Study of the sorption of dyes on titanium dioxide. Basic research. Being in nature

Titanium dioxide. Properties, application. Methods of obtaining.

Pure titanium dioxide (TiO2) is a colorless crystalline solid. Although colorless, in large quantities titanium dioxide is an extremely effective white pigment if it is well purified. TiO2 practically does not absorb any incident light in the visible region of the spectrum. Light is either transmitted or refracted through the crystal or reflected on surfaces.

TiO2 is a stable (the most stable of all known white pigments), non-volatile, insoluble in acids, alkalis and solutions under normal conditions. Titanium dioxide is characterized by high reaction resistance to various compounds, including toxic ones, contained in the air. Because of its inertness, titanium dioxide is non-toxic and is generally considered a very safe substance. It can come into contact with packaged foods, and in certain concentrations it can also be used as a food coloring.

TiO2- polymorphic and occurs in three main crystalline forms. There are three forms, anatase (octahedrite), rutile and brookite, the latter is rare in nature and, although this form is prepared in laboratories, it is of no commercial interest.

Rutile dioxide is approximately 30% better at scattering light (hiding power) than anatase dioxide, so the latter is used much less frequently. In addition, anatase is less weather resistant than rutile. Anatase works much worse in protecting the polymer (acrylate, plastic) from UV rays and leads to photocatalysis and loss of polymer properties (destruction, fading, chalking, etc. occurs).

Dispersive power

the ability of a pigment to reflect light from the visible part of the spectrum at certain wavelengths. This indicator for titanium dioxide directly depends on the diameter of TiO2 particles. At a particle size of 0.2 µm, the sum of scattered light for all wavelengths is maximum. As the particle size increases from 0.25 to 0.3 µm, the scattering of blue light decreases rapidly. But the scattering of green and red remains virtually unchanged. However, at a particle diameter of 0.15 µm there is maximum blue scattering, while red and green scattering are significantly lower.

Oil capacity

This is the ability of pigment particles to hold a certain amount of oil on their surface. It is expressed in grams per 100 grams of pigment and usually ranges from 10 to 20.

Covering power

the ability of a pigment to make color invisible when evenly distributed in volume source material. Hiding power is expressed in grams of pigment required to make the color of a surface area of ​​1 m2 invisible. White pigments provide coverage by scattering light wavelengths of any length in the visible spectrum. The lower this indicator is, the lower the consumption rate of titanium dioxide in the composition.

Color

the property of bodies to cause a certain visual sensation in accordance with the spectral composition and intensity of the visible radiation reflected or emitted by them. Dry titanium dioxide is characterized by high brightness, whiteness and its reflectivity is close to that of an ideal diffuser.

Lightfastness

the property of a material to retain its color when exposed to light rays. During operation, products, especially for outdoor use, change their original color under the influence of ultraviolet rays from natural light and artificial lighting sources emitting ultraviolet rays.

Weather resistance

the property of polymer compositions to resist the destructive effects of sunlight, rain, frost, snow, wind and other atmospheric factors (for example, gases and dust that pollute the lower layers of the atmosphere).

Surface treatment is necessary to increase resistance to external influences. Inorganic (Al2O3, SiO2) increases the resistance of titanium dioxide particles to acid attack, which can lead to the destruction of pigment particles. Organic treatment improves the distribution of pigment particles throughout the composition.

Physical properties of titanium dioxide

Pure titanium dioxide is a colorless crystalline substance that turns yellow when heated. In a finely crushed state it is a white powder. Practically insoluble in water and mineral acids, except hydrofluoric and concentrated sulfuric acid. Melting point for rutile: 1870°C. Boiling point for rutile: 2500°C. Density at 20°C for rutile: 4.235 g/cm3.

Chemical properties of titanium dioxide

Titanium dioxide is an amphoteric oxide, that is, it exhibits both acidic and basic properties.

