CC BY
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https://doi.org/10.29013/AJT-20-5.6-54-59
Rakhmatova Guzal Botirovna, Senior lecturer in Karshi Engineering Economics Institute,
Uzbekistan, ^rshi Е-mail: raxmatova85guzal@mail.ru Kurbanov Mingnikul Jumagulovich, Doctor of Chemistry Karshi State University
Uzbekistan, Karshi Е-mail: kurbanovmj@mail.ru Turabayeva Nargisa Bekmuradovna, Senior lecturer in Karshi Engineering Economics Institute,
Uzbekistan, ^rshi Е-mail: turabayeva75nargisa@mail.ru Tursunova Gulnoza Qaxxarovna, Senior lecturer in Karshi Engineering Economics Institute
Uzbekistan, ^rshi Е-mail: tursunovagulnoza@ mail.ru
STUDY OF INSPACTIVE PROPERTIES AGAINST CORROSION OF a-AMINOCETONES AND THEIR PRODUCTS
Abstract. The paper examines the anti-corrosion inhibitory properties of a-aminocetones such as thiainan and thiachromane. 15% HCl, 20% H2SO4, 1M HCl and 1M H2SO4 solutions were used as the aggressive medium. As the concentration of the studied compounds in solution increases, so does their protective effect. The increase in temperature showed an increase in the inhibition rate of the inhibitors during the corrosion process. Inhibitors containing morpholine fragment as the most effective inhibitor in aggressive environments were found to have higher inhibition rates.
Keywords: benzothiophene, thiainden, thiaindane, thiochroman, hydrochloric acid, sulfuric acid.
Corrosion of various industrial goods and priorities, undermines the operation of the plant
construction materials made of steel around the as a whole.
world due to corrosion is considered to be one The use of organic-based inhibitors in address-
of the most urgent problems today. This is caus- ing the above-mentioned global problem is currently
ing great economic and environmental damage to yielding good results. The use of corrosion inhibi-
any country. It is therefore attracting the attention tors is one of the most effective ways to prevent the
of chemists, technologists and scientists dealing corrosion process [1, 16657-16668]. Research on
with socio-economic problems all over the world. inhibitors of metal corrosion is a long-term impor-
In addition, the decline in efficiency in gas and tant investment and is of strategic importance from
oil refining, gas and oil refineries, which are the an economic and environmental point of view. The
mainstays of any country's economy and strategic world community is conducting international re-
search on the development of toxicologically nontoxic, biodegradable and highly effective inhibitors of corrosion protection of metals, in-depth study of the physicochemical aspects of protective coatings for corrosion protection of metals [2, 82-95].
In studying the anticorrosive properties of the synthesized compounds, we initially used the gravimetric (gravity) analysis method. This method is simple in nature in determining the degree of corrosion of metals, the method is one of the methods that does not require complex and expensive equipment
and can provide a very large amount of data, and has not lost its relevance to date.
In this study, the inhibitory properties of the following synthesized compounds were studied at different temperature ranges and concentrations of different aggressive media. For the study, a-piperidino-5-acetyl-2-methyl-1-thiaine (AIT-1), a-morphalino-5-acetyl-2-m ethyl-1-thiaine (AIT-2), a-piperidino-6- acetyl-1-thiochroman (AIT-3) and a-morphalino-6-acetyl-1-thiochroman(AIT).
