Method for using silica, precipitated from hydro-thermal heat carrier, as sorbent for gas chromatography

FIELD: chromatography.

SUBSTANCE: specific area of silica surface reaches 300,2/g, porosity - up to 1,1 cm3/g, average pores diameter - 12,0-16,0 nm. For separating and property detection couples of substances and carrier gas are let through chromatography column, filled with silica powder, which is precipitated from hydrothermal solution, with receipt at output of column of sequence of special components, recorded in form of peaks. Absorbent, received on basis of silica, precipitated from hydro-thermal solution, in several cases has better separating ability then traditional absorbents.

EFFECT: higher efficiency.

3 tbl

 

The invention relates to the recycling of minerals extracted from the hydrothermal fluid. Extraction and utilization of mineral component of the carrier is held in conjunction with the production of electric and thermal energy, which improves the efficiency of the heat carrier geothermal electric and teploelectrocental stations (the Plant, geothermal power station), as well as opening up opportunities for the extraction of fluid chemical compounds in the absence of geothermal energy production.

Physico-chemical characteristics of silica determining areas of its utilization depends on the fetch mode from hydrothermal solution. Among such characteristics are: 1) the concentration of impurities (CA, Mg, Al, Fe, and other); 2) the bulk density of the dispersed material; 3) microstructure: the size, shape of particles and their complexes; 4) characteristics of the pores: the diameter, area, pore volume; 5) the ability to absorb organic liquids; 6) sorption properties of the surface; 7) the optical properties of the surface and other

In accordance with the proposed method silica, precipitated from hydrothermal fluid is used as the sorbent in chromatographic columns for the separation of mixtures of organic liquid and gaseous substances and determine the concentration of components of the mixture. Dispersed to elnezem, fill the chromatographic column is a solid stationary phase through which the filtered mobile phase is a carrier gas containing components. Due to the different values of the distribution coefficients between the gas and solid phases occurs chromatographic separation eluruumid components of the mixture and record the result in the form of peaks in the chromatogram corresponding to the concentration of specific components.

The deposition of silica from the brine as follows. The heat carrier in the form of two-phase steam-water mixture flows from the hydrothermal reservoir to the surface through production wells to the Plant, geothermal power station. After separation of the mixture in the separator for vapor and liquid phase (hydrothermal separat) pairs served by a steam turbine to generate electric energy, and from separate conduct the deposition of silica. To achieve low concentration of impurities, and given the silica dispersion can be used as one alternative extraction method specified in the invention [1] (Potapov V.V., Kaspura NR. The method of extraction of amorphous silica from the hydrothermal fluid. RF patent №2186024, 2000), with a low impurity concentration.

Method [1] allows to precipitate silica in the form of amorphous fine powder with low content of p is imesa by pre-dispersion solution and the subsequent freezing of drops and differs the solution is sprayed at ambient temperatures from -30 to +10°on an exposed surface with a snow cover snow depth of 0.8-1.2 m, with an average specific discharge of solution on the surface of 2.0-3.5 g/m2.

Thus removing the silica is carried out in conditions of a geothermal power plant (geothermal power station in the period of existence of stable snow cover. The flow of the liquid phase waste of hydrothermal fluid with a temperature of 80-100°after dispersion through the perforated nozzle is served on an outdoor area with a layer of snow for the formation of a mixture of a slurry of silica and snow. The snow has vygorajivayuschii effect on the solution, contributing to the cooling and solidification of the droplets. Freezing of a solution of colloidal silica leads to the fact that ice crystals during their growth displace the solution, and the silica particles are concentrated in the solution between the crystals, which increases the rate of coagulation and deposition of particles and rapid formation of the first layer of sludge. The slurry of the silica in this layer acts as a flocculant, which further accelerates the precipitation of silica from the drops. Part of the slurry of silica periodically removed from the surface of the ground, accumulate, and then dried using hydrothermal heat.

Precipitated material after with whom the loud and goes to disperse the powder, the surface which is used for quantitative determinations for the chromatographic separation of gases.

