RU1790434C - Filtering material for cleaning water - Google Patents

Abstract

The material is a porous molded honeycomb structure having a hydroxy group on the surface. It can be made of silicon nitride, on the surface of which various coagulants or sorbing substances are applied. 1 ill., 7 tab.

Description

The invention relates to methods for purifying natural and wastewater from various impurities by filtration through inorganic porous filter materials.

A filter material is known consisting of an elastic open-cell foam carrier in which adsorbent particles are located.

The disadvantage of the material is its short life due to the destruction of the material.

A known method for extending the life of a filter layer in a device for treating water by filtering it through a porous structure. To increase

the duration of operation, a protective layer is applied to the surface of the porous structure containing coarse particles, insoluble in water and fine particles of the binder. The presence of such a protective coating of particles of different sizes practically does not increase the dynamic resistance, but prevents the destruction of the filter material.

A filter medium for a liquid at high temperature is known, which is a sintered mass with an average pore diameter of 500 microns to 1 mm with a porosity of 15-40%. containing 100 mol.h. refractory substance (corundum, mullite, bauxite, etc.), 15-30 mol.h. binder

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(clay, alumina, silica, glass) and 0.1-1 mol.h. sintering accelerator (fluoride and lithium oxide).

A disadvantage of the material is its low throughput.

A known filter medium with increased throughput, having a volume and weight of 1.70-2.27 and an apparent porosity of 39-51%. The mass contains 100 m.h. spekshegos alumina, carbide or silicon nitride j ё-18 may.ch. inorganic binder and 3-15 parts by weight combustible material.

The material can be successfully used to clean hot liquid media, however, with respect to large volumes of water, it is not effective due to its low throughput.

A filter material for water is known, formed by carbon particles glued into a single block with a polymeric material, and a filter is mounted from the material. The filter consists of shells inserted one into another, the inner shell is formed by particles of an angle of 0.037-0.177 mm fastened to each other, and externally - by particles of an angle of 0.177-0.84 mm in size.

Known material, with good filtration efficiency and a satisfactory degree of water purification from organic substances, does not provide a high degree for heavy metals.

A porous synthetic biofilter loading material is known in the form of honeycomb plates with tetrahedral cells, two faces of which are inclined to the horizontal plane at an angle of 45 °.

The material is suitable for biological purification of water, and it does not provide a high degree of purification in water purification by filtration.

Ceramic filtering materials of a honeycomb structure for gas purification are known. A certain arrangement of channels in a ceramic honeycomb filter makes it possible to provide a high degree of purification of gases from mechanical impurities.

However, the known ceramic honeycomb gas filters do not provide a satisfactory degree of water purification from organic and inorganic impurities.

The closest in technical essence to the achieved result is a filtering material made of metal having a honeycomb structure with openings of adjustable size. Moreover, to obtain acceptable pressure losses on the material

sieve surfaces give a wavy or corrugated shape, and by coating the material with various metals in addition to the filtering effect

can be obtained adsorbing and catalytic.

The disadvantage of the material is insufficient throughput while providing a high degree of purification.

The aim of the invention is to increase the throughput of the filter material while providing a high degree of purification,

This goal is achieved by the proposed filtering material, which is an inorganic porous hydrostatic molded honeycomb structure material with a through void of at least 50% and having

0 surface of the hydroxo group, the material being selected from the group: titanium nitride, silicon nitride, aluminosilicates, silicates, cordierite, metals and their alloys and metal carbides.

5 A distinctive feature of the proposed material is that the use of an inorganic porous substance selected from the above group and molded in the form of a honeycomb

The structure with a certain through void provides, upon its contact with water, the appearance of free hydroxo groups on the surface of the filter material, which have a coagulating effect on the impurities in the water, which ensures a high degree of purification. The proposed structure of the material allows coagulated impurities to freely penetrate through it and

0 settle as a separable sediment. High throughput of the material and therefore a long service life is ensured by the fact that coagulated impurities do not clog the pores of the material and its

5 through void remains unchanged throughout the entire period of operation. The indicated properties of the claimed material make it possible to use it as a base for applying various types of selective coatings, such as metal, oxide, carbon, etc., which in turn will make it possible to use it for cleaning various types of impurities contained in water . These include various

5 suspensions, heavy metals, radionuclides, organic compounds.

The drawing shows a fragment of filter material (filter element) with a cutout for clarity of the honeycomb structure.

The filter element contains a ceramic carrier 1 made of silicon nitride materials (for detailed manufacturing technology see below), having through cells 2, the surface of which can be coated with various adsorbents and coagulants, depending on. type and chemical composition of purified impurities. The lateral non-filtering surface 3 is shaped in a form capable of interfacing (e.g., gluing) individual elements into filter units and systems. To achieve this goal, the through void of the filter element must be at least 50%.

The filter material is made as follows. Silicon nitride (Si3N4) powders obtained by the method of self-propagating high temperature synthesis (C B C) were used to obtain a honeycomb structure made of ceramic based on silicon nitride with a porous microstructure.

The characteristics of the powders are given in table. 1.

Powder A differs significantly from powder B in phase composition and morphology, while their chemical composition and dispersion are similar.

The particle size distribution of the starting powders is given in table. 2.

Compositions A1 and B1 are starting powders A and B, respectively, subjected to ultrasonic dispersion in acetone for 5 minutes. Compositions A2 and B2 were obtained from different fractions of powders A and B each, respectively, separately mixed in a ratio in a vibrating mixer (dry for 30 minutes). During the mixing of the fractions, a pore-forming additive, polyvinyl alcohol (PVA), which has a particle size distribution shown in Table 2, was introduced into the compositions.