Reacts slowly with concentrated sulfuric acid, dissolving in it to form the corresponding sulfate:

TiO2+ 2H2SO4 = Ti(SO4)2 + 2H2O

Also, titanium dioxide gradually dissolves in concentrated solutions alkalis, for example, in sodium hydroxide, forming titanates (derivatives of titanic acid):

TiO2 + 2NaOH = Na2TiO3+ H2O

When titanium dioxide is heated in an ammonia atmosphere, titanium nitride is formed:

4TiO2 + 4NH3 = 4TiN + 6H2O + O2

Strong reducing agents, such as active metals (Ca, Mg, Na), carbon or hydrogen at high temperature Titanium dioxide is reduced to lower oxides. When heated with carbon in a chlorine atmosphere, titanium tetrachloride TiCl4 is formed - this technique is used on an industrial scale to purify titanium from various types of impurities.

Toxic properties of titanium dioxide

Being chemically inert, titanium dioxide is a low-hazard substance. It can enter the body in the form of an aerosol through inhalation or ingestion.

Applications

Paint and varnish materials:

decorative, architectural paints; emulsion semi-matte paints; emulsion gloss paints; primers, substrates, putties; Solvent based paints – glossy; plaster solutions; silicate paints; coatings for wood materials; cement plaster mortar; industrial paints; plaster based on synthetic resins; polymer coatings; paints for repair work; fine-grained powder paints; uv / uv - curable paints; paints cured with acid hardener; powder coatings; polyurethane coatings; epoxy coatings; paints for road markings; paints for marine coatings; highly filled paints; electrodeposited paints; printing inks.

Plastics:

high-strength polyvinyl chloride (for indoors); rubber; thermoplastic; thermosetting plastic; plastics based on unsaturated polyesters; elastomers, rubber; floor coverings (linoleum)

Paper and cardboard:

paper coverings; wallpaper; paraffin paper; colored paper

Synthetic fibers/fabrics:

for matting twisted fibers

Cosmetics:

toothpaste, soap, etc.

Food industry:

caramel, chewing gum, powdered and refined sugar, frog legs, chicken, pork and beef tongues, suckling pigs, flour, dough, sugar glaze, jams, milkshakes, feta cheese, whey, condensed milk, any fish and seafood products, etc. d.

Pharmaceutical industry:

pigment titanium dioxide, high chemical purity, to give high whitening and hiding effect in pharmaceuticals.

Printing ink:

to increase the resistance of coatings to atmospheric influences

Catalyst:

Titanium dioxide can be used as a catalyst, as a photocatalyst and as an inert ceramic base material for active components.

Other areas of use:

wood preservation (increasing weather resistance using optical filtration of solar radiation harmful to wood), filling rubber, glass enamels, glass and glass ceramics, electroceramics, air purification, welding fluxes, hard alloys, chemical intermediates, materials containing titanium dioxide, suitable for use at high temperatures (for example, fire protection for forced draft furnaces), analytical and experimental chromatography of liquids, decorative concrete (to give whiteness to cement paint)

Main uses of titanium dioxide:

manufacturers of paints and varnishes, in particular titanium white - 57% of total consumption (titanium dioxide of the rutile modification has higher pigment properties - light fastness, whitening ability, etc.)

plastic production - 21%

production of laminated paper - 14%

Other uses of titanium dioxide are in the production of rubber products, glass production (heat-resistant and optical glass), as a refractory (coating of welding electrodes and coatings of casting molds), in cosmetics (soap, etc.), in the food industry (food additive E171 ).

Titanium dioxide can be used to make solar cells - transformation sunlight into electricity; for hydrogen production; in the field of electronics for pseudo-capacitors, etc.

Methods of obtaining

Titanium dioxide pigments exist in two forms - anatase and rutile and are produced according to two technological schemes: sulfate and chlorine methods.

Compared to the sulfate chloride method, it is more environmentally friendly and advanced due to the ability to carry out the process in a continuous mode, which implies complete automation of production. However, it is selective in raw materials, and due to the use of chlorine and high temperatures, it requires the use of corrosion-resistant equipment.

