Corrosion Inhibition of Pipeline Carbon Steel (N80) in CO2-Saturated Chloride (0.5 M of KCl) Solution Using Gum Arabic as a Possible Environmentally Friendly Corrosion Inhibitor for Shale Gas Industry

The inhibition effect of gum arabic (GA) was investigated using weight loss measurements and electrochemical techniques. The results show that the inhibition efficiency of GA increased with an increase in the concentration of the inhibitor but decreased with the temperature. Immersion time was found to have a profound effect on the corrosion inhibition performance of the inhibitor. Polarization measurements revealed that GA was a mixed-type inhibitor, with higher influence on the anodic reaction. The inhibitor followed the Temkin’s adsorption isotherm, and the values of the standard free adsorption energy indicate a mixed-type adsorption, with the physical adsorption being more dominant. SEM–EDS and FT-IR measurements were also employed to support the findings.

Inhibiting Properties of Morpholine as Corrosion Inhibitor for Mild Steel in 2N Sulphuric Acid and Phosphoric Acid Medium

The inhibition effect of morpholine on the corrosion of mild steel in 2N sulphuric acid and phosphoric acid has been studied by mass loss and polarization techniques between 302K and 333K. The inhibition efficiency increased with increase in concentration. The corrosion rate increased with increase in temperature and decreased with increase in concentration of inhibitor compared to blank. The adsorption of inhibitor on the mild steel surface has been found to obey Temkin's adsorption isotherm. Potentiostatic polarization results reveal that morpholine act as mixed type inhibitor. The values of activation energy (Ea), free energy of adsorption (∆Gads), enthalpy of adsorption (∆H), and entropy of adsorption (∆S) were also calculated.

Investigation of Inhibition Effect of Acrylic acid on C-Steel Corrosion in Sulfuric Acid Solutions

Acrylic acid was tested as a corrosion inhibitor for C-steel in 0.5 M H2SO4 using gasometry, weight loss, and galvanostatic polarization techniques. Polymeric film is built up by cyclic voltammetry technique. The potentiodynamic polarization is used to examine the inhibition effect with the coated polymeric film. The data obtained from the different techniques coincide in that acrylic acid is a good mixed-type inhibitor. The inhibition process is based on the adsorption of acrylic acid on the surface of C-steel according to Temkin’s adsorption isotherm. The inhibition efficiency increases with inhibitor concentration and decreases with temperature. The thermodynamic parameters ΔE, ΔH*, ΔS*, and ΔG*ads were calculated to elaborate the mechanism of corrosion inhibition.