Thanks to the use of a plasticizer, the powder for extrusion has the ability to flow under pressure and then maintain the shape and dimensions imparted by the forming tool. The plasticizer should not interact with the powder during the extrusion and heat treatment of the finished product, and should also be easily removed.

Organic substances are widely used as plasticizers for ceramic powders, the main characteristics of which are presented in Table. 3.

As a plasticizer in the manufacture of plastics from SisN4 powder, a petrolatum mixture of high molecular weight solid carbons (paraffins and cerazines) with a small oil residue was used. Binder components (oleic acid and wax) are added in small quantities to provide desired rheological characteristics depending on the morphology of the particles and the dispersion of the powder mixture.

The physical properties of the plasticizer components are summarized in table. 4.

The preparation of the compositions of the plastic mass was carried out in a vacuum mixer using an organic binder (petrolatum) at a temperature of 85 ° C for

5–4 hours. Extrusion was carried out by direct extrusion of a plastic mass from a steel container through a nozzle at a temperature of 26–34 ° С. The optimal technological parameters of the process of sample formation are summarized in table. 5.

Sintering of the samples was carried out in a vertical induction furnace in a graphite crucible in a stream of nitrogen at a temperature of 1800 ° C for 60 min. Characteristics /

5 of the porous structure of silicon nitride materials are given in table. 6.

After the manufacture of block carriers of a honeycomb structure, adsorbents and coagulants are applied on them, satisfying the basic requirements of a high specific surface and high adsorption capacity.

Coagulants and adsorbents were applied using the solution method. For

By applying, for example, alumina as a coagulant, for example, a suspension was prepared containing distilled water and a fine powder of alumina. In such a solution, the suspension is lowered

0 finished block and incubated for 5 minutes (first cycle), after which the blocks are dried at a temperature of 170 ° C. Then, the operation is repeated 8-10 times, after which drying is carried out at a temperature of 200 ° C for 1 hour, and then firing at a temperature of 700 ° C for 20 minutes. All subsequent operations with the deposition of coagulants and adsorbents were performed on a layer of an alumina substrate. Similarly, you can apply coagulant NT 0 iron oxide, antimony oxide. The application time for one cycle is 10 minutes, the number of cycles is 5-8, the drying temperature is 120-140 ° C, and the final firing temperature is 450 500 ° C. A suspension for application is prepared as follows. 0.856 kg of metallic iron, 6.251 kg of HMO3 (specific gravity 1.38) i / 7.751 kg of distilled water are heated at a temperature of 60 ° C to form a solution, then 5.65 kg of Pb20z are added. B a 15% solution is added to this mixture

NhUOH up to PH-2.5. This mass is heated with constant stirring for 20 minutes. The honeycomb block is lowered into such a suspension, kept for no more than 10 minutes and dried at a temperature of 120 ° C. The cycle is repeated 6-8 times, after which final firing is carried out at a temperature of 500 ° C.

High quality soot with a specific surface of 50 m / g was also used as an adsorbent. The suspension is prepared from distilled water and a weighed portion of soot. Application is carried out by immersion of the block in suspension for 5 minutes. The operation is carried out 8-10 times, followed by drying at a temperature of 100 ° C and final firing at a temperature of 350-400 ° C.

A laboratory unit was assembled from sections of honeycomb structures made by the above-described method, through which natural water was passed containing the following impurities: iron 0.76 mg / L, cadmium 6 μg / L, zinc 22 μg / L, lead 6.3 μg / l, manganese 87 μg / l, DDT 0.9 μg / l, HCH 1.5 μg / l, metaphos 0.6 μg / l, nitrates 78 mg / l, nitrites 0.24 mg / l, coli index in 1 liter of water 27, the total total / -activity is 5- Ci / l.

The main characteristics of the experiment and its results are summarized in table. 7.

In addition, laboratory tests of the effectiveness of the claimed

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filtering material during water purification from radionuclides. To this end, according to the technology described above, two types of honeycomb blocks with oxide of iron, aluminum, antimony and high-quality soot were made.

From the district of the river. Water with a high content of radionuclides was taken near Chernobyl: the concentration of cesium was 137 1.4 Ci / l, strontium -90 1.35 Ci / l. Honeycombs were placed in this water and kept Yusut. Gamma radiation was measured before immersion of the blocks and after 10 days of exposure in water. The activity of gamma radiation after exposure to water on the block with the soot adsorbent increased by 5.8 times, and on the block with alumina by 3.7 times, respectively, the radioactivity of the purified water decreased. For strontium-90, the use of an alumina block for water purification showed that the radioactivity of the latter decreased by 1.5 times.

The positive effect of the use of the proposed filter material is due to its high filtration and sorption characteristics, increased throughput, which allows high volumes of water to be cleaned with high quality per unit time, ensuring a long and effective operation of the filter material without regeneration.

Claims (2)

SUMMARY OF THE INVENTION 40 1. Filtering material for purifying water from impurities based on an inorganic hydrostatic substance, characterized in that; that, in order to increase throughput while ensuring a high degree of purification, it contains a porous molded cellular substance structures with a through voidness of at least 50%, having a hydroxo group on the surface. 2. The material according to p. 1, characterized in that it contains a substance selected from the group: titanium or silicon nitrides, aluminosilicates, silicates, cordierite, metals and their alloys, metal carbides. Table 1 table 2 Continuation of Table 2 Table 3 eleven 1790434 12 table 4 Table 5 Table 6 Continuation of Table 7 Continuation of Table 7