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Kadirov Bakhodir Makhamadjanovich, deputy dean the faculty of "chemical technology of fuel and organic substances" Ergasheva Saodat Khasanova, student of 3rdcourse, Kodirov Khasan Ergashevich, the head of chair "Organic chemistry and technology
of the basic organic synthesis E-mail: Ulug85bek77@mail.ru
RESEARCH OF THE EFFICIENCY OF COMPLEX INHIBITORS OF SALT DEPOSITION, CORROSION AND BIOFOULING
Abstract: The modified process of the synthesis of the copper-zinc complex in the presence of citric acid and phosphoric acid (Cu: Zn-OEDP). The effect of the amount of copper and zinc on the degree of protection of metals against corrosion has been studied, and the optimal ratios have been determined. When carbamide is heated in the presence of phosphoric acid extraction and condensation of the obtained product with formaldehyde, carbamide-formaldehyde resin (CFS) is obtained. Prepared compositions based on CFS and Cu: Zn-OEDF. It was established that the degree of protection and the effectiveness of inhibition of the composition due to synergistic avtivnosti, 2-4 times more compared to pure Cu: Zn-OEDF.
Keywords: complexones, copper-zinc complexone, hydroxy ethylidenedi phosphonic acid, GI-PAN, urea-formaldehyde resin, multipurpose inhibitors, corrosion rate, inhibition efficiency, biocides.
At present, global production of polydentate the 20th century. It has been established that inhibi-
compounds has reached the maximum amount of tion of the process of salt deposition with the help
2.5-3.5 million tons per year. On average, 40% of of phosphonates is based on the phenomenon of a
these produced reagents, about 1.2 million tons, vapor (or substochiometric) effect. Theoccurrence
are used to obtain inhibitors of mineral salt depo- of threshold effect was discovered in the late thirties
sition and corrosion. Corrosion inhibitors that are of the twentieth century for sodium hexametaphos-
widely used: Dodicor-4543; Dodicor-4712, Danox phate: in doses from 1 to 10 ppm (ppm, 10-4%), it is
C1-252, Sepacorrts 3201; K-75w, Danox-CS102 able to delay (inhibit) the release of the solid phase
B and inhibitors of mineral salt deposition, such as from supersaturated calcium carbonate solutions.
IMSD-1, OEDP, NTP-3, HELAMIN, etc. The prob- Since then, polyphosphates have become widely
lem of the protection of process equipment from salt used as salt deposition inhibitors in industrial water
deposition, internal corrosion and water treatment circulation systems. Later, a similar effect was found
remains urgent [1]. in phosphonic acids.
Reagents of the new generation are mainly gen- However, due to the relatively high cost of such
erated on the basis of organophosphonates. The use products, at a price they cannot compete with other
of phosphorus-containing chelating agents for the inhibitors. Therefore, a possible way out of this situ-
stabilization treatment of water started in the 70 s of ation is to create a relatively inexpensive, maximally
effective composition containing organophosphate in an amount of 20-40% of the total mass of the reagent. Many studies have concluded that Zn-OED-Pis not an optimally effective metal corrosion inhibitor for heat supply systems. In addition, the increase in the efficiency of Zn-OEDPdue to the increase in concentration is impossible, due to the low MPC for OEDP, which is 0.6 mg / l.
One of the priority areas for solving this problem is the use of a synergistic effect, which occurs when: ethanolamines phosphoric acids [2]; ascorbic acid [3]; dodecyl sulfate [4]; acrylic acid ester, polyphosphates and benztriazole [5]; carbamide-formaldehyde resins [6] and others are added to Zn- OEDP.
