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Section 17. Chemistry
Section 17. Chemistry
Kaipbergenov Atabek Tulepbergenovich, Tashkent Institute of Chemical Technology, Researcher
Erkaev Aktam Ulashevich, Tashkent Institute of Chemical Technology, Doctor of Technical Sciences, Professor Kucharov Bahram Hayrievich, Tashkent Institute of Chemical Technology, Ph. D., Associate Professor E-mail: [email protected]
Basis of the obtained sodium sesquicarbonate carbonate and sodium bicarbonate
Abstract: We presented a theoretical analysis of the system Na2CO3-NaHCO3-2H2O with the definition of optimal conditions for obtaining sodium sesquicarbonate. In the laboratory, studied the process of obtaining and study the kinetics of decomposition of sodium bicarbonate, and determined the rheological properties of suspensions. With the proposal stage process for producing synthetic electrons (sodium sesquicarbonate).
Keywords: sodium sesquicarbonate, system, eutectic point, isotherms, components, sodium bicarbonate, sodium carbonate
In literature there is a lot of information on advantage and wide consumer properties trones and its receiving from natural ore [1].
Trona (also sodium sesquicarbonate or one-and-a-half soda is called) Na2CO3-NaHCO3-2H2O meets in the nature and can be received by a crystallization from mix of hot solutions of a carbonate and sodium bicarbonate. But in literature the receiving question trones from the last is taken insufficiently up.
For the physico-chemical studies on the process of producing the tronas of carbonate and sodium bicarbonate by interpolating data in the literature [2-3], a chart of the isotherm at 25, 80 °C solubility in the Na2CO3-NaHCO3-2H2O (Figure 1 and Table 1).
The data show that in the studied system as a new phase formed sodium carbonate monohydrate and dihydrate double salt Na2CO3-NaHCO3-2H2O — sodium sesquicarbon-ate.
Table 1. - Characteristic of Na2CO3-NaHCO3-2H2O system of nodal points
Nodal points Composition of the liquid phase Temperature, °C Solid phase
Na2CO3 NaHCO3 H2O
A80 31.23 0 68.77 80 Na2C°3‘H2°
e880 30.84 2.63 66.53 80 Na2CO3-H2O+ Na2CO3-NaHCO3-2H2O
e280 17.65 9.82 72.53 80 Na2CO3-NaHCO3-H2O+NaHCO3
B80 0 16.14 83.86 80 NaHCO3
A25 22.63 0 77.37 25 NaCO.HO 2 3 2
E25 22.25 1.14 76.61 25 Na2CO3-H2O+ Na2CO3-NaHCO3-2H2O
E25 Л,2 17.82 4.24 77.94 25 Na2CO3-NaHCO3-2H2O +NaHCO3
B25 0 9.2 90.8 25 NaHCO3
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Basis of the obtained sodium sesquicarbonate carbonate and sodium bicarbonate
Eutectic point of Na2CO3-H2O composition corresponds to 22.63% Na2CO3 and 77.32% H2O at 25 °C and 31.23%
Na2CO3 and 68.77% H2O at 80
C and NaHCO3-H2O —
CO3 and 83.86% H2O at 80 °C. Figure solubility isotherms of Na2CO3-NaHCO3-H2O at 25 and 80 °C for three fields separated solid phase crystallization: NaHCO3 and two new
Figure 1. Diagram solubility isotherms of Na2CO3-NaHCO3-H2O
These fields converge in the two triple points of co-existence of three solid phases, which established the equilibrium solution formulations (Table 1).
Fields crystallization Na2CO3-H2O at 80 °C occupy a smaller portion of the chart than the field of crystallization NaHCO3 and trones. This shows a good solubility in the system of sodium carbonate monohydrate, compared with sodium bicarbonate and trona. With decreasing temperature, the crystallization field Na2CO3-H2O and tronas narrowed while increasing the field of crystallization NaHCO3
Trone highlighted in the crystallization form and identify chemical, radiographic, and grav methods of physical and chemical analysis.
The chemical and physico-chemical analysis of solids extracted from the region of existence of the proposed Na2CO3-NaHCO3-2H2O, confirmed the formation of the latter.