The concentration of the main components in the original solution had the following values (mg/kg): Na+- 239,4,+- 42,0, NH4+- 1,1, CA2+to 1.6, Mg2+- 0,72, Li+- 0,71, Fe2+- 0,1, Al3+is 0.27, Cl-- 198,5, SO42-- USD 192.1, HS-- 5,0 HCO3-- 81,0, CO32-- 19,9, N3IN3- 106,9, SiO2- to 680.0, pH of 9.2, salinity - 1638,9 mg/kg, ionic strength - 14,22 mmol/kg

The density of wet sludge silica, precipitated by freezing equal to 2.0 g/cm3and bulk density of powder silica - 0,22-0,24 g/cm3. The chemical composition of the silica was as follows (weight percent, after drying at 105° (C): SiO2is 91.5, TiO2- 0,02, Al2About3- 0,46, Fe2About3to 0.08, FeO - 0,10, CaO - <0,1, Na2O - 0,67, K2On - 0,32, P2O5- 0,067, loss on ignition at 1000° - 6,79.

Samples of precipitated silica have an amorphous structure. Its thermochemical properties of precipitated material differed little from silicas having a hydroxyl film on the surface. According to thermogravimetric analysis at a heating such samples in the temperature range 100-200°separates physically adsorbed to the odes, at higher temperatures the mass loss of samples due to the destruction of surface silanol groups. The IR spectra of the samples were studied in the range of wave numbers from 250 to 4250 cm-1. In the range of wave numbers 250-1200 cm-1attended three high, respondents vibrations of Si-O-Si linkages in the tetrahedron SiO4two small maximum near 500 and 750-850 cm-1and one significant area 1096-1104 cm-1. In the range of 1200-4000 cm-1always there were two small peaks in the area 1600-1640 cm-1and 2344-2368 cm-1and one significant area 3440-3480 cm-1that corresponded to the vibrations of hydroxyl groups. The geometry of the curves of the IR spectra and the position of the two main peaks in the area 1096-1104 cm-1and 3440-3480 cm-1characteristic of various forms of silicon dioxide.

Method [1] provides a deposition from hydrothermal solution of silica of high specific surface area and pore volume and low concentrations of impurities (aluminum, iron, and calcium), which gives the opportunity to apply the silica in chemical, silicate and other industries.

Measurements of area and pore volume silica samples was performed by the adsorption method. The method is based on measuring the isotherms of adsorption-desorption of nitrogen at liquid nitrogen temperature, equal to about 77 K.

Led the rank of the specific surface area was determined by BET method. Found differential distribution of volume Vpand the area Sppores with diameters of dpwithin a certain range, and the integral value of the volume and area of pores with diameters from 1.7 nm to given values of dp.

Characteristics of long samples dispersed geothermal silica, obtained adsorption method, are shown in table 1. The notation in table 1 have the following meanings: SS- the area defined by one fixed value of pressure p/P0=0,200; SWET- the total area of the pores defined by the BET method (brunauer-Emmett-teller, BET-area); SMr- area of micropores with a diameter of about 1.7 nm; SAC- the total area defined by the curve of adsorption for pores with a diameter of 1.7 to 300,0 nm; SDC- the area defined by desorption curve for pores with a diameter of 1.7 to 300,0 nm; VS- the total volume of pores with a diameter less than 40,0 nm, determined at the fixed nitrogen pressure p/P0=0,950; VMr- the volume of micropores with a diameter of about 1.7 nm; VAC- the total volume of pores with a diameter from 1.7 to 300,0 nm, determined by adsorption curve; VDC- the total volume of pores with a diameter from 1.7 to 300,0 nm, determined by desorption curve; dWET- the average pore diameter of equal to 4·VS/SWET; dAnd- the average diameter of pores is calculated by the value of the m volume and square long obtained on the curve of adsorption, and equal 4·VAC/SAC; dD- the average diameter of pores, the calculated values of volume and square then received on the desorption curve and is equal to 4·VDC/SDC; P - pressure nitrogen, R0the pressure of the saturated nitrogen at 77 K.

As can be seen from table 1, the specific surface area of silica, obtained from the solution of the wells of the upper-Mutnovskaya geothermal power Plant, reaches 300 m2/g, porosity - 1.1 g/cm3the average diameter of the pores is a 12.7 to 16.6 nm. Area and volume of micropores in the samples geothermal silica was relatively small. The ratio of the area of micropores to the total area has been within 0,09-0,11, the ratio of the volume of the micropore and total pore volume of the samples even less of 0,005 0,009 (PL. 1).

