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METHODS OF RECEIVING MODIFIERS AND INHIBITORS TO PROTECT METAL STRUCTURES FROM CORROSION
Sapayeva Surayyo Gafurjanovna
PhD student of Urganch State University, Urganch, Uzbekistan Bekberganova Durdona Davronbek qizi
PhD student of Urganch State University, Urganch
ARTICLE INFO
ABSTRACT
Received: 04th July 2024 Accepted: 09th July 2024 Online: 10th July 2024 KEY WORDS
Corrosion, modifier, urotropin, sulfuric acid, phosphoric acid, corrosion rate, metal, acid corrosion.
Research and research work was carried out on the production of corrosion-detergents and anti-rust agents to replace imports against corrosion on the basis of organic and inorganic raw materials in Uzbekistan. The optimal conditions for obtaining corrosion modifiers were studied. The chemical composition, properties, and mechanism of the effect on the corrosion rate in different environments of the synthesized optimum composition were studied.
INTRODUCTION
It is an urgent issue to search for effective methods of obtaining anti-corrosion modifiers and inhibitors based on local raw materials, to study their chemical composition and properties.
Today's task is to create the scientific-technological basis for obtaining anti-rust agents on the basis of competitive local resources based on non-traditional new types of raw materials and industrial waste, and their wide application in practice. Taking this into account, the article studies the production of corrosion inhibitors based on local resources.
The study of corrosion processes and the development of methods of metal protection are today's scientific and technical problems. The use of inhibitors is one of the common methods of protection of metals, it reduces the rate of corrosion of metals and alloys when exposed to an aggressive environment in working conditions. As a result of corrosion processes, the destruction of metals occurs in a chemical and electro-chemical mechanism.
Fighting against corrosion is carried out in different ways. The most reasonable way to fight is to manufacture equipment and devices from corrosion-resistant materials, but they are not always used for various reasons.
Based on the above, the best solution to reduce the corrosion rate of metals is to use inhibitors and find effective ways to synthesize them. The main requirements for corrosion inhibitors are that they should have properties that allow not only to achieve a high protective effect, but also to maintain the technological regime under certain production conditions and exclude the possibility of environmental damage.
In this regard, the search for new and effective corrosion inhibitors is very urgent. This is especially important for the chemical industry, which involves the use and production of highly corrosive aggressive liquids.
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Currently, a large number of organic and inorganic substances that affect the corrosion rate of metals in an acidic environment are being studied. Among them, organic inhibitors are preferred and widespread, because they have the ability to form protective films on the metal surface. Effective organic inhibitors include substances with nitrogen, sulfur and oxygen atoms [1].
According to the literature, urotropin was used as an inhibitor of acid corrosion. In other data, organic compounds containing heteroatoms were used as effective corrosion inhibitors in sulfuric acid [2,3]. Triazole and tetrazole were used to reduce the corrosion rate of metals in acidic environment [4]. Some data suggest the use of imidazole to protect metal coatings [5].
Based on the information of F.K. Kurbanov, anion-type inorganic, inorganic substances are always used as inhibitors for a neutral environment. In acid corrosion, organic substances are used, that is, organic substances containing nitrogen and oxygen in the form of amino, carboxyl and carbonyl are used. But until now, effective inhibitors for alkaline environment have not been found [6].
EXPERIMENTAL RESULTS
Based on the above, the main task of scientific research work is to determine the optimal conditions for obtaining competitive, highly protective acid-resistant rust inhibitors based on local resources and industrial waste, and to use urotropin as a local raw material for obtaining corrosion inhibitors.
Phosphoric acid should be included in inhibitors in order to further strengthen the scope of protection of metals in multi-component saline environments. The concentration of phosphoric acid should not be high when preparing phosphate coatings. In this case, the concentration of phosphoric acid should not exceed 25%, otherwise it will lead to corrosion of metals. Phosphic acid forms a phosphate film on the metal surface and protects against corrosion. Urotropin synthesized from local waste was used to implement the inhibitory property. It is known that urotropin gives all the properties of amines and has the ability to form many salts and various complex compounds. It mainly protects against acid corrosion.