Chemical analysis of the isolated compounds gave the following result:
Found mass.,%: Na2O-41.5; CO2-39.0; H2O-14.3;
For Na2CO3 • NaHCO3 • 2H2O calculated mass.,%: Na2O-41.8; CO2-39.4; H2O-14.41.
Education tronas confirmed by X-ray analysis that Na2CO3-NaHCO3-2H2O has an individual crystal lattice, which is not characteristic of the initial components and corresponds to the literature [4] (Fig. 2).
Na2CO3; d1 = 3.21; 2.96; 2.58; 2.54; 2.37; 2.25; 2.18; 2.12; 2.03; 1.956; 1.884-A°;
NaHCO3; d1 = 3.07; 2.58; 2.18; 2.03; 1,965; 1,904; 1,519-A°;
NaHCO3-Na2CO3-2H2O; d1 = 9.83; 4.91; 3.18; 3.08; 2.76; 2.64; 2.47; 2.44; 2.25; 2.03; 1.78; 1.658-A°;
Study of thermal properties of the compounds Na2CO3-NaHCO3-2H2O shown that there is a DTA curve endotherm at 104.6 °C at a heating rate of 2 °C/min.
From the literature it is known that at a heating rate of 5, 15, 20 °C/min. minimum peak observed at 111.81, 132.41 and 138.46 °C, respectively.
This is due to the fact that with increasing heating rate of the temperature difference between samples increases. The degree of decomposition of the trona will be greater with slow heating (2 °C/min.) Than during rapid heating (5, 20 °C/min) (Fig. 3).
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Figure 2. XRD patterns of samples of trona obtained: a) solid phase, b) a liquid phase method Analysis of Na2CO3-NaHCO3-2H2O shows that to ob- concentration must be maintained in the ranges of 18-26%
tain a solution of carbonates and bicarbonates of sodium and 6-15%, respectively. The process comprises the steps of
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Basis of the obtained sodium sesquicarbonate carbonate and sodium bicarbonate
dissolving the starting components with the separation of the solid phase, the crystallization solution, the separation of sodium sesquicarbonate from the pulp and the circulation of the mother liquor at the beginning of the process.
To determine optimal process parameters of producing sodium sesquicarbonate Na2CO3 and NaHCO3 liquid
phase method, the kinetics of the decomposition process NaHCO3 depending on the mass ratio NaHCO3: H2O, temperature, ratio Na2CO3: NaHCO3:2H2O and rheological properties of the slurry formed in the preparation of sodium sesquicarbonate.
JOi%
DSC АетШтф ' 0.0
-0.5
-1 О
-1.5
-20
TG i% DSC АегШтф
t BM
Figure 3. Thermograms samples at a heating rate of 2 °C/min. a) a solid phase, b) a liquid phase
Table 2 shows that with increasing mass ratio of NaH-CO3: H2O and temperature from 60 to 90 °C, the degree of decomposition increased from 12.4-13.8 to 28.2-30.5% within 6 minutes. With an increase in the duration of up to 20 and 160 minutes it rises from 16.57-17.33, 37.17-39.96 to 24.3-24.5, 65.56-81.84 respectively; degree of degradation with increasing duration of the expansion from 5 to 160 min-
utes with increasing temperature from 60 to 90 °C increases 1.27-2.25, 2.7-3.34 times. Therefore, the dissolution process takes place within less than 20 minutes at a temperature of 90 °C. And NaHCO3: H2O ratio in intervals 3^7-4Th practically does not influence process.
Table 3 shows the results of a study of obtaining sodium sesquicarbonate in the laboratory.
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Section 17. Chemistry
The data shows that with increasing amounts of additives For example, when using 18% strength sodium solution
to soda NaHCO3 solution increases the solid phase in the sys- produced 8.17% solids, consisting of a mixture of sodium hy-
tem by 15% at 80 °C. drogen carbonate and trona.
