RU2034647C1 - Method and device for production of sorbent - Google Patents

Abstract

FIELD: purification of water. SUBSTANCE: sorbent is produced on base of natural limestone through grinding it to finely-dispersed state; then water is added to finely-dispersed powder of starting material and material is subjected to simultaneous action of hydrostatic pressure, ultrasound and electromagnetic field at frequency of electrophysical resonance of natural limestone; sorbent thus obtained is subjected to separation and drying; frequency of ultrasound and electromagnetic field is equal to 27.7 kHz at hydrostatic pressure of 450 atm. Device used for realization of this method has housing which is just hydraulic pressure chamber designed to create hydrostatic pressures of about 450 atm in which ultrasonic radiation and its excitation coil are placed in suspension of ground natural limestone. Excitation coil is made on base of insulated conductor which is simultaneously used as source of electromagnetic field at operating frequency of ultrasonic radiator. Hydraulic pressure chamber is provided with pressure-seal leads for furnishing the excitation signal from external generator tuned to frequency of electrophysical resonance of natural generator tuned to frequency of electrophysical resonance of natural limestone. Such sorbent may be used for purification of water in householding, food-processing and medical industry, as well as in technologically stressed production processes. Sorption capacity of activated sorbent exceeds that of starting limestone by three times. EFFECT: enhanced efficiency. 3 cl, 1 dwg, 1 tbl

Description

 The invention relates to ensuring environmental safety when treating water from radionuclides, pesticides and other common industrial pollutants.

 The proposed sorbent obtained by the method of electrophysical processing of environmentally friendly natural limestone is intended for the comprehensive purification of water from radioactive substances: strontium-90, cesium-137, the most toxic pesticides such as DDT and its derivatives, as well as polychlorobiphenyls.

A characteristic disadvantage of the known sorbents used to purify water from various technogenic pollutants is their selectivity with respect to sorbates. For example, a method of purifying water from radionuclides [1,2] where sorption of strontium is carried out on chabazite-type potassium zeolite with a certain ratio of SiО ₂ / Al ₂ O ₃ does not simultaneously sorb other technogenic pollutants, for example pesticides [3] In some cases, for purification waters use natural limestone (92-94%) CaCO ₃ , but in its natural form limestone has a small sorption capacity and also quite low versatility with respect to sorbates [4] Preparation of the sorbent according to the known method consists in grinding it to obtain finely dispersed state, which significantly increases its sorption capacity. Grinding can be carried out by any means available. However, grinding even to a powder state is not universal enough, which significantly limits the field of practical application of this sorbent.

 The technical result of the proposed method and device for its implementation is to eliminate the noted disadvantages of the known method by increasing the sorption capacity and versatility of the sorbent obtained on the basis of natural limestone.

This is achieved as follows. A suspension of finely divided powder of natural limestone in water with a mass concentration of 0.25-0.75 g / cm ^{3 is} placed in a pressure chamber, where it is subjected to complex electrophysical treatment for 1-3 min, providing for simultaneous exposure to hydrostatic pressure of 450 atm, ultrasound and electromagnetic field at the frequency of electrophysical resonance of limestone, followed by separation and drying. Such a complex effect causes a chain reaction in the source material to form additional active sorption centers, which leads to a significant increase in the sorption capacity of the sorbent, as well as a simultaneous increase in its versatility with respect to sorbates due to the dipole distribution of active centers, which contributes to sorption of both positive and negative pollutant ions.

 The essence of electrophysical processing is as follows.