Chlorine method:

The chlorine method for producing titanium dioxide is that the starting raw material (semi-finished product) is titanium tetrachloride. Titanium dioxide can be obtained from it by hydrolysis or combustion at high temperatures. Titanium tetrachloride hydrolyzes when aqueous solutions are heated, or in the gas phase under the influence of water vapor.

Sulfate method:

The production technology consists of three stages:

obtaining titanium sulfate solutions (by treating ilmenite concentrates with sulfuric acid). As a result, a mixture of titanium sulfate and iron (II) and (III) sulfates is obtained, the latter is reduced with metallic iron to the oxidation state of iron +2. After recovery, sulfate solutions are separated from the sludge using drum vacuum filters. Iron(II) sulfate is separated in a vacuum crystallizer.

hydrolysis of a solution of titanium sulfate salts. Hydrolysis is carried out by introducing seeds (they are prepared by precipitating Ti(OH)4 from solutions of titanium sulfate with sodium hydroxide). At the hydrolysis stage, the resulting particles of hydrolyzate (titanium dioxide hydrates) have a high adsorption capacity, especially in relation to Fe3+ salts; it is for this reason that at the previous stage, ferric iron is reduced to divalent. By varying the hydrolysis conditions (concentration, duration of stages, number of embryos, acidity, etc.), it is possible to achieve the yield of hydrolyzate particles with desired properties, depending on the intended application.

heat treatment of titanium dioxide hydrates. At this stage, by varying the drying temperature and using additives (such as zinc oxide, titanium chloride and using other methods, rutilization can be carried out (that is, the restructuring of titanium oxide into the rutile modification). For heat treatment, rotary drum furnaces 40-60 m long are used. During heat treatment, water evaporates (titanium hydroxide and titanium oxide hydrates are converted to the form of titanium dioxide), as well as sulfur dioxide.

Production titanium dioxide

In recent years, titanium dioxide production in China has been growing extremely rapidly.

In Russia, pigment titanium dioxide is not produced, but technical grades used in metallurgy are produced. In the CIS, titanium dioxide is produced in Ukraine by the enterprises "Sumykhimprom", the city of Sumy, "Crimean Titan", Armyansk) and the enterprise "Titanium-Magnesium Plant" (Zaporozhye). The Sumy State Institute of Mineral Fertilizers and Pigments (MINDIP) in its research works pays special attention to technologies for producing titanium (IV) oxide by the sulfate method: research, development of new grades, modernization of technology and instrumentation of the process.

Being in nature

In its pure form, it is found in nature in the form of the minerals rutile, anatase and brookite (in structure, the first two have a tetragonal system, and the latter - an orthorhombic system), with the main part being rutile.

The world's third largest deposit of rutile is located in the Rasskazovsky district of the Tambov region. Large deposits are also located in Chile (Cerro Bianco), the Canadian province of Quebec, and Sierra Leone.

In the modern world, the titanium industry is developing rapidly. It is the source of a large number of substances that are used in various industries.

Characteristics of titanium dioxide

Titanium dioxide has many names. It is an amphoteric oxide of tetravalent titanium. It plays an important role in the development of the titanium industry. Only five percent of titanium ore goes into the production of titanium oxide.

There are a large number of modifications of titanium dioxide. In nature, there are titanium crystals that have the shape of a rhombus or a quadrangle.

Titanium dioxide formula is presented as follows: TiO2.

Titanium dioxide is widely used in various industries. He is known all over the world as such food additives, like E-171. However, this component has a number of negative effects, which may indicate that titanium dioxide is harmful to the human body. This component is known to have whitening properties. This can be good in the production of synthetic detergents. The harm to the human body from this dietary supplement poses a threat to the liver and kidneys.

IN food industry There is a possibility of harm from titanium dioxide. If it is used in excess, the product may acquire an undesirable shade, which will only repel consumers.

Titanium dioxide has enough low level toxicity.

It may become toxic when interacting with other components of any product. Using products containing high levels of toxins can lead to poisoning or even death. Therefore, it is very important to know which elements you should not use titanium oxide with.