Table 2. - Speed of decomposition of sodium bicarbonates in suspension
№ NaHCO3: H2O Temperature, Significative Time, min
°C 5 10 20 40 80 160
1 Na2C°3 4.10 4.90 5.81 6.81 7.51 11.90
2 30:70 NaHCO3 15.90 15.60 14.60 12.10 11.10 4.50
3 Degree of decomposition 28.20 33.70 39.96 46.84 51.65 81.84
4 Na2C°3 4.90 5.80 6.54 7.20 8.15 12.30
5 35:65 90 NaHCO3 15.60 15.40 15.30 15.20 14.40 7.50
6 Degree of decomposition 28.86 34.16 38.34 42.40 48.00 72.44
7 Na2CO3 5.91 6.50 7.20 7.60 8.50 12.70
8 40:60 NaHCO3 15.36 15.30 15.20 15.00 14.80 10.10
9 Degree of decomposition 30.51 33.56 37.17 39.24 43.88 65.56
10 Na2CO3 2.20 2.51 2.60 3.10 4.60 6.20
11 30:70 NaHCO3 14.50 14.20 14.20 14.00 13.80 13.00
12 Degree of decomposition 15.13 17.26 17.88 21.32 31.64 42.64
13 Na2CO3 3.30 4.00 4.10 5.12 5.20 6.50
14 35:65 80 NaHCO3 14.20 14.00 13.90 13.50 13.30 12.90
15 Degree of decomposition 19.43 23.56 24.15 30.15 30.62 38.28
16 Na2CO3 3.40 4.34 4.74 5.51 6.50 6.80
17 40:60 NaHCO3 14.10 14.00 13.70 13.00 12.90 12.70
18 Degree of decomposition 17.55 22.41 24.47 28.45 33.55 35.11
19 Na2CO3 2.00 2.40 2.52 2.80 2.85 3.50
20 30:70 NaHCO3 12.50 12.00 11.80 11.60 11.50 11.40
21 Degree of decomposition 13.76 16.51 17.33 19.26 19.81 24.07
22 Na2CO3 2.27 2.59 2.87 2.90 3.75 4.16
23 35:65 60 NaHCO3 12.30 11.80 11.50 11.50 11.30 11.00
24 Degree of decomposition 13.37 14.90 15.14 17.08 22.08 24.50
25 Na2CO3 2.40 2.80 3.21 3.47 3.80 4.70
26 40:60 NaHCO3 11.70 11.40 11.00 10.94 10.81 10.70
27 Degree of decomposition 12.39 14.46 16.57 17.91 19.62 24.26
With increasing concentration of soda solution to 26% solids content of the image in the system reaches up to 20.5% (S: L=1:0.256).
The composition of the solid phase formed from a soda solution with a concentration of more than 22% of additives of 10-15% sodium bicarbonate, sodium sesquicarbonate occurs only with the insoluble residues of the starting components.
Soda and bicarbonate solutions and/or suspensions
prepared at 80 °C after separation of the solid phase is cooled to 30 °C. In the system, a new solid phase consisting of trona and mixed with sodium bicarbonate. With increasing concentration of the soda solution amount of the solid phase solid phase increases from 8.3 to 11.52%. Pure trone formed in 18-22% soda solution misfit adding 5% sodium bicarbonate, and the latter with the increase in the solid phase in the system consists of trona and sodium bicarbonate.
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Table 3. - Influence of technological parameters on the analytical performance of the process producing sodium sesquicarbonate in the liquid phase method
№ Concentration of the soda solution, mass.% O'' CO О U X a z +-» ö О. О P Process of preparation of the suspension at a temperature 80 C Process of preparation of the suspension at a temperature 30 C
Ratio S: L in suspension Chemical composition of a liquid phase Phase structure of a solid phase Ratio S: L in suspension Chemical composition of a liquid phase Phase structure of a solid phase
Na2C03 NaHC03 h2o Na2C03 NaHC03 h2o
1 18 5 - 18.5 4 77.5 - 0.090 18.6 3.8 77.6 Na2C03-NaHC03-2H20
2 10 - 18.4 8.7 72.9 - 0.094 18.0 4.0 78.0 Trona+ NaHC03
3 15 0.089 17.9 9.9 72.2 Trona+ NaHC03 0.105 17.9 4.1 78.0 Trona+ NaHC03
4 20 5 - 20.4 4 75.6 - 0.048 19.8 2.0 78.2 Na2C03-NaHC03-2H20
5 10 0.021 20 8.2 71.8 Na2C03-NaHC03-2H20 0.108 18.0 4.4 77.6 Trona+ NaHC03
