ISSN 1070-4272, Russian Journal of Applied Chemistry, 2016, Vol. 89, No. 11, pp. 1879−1886. © Pleiades Publishing, Ltd., 2016.
Preparation of Poly(naphthylamine-formaldehyde);
Application as a New and an Effective Inhibitor of Steel
in Hydrochloride Acid Solution
Banafsheh Norouzi*, Jabber Youseﬁ , and Navabeh Nami
Department of Chemistry, Qaemshahr Branch, Islamic Azad University,
Basig bolvard, Postal Code: 163, Qaemshahr, Iran
Received June 14, 2016
Abstract—In this research, we ﬁ rst prepared poly (naphthylamine-formaldehyde) (PNAF) and then investigated
its corrosion inhibition properties for polished steel specimens in 1 M HCl solution using chemical and electro-
chemical methods. Results showed that the PNAF could serve as an effective inhibitor of the corrosion of steel
in hydrochloric acid media (the inhibition efﬁ ciency of this polymer at an optimum concentration of 100 mg L
was 99.9 %). The effect of temperatures on the corrosion behavior of steel was studied in the temperature rang-
ing from 303 to 333 K for 1 M HCl at an optimum concentration of PNAF. It has been demonstrated that the
adsorption behavior of this polymer on steel in 1 M HCl was found to obey Langmuir adsorption isotherm. Also,
potentiodynamic polarization measurements showed that PNAF was a mixed type inhibitor.
The text was submitted by the authors in English.
Today, corrosion of the metals, especially steel is one
of the most serious problems that mankind has to face
. Acids increase amounts of corrosion because they
are widely used in industries such as pickling, cleaning,
descaling, and etc.
Among the different methods of corrosion control
such as cathodic protection [2, 3], anodic protection ,
coating  and alloying, the use of chemical inhibitors
is often considered as the most effective and practical
method of corrosion prevention. A corrosion inhibitor is
a chemical additive which reduces the rate of corrosion
when added to a corrosive aqueous environment.
Compounds containing nitrogen, sulfur, and oxygen have
been reported as inhibitors [6–11]. The efﬁ ciency of an
organic compound as an inhibitor is mainly dependent
upon its ability to get adsorbed on a metal surface, which
consists in the replacement of a water molecule at a
corroding interface. The adsorption of these compounds
is inﬂ uenced by the electronic structure of inhibiting
molecules, electron density at the donor site, aromaticity,
the steric factor, and the presence of functional group
such as –CHO, –N=N, R–OH, etc., molecular area, and
molecular weight of the inhibitor molecule [12–15]. A
large number of organic compounds are known to be
applicable as corrosion inhibitors for steel [6–11, 16, 17].
Recently, using of polymers as corrosion inhibitors
has attracted considerable attention. Polymers are used
as corrosion inhibitors because, through their functional
groups form complexes with metal ions and on the metal
surface, these complexes occupy a large surface area,
thereby blanketing the surface and protecting the metal
from corrosive agents present in the solution . The
inhibitive power of these polymers is related structurally
to the cyclic rings, heteroatom (oxygen and nitrogen) that
are the major active centers of adsorption.
The earlier studies [19–25]
have shown that inhibiting
properties of polyaniline and its derivatives on corrosion
of iron in hydrochloride acid solution are due to the
presence of electrons, the quaternary nitrogen atom and
large molecular size which ensures greater coverage of the