EP3452216A1

EP3452216A1 - Modified porous coatings and a modular device for air treatment containing modified porous coatings.

Info

Publication number: EP3452216A1
Application number: EP17740130.4A
Authority: EP
Inventors: Adriana ZALESKA-MEDYNSKA; Witold DYTRYCH; Micha NISCHK; Pawe MAZIERSKI
Original assignee: Phu Dytrych Sp Z Oo
Current assignee: Phu Dytrych Sp Z Oo
Priority date: 2016-05-05
Filing date: 2017-05-05
Publication date: 2019-03-13
Also published as: WO2017192057A4; PL417116A1; WO2017192057A1

Abstract

Modified porous coatings formed from a porous deposit, preferably ceramic cubes or nanotubes, containing titanium oxide Ti02 or titanium oxide surface-modified with platinum TiO₂-Pt as well as quantum dots. A modular device for air treatment containing modified porous coatings characterised in that it contains a dust removal module (1) for the removal of solid particles, an advanced oxidation module equipped with a chamber for conducting a photocatalytic reaction (2a) with the photocatalytic layer placed on the carrier in the form of a modified porous coating and a radiation source as well as a reaction chamber (2b) for contacting ozone with the contaminated gas phase, a residual ozone inactivation module (3) for the removal of ozone remains on the catalytic deposit, and also the adsorption module on activated carbon (4).

Description

Modified porous coatings and a modular device for air treatment containing modified porous coatings.

The invention concerns porous coatings modified with Ti0₂ or Ti0₂-Pt and quantum dots as well as a modular device for air treatment containing modified porous coatings.

Waste waters and solid waste contain contaminants in a form of organic and non-organic compounds, including the aroma compounds, as well as numerous saprophytic or opportunistic microorganisms, and sometimes pathogens or facultative pathogens. Such contaminants during waste water treatment processes and under the applied waste management technologies can be introduced into the air in the form of vapours, dusts, aerosols and bioaerosols and, as a result, they may have negative impact on the health of workers and local residents, and also lead to secondary contamination of soils, waters and plants. They may also migrate with water to deeper soil layers.

At the moment in Poland air streams emitted on the territory of a waste water treatment plant or on landfills are either not subject to any treatment/ deodorising, or biological methods are used, including biofilters. An undoubted advantage of biofiltration is a low cost of air treatment when compared with chemical methods. However, such technologies only enable the treatment of streams with low contaminants load. The effectiveness of work performed by microorganisms depends not only on the type and concentration of contaminants in the gas phase, but also on the temperature of the environment. Therefore, the operation of biofilters is not stable upon seasonal temperature variations. A sophisticated matrix in case of air streams emitted in such plants, being a mixture of organic and non-organic compounds as well as micro-organisms, and also huge negative impact on the environment and local residents require the development of modern and effective technologies of removing contaminants from the gas phase. Filters containing photocatalyst particles on their surface are known in the state of art. The description KR100535940 presents a device for air treatment, containing a semi-permanent photocatalytic filter. The device contains a Ti0₂ layer for the treatment of air leaving the pre-treatment filter, as well as an UV lamp which activates Ti0_2, sterilizes and treats contaminated air.

The description CN201399313 presents a device for indoor air treatment, consisting of a filtration fabric layer, two layers of active carbon fibres, a flat layer of granulated active carbon and an UV lamp. The activated carbon surface contains Ti0₂ with photocatalytic properties. The UV lamp is placed between two active carbon layers. The air flows from the lower to the upper part of the device, while noxious substances are filtered out, absorbed and degraded photocatalytically.