6 15 0.190 17.9 9.9 72.2 Trona+ NaHC03 0.105 17.9 4.1 78.0 Trona+ NaHC03
7 22 5 - 22.4 4 73.6 - 0.069 21.5 1.9 76.6 Trona
8 10 0.043 21.6 7.3 71.1 Na2C03-NaHC03-2H20 0.124 18.5 4.2 77.3 Trona
9 15 0.176 19.2 9.2 71.6 Trona 0.123 17.9 4.1 78.0 Trona+ NaHC03
10 24 5 - 24.6 - 75.4 - 0.078 22.4 1.7 75.9 Na2C03-NaHC03-2H20
11 10 0.071 23.4 5.8 70.8 Na2C03-NaHC03-2H20 0.124 20.6 2.4 77.0 Trona
12 15 0.228 20.8 7.9 71.3 Trona 0.122 17.9 4.1 78.0 Trona
13 26 5 - 26.8 4 69.2 - 0.104 22.4 1.7 75.9 Na2C03-NaHC03-2H20
14 10 0.101 25.1 5.5 69.4 Na2C03-NaHC03-2H20 0.126 22.8 1.9 75.3 Trona
15 15 0.256 22.6 6.8 70.6 Trona 0.134 20.4 2.2 77.4 Trona
Basis of the obtained sodium sesquicarbonate carbonate and sodium bicarbonate
Section 17. Chemistry
Table 4 shows the density of the slurry. It can be seen that with increasing concentrations of soda solutions under the same conditions (temperature and sodium bicarbonate content) increases the slurry density.
Table 4. - Density and viscosity of suspension
H2o Na2CO3 NaHCO3 Density, g/cm 3 Comment
20 °C 40 °C 60 °C 80 °C
74 26 5 1,290 1,287 1,283 1,279 jellification
10 1,300 1,296 1,292 1,289 jellification
15 1,319 1,313 1,310 1,307 jellification
76 24 5 1,270 1,265 1,261 1,259
10 1,280 1,270 1,650 1,630 jellification
15 1,301 1,290 1,280 1,276 jellification
80 20 5 1,232 1,225 1,224 1,222
10 1,245 1,23 1,227 1,231
15 1,262 1,260 1,252 1,244
82 18 5 1,216 1,210 1,201 1,194
10 1,220 1,214 1,212 1,217
15 1,230 1,220 1,225 1,230
For example, with increasing concentrations of soda becomes thick. Thus, on the basis of the above, we can
solutions from 18 to 24%, 5% sodium bicarbonate at 20 °C, conclude that for pure trones with high output is necessary
the system density increases from 1.216 to 1.270 g/cm 3. to maintain the content of sodium bicarbonate in 18-24%
With increasing content of sodium bicarbonate and a 10% strength soda solution is not more than 15%.
solution of soda concentration of more than 20%, the system
References:
1. US patents № 7.638.109, William C. Copenhafer. 2009 - P. 23.
2. Справочник по растворимости солевых систем. Том I, М.: Гос. Хим издат. 1953 г. - 671 с.
3. Справочник по растворимости солевых систем. Том II, М.: Гос. Хим издат. 1961 г. - 2221 с.
4. Миркин Л. И. Справочник по рентгеноструктурному анализу поликристаллов. М.: Гос.издат. Физико-математической литературы, 1961. - 862 с.
5. Sibel Örgül. Evaluation of soda ash production parameters from Beypazari trona ore. Turkey, 2003. - 170 c.
Khentov Victor Yakovlevich, South-Russian State Potechnical University, Professor, Doctor of Chemical Sciences E-mail: [email protected] Hussain Hanaa Hassan, South-Russian State Potechnical University,
Graduate student Semchenko Vladimir Vladimirovich, South-Russian State Potechnical University, Associate Professor, Candidate of Science.
Copper surface etching in the donor-acceptor systems
Abstract: Etching solutions based on the donor-acceptor systems containing aprotic solvent and organic ligands — Shiff bases - have been developed to remove scale and corrosion products from copper and its alloys. To increase the rate of dimensional etching a surfactant (tetra-n-butylammonium iodide) was introduced in the ligand non-aqueous solution at concentrations exceeding the critical concentration of micelles (CMC).
Keywords: non-aqueous solvent, a surfactant, a micelle, a ligand, etching thickness.
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