Computational and Experimental Studies of 4-Aminoantipyrine as Corrosion Inhibitor for Mild Steel in Sulphuric Acid Solution
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Date
2012-01-01
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Abstract
The inhibitive effect of 4-Aminoantipyrine (4-AAP) on the corrosion of mild steel in 0.5 M H2SO4
solution at 303 – 323 K was studied by weight loss measurement as well as computational techniques.
Results obtained showed that 4-aminoantipyrine (4-AAP) is a good inhibitor for the corrosion of mild
steel in sulphuric acid solution. The inhibition efficiency increased with 4-AAP concentration and also
synergistically increased in the presence of KI and KSCN, but decreased with temperature, which is
suggestive of physical adsorption mechanism. The adsorption of 4-AAP onto the mild steel surface
was found to follow the Langmuir adsorption isotherm. Thermodynamics of adsorption such as
enthalpy of adsorption, entropy of adsorption, equilibrium of adsorption and Gibbs free energy, were
calculated and discussed. Quantum chemical calculations using DFT at the B3LYP/6-31G*
level of
theory was further used to calculate some electronic properties of the molecule in order to ascertain
any correlation between the inhibitive effect and molecular structure of 4-aminoantipyrine.
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Keywords
4-Aminoantipyrine, Mild steel, Sulphuric acid, Langmuir isotherm, Density Functional Theory (DFT)