Properties of titanium dioxide

Titanium dioxide has a large number of characteristic properties. They determine the possibility of its use in various industries. Titanium dioxide has the following properties:

• excellent degree of whitening various types materials,
• interacts well with substances that are intended to form a film,
• resistance to high level humidity and environmental conditions,
• low level of toxicity,
• high level of resistance from a chemical point of view.

Preparation of titanium dioxide

More than five million tons of titanium dioxide are produced annually in the world. For lately China has greatly increased its production. The world leaders in the production of this substance are the USA, Finland, and Germany. It is these states that have great opportunities to obtain this component. They export it to different countries peace.

Titanium dioxide can be obtained by two main methods:

1. Production of titanium dioxide from ilmenite concentrate.

In production plants, the process of obtaining titanium oxide is thus divided into three stages. At the first of them, ilmenite concentrates are processed using sulfuric acid. As a result, two components are formed: ferrous sulfate and titanium sulfate. Then it increases the level of iron oxidation. Special filters separate sulfates and sludge. At the second stage, titanium sulfate salts are hydrolyzed. Hydrolysis is carried out by using seeds from sulfate solutions. As a result, titanium oxide hydrates are formed. At the third stage, they are heated to a certain temperature.

2. Production of titanium dioxide from titanium tetrachloride.

In this type of obtaining a substance, there are three methods, which are presented:

• hydrolysis of aqueous solutions of titanium tetrachloride,
• vapor-phase hydrolysis of titanium tetrachloride,
• heat treatment of titanium tetrachloride.

Table. Manufacturers of titanium dioxide.

Enterprise	Production volumes, thousand tons
DuPont Titanium Technologies	1150
National Titanium Dioxide Co	n/a
Ltd. (Cristal)	705
Huntsman Pigments	659
Tronox, Inc.	642
Kronos Worldwide, Inc.	532
Sachtleben Chemie GmbH	240
Ishihara Sangyo Kaisha, Ltd	230

IN modern world Titanium oxide is actively used in various industries.

Titanium dioxide has the following uses:

• Production of paint and varnish products. In most cases, titanium white is produced based on this component.
• use in the production of plastic materials.
• production of laminated paper,
• Production of cosmetic decorative products.

Titanium oxide has also found wide application in the food industry. Manufacturers add it to their products as one of the components of food-type dyes. It is practically not noticeable in food products. Manufacturers add it to minimum quantities so that their products are better stored and have an attractive appearance.

JOURNAL OF PHYSICAL CHEMISTRY, 2015, volume 89, no. 1, p. 133-136

PHOTOCHEMISTRY AND MAGNETOCHEMISTRY

UDC 544.526.5+549.514.6.352.26

PHOTOCATALYTIC ACTIVITY AND SORPTION PROPERTIES OF CALCIUM MODIFIED TITANIUM DIOXIDE © 2015 T.A. Khalyavka, N.N. Tsyba, S.V. Kamyshan, E.I. Kapinus

National Academy of Sciences of Ukraine, Institute of Sorption and Endoecology Problems, Kyiv

Email: [email protected] Received by the editor 02/05/2014

Mesoporous samples of titanium dioxide modified with calcium have been synthesized. Their structural, photocatalytic and sorption properties were studied. It has been established that the modified samples differ from titanium dioxide in their characteristics and properties: the specific surface area and average pore volume increase, and the average pore radius decreases; photocatalytic and sorption activity towards dyes and dichromate anion increases.

Key words: titanium dioxide, calcium, photocatalysis, sorption, dyes, dichromate anion. DOI: 10.7868/S0044453715010124

In the photocatalytic method of purifying aqueous solutions from toxic substances, in most cases titanium dioxide is used, which is a cheap and non-toxic catalyst. In addition, after the completion of the reaction, it can be easily separated from the solution by filtration or centrifugation. Currently, photocatalytic methods for removing harmful substances from aqueous solutions using titanium dioxide are becoming increasingly important.

The main disadvantage of this photocatalyst is its insufficiently high activity. Known various methods increasing its photoactivity, for example, by increasing substrate adsorption or increasing the kinetic rate constant. Adsorption can be increased by increasing the specific surface area, monolayer capacity and pore volume, and the kinetic rate constant by separating charges and reducing the recombination rate of the electron-hole pair.