·

(1) где α коэффициент поглощения звука;
ω круговая частота звуковой волны;
τ время релаксации;
С_о и C₁ скорости звука, зависящие от приложенного гидростатического давления при ωτ << 1 и ωτ > 1 соответственно, что вызывает образование кавитационных полостей, которые пульсируют, расширяясь в фазе разрежения и схлопываясь в фазе повышенного давления. При этом на частицы исходного материала, находящиеся в кавитационной области, действуют переменные давления, достигающие на частотах 20-30 кГц порядка нескольких тысяч МПа.Under the influence of ultrasonic vibrations on a suspension of finely divided powder of the starting material, relaxation sound absorption occurs, which is determined by the expression
α

·

(1) where α is the sound absorption coefficient;
ω circular frequency of the sound wave;
τ relaxation time;
C _o and C _{1 the} speed of sound, depending on the applied hydrostatic pressure at ωτ << 1 and ωτ> 1, respectively, which causes the formation of cavitation cavities that pulsate, expanding in the rarefaction phase and collapse in the phase of increased pressure. In this case, the particles of the source material located in the cavitation region are affected by variable pressures reaching at the frequencies of 20-30 kHz about several thousand MPa.

(C $\genfrac{}{}{0ex}{}{\text{2}}{\text{1}}$ -C $\genfrac{}{}{0ex}{}{\text{2}}{\text{o}}$ )

f(ωτ)

ωτ

0
1 + ω²τ²-2ω²τ² 0;
ω²τ²=1 отсюда имеем ωτ 1 (2)
Для природного известняка резонансная частота составляет
ω_р 27,7 кГц.The pressures increase by several orders of magnitude upon the occurrence of electrophysical resonance, the onset of which can be found from the equation of the first derivative, differentiating the variable part of the expression (1)
α

(C $\genfrac{}{}{0ex}{}{\text{2}}{\text{1}}$ -C $\genfrac{}{}{0ex}{}{\text{2}}{\text{o}}$ )

f (ωτ)

ωτ

0
1 + ω ² τ ² -2ω ² τ ² 0;
ω ² τ ² = 1 from here we have ωτ 1 (2)
For natural limestone, the resonance frequency is
ω _p 27.7 kHz.

 The existence of resonance is proved analytically (2). The value of this frequency is determined experimentally on an electrophysical setup by the method of successive approximation.

 Cavitation collapses additionally disperse the solid phase of the material and lead to the transformation of its molecular structure with the release of atomic and ionized components. For exposure to the simultaneously applied electromagnetic field, redistribution of charges and the formation of additional active electrical sorption centers of a dipole nature occur.

(3) где Z количество дополнительных центров сорбции;
K₁ константа в зависимости от характера взаимодействия сорбент-сорбат;
К₂ константа в зависимости от электрофизического воздействия.In this case, the Brunauer-Emmett-Teller sorption parameter has the form

(3) where Z is the number of additional sorption centers;
K ₁ constant depending on the nature of the interaction of the sorbent-sorbate;
K ₂ constant depending on the electrophysical effects.

(4)
Отношение θ_Z=

/θ_Z=0 дает количественную оценку тенденции повышения сорбционной емкости сорбента, получаемого по предлагаемому способу.In the absence of additional active sorption centers (Z = 0), expression (3) is reduced to the well-known Langmuir formula
θ _{Z = 0}

(4)
The relation θ _Z =

/ θ _{Z = 0} gives a quantitative assessment of the tendency to increase the sorption capacity of the sorbent obtained by the proposed method.

For example, at K 0.25, K = 1 and Z = 3, the sorption capacity of the starting material increases by 4.2 times. In addition, the dipole distribution of additional active sorption centers, due to the action of the electric component of the electromagnetic field, provides sorption of both positive and negative pollutant ions, significantly increasing the versatility of the use of the sorbent with respect to sorbates. The proposed sorbent retains its properties at ultra-high (up to 2 ˙ 10 ⁷ rad) doses of gamma radiation.

 The table shows the experimental data of a comparative verification of the effectiveness of sorbents on the example of the purification of tap water with previously added pollutants (the content of radionuclides 2 kBq / l, pesticides 0.25 g / l).

 The sorption properties of the sorbents are represented by a purification coefficient determined by the ratio of the specific radioactivity of the initial solution and the filtrate.

