RU2385362C1 - Inhibitor of metal corrosion in sulphuric, hydrochloric and orthophosphoric acids - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: inhibitor contains wt %: n-dipenthyl-amine-salicyl-al-2-amino-4-nytrophenol 15.8-12.1, (indolyl-3)acetyc acid 10.3-15.0, 3-ethyl-2[5'-(3'-ethyl-benzo-thiazolinyliden-2")pentadien-1',3'-yl]benzo-thiazoliyiodide 25.9-32.3, and urotropin 48.0-40.6.

EFFECT: application of inhibitor increases protection from corrosion of steel, titanium and indium in acids and reduces hydrogenation of steel.

2 tbl, 3 ex

Description

The invention relates to the protection of metals from acid corrosion using inhibitors and can be used for metal etching, well drilling and acid cleaning equipment.

It is known to use urotropin to reduce the rate of steel corrosion in hydrochloric and sulfuric acids (Altsybeeva A.I., Levin SZ, Metal corrosion inhibitors. - L .: Chemistry, 1968, p. 28-29). However, when corrosion is inhibited in the hydrochloric and sulfuric acids of steel and other metals (for example, titanium and indium), the effectiveness of urotropine is insufficient. In addition, urotropin is used in very high concentrations, reaching 2% (i.e., calculated in hundreds of millimoles per liter).

By technical nature and the results obtained, the closest to the proposed inhibitor is a known inhibitor, which is a condensation product of aniline and capric aldehyde (V. G. Turbina, N. G. Klyuchnikov. Protection against steel corrosion in hydrochloric acid by condensation products of amines and aldehydes: collection of articles “Metal Corrosion Inhibitors”, Central Research Institute of Shipbuilding Technology, Publishing House Sudostroenie, 1965, p.124-129).

The known inhibitor protects steel more effectively than urotropin, but the degree of protection is still not large enough (92.07; 95.50; 97.29%, respectively, in 3.5 and 7 N. hydrochloric acid). The effectiveness of the known inhibitor for titanium and indium is even lower. It very weakly protects steel from hydrogenation.

The technical task of the present invention is to increase the degree of protection of steel, titanium and indium from corrosion in sulfuric, hydrochloric and phosphoric acids, as well as the degree of reduction of hydrogenation of steel.

In order to achieve the indicated result, it is proposed to add an inhibitor to the named acids containing the condensation product of amine and aldehyde, which is used dipentylamino-4-nitrophenol, as well as (indolyl-3) acetic acid, 3-ethyl-2 [ 5 '- (3'-ethylbenzothiazolinylidene-2' ') pentadiene-1', 3'-yl] benzthiazolium iodide and urotropine.

The listed substances have the following structure:

n-dipentylaminosalicylal-2-amino-4-nitrophenol (hereinafter azomethine);

(indolyl-3) acetic acid (hereinafter derivative of acetic acid);

3-ethyl-2 [5 '- (3'-ethylbenzothiazolinylidene-2' ') pentadiene-1', 3'-yl] benzthiazolium iodide (hereinafter the thiazole derivative).

These components are contained in the composition of the proposed inhibitor in the following concentrations, wt.%:

azomethine 15.8-12.1 acetic acid derivative 10.3-15.0 thiazole derivative 25.9-32.3 urotropin 48.0-40.6

When using the proposed inhibitor, the components are dissolved in acids with vigorous stirring. The thiazole derivative previously dissolved in several milliliters of ethanol is added last.

The corrosion rate of steel, titanium and indium was determined both by the reduction in the mass of metal samples after etching them in pure acids, as well as in inhibited acids, and by the volume of hydrogen released during etching. Steel hydrogenation was measured by twisting the samples on a K-5 twisting machine until they broke (the number of revolutions of the wire sample to failure was measured).

The results of experiments on corrosion and hydrogenation for the proposed inhibitor are given in table 1 and examples. Table 2 contains the same for a known inhibitor.

Example I. In 500 ml of 3 N. H ₂ SO ₄ dissolved inhibitor (2.5 g) containing (wt.%) 12.1 azomethine; 15.0 acetic acid derivative; 32.3 thiazole derivative and 40.6 urotropine. On the net 3 n. sulfuric acid was placed 3 steel samples with a size of 30 × 20 × 1 mm Inhibited acid also contained 3 samples of the same size. The samples were preliminarily cleaned with thin sandpaper, degreased with acetone, kept in a desiccator for 2 hours over calcined calcium chloride, and weighed on an analytical balance.