The suggested method of obtaining inhibitors of universal action is carried out in the following sequence:
Stage 1. The reaction of condensation of urea with formaldehyde. Condensation of urea with formalde-
hyde was carried out in a three-necked flask equipped with a reverse water cooler, a drop funnel and a mechanical stirrer. 36.6 g of urea (0.61 mole) were placed in the reactor, and 40 ml of water were added in portions with vigorous stirring. The mixture was stirred for 25-30 minutes at a temperature of 30-40 °C. Then 126 ml (1.55 mole) of 37% formaldehyde was added to the solution, after 1 ml of a 27% solution of extraction phosphoric acid. Then 50 mg of ammonium chloride and 2.5 ml of 25% ammonia water were added to the reaction mixture. The resulting reaction mass was thoroughly stirred at a temperature of 80-84 °C for 1 hour, then the mixture was placed in a flask at a pressure of10 mm Hg, a temperature of 60 °C, and formaldehyde was distilled off. The code name of the condensation product CFR.
Elemental analysis data.
Found,%: C = 26.52; H = 6.68; N = 31.41
Calculated,%: C = 26.67; H = 6.66; N = 31.11
1000 3500 3000 2500 2000 1500 1000 400CM-1
Figure 1. IR spectrum of condensate product of urea with formaldehyde
In the infrared spectrum of condensation prod- deformation vibration - OH-groups, 650-900 and
ucts of urea with formaldehyde, intense absorption 1560-1640 cm-1 - stretching vibrations of the NH2
peaks were found in the regions: 1070-1150 cm-1 - group, 1490-1580 cm-1 - stretching vibration of the
stretching vibration - CO-groups, 3200-3400 cm-1 - NH-group.
Stage 2. Obtaining zinc complex of OEDP. A method is suggested for preparing crystalline Cu: Zn- OEDP in the presence of glycerin: a heat-resistant beaker is added to the reactor, water is poured in a calculated amount, and glycerol is added. The mixture is stirred for 5-7 minutes. Then add the calculated amount of OEDP. The temperature at the same time should be 30-35 °C. After that, sodium hydroxide, copper oxide and zinc oxide are sent to the reactor. The mixture is stirred until complete dissolution and a clear liquid is obtained. The finished product is cooled to room temperature.
The composition and structure of the obtained product is established by various physico-chemical methods of analysis.
The aqueous solution of the object was analyzed on chromatography-mass spectrometer "Agilent Technology" GC/MS AT 5973N using the DRUG-SP-SHORT.M method using a 30m x 0.25mm capillary column with 5% phenylmethylsiloxane at an injector temperature of280 °C, sample size 1 microliter (Figure 2).
Figure 2. Chromate of Cu: Zn
Conditions of chromate-mass-spectrum: temperature 280 °C, when programming the temperature of the column thermostat from 70 to 280 °C, sample size 1 microliter.
Comparison of the basic data of the device proves that the resulting Cu: Zn-OEDP has high purity.
Cu: Zn-OEDP IR - spectrometer (Figure 3) "AgilentTechnologyFTIR-640" under the following analysis conditions: the recording range is 4000-400 cm - 1, the number of scans is 12.
In the spectrum of the preparation, there is a band at 1250-1300 cm-1, related to the localized P = O bond; the band at 2500-2700 cm- 1 refers to the stretching vibrations of the group of
-mass-spectrum OEDP
the fully deprotonated PO3 group; there are also bands at 1180-1240 and 2500-2700 cm- 1 related to the stretching vibrations of the P - O(H) bond of the protonated phosphate groups, which indicates that the complexes are partially protonated; the intense band at 1046-1000 cm- 1 refers to the stretching vibrations of the Cu - O bond, the band at 650-750 cm- 1 to the stretching vibrations of the C - P bond, and the intense band at 570-550 cm- 1 to the stretching vibrations of the Zn - O bond; the absorption bands at 480-460 cm-1 to the deformation vibrations - O - P - O. This allows us to conclude that the coordination of the PO3 group with the Zn atom occurs with the localized n-bond
P = O, the oxygen atoms in the PO3 group do not ic acid in an amount of 100.0 and 27.0 ml are poured, equal rights. respectively, and citric acid, the products obtained in Stage 3. The preparation of the composition of the the first and second stages in different ratios in turn. inhibitor is of universal action. To do this, the reactor The mixture is stirred for 12-15 minutes. This prodis a heat-resistant glass, water and extracted phosphor- uct was provisionally named "IMSD-UNI".