 When working with pesticides, standards of toxic chemicals labeled with C-14 radioactive carbon were introduced into the aqueous solution. The coefficient of water purification from pollutants such as polychlorobiphenyls (PCBs)) was determined by gas chromatography of an aqueous mixture. An American standard of the arachlor-54 type was introduced into the mixture, followed by extraction.

 Sorption was carried out under normal environmental conditions, the consumption of sorbents was 2.5 g per 1 liter of purified water. The grain size of the sorbents was 1 μm.

 From the table it is seen that the sorbent obtained by the proposed method has a significantly larger sorption capacity (more than 3 times) and the versatility of practical application, which corresponds to the purpose of the proposed invention.

 A device for implementing the proposed method for producing a sorbent is a pressure chamber chamber designed to generate hydrostatic pressures of the order of 450 atm, where an ultrasonic emitter and its excitation coil, made on the basis of an insulated conductor and at the same time a source of electromagnetic field, are placed in a suspension of fine powder of natural limestone the frequency of operation of the ultrasonic emitter.

 The housing contains pressure glands for supplying an excitation signal from an external generator tuned to the frequency of electrophysical resonance of limestone (27.7 kHz). The power of the ultrasonic emitter is selected from the calculation of 1000 W / l of the working medium. The duration of the electrophysical treatment is 1-3 minutes. Then the resulting sorbent is subjected to separation and drying.

 The drawing shows a structural diagram of a device for producing a sorbent based on natural limestone.

 It has a compressor pressure chamber housing 1, an input channel for supplying source material 2, a compressor 3, a nozzle 4, an excitation generator of an ultrasonic emitter 5, a pressure seal 6, an excitation coil of an ultrasonic emitter, which is at the same time an electromagnetic field source, an ultrasonic emitter 8, an output channel of activated material 9, a centrifuge 10, a drying chamber 11, a storage hopper 12.

 A suspension of finely divided powder of natural limestone in water through a previously open valve 2 is fed into the internal cavity of the pressure chamber 1. After that, valve 2 closes. The compressor 3 is connected, connected to the housing 1 by a high-pressure fitting 4. According to the condition of reaching 450 atm in the interior of the pressure chamber, compressor 3 is turned off. In this case, the excitation frequency generator of the ultrasonic emitter 5 is turned on. The excitation signal of the external generator 5 through the electrical conductors through the pressure glands 6 integrated in the housing 1 is fed to the excitation coil of the ultrasonic emitter 7 made of an insulated conductor, then to the ultrasonic emitter 8 itself. 7, generating an electromagnetic field, and an ultrasonic emitter 8 are located inside the housing 1 directly in the environment of the source material. Thus, the starting material is subjected to the simultaneous effect of hydrostatic pressure, as well as ultrasound and electromagnetic fields at the frequency of electrophysical resonance of natural limestone. At the end of 1-3 minutes, the generator 5 is turned off. Then the activated material through the outlet valve 9 enters the centrifuge 10 and the drying chamber 11 connected in series by the product pipeline, and then into the storage hopper 12. After that, the outlet valve 9 closes and the device returns to its original state.

 Such a sorbent can be successfully used for individual water purification at home, for the needs of the food and medical industries, as well as used in environmentally intensive technological processes.

Claims (2)

 1. A method of producing a sorbent for water purification based on natural limestone, including grinding it to a finely divided state, characterized in that a suspension of finely dispersed powder of natural limestone in water is subjected for 1 to 3 minutes to the simultaneous effect of hydrostatic pressure of 450 atm, as well as ultrasound and electromagnetic fields at the frequency of electrophysical resonance of limestone, followed by separation and drying.  2. A device for producing a sorbent based on natural limestone, comprising a housing, characterized in that the device is equipped with an ultrasonic emitter with an excitation coil made of an insulated conductor and placed inside the housing, as well as hermetic inputs integrated into the housing from an external generator tuned to a frequency electrophysical resonance of limestone.

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