CZ2011502A3 - Adsorbents for removing arsenic and selenium from water - Google Patents

Abstract

The adsorbents of the invention contain amorphous ternary hydrated Fe-Ti-Si oxides, in the Fe.sup.3 + molar ratio: Ti.sup.4 + .n1 to 3: 3 to 1, and the silicon content in relation to the total weight of iron oxide, titanium and silicon is between 5 and 25% by weight. The amorphous ternary hydrated Fe-Ti-Si oxides are preferably on a carrier and the weight ratio of amorphous ternary hydrated Fe-Ti-Si oxide to carrier is in the range of 1 to 25% and the resulting form is a powder or granules. The carrier is selected from the group consisting of kieselguhr, bentonite, laterite, granular or powdered activated carbon, quartz sand, porcelain grains, pottery clay, pumice, limestone, granular clay, manganese sand, anthracite, zeolite, kaolin, red mud (sludge from production The adsorbents obtained are suitable for the removal of arsenic and selenium from both drinking water and waste water.

Description

Adsorbents for removing arsenic and selenium from water

Technical field

The present invention describes a novel adsorbent based on amorphous ternary hydrated oxides of iron, titanium and silicon (FTS) for the removal of arsenic and selenium from water, a process for its preparation and the possibility of its application. The present invention spans two fields of application - water management and the environment. It refers to the removal of the toxic element of arsenic, especially arsenates from water. This form of arsenic occurs in an oxic environment, even in well aerated groundwater. The basic components of the material are amorphous ternary hydrated oxides of Fe-Ti-Si. The present invention discloses high adsorption capacity adsorbents that are affordable, and methods, respectively. methods of their preparation and possible applications in treatment and purification technologies.

It should be noted that the material contemplated can also be used to remove selenite from water.

BACKGROUND OF THE INVENTION

According to recent studies and the latest research, the presence of arsenic in drinking water C 4. 3.

threatens the health of the population in more than 70 countries. It is therefore an increased concentration of. g arsenic exposed approximately 137 million people. Arsenic has, for example, significant negative properties compared to organic pollution of water resources. Unlike organic pollution, it does not decompose spontaneously or controlled, but enters into circulation, circulates there, or accumulates in different places of the environment or in various organs or tissues of animals. We can speak of a "global threat" in a figurative sense.

Acute arsenic intoxication has been identified by ingestion of water containing 1.2 to 2.1 mg / l. The arsenic content of water resources and thus of drinking water has an immediate impact on human health. The most common manifestation of water intake with higher arsenic content in man is garlic bad breath, sweating, muscle weakness, fatigue and changes in skin pigmentation. A more pronounced manifestation, including anemia, is a decrease in the feeling in the hands and damage to the peripheral nervous system, peripheral nervous tremor, skin and limb skin changes, and liver and kidney problems. The constant presence of arsenic in the body can lead to gangrenal disability (gangrene). Increased pigmentation of limbs and feet was found

At a daily consumption of drinking water at a daily dose of arsenic of about 0.4 mg per kg of body weight. This means that even persistently low arsenic concentrations in drinking water can lead to acute disability.

The Ministry of Health (drinking water quality defined by Decree No. 252/2004 Coll., As amended) and the World Health Organization WHO (SR 98/83 / EEC) cite 10 pg / l as the highest limit value for arsenic concentration in drinking water. In comparison, for example, purified industrial waters have an emission standard for arsenic of 0.5 mg / l.

Various methods can be used to remove arsenic from water, such as ion exchange based on the principle of cation or anion exchange, coagulation or precipitation. Coagulation with ferric coagulants and subsequent filtration is effective only in some cases. In general, however, ion exchange and coagulation methods have several disadvantages. These include high costs, the generation of toxic waste (both liquid in the case of ion exchangers and sludge in the case of coagulation) or the unsuitability of their use under certain conditions, such as groundwater containing low iron concentrations or in decentralized areas. For this reason, the adsorption process is one of the physicochemical processes that is effective in removing arsenic and has advantages over other methods due to low operating costs, subsequent waste management, reduced sludge volume, lower reagent consumption and relatively easy transport and storage .

