SYNTHESIS OF ANTI-CORROSIVE COATING BASED ON MONOETHANOLAMINE AND PHOSPHORIC ACID AND ITS APPLICATION

ABSTRACT

In this article, the optimal conditions for synthesizing anti-corrosive coating based on compounds containing nitrogen and phosphorus, i.e., monoethanolamine, phosphoric acid, and formalin, are studied. In this case, the mole ratios of the starting materials were taken in a 1:1:1 mole ratio. First, monoethanolamine and phosphoric acid were mixed in a 1:1 mol ratio at a temperature of 65-70 ^оC for 15 minutes, then 1 mol of formalin was added dropwise and the temperature was increased to a temperature of 95-100 ^оC, and the reaction was stirred for 90 minutes. The structure of this obtained anti-corrosive coating was analyzed by IR-spectra.

АННОТАЦИЯ

В данной статье изучены оптимальные условия синтеза антикоррозионного покрытия на основе азотсодержащих соединений: моноэтаноламина, фосфорной кислоты и формалина. В этом случае мольные соотношения исходных веществ принимались в мольном соотношении 1:1:1. Сначала моноэтаноламин и фосфорную кислоту смешивали в мольном соотношении 1:1 при температуре 65-70 ^оС в течение 15 минут, затем по каплям добавляли 1 моль формалина и повышали температуру до 95-100 ^оС, Реакционную смесь перемешивали в течение 90 минут. Структура полученного антикоррозионного покрытия была проанализирована с помощью ИК-спектров.

Keywords: monoethanolamine, phosphoric acid, formalin, anti-corrosive coating, IR-spectrum.

Ключевые слова: моноэтаноламин, фосфорная кислота, формалин, ингибитор коррозии, ИК-спектр.

Introduction.

The process of corrosion is a process of chemical and electrochemical as well as biological degradation of metals as a result of environmental effects [1,2]. According to the mechanism of the process, there is chemical, electrochemical, and biochemical corrosion. Corrosion begins at the surface of the metal and spreads deeper with further development of the process. The environment in which metal corrosion occurs is various liquids and gases [3]. Various amines, ketones, aliphatic carboxylic acids, and amino acids, as well as products of the interaction of amino alcohols and their derivatives with sulfonamides, carboxylic acids, ethers, and aldehydes, are used as organic inhibitors [3]. Amino acids such as glycine, methionine, and histidine glutamic acid are used as inhibitors against steel corrosion in sulfuric acid, aspartic acid in hydrochloric acid, alanine chloride, and sulfuric acid [4]. The problem of the occurrence of corrosion damage in metal equipment of the petrochemical industry was studied. An analysis of the quality of water in the system was carried out by taking water samples at certain points of the installation, and an attempt was made to find the causes of equipment corrosion [5]. Special attention was paid to the thermal circuit, which includes heat exchange equipment. A detailed description of all components of the scheme, and the principle of operation of some elements of the scheme is given [6]. In conclusion, some methods of corrosion prevention and control, including the introduction of inhibitors, are proposed as one of the modern methods of combating heat exchange equipment passages [7].

Experimental part.

Materials. Monoethanolamine (MEA) – Colorless liquid, belongs to the class of amino alcohols. Chemical formula - C₂H₇NO, molar mass - 61 g/mol, boiling point - 170°C, density - 1.01 g/cm³. Phosphoric acid is a moderately strong inorganic acid with the chemical formula H₃PO₄, a colorless hygroscopic crystal under standard conditions. Orthophosphate (or simple phosphate) acid is usually referred to as an 85% aqueous solution (colorless, odorless syrupy liquid). Formaldehyde is the primary representative of the class of aliphatic aldehydes (chemical formula CH₂O or HCHO). The molar mass is 30.03 g/mol. Density at 0.8153 g/cm³ (-20°C). The melting point is -118 °C and the boiling point is -19 °C. All chemical reagents: orthophosphoric acid, monoethanolamine, and formaldehyde were purchased "chemically pure" from “Merit Chemicals” company.

Methods. The structure of this synthesized anti-corrosive coating was carried out and analyzed on a SHIMADZU (IRAffinity-1S) device. The gravimetric method was used to determine the inhibition efficiency of the synthesized inhibitor.

Synthesis of MFP-1 brand anti-corrosive coating. It was carried out in a 250 cm³ round-bottomed flask equipped with a stirrer, a reflux condenser and a thermometer. In this case, the mole ratios of the starting materials were taken in a 1:1:1 mole ratio. First, monoethanolamine and phosphoric acid were mixed in a 1:1 mol ratio at a temperature of 65-70 ⁰C for 15 minutes, then 1 mol of formalin was added dropwise and the temperature was increased to a temperature of 95-100 0C, and the reaction was stirred for 90 minutes. Reaction product. It is 88,9 % and it is a pale yellow and dark substance, which dissolves well in hot water.

Results and Discussion

IR spectroscopy analysis. According to the results of the IR spectrum of MFP-1, groups corresponding to absorption maxima in the following range are given: 2931-2819 cm^-1 n (ON), 1635-1525 cm^-1, n (-CONHR), 1458 cm^-1 ns(-O- CH₂-), ns(-N-CH₂), 1340 cm^-1 ns(R=O), 1037 cm^-1 n (P-O-C) (Fig. 1).

Figure 1. IR spectrum image of MFP-1 brand anti-corrosive coating

According to the analysis of the IR spectrum of MFP-1, vibrational lines of the (OH) bound hydroxyl group appeared in the 2931-2819 cm^-1 range, valence deformation vibration lines of the secondary amide group appeared in the n (-CONHR) range of 1635-1525 cm^-1, and, ns(-O-CH2-), ns(-N-CH₂) groups in the 1458 cm^-1 area, phosphorus oxygen bond in the 1340 cm^-1 ns(R=O) area, 1111 cm^-1 bond, absorption maxima corresponding to n (P-O-C) ether group at 1037 cm-1 were formed. According to the results of IR analysis, the formula of this substance can be said as follows[8].

Conculusion.

In this research, the optimal conditions for the synthesis of MFP-1 brand anti-corrosive coating based on monoethanolamine, phosphoric acid, and formalin were determined. The structure of the synthesized anti-corrosive coating was analyzed using IR spectra. Also, its absorption efficiency in aqueous medium was 88,9 % when it was organized using the gravimetric method.

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