Devices described in the state of the art do not contain quantum dots, which may be used for the construction of a heterojunction with Ti0₂ with the view to freeing the accumulated charges through the acceleration of transfer and migration of photogenerated charges; if they are constructed using a semi-conductor with the band gap <2.8 eV, they can absorb radiation from the visible range, and then they can transfer the electron to the Ti0₂ conductive band. The quantum dots may also be used for resonance transfer of excitation energy according to the so- called FRET mechanism. The objective of the invention was to develop modified porous coatings and a device containing them, to be used for air treatment that could remove: (a) volatile organic compounds, NOx, S0₂ and (b) microorganisms, such as bacteria and fungi, what could among others enable a reduction of contaminants level and air deodorisation on the territory of landfills and waste water treatment plants, and thus the protect surface and ground waters through the elimination of a serious contamination source.

Modified porous coatings according to the invention are formed from a porous deposit, preferably ceramic cubes or nanotubes, containing titanium oxide Ti0₂ or titanium oxide surface-modified with platinum Ti0₂-Pt as well as quantum dots. In the case of modified porous coatings in the form of ceramic cubes, Ti0₂ or Pt-Ti0₂ in the form of a paste is applied onto the surface of the deposit by means of cubes immersion in the paste, which are later dried and calcined. Ti0₂ or Pt-Ti0₂ paste is prepared by mixing and heating of terpineol, butyl carbitol, ethyl cellulose, sorbitan trioleate and dibutyl phtalate until uniform consistency has been obtained, after which Ti0₂ orTi0₂-Pt is added to the mixture and the components are blended until uniform consistency has been obtained. Ti0₂-Pt is obtained using a chemical reduction method, consisting in the introduction of aqueous solution of K₂PtCl₄ into the suspension of Ti0₂ in alcohol solution, and the subsequent addition of a reducer in the form of sodium borohydride NaBH₄. The resulting Ti0₂-Pt sediment is rinsed with deionised water and ethanol and dried. Then quantum dots, preferably Bi₂S₃, Ag₂S, CdS and SnS, are applied to TiO or Ti0₂-Pt photocatalysts surface using a chemical bath deposition method, consisting in immersing a photocatalyst successively in the cation and anion precursor of the quantum dot. In a case of modified porous coatings in a form of Ti0₂ or Ti0₂-Pt nanotubes, a substrate in the form of titanium film is used. At the first stage the film is cleaned by means of immersion in at least one solvent and it is subject to ultrasound treatment. Then the substrate is rinsed with demineralised water stream, dried and placed in an electrolyte, consisting of ethylene glycol, water and ammonium fluoride, and later it is anodised using a platinum net as a cathode. The matrix of Ti0₂ nanotubes formed during the electrochemical process on the surface of the base material, which is later rinsed with demineralised water, dried and exposed to ultrasounds with the view to removal of surface contaminants. Thus formed nanostructures are dried and calcined. Platinum nanoparticles are deposited on the surface of Ti0₂ nanotubes using a photodeposition method. A titanium board with the formed Ti0₂ nanotubes is immersed in HC1 solution with pH 5. During the subsequent stage the board is immersed in the solution of K₂Cl₆Pt metal precursor. Then isopropanol is introduced into the photoreactor and it is run through N₂ solution to remove air. In order to immobilise nanoparticles of noble metals, the solutions together with the immersed titanium plate covered with Ti0₂ nanotubes are exposed to UV-Vis radiation. After completed photodeposition the board is subject to drying. Quantum dots are applied to photocatalysts in the form of TiO or Ti0₂-Pt nanotubes, preferably Ag₂S or Bi₂S_3; ones using a chemical bath deposition method, consisting in immersing a photocatalyst successively in the cation and anion precursor of the quantum dot.

A modular device for air treatment containing modified porous coatings according to the invention contains a dust removal module for the removal of solid particles, an advanced oxidation module equipped with a reaction chamber for contacting ozone with the contaminated gas phase and a reaction chamber for conducting a photocatalytic reaction with the photocatalytic layer, located on the carrier in the form of a modified porous coating and a radiation source, a residual ozone inactivation module for the removal of ozone remains on the catalytic deposit, and also the adsorption module on activated carbon. The chamber for conducting a photocatalyst reaction with a photocatalyst layer and a radiation source operates in the contaminants degradation mode, corresponding to the radiation intensity scope from the radiation source of between 0.2 and 20 mW/cm² and in the mode of photocatalytic layer treatment, corresponding to the radiation intensity scope from the radiation source of between 10 and 60 mW/cm². The time ratio of device operation in the contaminants degradation mode and in the photocatalytic layer treatment mode is between 5: 1 and 50: 1, preferably between 5: 1 and 15: 1.

