Heterocyclic Mannich
bases,
N
-(3-oxo-3-phenylpro-pyl)thiazol-2-aminium
chloride (DTZA) and
N
-(3-oxo-3-phenylpropyl)-1
H
-pyrazol-3-aminium chloride (DPZA), were developed for
the corrosion inhibition of N80 steel in a 15 wt % lactic acid solution.
Weight loss measurements, electrochemical techniques, surface characterization,
and theoretical calculations were combined to investigate their anticorrosion
performance and mechanism. The results showed that DTZA exhibited
a satisfactory inhibitor efficiency of 97.56% with a dosage of 0.15%
at 363 K, while DPZA achieved only 58.3% under the same conditions.
Adsorptions of both inhibitors on the metal surface followed the Langmuir
model with physical and chemical adsorptions. Based on X-ray photoelectronic
spectroscopy (XPS) analysis, DFT calculations, and molecular dynamics
(MD) simulations, stronger interactions between DTZA and iron than
those in the case of DPZA were revealed, leading to the formation
of a compact protective film on the metal surface, which is attributed
to the presence of a thiazole ring in the DTZA chemical structure.