Abstract:
Ampicillin
[(2S,6R)-6-(2-(aminomethyl)benzamido)-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo(3.2.0)
heptanes-2-carboxylic
acid],
an
antibiotic
drug
was
investigated
as
corrosion
inhibitor
for
mild
steel
in
HCl
using
gravimetric
method.
The
results
obtained
showed
that
various
concentrations
of
ampicillin
studied
inhibited
the
corrosion
of
mild
steel
in
solutions
of
HCl.
The
inhibition
efficiency
increased
with
increase
in
the
concentrations
of
ampicillin
and
decreased
with
increase
in
temperature
of
which
the
inhibitor
of
concentration
5
×
10−3M
at
30◦C
had
the
highest
inhibition
efficiency
of
75.85%.
Its
adsorption
was
found
to
be
physical,
exothermic
and
spontaneous
as
confirmed
by
values
of
activation
energy
and
free
energy
of
adsorption
(around
−20
kJ
mol−1for
adsorption
and
below
80
kJ
mol−1for
activation
energy)
and
also
fitted
the
Langmuir
adsorption
model.
Quantum
chemical
calculations
results
show
that
ampicillin
possesses
a
number
of
active
centers
concentrated
mainly
on
the
nitrogen
atoms
and
the
neighboring
C
atoms.
The
HOMO
and
LUMO
plots
of
ampicillin
further
present
ampicillin
as
an
effective
corrosion
inhibitor.