In order to obtain an inhibitor, 70 ml of distilled water was added to a 250 ml flask, heated to 45°C - 47°C, and 25 ml of phosphoric acid with a concentration of 20% was added while stirring in a magnetic stirrer. 0.5 g of urotropin, 0.2 g of potassium dichromate and 0.3 zinc sulfate are added to increase the inhibitory properties of the product. Potassium dichromate and zinc sulfate together create a synergistic phenomenon. 2% ascorbic acid and 0.2% sodium hydrogen phosphate are added to the mixture. The temperature of the reaction mixture was increased from 47°C to 50°C and was maintained at this temperature for one and a half hours. After the completion of the reaction, the reaction mixture was cooled and a pale green homogeneous inhibitor was obtained. The inhibitor was tested on 50x50x5 mm steel.
Table 1
Mass reduction of steel plate in salt solution under the influence of corrosion inhibitor
Metal Initial Mass loss of metal versus time in Degre
size, mm mass of 3%NaCl, min e of
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the 40 60 120 180 Corrosio protec
metal, g n rate, gr/m2 -tion, %
1 50х50х5 51.7292 50.6291 50.6133 50.5837 49,8292 1,9 -
50х50х5 50.4797 50.4795 50.4793 50.4791 50.4789 0.0008 100
(inhibitor y)
2 50х50х5 52.4591 52.3875 12.3582 51.2294 50.1591 2,3 -
50х50х5 52.5716 52.5716 52.5712 52.5692 52.5666 0,005 97,4
(inhibitor y)
3 50х50х5 52.894 52.850 51.817 51.808 51,394 1,5 -
50х50х5 51.983 51.980 51.977 51.975 51.973 0,01 91,8
(inhibitor y)
Table 1 above shows the test results of the study of the effect of an inhibitor on the corrosion protection level of a metal plate in a salt solution without the presence of an inhibitor. When the experiments were carried out in 3.0 % NaCl solution without the presence of an inhibitor, the corrosion of the metal plate was observed, and when the inhibitor was added to the reaction mixture, it was observed that the level of protection of the metal plate against rust increased by 100%. (Table 1, experiment 1-2).
The following table shows the test results of the protection level of steel plate under the influence of corrosion inhibitor in sulfuric acid solution for 40-180 min (Table 2).
Table 2
Mass reduction of steel plate in sulfuric acid solution under the influence of corrosion inhibitor
Metal size, mm Initial mass of the Mass loss of metal versus time in 5 % H2SO4, min Corrosion rate, gr/m2 Degree of protect -tion, %
metal, g 40 60 120 180
1 50х50х5 51.702 8 50.0085 50.0012 49.9801 49.6828 2.02 -
50х50х5 (inhibitory) 51.856 3 51.6782 51.6034 51.5672 51.5563 0.3 85,3
2 50х50х5 52.8942 52.8506 50.817 49.808 48,2942 4,6 -
50х50х5 (inhibitory) 51.9834 51.9691 51.6517 51.5379 51,4834 0,5 82,7
3 50х50х5 53,7461 51,5467 49,6974 49,1471 48,6461 5,1 -
50х50х5 52,8618 52,5473 52,1473 52,0943 51,9618 0,9 81,3
«
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(inhibitory)
From the results of the table, it can be said that there is no level of corrosion protection of the plate in the 5.0% H2SO4 solution without the inhibitor (Table 2, experiment 1), and when the inhibitor was added to the reaction mixture, it was observed that the level of protection of the metal increased by 85.3% (Table 2 experiment 2).
From the given results, it can be concluded that the mass reduction of the obtained experimental samples gave a high index in water and saline solutions, and a low index in acids. This inhibitor has a metal protective effect against acid corrosion.
Testing of this composition was carried out to evaluate the protective ability of acid corrosion inhibitors according to the requirements of the GOST 9.505-86 standard. The obtained composition was tested in water, 3% NaCl solution and sulfuric acid solutions. The results showed that this composition can act as a new type of inhibitor in acid corrosion protection.
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