PetefltT ^ (2006 ^ 091078 A1 is focused on the removal of arsenic from water by clusters or granules that are activated on the surface by a crystalline structure of titanium dioxide with a particle size of 1 -X30 nm. however, it is expensive and thus not available to the population in countries where people live in deep poverty.

Research studies by K. Gupt et. al. under the title “Arsenic removal using hydrous nanostructure iron (III) -titanium (IV) binary mixed oxide (NHITO) from aqueous solution” are aimed at removing arsenic using binary oxides (NHITO). They state that the materials have high efficiency for the removal of arsenic. The XRD spectra of said material show that it consists of magnetite (FeaCU) modification γ FeO (OH) and crystalline form TiO ₂ . The particle size of NHITO is in the range of 6 * 8 nm. The BET surface size was reported by 77.8 m ² / g and the adsorption capacity calculated from the Langmuir model of 14.0 mg As (V) / g. However, the problem of conventional technological application is the difficulty of separating the sorbent from the aqueous phase, since the adsorbent has a powder character.

In the Czech Republic, the only industrially manufactured and imported sorbent GEH, a granulated iron hydroxide, specifically developed for the selective adsorption of heavy metals, especially arsenic from water, has a particle size of 0.3 to 2.0 mm and a specific surface area. The BET is 220 m ² / g.

It follows from the above that for the removal of arsenic from water, it is necessary to focus on the development of new materials that will not be expensive, but which will have sufficient efficiency for its removal, not only in the drinking water field, industrial waste water

SUMMARY OF THE INVENTION

The present invention is directed to the removal of arsenic and selenium from waters, particularly As (V) arsenates and Se (IV) selenites.

The adsorbents of the invention contain amorphous ternary hydrated oxides of Fe-Ti-Si (FTS), in a molar ratio of Fe ³⁺ : Ti ⁴⁺ 1 to 3: 3 to 1, and the silicon content relative to the total weight of iron, titanium and silicon oxides is in the range of 5 to 25% by weight. Amorphous ternary hydrated oxides of Fe-Ti-Si are a complex of amorphous forms of ferric oxide (ie Fe ₂ O 3. XH ₂ O and / or FeOOH), titanium dioxide (ie TiO ₂ .YH ₂ O and / or TiO (OH) ₂ and oxide Silica (SiO ₂ ).

The amorphous ternary hydrated oxides of Fe-Ti-Si are preferably supported and the weight ratio of amorphous ternary hydrated oxides of Fe-Ti-Si to the support is in the range of 1 to 25 °. They are in the form of powder or granules.

The carrier is selected from the group of powdered carriers comprising bentonite, powdered laterite, powdered activated carbon, powdered zeolite, powdered kaolin, red mud (sludge from aluminum production) and fly ash, or a group of granulated carriers made of diatomaceous earth, granulated laterite, granulated activated carbon, porcelain grains, pottery, pumice, limestone, granulated clay, manganese sand, anthracite, granulated zeolite, granulated kaolin and magnetic Fe ₃ O ₄ .

The adsorbents preferably have a particle size of amorphous ternary hydrated Fe-Ti-Si oxides of 2 to 10 nm and a specific surface area of 65 to 230 m ² / g.

The process for preparing the FTS adsorbent according to the invention consists in preparing individual solutions of iron salts (Fe ³⁺ ), titanium (Ti ⁴⁺ ), y solutions (/ sodium metasilicate (Na 2 S 2 O 3) and sodium hydroxide (NaOH), solutions of Fe salts ^{The 3+} and Ti ⁴⁺ are mixed in a molar ratio of 1 to 3: 3 to 1 and then mixed with sodium metasilicate (Na 2 S 2 O 3) and sodium hydroxide (NaOH) to adjust the pH of the mixture between 5 and 9, allowing the mixture to mature at rest for 10-14 hours, the solid phase is separated and dried at 190-200 ° C for 11-13 hours.

The process for preparing the adsorbent on a carrier in powder form according to the invention consists in preparing the individual solutions of iron (Fe ³⁺ ), titanium (Ti ⁴⁺ ), sodium metasilicate (Na 2 S 2 O 3) and sodium hydroxide (NaOH), salt solutions. Fe ³⁺ and Ti ⁴⁺ are mixed in a molar ratio of 1 to 3: 3 to 1 and then mixed with a carrier, to which sodium metasilicate (Na 2 S 2 O 3) and sodium hydroxide (NaOH) are added to adjust the pH of the mixture over 5 9 to 9, the mixture is aged for 10 to 14 hours, the solid phase is separated and dried at 190 to 200 ° C for 11 to 13 hours.