Table 2 presents data on the dependence of the area and pore volume from diameter of the silica powder. As can be seen from table 2, the pore size of the silica sample are concentrated in a narrow range of small diameters. Differential distribution of volume in pore diameters has a maximum in the region of dp=30,4 nm, and the distribution of the square of the diameters is characterized by two friends and about the same peaks in the area of 12.6 and 9.1 nm (table. 2). For pores with diameters of dp=5,18-of 20.6 nm accounts for 71.1% of the total volume in pores with diameters of dp=5,18-26,5 nm - 79,8 volume, for pores with diameters of dp=5,18-40,0 nm to 88.3%. While 60.9% of the entire surface area accounted for by pores with diameters of dp=5,18-26,5 nm, and the pores with diameters of dp=5,18-40,0 nm - 76,4% of the total area.

The amount of silica, which can be precipitated from hydrothermal solution depends on the solution temperature in the hydrothermal reservoir. Original silicon is fed into the solution together with other compounds as a result of chemical interaction of water with aluminosilicate minerals rocks hydrothermal deposits at a depth of 1.0 to 3.5 km in the areas of thermal anomalies at elevated temperatures (250-350°C) and pressure (4,0-16,0 MPa and above).

At a temperature of 250-350°silicon is present in solution mainly in the form of individual molecules of orthosilicic acid, H4SiO4. The total content of Ctsilica SiO2in water under these conditions can be estimated from the solubility of quartz at 250-350°C. During movement on the surface in a productive wells the Plant, geothermal power station pressure and temperature of the solution is reduced and there is a separation of the solution on the steam and liquid phases. Consequently, on the surface of the aqueous solution becomes supersaturated relative to the solubility of amorphous silica, and the solution is evolving processes of nucleation and polymerization of silicic acid molecules by condensation of silanolate, the formation of siloxane linkages and partial dehydration.

As a result of nucleation and polymerization in solution are formed colloidal particles of hydrated silica mSiO2·nH2O with radii of 3-5 nm, and more. Part of the silanol SiOH groups on the surface of the particle dissociates with the removal of a proton (H+and the surface of the particle acquires a negative electric charge. Negative surface charge prevents coagulation of the particles due to the electrostatic forces of repulsion and ensures the stability of the colloidal silica in solution. After completion of the polymerization reaction and the formation of colloidal particles of colloid and Monomeric silica is at equilibrium, the concentration of Monomeric silica is equal to the solubility of amorphous silica. In addition to colloidal particles and molecules of silicic acid in the solution is present a small amount of ions orthosilicic acid (H3SiO4-H2SiO42-and macromolecule poly acids.

Currently, methods have been developed for extraction of hydrothermal fluid and the use of silica-containing material[1, 2, 3, 4]. For example, the method is similar is to use silica, precipitated by freezing dispersed hydrothermal solution, and the liquid for drinking, preparing sodium glass [4] (Kaspura V.N., Potapov V.V. Way to use geothermal silica for the manufacture of sodium water glass. RF patent №2186025, 2000). The claimed method allows the use of the sorption properties of the surface of precipitated silica, which expands the field of recycling of the material, increases the cost and increases the efficiency of hydrothermal fluid. The method eliminates the cost of expensive reagents in the production of traditional dispersed synthetic amorphous silicas, employees starting material for the preparation of sorbents for chromatography.

Example 1. Performed the experiments on the separation component of the mixture of organic compounds in two chromatographic columns, one of which is filled with silica, precipitated from hydrothermal fluid freezing method [1]and the second is industrially produced by the sorbent silochrome C-80. The fraction of particles silochrome C-80 was within 0,315-0.5 mm, specific surface area of powder - 80,0 m2/g, an average pore diameter of - 40,0-50,0 nm, specific pore volume of 1.3 cm3/, Both columns are equal in training and worked in parallel. The length of the columns was 1.8 m, an internal diameter of 2.0 mm, the mass of sorbent in the column, full of silochrome With-80 - of 4.67 g, column filled geothermal silica - 1,45, the Analyzed components loirevalley caretcolumn the carrier gas is helium, the helium flow through each column was 0.2 ml/sec, the temperature of the experiments was 130°C. For registration of chromatographic peaks was used a flame ionization detector, the flow rate of hydrogen in the detector was equal to 0.5 ml/s, the air flow rate of 5.0 ml/s