The advantage of porous coatings modified with Ti0₂ or Ti0₂-Pt and quantum dots according to the invention is high effectiveness of contaminants removal from the gas phase, and also the possibility of using radiation from the visible scope or low power emitters for the formation of active oxygen forms on the photocatalytic surface, which are responsible for the degradation of organic and non-organic contaminants as well as micro-organisms present in the air. A layer of Ti0₂-Pt modified with quantum dots demonstrated longer usage stability when compared with layers made from Ti0₂ or Ti0₂-Pt alone, since their surface is not subject to deactivation. The advantage of the modular device for air treatment containing modified porous coatings is the application of modern oxidation processes - the combination of photocatalytic oxidation and ozonisation for the removal of contaminants mixture generated on the territory of a waste water treatment plant and landfills. The application of the modular device enables the simultaneous degradation of contaminants using the mixture of two strongest oxidisers, hydroxyl radicals and ozone, as well as the inactivation of micro-organisms in the gas phase.

The subject of the invention was presented in the Examples in the figures, in which Fig. 1 presents the pictures of obtained Ti0₂ and Ti0₂-Pt pastes from the left to the right, Fig. 2 presents the pictures of ceramic cubes immersed in the pastes and cubes after calcination, Fig. 3 presents the diagram of the modular device for air treatment containing a dust removal module 1, an advanced oxidation- ozonisation module 2b, an advanced oxidation - photocatalysis module 2a, residual ozone removal module 3, and adsorption on active carbon module 4.

Example 1. Obtaining T1O₂ surface-modified with platinum using a chemical reduction method.

10 g of Ti0₂ were added into the beaker containing 75 ml of deionised water and 75 ml of ethanol and the mixture was stirred using a magnetic stirrer for 1 hour. Then appropriate amount of aqueous solution of K₂PtCl₄ with the concentration of 0.000125 M was added into Ti0₂ suspension and it was stirred for half an hour. At the next stage the reducer in the form of sodium borohydride NaBH₄ was added to the suspension and it was stirred for 1 h. Finally, Ti0₂ sediment modified with platinum was rinsed a couple of times with deionised water and ethanol, after which it was dried at the temperature of 50 °C for 5h. 0.1 mole % of platinum was sedimented on the surface of titanium dioxide.

Example 2. Obtaining T1O₂ surface- modified with platinum and pure Ti0₂paste

At first, 7.5 ml of terpineol, 120 ml of butyl carbitol, 4.5 g of ethyl cellulose, 7.5 ml of Span 85 and 7.5 ml of dibutyl phtalate were added into a ceramic vessel. Then the components were stirred and heated while maintaining the temperature of 70 °C until uniform consistency was obtained. Upon obtaining uniform consistency, 10 g of Ti0₂ orTi0₂-Pt were added into the ceramic vessel and blended. The blending was conducted until obtaining uniform consistency. Fig. 1 presents the pictures of obtained Ti0₂ pastes.

Example 3. Pastes application onto ceramic cubes

Each of the prepared Ti0₂ and Ti0₂-Pt pastes was applied onto ceramic cubes with the dimensions of 2x3 cm by means of immersion of the cubes in the paste for 5 minutes, 2.5 minutes per each side. After removal from the paste the ceramic cubes were blown through with an air stream with the view to excess paste removal. All obtained layers were subject to drying at 120 °C for 3 hours and later to calcination at 450°C - with temperature increase of 10°C/min up to 450°C, which was maintained for 3h. Fig. 2 presents the picture of ceramic cubes immersed in the pastes and cubes after calcination. Example 4. The application of quantum dots onto Ti0₂-Pt and pure Ti0₂ catalysts deposited on ceramic cubes.