The present invention provides a process for preparing an adsorbent on a magnetic carrier in powder form, wherein the carrier is magnetite, comprising preparing individual solutions of iron (Fe ³⁺ ), titanium (Ti ⁴⁺ ), sodium metasilicate (Na 2 S 2 O 3) and sodium hydroxide solutions. (NaOH), the Fe ³⁺ and Ti ⁴⁺ salt solutions are mixed in a molar ratio of 1 to 3: 3 to 1 and then mixed with magnetite, to which sodium metasilicate (Na ₂ SO ₃ ) and sodium hydroxide (NaOH) are added. to adjust the pH of the mixture over a period of 5 to 9, the mixture is aged for 10 to 14 hours, the solid phase is separated and dried at 80 ° C for 11 to 13 hours.

The process for preparing granular FTS and / or FTS adsorbents on a powder carrier according to the invention consists in mixing the powdered FTS and / or FTS adsorbents on a powder carrier with a 30 wt.% Na ₂ SiO ₃ solution. Subsequently, the wet mixture is subjected to granulation in a granulator (spherical particle formation) under control of the average particle size.

The process for preparing adsorbents on a carrier in granular form according to the invention consists in preparing individual solutions of iron salts (Fe ³⁺ ), titanium (Ti ⁴⁺ ), sodium metasilicate solution (Na2SiO3) and sodium hydroxide (NaOH), solutions of Fe salts ^{The 3+} and Ti ⁴⁺ are mixed in a molar ratio of 1 to 3: 3 to 1 and then mixed with the granular carrier, to which sodium metasilicate (Na 2 S 2 O 3) and sodium hydroxide (NaOH) are added to adjust the pH of the mixture over time. 5 to 9, the mixture is aged for 10 to 14 hours, the solid phase is separated and dried at 190 to 200 ° C for 11 to 13 hours.

The adsorbents of the invention are useful for removing arsenates and selenites from water.

The problem of sorbent separation is eliminated by applying an FTS layer to a carrier, which may be diatomaceous earth, bentonite, laterite, granulated or powdered activated carbon, quartz sand, porcelain grains, pottery, pumice, limestone, granulated clay, manganese sand, anthracite, zeolite, kaolin, red mud (aluminum sludge), fly ash and magnetic Fe ₃ C> 4, which can also be used for magnetic separation.

The adsorbents of the present invention exhibit higher adsorption capacities due to higher affinity for arsenates and greater surface area of the ternary hydrated oxides of Fe-TiSi compared to the crystalline form of the individual components FeO 2, TiO ₂ , TiO (OH) ₂ and binary Fe-Ti oxides alone.

The adsorbents of the present invention, due to the complexation of Fe and Si, Ti and Si in amorphous ternary hydrated oxides, exhibit a stronger bond with the carrier than hydrated oxides alone.

Iron salt salts FeCl ₃ , Fe (NO) ₃ , Fe ₂ (SO ₄ ) ₃ , titanium salts TiCl ₄ , Ti ₂ (SO ₄ ) ₃ , TiBr ₄ , TiCSO ₄ xH ₂ SO ₄ - xH ₂ O are used for the preparation of salt solutions. , TiO [CH ₃ COCH = C (O-) CH ₃ ] ₂ or *

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TiOSO ₄ xH ₂ O, Ti (OC ₃ H ₇ ) ₄ , sodium silicate (Na ₂ SiO ₃ ) and sodium hydroxide solution NaOH.

The present invention has the following advantages.

With respect to the present invention, the prepared adsorbent (on a surface with a thin, mechanically strong layer of amorphous ternary hydrated oxides of Fe-Ti-Si deposited on a support such as diatomaceous earth, bentonite or magnetite Fe ₃ O ₄ ) has particle sizes corresponding to technological applications in treatment of drinking water and also shows magnetic properties. It can therefore be used in conventional devices (filters) to remove arsenic from water. FTS adsorbent exhibits excellent adsorption properties, its arsenic removal capacity is 64.5 mg / g.