Table 1
Ingib. cipher Ingib. amount mg/l Time, hour 15% HCl 20% H2SO4
K/ 2 Y Z% K/ 2 r/M2H Y Z%
1 2 3 4 5 6 7 8 9
AIT -1 50 2 0.84 23.80 95.80 1.84 16.64 93.99
4 0.89 23.59 95.76 0.97 30.61 96.73
6 0.84 27.26 96.33 0.95 31.78 96.85
100 2 0.46 43.47 97.70 0.87 35.97 97.22
4 — — — 0.93 31.93 96.86
6 — — — 0.92 32.82 96.95
250 2 0.48 41.66 97.60 0.50 62.60 98.40
4 0.33 55.26 98.12 0.45 66.00 98.48
6 0.38 60.26 98.34 0.45 67.11 98.50
500 2 0.48 41.66 97.60 0.48 65.20 98.46
4 0.36 58.33 98.28 0.36 82.50 98.78
6 0.31 73.87 98.64 0.39 77.43 98.70
1000 2 0.55 36.36 97.25 0.38 82.36 98.78
4 0.45 46.66 97.85 0.34 87.35 98.85
6 0.39 58.71 98.29 0.36 83.88 98.80
AIT -2 25 2 1.15 17.39 94.25 0.95 32.94 96.96
4 1.16 18.10 94.47 — — —
100 2 0.89 22.47 95.55 0.89 35.16 97.15
4 0.78 26.92 96.28 — — —
250 2 0.59 33.89 97.05 0.53 59.05 98.30
4 0.49 42.85 97.66 — — —
500 2 0.48 41.66 97.60 0.34 92.05 98.91
4 0.39 53.84 98.14 — — —
1000 2 0.35 57.14 98.25 0.20 156.5 99.36
4 0.38 55.26 98.19 — — —
The data in the table show that the inhibitory in 15% HCl and 20% H2SO4 solutions ofAIT-1 and efficiency of inhibitors increases in parallel with in- AIT-2. Based on the results, it can be said that the creasing inhibitory concentration and time at 200 °C inhibitory properties ofAIT-1 and AIT-2 inhibitors
in sulfuric acid solution were higher than in hydrochloric acid solution. The melting rate of the metal decreases rapidly when a sample of steel grade St.3 is added to a solution of 15% HCl and 20% H2SO4 at a temperature of 200 °C with a concentration of 10-4 mol/l (25 mg/l) ofinhibitors AIT-1 and AIT-2. Showed that the inhibition coefficient remained the same when the inhibitor concentration was increased from 4 x 10-3 to 2 x 10-3 mol / l (100 to 500 mg/l).
Table 2
It has been shown that the effectiveness of inhibitors in sulfuric acid solution increases in parallel with the increase in inhibitor concentration. Showed that the inhibition coefficient ofAIT-1 and AIT-2 inhibitors 1 x 10-4 and 4 x 10-4 mol/l increased with time. Table 2 below provides information on the protection levels of AIT-3 and AIT-4 inhibitors.
Efficacy of AIT-3 and AIT-4 inhibitors in 15%
HCl and 20% H2SO4 solution at 20 °C
Ingib. cipher Ingib quantity, mg/l Time hour 15% HCl 20% H2SO4
K/ 2 r/M2H Y Z% K/ 2 r/M2H Y Z%
AIT -3 50 2 1.77 11.31 91.15
4 1.50 14.00 92.86
6 1.17 19.61 94.90
1000 2 0.94 21.29 95.30 0.40 78.25 98.72
4 0.68 30.88 96.76 0.35 84.86 98.82
6 0.59 38.88 97.42 0.52 58.12 98.91
AIT -4 50 2 0.68 29.42 96.60 0.44 71.14 98.59
4 0.58 36.20 97.23 0.26 114.2 99.12
6 0.48 47.79 97.90 0.33 91.58 98.91
1000 2 0.50 40.02 97.50 0.17 184.0 99.46
4 0.30 70.00 98.57 0.15 198.0 99.49
6 0.30 76.46 98.69 0.14 215.8 99.54
During the study, a mass reduction in the temperature range of 60-95.50S in a working system of 15% HCl and 20% H2SO4 at a concentration of 1000 mg/l for 6 hours in a St.3 sample of AIT-3 and AIT-4 inhibitors was determined by gravimetric measurement. Measurement of the mass reduction of the sample before the working solution and after a certain time in the working solution is useful in evaluating parameters such as corrosion rate (g) and the effectiveness
Table 3.
