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Keywords:
corrosion inhibitors, metal protection, imidozoline, monoethanolamine, heterocyclic
compound, ethylenediamine
INTRODUCTION.
Today, in developed countries, corrosion damage is estimated at 2-
4% of the gross domestic product (GDP). In the US, according to NACE, damage from
corrosion, including the cost of combating it, is 3.1% of GDP ($ 276 billion per year), in
Germany - 2.8% of GDP. Losses from broken metal structures, products and equipment amount
to 10-20% of the annual steel production. Even greater damage is caused by indirect losses
during equipment downtime during the replacement of corroded parts and assemblies, with oil
and gas leaks, and disruption of technological processes. Losses from corrosion, therefore,
Chemistry and chemical technology
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cannot be reduced only to direct losses - the cost of destroyed structures, replacement of
equipment and the cost of measures to protect against corrosion. In the CIS countries there are no
official statistics reflecting the economic damage from corrosion, but, according to experts, it is
at least 5% of GDP [1, 2]. These figures necessitate a comprehensive theoretical study of
corrosion, which, in turn, serves as the basis for the development of methods for combating
corrosion processes.
An analysis of the patent and scientific and technical literature showed that there are
dozens of companies specializing in the development of inhibitors and technology for their use.
The production and range of inhibitors are expanding from year to year, but their composition,
production technology, production volume are carefully protected by manufacturers. A
systematization and analysis of the selected patent information on the substances used in the
composition of corrosion inhibitors was carried out.
The known composition of a metal corrosion inhibitor based on water-soluble polymers,
including a water-soluble polyelectrolyte, which is obtained by polymerization of the quaternary
ammonium salt of 1,2-dimethyl-5-vinylpyridinium methyl sulfate in an aqueous medium in the
presence of a redox initiator β-hydroxypropyl-tert-butyl peroxide [3 ]. The inhibitory effect of
this inhibitor is that, being adsorbed on the metal surface, it forms a thin protective film that
prevents redox processes.
The works [4 - 8] suggest universal corrosion inhibitors based on aminophenols, as well as
heterocyclic amines of the SNPKh brand. For this, a series of functionally substituted alkyl-
[poly- (ethyleneoxy)] - phosphoryl pyridine, alkyl- [poly- (ethyleneoxy)] - phosphoryl quinoline,
aryl- [poly- (ethyleneoxy)] - phosphoryl pyridine and aryl- [poly- (ethyleneoxy)] - phosphoryl
quinoline salts and systematic studies of their properties have been carried out.
It was found that a number of synthesized compounds have high anticorrosive properties in
highly mineralized hydrogen sulfide and carbon dioxide-containing aqueous media, as well as
the dependence of the anticorrosive activity of the synthesized compounds on the length of the
alkyl substituent in the alkyl and aryl radicals, and the degree of oxyethylation. The dependence
of the anticorrosive action of the synthesized compounds on concentration and time has been
studied. It was shown by IR spectroscopy that the phosphoryl group present in the structure of
the synthesized compounds provides chemisorption of inhibitor molecules on the metal surface
due to the formation of complex compounds with iron (II) ions. It was found by the method of
probe electron microscopy that the synthesized heterilonium salts form an adsorption film on the
metal surface, which prevents corrosion damage. Taking into account the high cost and the
impossibility of using individual heterocyclic amines for large-scale production, the synthesis of
the corresponding heterilonium salts of phosphorous acids based on coke-chemical raw materials
- isoquinoline fraction, which is a mixture of quinoline, isoquinoline, toluidines and other
heterocyclic compounds, was performed. A high degree of anticorrosive protection of
synthesized heterilonium salts of phosphorous acids as corrosion inhibitors of oilfield equipment
in aqueous media containing hydrogen sulfide and carbon dioxide has been shown. A new water-
soluble corrosion inhibitor SNPKh-6474 has been developed [7].
The effectiveness of low concentrations of acid corrosion inhibitors has been studied:
castazole, telaz, benotriazole, as well as inhibitors of CJSC "AMDOR" [9 - 13], INKORGAZ-
01OH and INKORGAZ-11OH as universal inhibitors of general, hydrogen sulfide, carbon
dioxide corrosion and hydrogenation of steel St. 3 [ 14 - 19].
The study of complex reagents SNPKh-PKD-515 and SNPKh-PKD-515H showed [20 -
25] that the latter exhibits high surface activity (less than 2.5 mN / m at a concentration of more
than 0.2%). Determination of the interfacial tension at the interface with kerosene after
adsorption of reagents in a bentonite suspension on clay showed that the filtrate with SNPKh-
PKD-515N is also more active, but in this case the σ values are an order of magnitude higher.
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