Table 3 shows the results of experiments to obtain the chromatographic peaks of isobutane and vapors of organic liquids: hexane, heptane, benzene, toluene, o-xylene. A pair of fluid received at the temperature of the evaporator 200°C. As can be seen from table 3, the retention time tReach more components in the column filled geothermal silica. Subsequent analysis of mixtures of these substances also showed greater retention time component for the column with silica derived from hydrothermal solution, pointing at his best separation ability in comparison with silochrome C-80.

Table 1

Size, surface area and pore volume of the samples of silica deposited from hydrothermal solutions
SSm2/g263,53
SWETm2/g274,64
SMrm2/g26,33
SACm2/g260,25
SDCm 2/g333,52
VScm3/g0,871
VMrcm3/g0,00827
VACcm3/g1,078
VDCcm3/g1,088
dWETnm12,692
dAnm16,575
dDnm13,058

Table 2

The volume and size depending on the diameter of the pores of the silica according to the adsorption analysis.
The pore diameter of dpnmThe mean diameter, nmPore volume, g/cm3The total pore volume, g/cm3The area then, m2/gThe total area of the pore, m2/g
333,0-125,1150,030,02380,02380,6350,635
125,1-88,9100,890,03330,0571of 1.3211,956
88,9-72,779,10,02840,08561,4383,394
72,7-40,0to 47.20,15390,239513.0316,42
4,0-26,5 30,40,16690,406521,9438,37
26,5-20,622,70,13030,536822,9061,27
20,6-16,718,20,11820,655025,9387,20
16,7-14,015,10,09600,751025,35112,55
14,0-11,612,60,10050,851631,89144,45
the 11.6-10,310,890,05500,9066on 20, 23164,68
10,3-at 8.369,110,07640,983133,57198,25
at 8.36-7,00at 7.550,04251,025722,55220,80
7,00-5,976,400,02431,050115,25236,06
5,97-5,185,520,01411,064210,24246,310
5,18-4,544,810,00791,07226,624252,93
4,54-was 4.024,240,00391,07613,760256,69
as 4.02-to 3.58of 3.770,00111,07731,226257,92
to 3.58-3,203,360,0000611,07740,072257,99
3,20-1,962,010,0000591,0774amount of 0.118258,11
1,96 is 1.861,910,000461,07790,963259,07
1,86-1,761,810,000531,07841,178260,25

Benzene
Table 3

Comparative retention time of different substances on columns with a length of 1.8 m and a diameter of 2.0 mm, filled with silica, precipitated from hydrothermal fluid, and silochrome C-80.
SubstanceThe volume of the sample, álRetention time (tR)
Silagra C-80Geothermal silica
Isobutane200,044 sec53,7 sec
Hexane0,11 min 11 sec1 min 30.2 sec
Heptane0,11 min 43 sec2 min 13 sec)
0,11 min 22,5 sec3 min of 22.3 seconds
Toluene0,12 min 26 sec6 min 33.5 sec
O-xylene0,14 min 36,9 sec13 min 08,7 sec

Literature

1. Potapov V.V., Kaspura NR. The method of extraction of amorphous silica from the hydrothermal fluid. RF patent №2186024, 2000.

2. Kaspura V.N., Potapov V.V. and other Method of electrochemical machining of hydrothermal fluid. RF patent №2185334, 2000.

3. Potapov V.V., Karpov G.A., Cooks C.O Method of deposition of silica from the hydrothermal fluid with simultaneous addition of lime and sea water. RF patent №2219127, 2002.

4. Kaspura V.N., Potapov V.V. Way to use geothermal silica for the manufacture of sodium water glass. RF patent №2186025, 2000.

The method of using amorphous silica, precipitated from the liquid phase of the hydrothermal fluid, characterized in that the silica is used as a sorbent for the chromatographic separation of organic liquid and gaseous substances by passing the carrier gas with a mixture of vapors of the analyzed substances through the bed of sorbent in a chromatographic column and receiving output from the column sequence eluruumid is komponentov, recorded as peaks.



 

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