rate ◽

Flow Velocity ◽

Galvanic Corrosion ◽

Cell Formation ◽

Operating Conditions ◽

Concentration Cell ◽

Galvanic Current ◽

Solution Flow ◽

New Findings

AbstractThe wastewater of petroleum refineries consists of various corrosive pollutants that are harmful not only for human and living organisms but also for the equipment and materials exposed to it. The galvanic corrosion of carbon steel in MgCl2 solution as a pollutant in petroleum refinery wastewater was studied under concentration cell formation. The influence of different operating parameters on the galvanic corrosion established by concentration cell was studied, and the concept of concentration cell corrosion was examined and discussed versus experimental results. The effects of some operating conditions on the galvanic behavior, such as the concentration of MgCl2 (0–2500 ppm) and solution flow velocity (150–1000 rpm), on corrosion rate, corrosion potentials, and corrosion current were investigated. New findings regarding the effect of corrosive substance concentration and the hydrodynamics on the corrosion rate of each electrode and the galvanic current were reported. It was found that the corrosion rate of carbon steel in both cell poles increases with increasing MgCl2 concentration in both free and galvanic corrosion. Increasing MgCl2 concentration also led to an increase in the galvanic currents and the corrosion rate of the two electrodes. The flow velocity in either cell terminal considerably influences the potentials, corrosion rates of both electrodes, and the galvanic current passing in the cell. A high flow velocity in the compartment with the more negative potential caused polarity reversal on some occasions.

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