of inhibitors (Z%). The following equation was used to determine these parameters and the results of the study were summarized in where: m1 is the weight of the sample before the study, in grams, m2 is the weight of the sample after the study, in grams, s is the area of the sample in square meters (m2) and t is the duration of the experiment, in hours. Efficacy results of inhibitors at different temperatures and 15% HCl and 20%
H2SO4 environments
Ingib. cipher Environ-ment% Inh AmoMr/i Time hour 60 °C 95,5 °C
K2 r/M H Y Z% k2 r/M H Y Z%
1 2 3 4 5 6 7 8 9 10
AIT -3 HCl 15% 1000 1 — — — 61.74 51.4 88.05
2 3.16 106.50 99.06
4 3.01 122.53 99.18
6 3.81 106.91 99.06
1 2 3 4 5 6 7 8 9 10
AIT -4 HCl 15% 1000 1 — — — 68.66 46.19 79.84
2 7.07 51.46 98.06
4 6.06 63.14 98.42
6 6.74 59.20 98.31
AIT -3 H2S°4 20% 1000 1 — — — 5.38 543.5 99.82
2 1.28 338.64 99.70
4 1.35 372.07 99.73
6 1.20 394.78 99.75
AIT -4 H2S°4 20% 1000 1 — — — 8.30 351.6 99.72
2 3.01 144.01 99.31
4 3.37 149.05 99.33
6 2.90 163.36 99.39
Raising the temperature to 600S leads to an increase in the inhibition rate even in 15% HCl and 20% H2SO4 media of all inhibitors under study. However, raising the temperature to 95.5 °C and above indicates that the inhibitors being studied in the hydrochloric acid environment are shifting in the direction of decreasing inhibition. However, an increase in temperature to 95.5oC was found to give a positive result (99.72%) for the AIT-4 inhibitor in a sulfuric acid environment. The protective properties of the metals
of the compounds under study are stable over time in hydrochloric and sulfuric acid environments. The data obtained show that the inhibitors studied slow down the corrosion rate by 12-32 times in an aggressive environment of hydrochloric acid at a dose of 50 mg/l, while at a rate of 1000 mg / l slow down the corrosion rate by 75-140 times. Similarly, it was found that the protective properties of the inhibitors under study in hydrochloric and sulfuric acids increase periodically with increasing temperature.
Figure 1. shows the dependence of the inhibitor of the series of thiachromanic anions on the corrosion inhibition coefficient in the H 2SO4 medium Figure 1 below shows a graph of the correlation inhibition coefficient of the corrosion inhibitors of
Figure 2. shows the dependence of the inhibitor of the series of thiachromanic anions on the corrosion inhibition coefficient in the H 2SO4 medium the corrosion inhibitors AIT-1 and AIT-3 containing the thiain and thiachroman fragment in the
hydrochloric acid environment. The graph of the corrosion inhibition coefficient of the inhibitors studied above in the sulfuric acid environment depends on the inhibitor concentration.
The process of time-dependent reduction of the mass in the presence of an inhibitor in a 20%
H2SO4 solution of the St.3 sample obtained for the study can be represented by the image in Fig. 1. As can be seen from the figure, the melting rate of a steel sample in a solution with an inhibitor relative to a solution without an inhibitor significantly reduced.
Figure 1 Decrease in mass of steel St.3 in 20% H2SO4 solution over time
The UV spectra of this solution were analyzed UV spectra were obtained in the absence of an into confirm the formation of an In-Fe complex in a hibitor in the working solution and 6 h after the ad-system containing 1000 mg/l AIT-4 inhibitor in 1 dition of the inhibitor. Comparative images of these molar sulfuric acid obtained as a working solution. UV spectra are shown in (Figure 2).
Without inhibitors in a solution | 1 M HCl with Inhibitor AIT-4 of 1M NCI
Figure 3. SEM-microphotography of Pulat St.3 sample
The figure shows the absorption values and the deviation of their intensity. After immersion of the steel in the solution, an increase in absorption for the AIT-4 inhibitor is observed. This indicates the formation of a mutually stable complex between the Fe2 + ions and the functional-active groups of the inhibitor. The formation of this complex may be the cause of the observed deviation in the values of the absorption process and its intensity, which in turn leads to the anticorrosive activity of the inhibitor. In order to confirm the effectiveness of AIT-4 as a corrosion inhibitor, the images in (Figure 3) were obtained using SEM. As can be seen from the figure, the image of a steel sample lowered into the working system without the addition of an inhibitor reflected many cracks and
abrasions on the steel surface. The image of the same steel ngamuna in the working solution of the inhibitor-added system shows that there are no cracks of the above appearance and that the erosion is not noticeable at all.
Thus, during the gravimetric study of the anti-corrosive properties of the inhibitors studied, it was found that they are inhibitors that give good results to the corrosion process that takes place in the acidic environment. The binding of the sulfur atom in all synthesized inhibitors to the aromatic ring on the one hand and the poluaromatic ring on the other shows that the inhibitor molecules studied in these corrosive aggressive systems are capable of forming strong chemisorption-type bonds with structural materials.
References:
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2. Finsgar M., Kek D., Merl, 2-mercaptobenzoxazole as a copper corrosion inhibitor in chloride solution: electrochemistry, 3D-profilometry, and XPS surface analysis, Corros. Sci.— 80. 2014.— P. 82—95.
3. Nesic' S., Sun W. 2.25 — Corrosion in acid gas solutions, in: J.A.R. Tony (Ed.), Shreir 's Corrosion, Elsevier, Oxford, 2010.— P. 1270—1298.
