ABSTRACT
The inhibition efficiencies of tryptophan and histidine Schiff base
of para-dimethylamino benzaldehyde as corrosion inhibitors on mild steel in 1.0
M H2SO4 medium at 303K, 313K, 323K and 333K at
concentration range of 0.1 to 0.4 % using weight loss technique were
investigated. The surface characterization was done using Fourier transform
infrared (FT-IR) spectroscopic technique and scanning electron microscope
(SEM). FT-IR spectra revealed some of the functional groups responsible for the
adsorption of the inhibitors on the metal surfaces. Comparison of the
inhibition efficiencies of the two Schiff bases shows that the tryptophan Schiff
is a better inhibitor than histidine and with maximum inhibition efficiency of
tryptophan Schiff base reaching 96.43% at the inhibition concentration of 0.4%.
The Schiff bases of tryptophan and histidine of para-dimethyl amino
benzaldehyde gave good yields of 55.3 and 59.79 % respectively. The solubility
tests showed that the tryptophan Schiff base is soluble in ethanol, chloroform
and ethyl acetate but insoluble in hexane while the solubility tests for the
histidine Schiff base showed that it is soluble in chloroform and ethyl acetate
but partly soluble in ethanol and insoluble in hexane. The negative and low values of the reaction
constant (B) of both Schiff bases on mild steel indicate that the corrosion
rate is inversely proportional to the concentration of the inhibitors. The
increase in rate constant with increase in temperature indicates the increase
in corrosion rate with temperature. The activation energies in the presence of
inhibitors were found to be higher than the uninhibited solution. This implies
that the energy required for corrosion to occur in the inhibitor molecule is
higher. The adsorption parameters showed that the adsorption of trytophan and
histidine Schiff bases on mild steel fitted perfectly into Freundlich
adsorption isotherm model. The values of Gibbs free energy calculated were found
to be negative indicating the spontaneity of the corrosion inhibition process
on mild steel in both Schiff bases in 1.0 M H2SO4 medium.
Values of entropy and enthalpy of activation were found to be positive and
negative for both Schiff bases in 1.0 M H2SO4 medium on
mild steel. Positive values of enthalpy indicate endothermic nature of mild
steel dissolution process. Negative values of entropy of activation are
indication of formation of activated complex in the rate determining step which
represents association rather than disassociation step. It can be seen that
uninhibited mild steel surface in 1.0 M H2SO4 medium has
a very rough surface morphology due to corrosion by H2SO4 solution while
the mild steel surface after inhibition by the Schiff bases showed a lesser
degree of roughness in comparison to the mild steel surface in the uninhibited
acid solution. This could be attributed to the adsorption of the inhibitor on
the metal surface thereby preventing aggressive corrosion on the metal.
Attempts should be made to synthesize other novel Schiff bases from tryptophan,
histidine and para-dimethyl amino benzaldehyde and their corrosion inhibitory
properties on the metal surfaces should be investigated.
GABRIEL, O (2024). Syntheses, Characterization And Corrosion Inhibition Studies Of Trytophan And Histidine Schiff Bases Of Para- Dimethyl Amino Benzaldehyde on Mild Steel in 1.0 M H2SO4 Medium :- Ibe, Gabriel O. Mouau.afribary.org: Retrieved Sep 08, 2024, from https://repository.mouau.edu.ng/work/view/syntheses-characterization-and-corrosion-inhibition-studies-of-trytophan-and-histidine-schiff-bases-of-para-dimethyl-amino-benzaldehyde-on-mild-steel-in-10-m-h2so4-medium-ibe-gabriel-o-7-2
OKO, GABRIEL. "Syntheses, Characterization And Corrosion Inhibition Studies Of Trytophan And Histidine Schiff Bases Of Para- Dimethyl Amino Benzaldehyde on Mild Steel in 1.0 M H2SO4 Medium :- Ibe, Gabriel O" Mouau.afribary.org. Mouau.afribary.org, 18 Jul. 2024, https://repository.mouau.edu.ng/work/view/syntheses-characterization-and-corrosion-inhibition-studies-of-trytophan-and-histidine-schiff-bases-of-para-dimethyl-amino-benzaldehyde-on-mild-steel-in-10-m-h2so4-medium-ibe-gabriel-o-7-2. Accessed 08 Sep. 2024.
OKO, GABRIEL. "Syntheses, Characterization And Corrosion Inhibition Studies Of Trytophan And Histidine Schiff Bases Of Para- Dimethyl Amino Benzaldehyde on Mild Steel in 1.0 M H2SO4 Medium :- Ibe, Gabriel O". Mouau.afribary.org, Mouau.afribary.org, 18 Jul. 2024. Web. 08 Sep. 2024. < https://repository.mouau.edu.ng/work/view/syntheses-characterization-and-corrosion-inhibition-studies-of-trytophan-and-histidine-schiff-bases-of-para-dimethyl-amino-benzaldehyde-on-mild-steel-in-10-m-h2so4-medium-ibe-gabriel-o-7-2 >.
OKO, GABRIEL. "Syntheses, Characterization And Corrosion Inhibition Studies Of Trytophan And Histidine Schiff Bases Of Para- Dimethyl Amino Benzaldehyde on Mild Steel in 1.0 M H2SO4 Medium :- Ibe, Gabriel O" Mouau.afribary.org (2024). Accessed 08 Sep. 2024. https://repository.mouau.edu.ng/work/view/syntheses-characterization-and-corrosion-inhibition-studies-of-trytophan-and-histidine-schiff-bases-of-para-dimethyl-amino-benzaldehyde-on-mild-steel-in-10-m-h2so4-medium-ibe-gabriel-o-7-2