Figure 3. Cu: Zn-OEDP IR - spectrometer
To determine the optimal composition of the OEDP: Me, compositions were prepared at ratios of 3:1-2:1. The ratios varied from 0.25: 0.75 to 0.75: 0.25.
Tests of the obtained compositions as corrosion inhibitors were carried out on industrial waters with hardness of 9-10 mg. eq./l. The results are presented in tables 2 and 3 and in figures 5-6.
Table 2.- The influence of complexions based on Cu: Zn-OEDPon the corrosion rate of steel grades in stage 3 (K = 0.240 mm/a year)
Reagent Mole ratio Corrosion rate, mm/a year At the reagent concentration, mg/l
6 10
Cu: Zn-OEDP 0.5 : 0.5 : 2.0 0.043 ± 0.002 0.024 ± 0.001
Cu: Zn-OEDP 0.33 : 0.66 : 2.0 0.014 ± 0.004 0.007 ± 0.002
Cu: Zn-OEDP 0.66 : 0.33 : 2.0 0.082 ± 0.001 0.065 ± 0.003
Cu: Zn-OEDP 0.75 : 0.25 : 2.0 0.113 ± 0.003 0.106 ± 0.001
Cu: Zn-OEDP 0.66 : 0.33 : 3.0 0.062 ± 0.004 0.053 ± 0.003
Cu: Zn-OEDP 0.33 : 0.66 : 3.0 0.031 ± 0.002 0.022 ± 0.001
Cu: Zn-OEDP 0.75 : 0.25 : 3.0 0.106 ± 0.001 0.096 ± 0.001
Cu: Zn-OEDP 0.25 : 0.75 : 3.0 0.110 ± 0.004 0.106 ± 0.001
molar ratio Cu: Zn - OEDP
Figure 5. Depenence of the protective effect of corrosion inhibition on the molar ratio Cu: Zn-OEDP, with the ratio OEDP: Me = 2 : 1
From the data presented in (Table 2) and in (Figure 5), the following conclusions can be drawn:
a) all investigated Cu: Zn-OEDP for the given molar ratios of OEDP: Me reduce the corrosion
rate of constructional steel in water with hardness of 9-10 mg eq/l to normal values less than 0.1 mm/a year.
100 90 80 70 60 50 40 30 20 10 0
74
78
0,5:0,5:3,0
87
91
60
0,33:0,66:3,0 0,66:0,33:3,0
molar ratio Cu: Zn — OEDP
56
54
■
i m
»■I
■ ■
0,75:0,25:3,0
Figure 6. Dependence of the protective effect of corrosion inhibition on the molar ratio of Cu: Zn-OEDP, with the ratio of OEDP: Me = 3 : 1
b) compositions with a ratio of OEDP: Me^2:1 have a greater corrosion inhibiting efficiency than compositions with a ratio of 3:1, due to an increase in the composition of such compositions of zinc complexates. The protective effect of compositions with ratio OEDP: Me is equal to 3:1 does not exceed 78%, while for compositions with ratio OEDP: Me is equal to 2: 1 it reaches 86%.
c) an increase in the composition of the molar fraction of zinc compared to the proportion of copper (compositions with ratios Cu: Zn equal to 0.75: 0.25 and 0.66: 0.33) increases the ability of the compositions to inhibit the corrosion of steel in stage 3, minimum protective effect of such compositions is 57% and increases to 86%.