The preparation of amorphous ternary hydrated oxides of Fe-Ti-Si can be carried out in conventional chemical reactors or equipment. Adsorbents can commonly be used in water technology to remove arsenates and selenates from water. The present invention discloses both methods for preparing amorphous ternary hydrated Fe-Ti-Si oxides, and documents possible applications of the prepared products in the removal of arsenates and selenites from water. The name amorphous ternary hydrated oxides of Fe-Ti-Si refers to the higher specific surface area of the product, which results in higher adsorption capacity, which can be used not only for the adsorption of arsenates but also of selenites. The amorphous ternary hydrated Fe-Ti-Si oxides disclosed in the present invention may preferably consist of separate nanoparticles, but aggregates thereof may also be present.

Overview of pictures.

Figure 1 shows X-Ray diffraction of Fe-Ti-Si adsorbent (FTS)

Figure 2 shows the particle size of the adsorbent as a transmission electron microscope (TEM)

Figure 3 shows a diagram of a reactor and a settling tank for removing arsenic from water.

Figure 4 shows an adsorption filter column.

Figure 5 shows a diagram of a device for magnetic adsorbent separation.

Examples

Example 1

Preparation and characterization of powdered amorphous ternary hydrated oxides of Fe-TiSi (FTS)

400 ml of 0.09 mol / l FeCl ₃ solutions were stirred in the rotary reactor. XH2O at a concentration of 0.03 mol / l. In the initial phase of vigorous mixing of the solutions of both salts, a 39% Na ₂ SiO ₃ solution was quickly added followed by a solution

NaOH at a concentration of 5 mol / L in an amount such that a pH of 5 to 9 is achieved. Subsequently, the mixture was stirred for 30 minutes and aged for 12 hours. Finally, the suspension was dewatered, filtered and dried at 190-200 ° C for 12 hours. The characteristics of the FTS sorbent are shown in Figures 1 and 2 and other properties are shown in Tables 1 and 2. Figure 1 by X-Ray diffraction shows the morphology of the product, no crystalline structures are present, only the amorphous form. Figure 2 is a transmission electron microscope (TEM) output and illustrates the particle size of the product as compared to the scale shown in the lower right corner of the figure. Table 1 shows the basic physical properties of the FTS adsorbent and Table 2 shows its adsorption capacity. As can be seen from Table 2, the FTS adsorbent has a higher adsorption capacity for selenites than for arsenates.

Tab.1. Physical properties of FTS adsorbent

Pointer Value Specific surface area (m ² / g) 230 Average pore size (nm) 3.14 Pore volume (cm ³ / g) 0.0408 Particle size (nm) 2 to 10 pH zero point of charge 3.6

Tab.2. Adsorption capacity of FTS adsorbent

metal value (mg / g) As (V) 64.52 Se (IV) 85.47

Example 2

Preparation of powdered amorphous ternary hydrated Fe-Ti-Si oxides on bentonite (BFT) support

400 ml of 0.09 mol / l Fe (NO ₃ ) ₃ solution and 0.03 mol / l Ti ₂ (SO 4) ₃ solution were stirred in the rotary reactor. Subsequently, 45 g of bentonite having a particle size of 2 to 10 µm were added and the mixture was stirred for 5 minutes. Then, for 6 hours, the resulting mixture was left to allow the Fe ³⁺ and Ti ⁴⁺ particles to penetrate the bentonite pores. This was followed by rapid, vigorous stirring of the mixture, and immediately at the beginning of vigorous stirring, a solution of Na ₂ SiO ₃ at a concentration of 39r / o was added rapidly, followed by NaOH at a concentration of 5mol / l in such a quantity as to reach a pH in 5 to 9. the mixture was stirred for 30 minutes and aged for 12 hours at room temperature. Finally, the suspension was dewatered, filtered and dried at 190-200 ° C for 12 hours. Moisture content of the obtained ternary oxide (FTS)

The bentonite enriched in the BFT was less than 10% by weight. The ratio of U to about 4uo cFTS to bentonite was approximately 25 wind ·%. The specific surface area and adsorption capacity of arsenic bentonite (B) and BFT alone is given in Table 3.

