Kinetics and thermodynamic study of corrosion inhibition of mild steel in 1.5m HCl medium using cocoa leaf extract as inhibitor

Abstract

This study examined the corrosion inhibition of mild steel in 1.5M HCl solution using cocoa leaf extract as an inhibitor. The effect of inhibitor concentrations, kinetics, and time of immersion were undertaken at 30 o C while the thermodynamic parameters were determined with temperature range of 35 o C-55 o C. FTIR result indicated that the actual adsorption of the inhibitor is as a result of donation of single pair of electrons on oxygen to the vacant d-orbitals of the metal (mild steel) that leads to the formation of complexes on the mild steel surface. The corrosion rate decreased from 1.64 g/cm 2 hr to 0.09gm/cm 2 hr in the presence of inhibitor used. However, increased in temperature showed a decreased in inhibition efficiency this resulted to an increase in rate of corrosion. Half-life of the corrosion kinetics ranges from 49.71-53. 15hr which is directly proportional to the inhibitor concentrations. Activation energy Ea, enthalpy (∆H o), and entropy (∆S o) calculated showed good interactions. The enthalpy of activation ranges from 63.28kJ/mol to 97.55kJ/mol. Rise in activation energy with inhibitor concentration confirmed the physical (physisorption) adsorption mechanism for the corrosion of mild steel surface. Endothermic nature of the corrosion process is ascertained with the positive value of ∆H o obtained.

The role of organic acid metabolites in geo-energy pipeline corrosion in a sulfate reducing bacteria environment

“…The reaction at the metal surface requires a small activation energy and activation enthalpy to proceed if the acid solution concentration is increased. The positive sign for both E act and ΔH act reflects the endothermic nature of the corrosion process while the increase of ΔS act implies an increase in disordering takes place on going from reactants to the activated complex (Go et al, 2020;Okewale and Adesina, 2020). These observations on kinetic parameters of activation corrosion support the PDP and EIS results.…”

A Green Approach: Evaluation of Combretum indicum (CI) Leaf Extract as an Eco-friendly Corrosion Inhibitor for Mild Steel in 1M HCl

“…The corrosion inhibitive property of Gentiana olivieri [12] was observed in 0.5M HCl. Irvingia wombolu [13] Euphorbia heterophylla L [14] Cocoa leaf [15] showed good inhibition efficiency for mild steel in 1.5M HCl. Tephrosia purpurea [16] extract prevented the corrosion on the mild steel surface in 1N HCl.…”

Corrosion Inhibition Efficiency, Adsorption Behavior, Kinetics and Thermodynamic Studies of Lannea Acida Ethanol Leaves Extract on Mild Steel in Hydrochloric Acid

“…The values of ΔGads obtained were also negative, ranged from -8.32 to -10.14 kJ mol -1 which is also less than -20.00 kJ mol -1 and this supports the physical adsorption mechanism. The values of 1/n obtained which is the intensity of the adsorption process of mild steel surface shown in Table 6 are less than unity which indicates favorable adsorption (Okewale and Adesina, 2020). The values of 1/n also speak of the degree of heterogeneity of the adsorption surface.…”

“…The comprehensive adsorption mechanism suggested in the work is thought to occur in succession. First by physical adsorption due to the effective adsorption of molecules of water on the surface of mild steel, then complemented by a chemical interaction between the mild steel surface and the unused part of the water molecules which initiates the chemical adsorption process (Okewale and Adesina, 2020).…”