The purpose of the work is to obtain and study samples of titanium dioxide modified with calcium citrate method, which are characterized by a high specific surface area, mesoporous structure and increased photocatalytic activity in the reactions of destruction of dyes and photoreduction of the bichromate anion.

EXPERIMENTAL

To obtain titanium dioxide samples modified with calcium using the citrate method

initial mixtures were prepared: tetrabutoxy titanium (IV) polymer (Aldrich) (3 g), citric acid (0.06 g), glycerin (2 ml), as well as calcium chloride additives - 0.05 g, 0.1, 0.2, 0.5 and 1 g, respectively, the obtained samples are designated as 1Ca/1O2, 2Ca/1O2, 3Ca/1O2, 4Ca/1O2, 5Ca/1O2. To obtain pure titanium dioxide, we took the same mixture, but without the addition of calcium chloride salt. This synthesis method makes it possible to easily vary the ratios of components in the samples.

The mixtures were calcined at 500 °C for 2 hours in the presence of atmospheric oxygen in a muffle furnace at a heating rate of 2 K/min. After cooling, the resulting powders were thoroughly ground until a homogeneous mass was obtained.

X-ray phase analysis was performed on a DR0N-4-07 diffractometer (Russia) with Cu^ radiation (with a copper anode and a nickel filter) in a reflected beam and registration geometry according to Breguet-Brentano (2© = 10-70°). The average crystallite size was determined by the broadening of the most intense band using the Debye-Scherrer equation: D = 0.9X/(B x cos©), where 0.9 is a constant, X is the wavelength, nm. The crystallite sizes were determined from the most intense peaks characteristic of anatase.

The specific surface area of ​​the samples 05ud), as well as the pore distribution, were determined using a Quantachrom NovaWin2 device. The specific surface area of ​​the samples (Ssp) was determined by the Brunauer-Emmett-Teller (BET) method using nitrogen sorption-desorption isotherms. The pore radius (R) as well as the pore volume (V) were calculated from the desorption branches of the isotherms using the Barret-Joyner-Halenda method.

HALYAVKA, etc.

Rice. 1. Diffraction patterns of the obtained samples: 1 - TiO2, 2 - 3Ca/TiO2, 3 - 5Ca/TiO2. For other designations, see text.

Rice. Fig. 2. Nitrogen sorption-desorption isotherms obtained at 20°C for samples: 1 - 5Ca/TiO2, 2 - 4Ca/TiO2, 3 - 3Ca/TiO2, 4 - TiO2.

Photocatalytic activity was studied using the example of model reactions of destruction of the dyes safranin T and rhodamine, as well as photoreduction of the dichromate anion in aqueous solutions with a photocatalyst content of 2 g/l of solution. Irradiation was carried out with a BUV-30 mercury lamp with a radiation maximum at 254 nm at room temperature in a cylindrical quartz reactor equipped with an electrically driven mechanical stirrer. The change in dye concentration was monitored spectrophotometrically (Lambda 35, PerkinElmer Instruments).

DISCUSSION OF RESULTS

The crystal structure of the samples was studied using X-ray phase analysis (Fig. 1). The diffraction patterns of all samples contain intense, clearly defined reflections characteristic of the anatase crystal lattice (A). Thus, in the diffraction pattern of the dioxide sample

Table 1. Sample characteristics

Sample Bud, m2/g Ksr, cm3/g Gsr, nm

TiO2 43.4 0.13 5.89

1Ca/TiO2 46.7 0.13 5.4

2Ca/TiO2 71.2 0.14 4.8

3Ca/TiO2 75.3 0.15 4.1

4Ca/TiO2 83.9 0.18 4.25

5Ca/TiO2 76.2 0.19 5

Designations: Bud - specific surface area, Usr - average pore volume, gsr - average radius.

Titanium shows the presence of intense peaks 20 = 25.5, 37.8, 54.0, 55.0, which are attributed to the anatase phase (Fig. 1).