Similar to Example 2, powdered adsorbents can be prepared in which the carrier is powdered activated carbon, laterite, zeolite, kaolin, red mud (aluminum sludge) and fly ash.

Tab.3. Specific surface area and adsorption capacity of bentonite (B) and adsorbent BFT

Pointer (B) BFT Specific surface area (m ² / g) 58.2 163.3 Adsorption capacity [mg As (V) / g] 0.53 48.78

Example 3

Preparation of granulated Fe-Ti-Si adsorbents of amorphous ternary hydrated oxides (GFT)

Granular Fe-Ti-Si amorphous ternary hydrated oxides were prepared by mixing amorphous ternary hydrated oxides of Fe-Ti-Si, FTS (obtained and listed in Example 1) with a solution of Na ₂ SiO ₃ at a concentration of 30% v / v. Subsequently, the wet mixture was subjected to granulation in a granulator (spherical particle formation) under control of the average particle size. The prepared granulated adsorbent was further dried for 12 hours at 190-200 ° C. The Na 2 SiO 3 content was 5% by weight relative to the total weight of the GFT.

Example 4

Preparation of granulated adsorbents of Fe-Ti-Si amorphous ternary hydrated oxides supported - bentonite (GBFT)

Granulated amorphous ternary hydrated Fe-Ti-Si oxides incorporated into bentonite (GBFT) were prepared by mixing amorphous ternary hydrated oxides of Fe-Ti-Si, BFT (obtained and listed in Example 2) with a 30 wt% solution of Na ₂ SiO ₃ . Subsequently, the wet mixture was subjected to granulation in a granulator (spherical particle formation) under control of the average particle size. The prepared granulated adsorbent was further dried for 12 hours at 190 at 200 ° C. The content of Na ₂ SiO ₃ was 5 weight% in relation to the total weight of GBFT.

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Example 5

Preparation of Fe-Ti-Si powder adsorbents of amorphous ternary hydrated oxides on a magnetite carrier (MFT)

In a rotary reactor or vessel placed on a magnetic stirrer, 400 ml of a 0.09 mol / l FeCl ₃ solution and 0.03 mol / l FeCl ₃ solution (see Example 1) were stirred. Subsequently, 45 g of magnetite having a particle size of 10 to 50 nm was added and the mixture was stirred for 5 minutes. Thereafter, the resulting mixture was stirred for 30 minutes to bring the magnetite powder and Fe ³⁺ and Ti ⁴⁺ particles in close contact. This was followed by rapid, vigorous stirring of the mixture, and immediately at the beginning of vigorous stirring, a solution of Na ₂ SiO ₃ at a concentration of 3S rychle / o was added rapidly, followed by NaOH at a concentration of 5 mol / l in such a quantity as to reach a pH of 5-9. After reaching pH, the mixture was stirred for 30 minutes and aged for 12 hours at room temperature. Finally, the suspension was dewatered, filtered and dried at 80 ° C for 12 hours. The ratio of FTS to magnetite support was approximately 3: 1. The specific surface area and adsorption capacity for arsenic of magnetite alone (M) and MFT is shown in Table 4.

Tab.4. Specific surface area and adsorption capacity of magnetite (M) and MFT adsorbents

Pointer M MFT Specific surface area (m ² / g) 58.2 185.3 Adsorption capacity [mg As (V) / g] 13.88 60.60

Example 6

Preparation of granulated Fe-Ti-Si adsorbents of amorphous ternary hydrated oxides on kieselguhr carrier (DFT)