A chemical bath deposition method was used for the application of quantum dots on photocatalysts surface. In short this method consists in immersing a photocatalyst successively in the cation and anion precursor of the quantum dot. The detailed description of application of four different quantum dots onto the surface of Ti0₂-Pt and pure Ti0₂ catalysts deposited on ceramic cubes has been presented below.

• A CdS quantum dot

At first, ceramic cubes with the applied Ti0₂-Pt and pure Ti0₂ photocatalyst were immersed for 5 minutes in 0.5 M of pure Cd(N0₃)₂ solution in ethanol, rinsed with ethanol and later immersed for the next 5 minutes in 0.2 M of Na₂S solution in methanol and rinsed with methanol. These activities were repeated five times. The obtained photocatalysts were dried at the temperature of 60 °C for 6 hours. • A SdS quantum dot

At first, ceramic cubes with the applied Ti0₂-Pt and pure Ti0₂ photocatalyst were immersed for 5 minutes in 0.5 M of aqueous SnCl₂ solution, rinsed with water and later immersed for the next 5 minutes in 0.2 M of aqueous Na₂S solution and rinsed with water. These activities were repeated five times. The obtained photocatalysts were dried at the temperature of 60 °C for 6 hours.

• An Ag2S quantum dot

At first, ceramic cubes with the applied Ti0₂-Pt and pure Ti0₂ photocatalyst were immersed for 5 minutes in 0.03 M of AgN0₃ solution, being the ethanol/ water solution in a volume-to-volume ration of 4/1 and they were rinsed with ethanol, and later immersed for the next 5 minutes in 0.03 M of Na₂S solution, being the ethanol/ water solution in a volume-to-volume ration of 4/1 and rinsed with ethanol. These activities were repeated five times. The obtained photocatalysts were dried at the temperature of 60 °C for 6 hours.

• A Bi₂S₃ quantum dot

At first, ceramic cubes with the applied Ti0₂-Pt and pure Ti0₂ photocatalyst were immersed for 5 minutes in 4 M of Bi(N0₃)₃ solution in acetone, rinsed with acetone and later immersed for the next 5 minutes in 0.25 M of aqueous Na₂S solution and rinsed with water. These activities were repeated five times. The obtained photocatalysts were dried at the temperature of 60 °C for 6 hours.

Bi₂S₃, Ag₂S, CdS and SnS quantum dots were also applied onto clean ceramic cubes without photocatalysts in the form of pure Ti0₂ surface-modified with platinum.

The activity of toluene samples degradation using different variants of photocatalyst cubes was measured in the presence of a LED 375 nm diode after 20 minutes and a LED 465 nm diode after 60 minutes. Table 1 Toluene degradation in the presence of CdS QD - Pt - Ti0₂ photocatalyst cube

Table 3 Toluene degradation in the presence of Ag₂S QD - Pt - Ti0₂ photocatalyst cube

Sample name Short sample description Toluene Toluene

degradation [%] degradation [%] of the LED 375 of the LED 465 nm diode after nm diode after 20 minutes 60 minutes a cube A ceramic cube 0 0

Ti0₂ cube A ceramic cube with Ti0₂ 78% 0

Pt - Ti0₂ cube A ceramic cube with Ti0₂ 86% 30%

surface-modified with platinum

an Ag2S QD - ΤΊ02 cube A ceramic cube bearing a 88% 50%

quantum dot an Ag₂S QD - Pt - Ti0₂ A ceramic cube with Ti0₂ 96% 61% cube surface-modified with platinum

bearing a quantum dot

Table 4 Toluene degradation in the presence of Bi₂S₃ QD - Pt - Ti0₂ photocatalyst cube