The work states that in titanium dioxide powders modified with various alkaline earth metal ions, only the anatase phase is present, which the authors explain by the low content of modifiers in their samples. In contrast to this work, in our case (Fig. 1) peaks 20 = 27.4, 41.2 were also detected, which belong to the rutile (P) phase.

For modified samples, peaks are observed at 20 = 31, which are characteristic of brookite (B). Their intensity increases with increasing calcium content in the powders. The same peaks were found by the authors for TiO2 films modified with calcium ions.

The crystallite sizes in titanium dioxide agglomerates, calculated using the Debye-Scherrer equation, are 9 nm; in the case of modified samples, their value increases to 12.4 nm, which is consistent with literature data, since the presence of modifiers accelerates the crystallization of titanium dioxide and leads to an increase in size crystallites.

The study of nitrogen sorption-desorption isotherms obtained at 20°C for the synthesized samples showed the presence of a hysteresis loop (Fig. 2), which indicates the mesoporous structure of the powders.

The specific surface area of ​​the modified samples doubles compared to pure titanium dioxide (Table 1). In the series of samples from TiO2 to 5Ca/TiO2 (Table 1), the value of the average pore volume increases from 0.13

PHOTOCATALYTIC ACTIVITY

to 0.19 cm3/g, and the average pore radius, on the contrary, decreases from 5.89 to 5 nm. The pore size distribution area is shown in Fig. 3. As can be seen, for samples 4Ca/TiO2 and 3Ca/TiO2 a narrower distribution of pores is observed than for pure titanium dioxide and a sample with the largest number calcium - 5Ca/TiO2.

To determine the optimal conditions for the destruction of toxic substances in aqueous solutions, it is important to study the kinetics of their sorption on photocatalysts. It was found that the sorption equilibrium in the photocatalyst - safranin T system was established in approximately 1 hour, and for the photocatalyst - rhodamine and photocatalyst - potassium bichromate systems in 2 hours.

The studies carried out showed that for all the studied adsorptive agents and adsorbents, the kinetic adsorption curves have the usual smooth character: a smooth course and small adsorption values ​​(Table 2).

In all studied cases, the photocatalytic reaction is satisfactorily described by a first-order kinetic equation.

To determine the optimal amount of photocatalyst in the studied reactions, their concentration was increased while the substrate concentration remained unchanged. It was found that at a low concentration of photocatalyst (<2 г/л) наблюдается рост констант скорости деструкции красителей и фотовосстановления бихромат-аниона с увеличением содержания фотокатализатора в растворе с последующим выходом на плато при концентрациях фотокатализатора вблизи 2 г/л. Все последующие фотокаталитические реакции проводили при концентрации фотокатализатора 2 г/л.

In the series from 1Ca/TiO2 to 4Ca/TiO2, an increase in photocatalytic activity in dye destruction reactions is observed (Table 2). Thus, the rate constant of photocatalytic destruction of safranin T increases from 3.5 to 5.7 x 10-4 s-1, rhodamine - from 1.7 to 2.5 x 10-4 s-1. Similar data were obtained by the authors for samples

Rice. Fig. 3. Pore size distribution for synthesized samples: 1 - 4Ca/TiO2, 2 - 3Ca/TiO2, 3 - 5Ca/TiO2, 4 - TiO2; r - pore radius, Ktot. - total pore volume.

titanium dioxide doped with calcium ions using the sol-gel method and calcium titanate in the work.

In addition, in the series of samples from 1Ca/TiO2 to 4Ca/TiO2, their sorption capacity towards dyes increases (Table 2), which is associated with their structural characteristics (Table 1). The 5Ca/TiO2 sample, compared to the 3Ca/TiO2 and 4Ca/TiO2 powders, has significantly lower sorption and photocatalytic activity towards dyes.