At 20 ° C, the samples were kept in an acid solution (without inhibitor and with inhibitor) for 48 hours, at 90 ° C for 0.5 hours. The accuracy of temperature maintenance was ± 1 ° C. According to the data obtained on reducing the mass of the samples, the corrosion rates were calculated, and then the braking coefficients (γ) for the inhibitors were determined from the latter, which are equal to the following values:

at 20 ± 1 ° C γ = 46.6

at 90 ± 1 ° C γ = 200

Braking factors were converted to the degree of protection according to the equation

Z ₂₀ = 97.9%,

Z ₉₀ = 99.5%.

For the individual components of the inhibitor, the following values of inhibition coefficients were obtained:

20 ° C 90 ° C azomethine 1.7 2.5 acetic acid derivative 2.2 3.8 thiazole derivative 2.9 4,5 urotropin 1,5 2,3

The product of γ (conditionally theoretical) at 20 ° C is 16.3, at 90 ° C - 98.3. The resulting products exceed the experimentally found values of the coefficients by 2.9 and 2 times, respectively. Such significant differences in the values indicate that when the acids are in a solution together, the components of the inhibitors enhance the protective effect of each other, i.e. lead to a synergistic effect. A comparison of polarization curves leads to the same conclusion: both the anodic and cathodic polarizations in a 4-component solution of the inhibitor are approximately 6 times higher than those obtained in acids with individual components.

In experiments with a known inhibitor (5 g / l), the degree of corrosion protection is 91%, and only 5% against hydrogen pickup.

Example II In 500 ml of 7 N. HCl dissolved 2.5 g of a 4-component inhibitor of the same composition as in Example I. In this solution, experiments were carried out to measure the corrosion rate of titanium at 20 ± 1 ° C and 90 ± 1 ° C. Similar experiments were carried out in the same hydrochloric acid solution with a known inhibitor taken at the same concentration as the proposed one (5 g / l). Corrosion protection degrees of titanium with a 4-component inhibitor were 90.1% (at 20 ° C) and 92.9% (at 90 ° C), with the known - 30.1% and 41.0%, respectively.

Corrosion rates were measured at the same temperatures in 7 N solutions. HCl with individual components of the inhibitor, the concentrations of which were the same as the concentrations in the proposed inhibitor. As a result, the following values of the braking coefficients were obtained:

20 ° C 90 ° C azomethine 1.7 2,3 acetic acid derivative 1,2 1.3 thiazole derivative 1,6 1.9 urotropin 1.3 1.4

Multiplication of the obtained coefficients yields γ = 4.2 for 20 ° C and γ = 8.0 for 90 ° C (taken as theoretical values, i.e., not taking into account the possibility of mutual enhancement of the protective effect of the components). The experimental γ at the indicated temperatures is approximately 2 times greater (10.1 and 14.1), which allows us to draw a conclusion about the synergistic action of the components for titanium.

Example III Under the same conditions as in the previous examples, but with 5 n. phosphoric acid experiments were carried out with indium. The corrosion protection levels for indium are 53.9 (20 ° C) and 58% (90 ° C), which significantly exceeds the values of this indicator obtained with the known inhibitor 19.2 (20 ° C) and 29.5 (90 ° C) For indium, there is also a synergistic increase in the protective effect of the 4-component inhibitor compared to the theoretical value determined by multiplying the braking coefficients of individual inhibitors: for the proposed inhibitor, γ ₂₀ = 2.2, γ ₉₀ = 2.4, while for the product of the value at 20 ° C and 90 ° C it is almost 2 times less (1.2 and 1.4, respectively).

Thus, the data given in tables 1 and 2, as well as in examples I-III clearly indicate the advantage of the proposed inhibitor in terms of protection efficiency in acidic media for steel and is especially bright for titanium and indium. Significantly higher for the proposed inhibitor and the degree of protection against hydrogenation of steel compared with the known inhibitor (superiority several times).

Additional experiments conducted with the PB-5 inhibitor, which is widely used in the practice of anticorrosive protection of steel, showed a significant advantage of the proposed inhibitor: for the first, the corrosion inhibition coefficient was 44, and for the proposed one it was about 60. In addition, PB-5 coagulates when iron salts accumulate in pickling bath, while the proposed remains in the acid solution.

The proposed inhibitor can be used for the etching of steel, titanium and indium, as well as for acid leaching of equipment in which there are these metals.