Sample name Short sample description Toluene Toluene

degradation [%] degradation [%] of the LED 375 of the LED 465 nm diode after nm diode after

20 minutes 60 minutes a cube A ceramic cube 0 0

Ti0₂ cube A ceramic cube with Ti0₂ 78% 0

Pt - Ti0₂ cube A ceramic cube with Ti0₂ 86% 30%

surface-modified with platinum

a Bi2S3 QD - Ti02 cube A ceramic cube bearing a 89% 47%

quantum dot

a Bi₂S₃ QD - Pt - Ti0₂ cube A ceramic cube with Ti0₂ 95% 56%

surface-modified with platinum

bearing a quantum dot

Both in the case of UV radiation (LED 375 nm) and in the case of Vis radiation (LED 465 nm), a significant growth of effectiveness of toluene removal from the gas phase was observed.

Example 5. Obtaining porous photocatalysts in the form of Ti0₂ nanotubes.

A substrate in the form of titanium film is used for the formation of photocatalytic layers in the form of Ti0₂ nanotubes. Film preparation included its purification by means of subsequent immersion in acetone, isopropanol and methanol as well as ultrasound treatment in each of the above-mentioned solvents for 10 minutes. Then the substrate was rinsed with a demineralised water stream and dried in the air. During the next procedure stage a base material was placed in electrolyte consisting of 98 volume % of ethylene glycol, 2 volume % of water and 0.09 mole/dm³ of ammonium fluoride, after which it was anodised for 60 minutes using a platinum net as a cathode under 30 V voltage. The matrix of Ti0₂ nanotubes was formed on the surface of base material during the electrochemical process. The base material with the formed matrix of Ti0₂ nanotubes was removed from the solution, rinsed with demineralised water and dried in the air for 12 h, after which it was placed in a vessel with demineralised water and exposed to ultrasounds for 5 minutes with the view to removal of surface contaminants. Then the formed nanostructures were dried at 80 °C for 24 h. During the last stage the matrix of Ti0₂ nanotubes on the titanium base was placed in the furnace and it was calcined in air atmosphere with the temperature increase of 2°C/min until reaching the temperature of 450 °C, which was maintained for 1 h.

Example 6. Obtaining porous photocatalysts in the form of Ti0₂ nanotubes surface- modified with platinum.

Platinum nanoparticles on the surface of Ti0₂ nanotubes were deposited using a photodeposition method. A titanium board with the formed Ti0₂ nanotubes is immersed in HC1 solution with pH 5 during 10 minutes. Then the board was immersed in 30 cm³ solution of K₂Cl₆Pt metal precursor without previous rinsing. After 2 h 0.69 cm³ of isopropanol was introduced into the photoreactor and it was run through N₂ solution for 1 h with the view to air removal. With the view to immobilising nanoparticles of noble metals, the solutions together with the immersed titanium plate covered with Ti0₂ nanotubes were exposed to UV-Vis radiation for 2 h using a xenon lamp with the power of 250 W. After the completed photodeposition the board was dried at the temperature of 110°C during 12h. Three different platinum quantities were deposited on the surface of Ti0₂ nanotubes: 0.5, 1.0 and 1.5 mole %. Example 7. Applying quantum dots onto photocatalysts in the form of Ti0₂ nanotubes surface-modified with platinum nanoparticles.

• An Ag2S quantum dot

At first, Ti0₂ nanotubes surface-modified with platinum were immersed for 5 minutes in 0.03 M of AgN0₃ solution, being the ethanol/ water solution in a volume-to-volume ration of 4/1, they were rinsed with ethanol and later immersed for the next 5 minutes in 0.03 M of Na₂S solution, being the ethanol/ water solution in a volume-to-volume ration of 4/1 and they were rinsed with ethanol. These activities were repeated 2, 4, 6 and 8 times. The obtained photocatalysts were dried at the temperature of 60 °C for 6 hours.