In the case of photoreduction of the dichromate anion, the 5Ca/TiO2 sample turned out to be the most photocatalytically active (kA = 3.9 x 104, s-1), which is consistent with the work in which it was found that the addition of calcium titanate to titanium dioxide

Table 2. Photocatalytic k x 104, s 1) and sorption (adsorption value A, mg/g) activity of titanium dioxide samples modified with calcium in relation to dyes and dichromate anion

Sample Safranin T Rhodamine Bichromate anion

ky x 10-4, s"1 A x 10 4, mg/g ky x 10-4, s"1 A x 10 4, mg/g ky x 10-4, s"1 A x 10-6, mg /G

BELIKOV M.L., LOKSHIN E.P., SEDNEVA T.A. - 2012

DEPENDENCE OF THE RATE OF PHOTOCATALYTIC DESTRUCTION OF SAFRANIN ON THE CONCENTRATION OF THE CATALYST

KHALYAVKA T.A., VIKTOROVA T.I., KAPINUS E.I. - 2009

KINETICS OF PHOTOCATALYTIC DESTRUCTION OF ORGANIC COMPOUNDS: INFLUENCE OF SUBSTRATE AND CATALYST CONCENTRATIONS

KAPINUS E.I. - 2012

UDC 677.077.62

M. A. Salyakhova, I. Sh. Abdullin, V. V. Uvaev, E. N. Pukhacheva

STUDY OF ADSORPTION PROPERTIES OF COMPOSITE MATERIALS

WITH IMPROVED TITANIUM DIOXIDE

Key words: composite material with embedded titanium dioxide, titanium dioxide, silicon dioxide, sorption,

adsorption properties.

The adsorption properties of a photocatalytic composite material are assessed by two indicators: the equilibrium value of sorption of saturated benzene and ethyl acetate vapors by material samples and the maximum volume of the sorption space of material samples.

Keywords: composite material with embedded titanium dioxide, titanium dioxide, silica, sorption, adsorption properties.

Adsorption properties of photocatalytic composite material is evaluated by two parameters: the value of the equilibrium sorption of saturated vapors of benzene and ethyl acetate samples of material and limit the volume of sorption space material samples.

In recent years, research and development of new generation protective materials and products made from them using nanosystems have been intensively developing. Titanium dioxide is most often used in the photocatalytic process as one of the most chemically and thermally stable and non-toxic products. Nano-sized inorganic oxides can be used to disinfect materials contaminated with dangerous toxic substances, including toxic substances, as well as to purify the air from impurities of vapors and gases of toxic chemicals.

The composite material is obtained by sequentially forming an adsorbent layer on a woven cellulose-containing textile base, then a photocatalytic layer. The formation of an adsorbent layer on a woven or non-woven cellulose-containing textile base occurs using sol-gel technology as a result of impregnation of the textile base with an aqueous dispersion containing nano-sized particles of aluminum oxide and drying at a temperature of (100±5) oC. Positively charged alumina particles are attached to the negatively charged surface of the textile base, both due to electrostatic interaction and due to mechanical retention of the alumina particles by the textile base fiber. The formation of a photocatalytic layer on a woven cellulose-containing textile base containing an adsorbent layer occurs using sol-gel technology as a result of impregnation of a material sample with an aqueous dispersion containing a complex of silicon dioxide and titanium dioxide, drying the impregnated sample at a temperature of (80-90) oC for 30 minutes followed by washing with water and drying at a temperature of (100±5) oC. The developed surface of aluminum oxide fixed on the surface of the textile base ensures good adhesion of the silicon dioxide complex with titanium dioxide on the surface of the adsorbent layer.

When forming an adsorbent layer and a photocatalytic layer on a textile basis,

The effective fibers are not damaged and the texture of the textile base does not change.