Table 1 The degree of corrosion protection of steel, titanium and indium, as well as the degree of protection against hydrogenation of steel by the proposed inhibitor (concentration, 5 g / l). No. p / p Metal The concentration of inhibitor components, wt.% Acid, concentration, equiv / l t ° C Degree of protection, % azomethine acetic acid derivative thiazole derivative urotropin against corrosion from hydrogenation one 2 3 four 5 6 7 8 9 10 one steel 15.8 10.3 25.9 48.0 H ₂ SO ₄ , 3 twenty 94.6 27.3 2 - // - 14.0 12.9 29.0 44.1 - // - 95.5 3 - // - 12.1 15.0 32,3 40.6 - // - 97.9 36.9 four - // - 15.8 10.3 25.9 48.0 H ₂ SO ₄ , 3 90 94.6 5 - // - 14.0 12.9 29.0 44.1 - // - 97.9 6 - // - 12.1 15.0 32,3 40.6 - // - 99.5 7 - // - 15.8 10.3 25.9 48.0 H ₂ SO ₄ , 5 twenty 98.4 39.0 8 - // - 14.0 12.9 29.0 44.1 - // - 99.1 9 - // - 12.1 15.0 32,3 40.6 - // - 99.5 46.1 10 - // - 15.8 10.3 25.9 48.0 - // - 90 98.0 eleven - // - 14.0 12.9 29.0 44.1 - // - 99.3 12 - // - 12.1 15.0 32,3 40.6 - // - 99.7 13 - // - 15.8 10.3 25.9 48.0 HCl, 3 twenty 99,2 25.8 fourteen - // - 14.0 12.9 29.0 44.1 - // - 99.6 fifteen - // - 12.1 15.0 32,3 40.6 - // - 98.3 34.5 16 - // - 15.8 10.3 25.9 48.0 - // - 90 94.5 17 - // - 14.0 12.9 29.0 44.1 - // - 98.6 eighteen - // - 12.1 15.0 32,3 40.6 - // - 99.8 19 - // - 15.8 10.3 25.9 48.0 HCl, 5 twenty 99.3 25.8 twenty - // - 14.0 12.9 29.0 44.1 - // - 99.8

one 2 3 four 5 6 7 8 9 10 21 steel 12.1 15.0 32,3 40.6 HCl, 5 twenty 99.9 41.3 22 - // - 15.8 10.3 25.9 48.0 HCl, 5 90 95.4 23 - // - 14.0 12.9 29.0 44.1 - // - 96.0 24 - // - 12.1 15.0 32,3 40.6 - // - 99.5 25 - // - 15.8 10.3 25.9 48.0 HCl, 7 twenty 97.9 26 - // - 14.0 12.9 29.0 44.1 - // - 99.0 27 - // - 12.1 15.0 32,3 40.6 - // - 99.9 28 - // - 15.8 10.3 25.9 48.0 HCl, 7 90 95.0 29th - // - 14.0 12.9 29.0 44.1 - // - 95.4 thirty - // - 12.1 15.0 32,3 40.6 - // - 98.0 31 - // - 15.8 10.3 25.9 48.0 H ₃ PO ₄ , 5 twenty 98.8 32 - // - 14.0 12.9 29.0 44.1 - // - 99.0 33 - // - 12.1 15.0 32,3 40.6 - // - 99.7 34 - // - 15.8 10.3 25.9 48.0 - // - 90 94.5 35 - // - 14.0 12.9 29.0 44.1 - // - 95.8 36 - // - 12.1 15.0 32,3 40.6 - // - 97.9 37 titanium 15.8 10.3 25.9 48.0 H ₂ SO ₄ , 8 twenty 71.5 38 - // - 14.0 12.9 29.0 44.1 - // - 71.9 39 - // - 12.1 15.0 32,3 40.6 - // - 73.7 40 - // - 15.8 10.3 25.9 48.0 - // - 90 86.1 41 - // - 14.0 12.9 29.0 44.1 - // - 86.9 42 - // - 12.1 15.0 32,3 40.6 - // - 91.5 43 - // - 15.8 10.3 25.9 48.0 HCl, 7 twenty 87.3 44 - // - 14.0 12.9 29.0 44.1 - // - 89.9 45 - // - 12.1 15.0 32,3 40.6 - // - 90.1 46 - // - 15.8 10.3 25.9 48.0 - // - 90 89.2 47 - // - 14.0 12.9 29.0 44.1 - // - 91.5 48 - // - 12.1 15.0 32.3 40.6 HCl, 7 90 92.9