400 ml of a 0.09 mol / l Fe ₂ (SO ₄ ) ₃ solution was stirred in a rotary reactor. XH2SO4. xH ₂ O at a concentration of 0.03 mol / l. 100 g of diatomaceous earth having a particle size of 1 to 2 mm were then added and the mixture was stirred for 5 minutes. Then, for 6 hours, the resulting mixture was left to allow the Fe ³⁺ and Ti ⁴⁺ particles to penetrate the pores of the diatomaceous earth particles. This was followed by rapid, vigorous stirring of the mixture, and immediately at the beginning of vigorous stirring, a solution of Na ₂ SiO ₃ at a concentration of 39% was added rapidly followed by NaOH at a concentration of 5 mol / l in such a quantity as to reach a pH of 5-9. After reaching pH, the mixture was stirred for 30 minutes and aged for 12 hours at room temperature. Finally, the suspension was dewatered, filtered and dried at 190-200 ° C for 12 hours. The moisture content of the obtained ternary oxide (FTS) enriched in diatomaceous earth, i.e. the DFT product, was less than 10% by weight. The ratio of FTS to carrier-kieselguhr content was approximately 10% by weight. The specific surface area and adsorption capacity for arsenic of diatomaceous earth (D) and DFT alone is given in Table 5.

Tab.5. Specific surface area and adsorption capacity of diatomaceous earth (D) and DFT adsorbent

Pointer D DFT Specific surface area (m ² / g) 31.8 65.5 Adsorption capacity [mg As (V) / g] 0.21 10.67

Similar to Example 6, granular adsorbents can be prepared wherein the carrier is granular laterite, granular activated carbon, silica sand, porcelain grains, granular pottery, pumice stone, limestone, granular clay, manganese sand, and anthracite.

The present invention also provides a method of applying amorphous ternary hydrated Fe-Ti-Si oxides to remove arsenates from water. It should be noted that these types of adsorbents can also be used to remove selenite. The preparation of adsorbents and their use has been mentioned above.

The powdered adsorbents shown in Example 2 can be used in the purification of water in the arrangement shown in Figure 3. Contaminated arsenic water is fed to the reactor 1, where the adsorbent is also fed with stirring. The homogenized mixture overflows into settling tank 2, where the adsorbent (sludge) is sedimented and the treated arsenic-depleted water is discharged from the level of the settling tank. The adsorbent can be reused (recycled). The method is more suitable for waste water treatment.

The granulated adsorbents shown in Examples 3, 4, 6 can be used in the purification of water in the arrangement shown in Fig. 4. Contaminated arsenic water is fed to the adsorption filter column 1 packed with adsorbent and purified or treated water is removed from the bottom of the column. The method is suitable for both drinking water treatment and waste water treatment.

The magnetite adsorbents shown in Example 5 can be used in the purification of water in the arrangement shown in FIG. 5. The arsenic contaminated water is fed to the reactor 4, where the adsorbent is also fed with stirring. The homogenized mixture is sent to a magnetic separator 2 where the adsorbent is magnetically separated from the purified water. The adsorbent can be reused (recycled). The treated arsenic-free water is drained from the bottom of the magnetic separator. The method is suitable for both drinking water treatment and waste water treatment.

Said adsorbents, amorphous ternary hydrated oxides of Fe-Ti-Si can also be used as color pigments in color production or as color glaze in the ceramic industry.

Industrial use

The invention is useful for removing arsenic and selenium from drinking and industrial waters.

Claims (13)