A photocatalytic composite material containing a woven or cellulose-containing textile base, a photocatalytic layer including a complex of silicon dioxide modified with aluminate ions and titanium dioxide of anatase modification, and an adsorbent layer containing aluminum oxide with a boehmite structure located between the photocatalytic layer and the textile base, characterized by increased adsorption properties in relation to polar and non-polar chemical compounds, exhibits high photocatalytic activity and antibacterial properties when irradiated with UV light. An aqueous dispersion of aluminum oxide is used as a material to form an adsorbent layer. The aqueous dispersion contains nano-sized particles of aluminum oxide with a boehmite structure in an amount of 9.0-9.5 wt.%, solution pH 3.8. Using powder diffractometry, it was established that nanosized aluminum oxide has the orthorhombic crystal structure of boehmite (y-AОOH) (No. 01-083-1506 in the PDF-2 database). Aluminum oxide with a boehmite structure has a developed surface, a high electropositive charge, has adsorption properties towards polar and non-polar chemical compounds, and the ability to trap microorganisms.

The adsorption properties of a photocatalytic composite material are assessed by two indicators: the equilibrium value of sorption of saturated benzene and ethyl acetate vapors by material samples and the maximum volume of the sorption space of material samples under conditions of static activity at a temperature of 25°C. The adsorption properties of the photocatalytic composite material based on cotton fabric are presented in Tables 1 and 2.

Table 1 - Adsorption properties of photocatalytic composite material based on cotton fabric

photocatalytic benzene

composite material,%

Photo-Connect-Adsor-Equal-Limit-

catalytic SiO2mo bent spring volume

congestion difi- (Y-value we eat sorb-

TiO2, ziro- A1OOH) sorption

anatase bath and boehmite AS, mg/g pro-

A1(OH)4- countries

25 25 50 104 118

The equilibrium value of sorption of saturated vapors of a chemical compound by a sample of a material is determined as the ratio of the amount of vapors of a chemical compound absorbed by this sample to the mass of the sample. The limiting volume of the sorption space of a material sample is calculated based on the equilibrium value of sorption and the density of the chemical compound.

Table 2 - Adsorption properties of photocatalytic composite material based on cotton fabric

As can be seen from the examples given in Tables 1 and 2, the composite material with embedded titanium dioxide is characterized by increased adsorption properties in relation to polar and non-polar chemical compounds due to an increase in the available surface area of ​​two adsorbents - nanodispersed oxides of silicon and aluminum.

Literature

1. Filtering and sorbing material with an embedded photocatalyst / M.A. Salyakhova [et al.] // Bulletin of the Kazan Technological University. -2013.t.16. No. 23. - pp. 52-53.

2. Photochemical destruction of textile materials / M.A. Salyakhova [et al.] // Bulletin of the Kazan Technological University. - 2013.t.16. No. 17. - From 92-93.

3. Shabanova, N.A. Chemistry and technology of nanodispersed oxides [Text] / N.A. Shabanova, V.V. Popov, P.D. Sarkisov - M.: ICC “Academkniga”, 2007. - 309 p.

Photo-catalyst TiO2, anatase Binder SiO2 modified A1(OH)4- Adsorbent (Y- A1OOH) boehmite Equilibrium sorption value aS, mg/g Limit volume of sorption space WS, cm3/g

25 25 50 134 152

25 30 45 130 148

25 35 40 128 145

30 30 40 126 143

30 35 35 122 139

35 35 30 119 135

© M. A. Salyakhova - asp. department plasmachemical and nanotechnologies of high-molecular materials KNRTU, [email protected]; I. Sh. Abdullin - Doctor of Engineering. Sciences, prof., head. department plasmachemical and nanotechnologies of high-molecular materials KNITU, ab(M1t^@k51i.gi; V.V. Uvaev - Candidate of Chemical Sciences, General Director of JSC KazKhimNII; E.N. Pukhacheva - Candidate of Technical Sciences , senior scientific worker, laboratory No. 5, KazKhimNII [email protected].

©M. A. Salyahova - postgraduate of chair of plasmachemical and nanotechnologies of high-molecular materials KNRTU, [email protected]; I. Sh. Abdullin - doctor of technical science, professor of chair of plasmachemical and nanotechnologies of high-molecular materials KNRTU, and [email protected]; V. V. Uvaev - candidate of technical sciences, General Director, of Kazan Chemical Scientific-Research Institute; E. N. Pukhacheva - candidate of technical sciences, Senior researcher of Laboratory of Kazan Chemical Scientific-Research Institute, [email protected].