• A Bi₂S₃ quantum dot

At first, Ti0₂ nanotubes surface-modified with platinum were immersed for 5 minutes in 4 mM of Bi(N0₃)₃ solution in acetone, rinsed with acetone and later immersed for the next 5 minutes in 0.25 M of aqueous Na₂S solution and rinsed with water. These activities were repeated 2, 4 and 6 times. The obtained photocatalysts were dried at the temperature of 60 °C for 6 hours.

Bi₂S₃ and Ag₂S quantum dots were also applied to clean T1O₂ nanotubes which were not surface modified with platinum.

The activity of toluene samples degradation using different variants of photocatalyst nanotubes was measured in the presence of a LED 375 nm diode after 20 minutes and a LED 465 nm diode after 60 minutes. The best conditions correspond to the content of platinum and/ or quantum dot on the surface of T1O₂ nanotubes, at which the highest degree of toluene degradation was observed.

Table 5 Toluene degradation in the presence of Bi₂S₃ QD - Pt - T1O₂ NTs photocatalyst

Sample name Short sample Toluene Toluene description degradation degradation

[%] of the [%] of the

LED 375 nm LED 465 nm diode after 20 diode after 60 minutes minutes

Ti0₂ NTs Clean nanotubes 65% 3%

0.5%Pt-TiO₂ NTs Samples differing by 77% 25%

1.0%Pt-TiO₂ NTs platinum content 80% 30%

1.5%Pt-Ti0₂ NTs 72% 22%

10Bi₂S₃-TiO₂ NTs The samples which 85% 33%

20Bi₂S₃-TiO₂ NTs differed by the amount 90% 40%

30Bi₂S₃-TiO₂ NTs of the quantum dot on 81% 36% the nanotubes surface

20Bi₂S₃-1.0%Pt -Ti0₂ Best conditions 100% 47% NTs

Table 6 Toluene degradation in the presence of Ag₂S QD - Pt - Ti0₂ NTs photocatalyst

Example 8. A modular device for air treatment and deodorising

A device for the air treatment and deodorising consists of four basic modules: dust removal 1, advanced oxidation- ozonisation 2b, advanced oxidation - photocatalysis 2a, residual ozone removal 3, and adsorption on active carbon 4.

The diagram of a modular device has been presented in Fig. 3. Equipping the installation in the preliminary dust removal module 1 enables the removal of solids particles from the air stream entering the advanced oxidation module and thus it extends the operation time and effectiveness of this module. The advanced oxidation module enables the degradation of contaminants using hydroxyl radicals with the oxidation potential of 2.80 V in the photocatalytic part 2a and then the oxidation of contaminants using strong oxidation in the form of ozone with the oxidation potential of 2.07 V in the ozonising part 2b. The combination of nonselective hydroxyl radicals and selective oxidiser in the form of ozone enables the increase of degradation effectiveness of contaminants and micro-organisms which contaminate the air, including highly resistant malodorous compounds. A chamber for conducting a photocatalyst reaction 2a with a photocatalyst layer and a radiation source operates in the mode of contaminants degradation, corresponding to the radiation intensity scope from the radiation source of 0.2 mW/cm² and in the mode of photocatalytic layer treatment, corresponding to the radiation intensity scope from the radiation source of 10 mW/cm². The time ratio of device operation in the contaminants degradation mode and in the photocatalytic layer treatment mode is 5: 1. The residual ozone inactivation module 3 enables the destruction of unreacted ozone and thus it protects against 0₃ emissions into the environment. Equipping the installation in the module of adsorption on active carbon 4 enables the removal of volatile remains of organic contaminants in the outlet stream. The installation is equipped with sensors enabling the monitoring of both ozone content and the content of a model organic substance in the outlet stream, which enables constant control of effectiveness of device operation, which has not been presented in Fig. 3.