one 2 3 four 5 6 7 8 9 10 49 titanium 15.8 10.3 25.9 48.0 H ₃ PO ₄ , 5 90 80.1 fifty - // - 14.0 12.9 29.0 44.1 - // - 81.5 51 - // - 12.1 15.0 32,3 40.6 - // - 83.0 52 indium 15.8 10.3 25.9 48.0 H ₂ SO ₄ , 3 twenty 64.5 53 - // - 14.0 12.9 29.0 44.1 - // - 69.2 54 - // - 12.1 15.0 32,3 40.6 - // - 75.7 55 - // - 15.8 10.3 25.9 48.0 H ₂ SO ₄ , 3 90 73.7 56 - // - 14.0 12.9 29.0 44.1 - // - 78.0 57 - // - 12.1 15.0 32,3 40.6 - // - 80.7 58 - // - 15.8 10.3 25.9 48.0 HCl, 3 twenty 71.7 59 - // - 14.0 12.9 29.0 44.1 - // - 75,4 60 - // - 12.1 15.0 32,3 40.6 - // - 76.1 61 - // - 15.8 10.3 25.9 48.0 - // - 90 69.9 62 - // - 14.0 12.9 29.0 44.1 - // - 71.9 63 - // - 12.1 15.0 32,3 40.6 - // - 79.2 64 - // - 15.8 10.3 25.9 48.0 HCl, 5 twenty 74.5 65 - // - 14.0 12.9 29.0 44.1 - // - 76.9 66 - // - 12.1 15.0 32,3 40.6 - // - 83.3 67 - // - 15.8 10.3 25.9 48.0 - // - 90 67.7 68 - // - 14.0 12.9 29.0 44.1 - // - 69.2 69 - // - 12.1 15.0 32,3 40.6 - // - 78.7 70 - // - 15.8 10.3 25.9 48.0 H ₃ PO ₄ , 5 twenty 46.9 71 - // - 14.0 12.9 29.0 44.1 - // - 50.8 72 - // - 12.1 15.0 32,3 40.6 - // - 53.9 73 - // - 15.8 10.3 25.9 48.0 - // - 90 48.0 74 - // - 14.0 12.9 29.0 44.1 - // - 49.2 75 - // - 12.1 15.0 32,3 40.6 - // - 58.0

table 2 The degree of protection against corrosion and hydrogenation for a known inhibitor (5 g / l) No. p / p Metal Acid,
concentration,
equiv / l t ° C Degree of protection, % against corrosion from hydrogenation one 2 3 four 5 one steel H ₂ SO ₄ , 3 twenty 91.0 5 2 - // - - // - 90 90.8 3 - // - H ₂ SO ₄ , 5 twenty 91.1 9 four - // - - // - 90 87.7 5 - // - HCl, 3 twenty 92.5 3 6 - // - - // - 90 90.2 7 - // - HCl, 5 twenty 94.9 3 8 - // - - // - 90 90.0 9 - // - HCl, 7 twenty 97.3 four 10 - // - -II- 90 96.2 eleven - // - H ₃ PO ₄ , 5 twenty 90.3 12 - // - -II- 90 87.5 13 titanium H ₂ SO ₄ , 8 twenty 44.3 fourteen - // - - // - 90 46.0 fifteen - // - HCl twenty 30.1 16 - // - -II- 90 41.0 17 - // - H ₃ PO ₄ , 5 twenty 36.3 eighteen - // - - // - 90 33.1 19 indium H ₂ SO ₄ , 3 twenty 39.0 twenty - // - 90 42.9 21 H ₂ SO ₄ , 5 twenty 36,4 22 - // - 90 40.5 23 HCl, 3 twenty 34.5 24 - // - 90 44.8 25 HCl, 5 twenty 44.9 26 - // - 90 48.3 27 H ₃ PO ₄ , 5 twenty 19.2 28 - // - 90 29.5

Claims (1)

Corrosion inhibitor of metals in sulfuric, hydrochloric and phosphoric acids based on urotropine and the condensation product of amine and aldehyde, characterized in that it additionally contains (indolyl-3) acetic acid and 3-ethyl-2 [5 '- (3'-ethylbenzothiazolinylidene- 2 '') pentadiene-1 ', 3'-yl] benzthiazolium iodide, and as a condensation product of n-dipentylaminosalicylal-2-amino-4-nitrophenol in the following ratio, wt.%:
n-dipentylaminosalicylal-2-amino-4-nitrophenol 15.8-12.1 (indolyl-3) acetic acid 10.3-15.0 3-ethyl-2 [5 '- (3'-ethylbenzothiazolinylidene-2 ") pentadiene-1 ', 3'-yl] benzthiazolium iodide 25.9-32.3 urotropin 48.0-40.6