Patent claims Adsorbents for the removal of arsenic and selenium from water, their preparation and use, characterized in that they contain amorphous ternary hydrated oxides of Fe-Ti-Si, which are in the form of powder or granules, wherein the molar ratio Fe ³⁺ : Ti ⁴⁺ is 1 to 3: 3 to 1, and the silicon content in relation to the total weight of iron, titanium and silicon oxides is in the range of 5 to 25% by weight. Adsorbents according to claim 1, characterized in that the amorphous ternary hydrated Fe-Ti-Si oxides are a composition of an amorphous form of ferric oxide (ie Fe ₂ C 3 x x ₂ H ₂ O and / or FeOOH), titanium dioxide (ie TiO ₂₎ . ? H ₂ O and / or TiO (OH) ₂ and silica (SiO ₂ ). Adsorbents according to claims 1 and 2, characterized in that they consist of iron, titanium and silicon oxide nanoparticles. Adsorbents according to claims 1 to 3, characterized in that the particle size of the amorphous ternary hydrated Fe-Ti-Si oxides is 2 to 10 nm and the specific surface area is 65 to 230 m ² / g. 5. Adsorbents according to claim 1, characterized in that they contain supported amorphous ternary hydrated oxides of Fe-Ti-Si and the weight ratio of amorphous ternary hydrated oxides of Fe-Ti-Si to carrier is between 1.0 and 25% and the resulting form is a powder or granules. Granular adsorbents according to claims 1 to 5, characterized in that the content of Na ₂ SiC> 3 in relation to the total weight of the prepared adsorbents is 5% by weight. • * · TV - Τ © 2_ Adsorbents according to claim 5, characterized in that the carrier is selected from the group of powdered carriers consisting of bentonite, powdered laterite, powdered activated carbon, powdered zeolite, powdered kaolin, red mud (sludge from aluminum production) and fly ash, or a group of granulated carriers. kieselguhr, granular laterite, granular activated carbon, porcelain grains, pottery, pumice stone, limestone, granular clay, manganese sand, anthracite, granular zeolite, granular kaolin and magnetic Fe ₃ O ₄ . A process for the preparation of an adsorbent in powder form according to claims 1 to 4, characterized in that individual solutions of iron (Fe ³⁺ ), titanium (Ti ⁴⁺ ), sodium metasilicate (Na 2 SO 3) and sodium hydroxide (NaOH) solutions are prepared, solutions of Fe ³⁺ and Ti ⁴⁺ salts are mixed in a molar ratio of 1 to 3: 3 to 1 and then mixed with sodium metasilicate (Na 2 S 2 O 3) and sodium hydroxide (NaOH) to adjust the pH of the mixture within 5 to 9, It is aged for 10 to 14 hours, the solid phase is separated and dried at 190 to 200 ° C for 11 to 13 hours. A process for preparing a supported adsorbent in powder form according to claim 5, characterized in that individual solutions of iron salts (Fe ³⁺ ), titanium (Ti ⁴⁺ ), sodium metasilicate (Na 2 SO 3) and sodium hydroxide (NaOH) solutions are prepared, solutions of Fe ³⁺ and Ti ⁴⁺ salts are mixed in a molar ratio of 1 to 3: 3 to 1 and then mixed with a powdered carrier, to which sodium metasilicate (Na ₂ SO ₃ ) and sodium hydroxide (NaOH) are added to adjust the value The pH of the mixture is between 5 and 9, the mixture is aged for 10 to 14 hours, the solid phase is separated and dried at 190 to 200 ° C for 11 to 13 hours. A process for the preparation of a supported adsorbent in granular form according to claim 5, characterized in that individual solutions of iron (Fe ³⁺ ), titanium (Ti ⁴⁺ ), sodium metasilicate (Na ₂ SiO ₃ ) and sodium hydroxide () solutions are prepared. NaOH), the solutions of Fe ³⁺ and Ti ⁴⁺ salts are mixed in a molar ratio of 3 to 1: 1 to 3 and then mixed with the granulated carrier, to which sodium metasilicate (Na ₂ SiO ₃ ) and hydroxide are added. sodium (NaOH) to adjust the pH of the mixture in the range of 5-9, the mixture is aged for 10-14 hours, the solid phase is separated and dried at 190-200 ° C for 11-13 hours. A method for preparing adsorbent on a support, wherein the support is magnetite according to claim 5, characterized in that individual solutions of iron salts (Fe ³⁺ ), titanium (Ti ⁴⁺ ), sodium metasilicate solution (Na 2 S 2 O 3) and sodium hydroxide () are prepared. NaOH), the solutions of Fe ³⁺ and Ti ⁴⁺ salts are mixed in a molar ratio of 3 to 1: 1 to 3 and then mixed with magnetite, to which sodium metasilicate (Na ₂ SO ₃ ) and sodium hydroxide (NaOH) are added. pH adjustment of the mixture in the range of 5 to 9, aged at rest for 10 to 14 hours, solid phase is separated and dried at 80 ° C for 11 to 13 hours Process for the preparation of granulated adsorbents according to claims 1 to 5, characterized in that the powdered adsorbents Fe-Ti-Si or Fe-Ti-Si are mixed with a sodium metasilicate solution of Na ₂ SiO ₃ , the mixture is subjected to granulation in a granulator , the granulated adsorbent is dried at 190-200 ° C for 12 hours. Use of adsorbents according to claims 1 to 5 based on amorphous ternary hydrated Fe-Ti-Si oxides for the removal of arsenates and selenites from water.