Table 3.- Influence of compositions on the corrosion rate of steel grades in stage 3 in water hardness 9-10 mg.eq./l (K = 0.240 mm/a year)
Reagent Corrosion rate, mm/a year at the portion of reagent, mg/l
4 6 8 10
CFR 0.163 ± 0.002 0.137 ± 0.002 0.134 ± 0.004 0.134 ± 0.002
Cu: Zn-OEDP 0.053 ± 0.002 0.038 ± 0.004 0.029 ± 0.001 0.024 ± 0.001
IMSD-UNI-1 0.048 ± 0.003 0.031 ± 0.002 0.019 ± 0.002 0.007 ± 0.002
IMSD-UNI-2 0.084 ± 0.001 0.062 ± 0.004 0.048 ± 0.002 0.036 ± 0.001
In order to study the synergistic activity of the of CFR ^ Cu: Zn-OEDP, obtained at a molar ratio
CFR and Cu: Zn-OEDP, compositions with different of initial reagents of 1:2 (trade name IMSD-UNI-1)
compositions were prepared: the inhibiting proper- and 1:1 (trade name IMSD-UNI-2). The results are
ties of the products obtained in stages 1 and 2 in presented in (Table 3) and in (Fig. 7) (the corrosion
pure form were compared; composition consisting rate in the control experiment was 0.18 mm/a year).
N
100 90 80 70 60 50 40 30 20 10 0
97
84
87
92
Kg
32
WÈK ' ■ Wrn ■
80
65 |
43
■ i ■
-1-
74 74
4
6
8
10
Figure 7. Dependence of the protective effect of inhibiting the corrosion of steel in stage 3 of the concentration and type of reagent
From the data presented in (Table 3) and in (Fig. 7), it can be seen that adding a CFR to the composition can significantly increase the efficiency of the initial Cu: Zn-OEDP reagent as a corrosion inhibitor. The protective effect against corrosion of structural steel using IMSD-UNI-1 reagent is more than 80% at all concentrations studied, while using Cu: Zn-OEDP this effect is achieved only at concentrations of more than 6 mg/l. At the
4 3 2
250-
200-
▲ i i A
4.5-
30
3.0-
25-
20 1.5-
40-
30-
20-
10-
same time, the increase in the cost of the modified inhibitor does not exceed 30-50% of the cost of the initial OEDP reagent.
From previous studies, it is known that the IMSD-1 copper-containing complexonates with a molar ratio of IMSD-1 : Cu = 2: and IMSD-1: Cu = 1 : 1, besides inhibiting scaling, exhibit biocidal properties and effectively inhibit vital activity microorganisms, and hence biofouling.
4 3 2
40
250
200
▲ i k A
4.5
30
3.0
25-
20 1.5
30
20
10
temperature, °C 25
28
36
temperature, °C 25
28
36
A)
B)
Figure 9. The effect of IMSD-UNI-1 (A) and IMSD-UNI-2 (B) preparations on algae E. claraskuja belonging to the family EuglenaEhr
The experiments were carried out on the basis of standard algological requirements in the following order: objects of experience (or research) were carried out in microalgae: Chlorella, Scenesmus-Chlorellavulgaris, Scenedesmusoblianus and also in E. Clara cultures related to the Euglena Ehr family. Experiments were performed in standard living food conditions for cultures.
Figure 9 shows the results of the experiments carried out in the food media of the E. Clara culture belonging to the Euglena Ehr family.
The result shows that the preparations inhibit the development of algae E. Clara, which is expressed by a decrease in activity in metabolic processes, in particular a sharp decrease in the activity of photosynthesis and breathing processes, the number of
living cells, and consequently, the accumulation of biomass cells.
Conclusion. Thus, it was found that in compositions of carbamide-formaldehyde resins (CFS) with copper-zinc complexates of hydroxyethylidenedi-phosphonic acid, they can increase the effectiveness of salt deposition and corrosion by 2-4 times with the content of the latter up to 40% of end products.
Based on the CFS and Zn: Cu-OEDP reagents, complex inhibitors of salt deposition, corrosion and biofouling have been developed. It has been established that the use of the IMSD-UNI-1 reagent provides both a non-boiling regime and a reduction in the corrosion rate in waters of various chemical compositions and in highly mineralized waters when salts are concentrated in water supply systems.
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