The essential element of the device is an advanced oxidation module equipped with a reaction chamber for contacting ozone with the contaminated gas phase and a reaction chamber for conducting a photocatalytic reaction with the photocatalytic layer, located on the carrier in the form of a modified porous coating and a radiation source.

The modular system enables easy adaptation of the installation to individual requirements in the application site, depending on the volume of contaminated air stream, the type and concentration of contaminants and the requirements concerning the contaminants content in the treated air. The effectiveness of the installation can be easily increased by multiplying specific modules. The installation can also be used for internal air treatment in production halls, public utility buildings, sports facilities and health service buildings. An air stream in the volume of 60 m³/h was introduced into the modular installation with the view to determining the effectiveness of contaminants removal, which corresponded to linear flow speed through specific modules equal to 0.1 m/s. The air contained the following model contaminants: toluene (50 ppm), ethanethiol (20 ppm), trimethylamine (20 ppm), butyric acid (10 ppm) and ammonia (20 ppm). Two ozonisation modules were used at the advanced oxidation stage, each of them containing 10 ozone lamps, which together ensured the production of ozone in the amount corresponding to the concentration of at least 25 ppm. Apart from ozonisation modules, two photocatalytic modules were used during the advanced oxidation stage, the photocatalytic layers of which (each with the geometrical surface of 0.16 m²) were constructed from porous ceramic material with the thickness of 20 mm, onto which Ti0₂ based pastes were applied, subsequently subject to drying at 120°C and calcination at 450°C. The surface of photocatalytic layers was evenly lit with lamps emitting radiation within the UV-A range with the intensity of 20 mW/cm². The air stream leaving the photocatalytic and ozonisation modules connected in series only contained trace remains of organic contaminants, i.e. <2 ppm (toluene, ethanethiol, trimethylamine, butyric acid), which were later fully absorbed in the first part of the adsorption module containing the active carbon deposit. Ammonia was fully removed in the second part of the adsorption module containing the deposit of 5A molecular sieves. Ozone remains were completely removed in the residual ozone inactivation module, containing a catalyst deposit on the basis of manganese oxide.

Claims

Patent claims

1. Modified porous coatings characterised in that they are formed from a porous deposit, preferably ceramic cubes or nanotubes, the porous deposit containing titanium oxide Ti0₂ or titanium oxide surface-modified with platinum Ti0₂-Pt as well as quantum dots.

2. Modified porous coatings according to claim 1, characterised in that Ti0₂ or Pt-Ti0₂ in the form of paste is applied onto the surface of ceramic cubes by means of cubes immersion in the paste, drying and calcination.

3. Modified porous coatings according to claim 2 characterised in that Ti0₂ or Pt-Ti0₂ paste is prepared by mixing and heating of terpineol, butyl carbitol, ethyl cellulose, sorbitan trioleate and dibutyl phtalate,

4. Modified porous coatings according to claim 3 characterised in that Ti0₂ or Ti0₂-Pt is added to the mixture.

5. Modified porous coatings according to claim 4 characterised in that Ti0₂- Pt is obtained using a chemical reduction method, consisting in the introduction of aqueous solution of K₂PtCl₄ into the suspension of Ti0₂ in alcohol solution, and the subsequent addition of a reducer in the form of sodium borohydride NaBH₄.

6. Modified porous coatings according to claim 1 or 2 or 3 or 4 or 5, characterised in that quantum dots are applied to the surface of ceramic cubes containing titanium oxide Ti0₂ or titanium oxide surface-modified with platinum Ti0₂-Pt, preferably Bi₂S₃, Ag₂S, CdS and SnS_; ones using a chemical bath deposition method, consisting in immersing a photocatalyst successively in the cation and anion precursor of the quantum dot.

7. Modified porous coatings according to claim 1, characterised in that a substrate in the form of titanium film is used for the formation of porous coatings in the form of Ti0₂ or Ti0₂-Pt nanotubes.

8. Modified porous coatings according to claim 7 characterised in that at the first stage the film is purified by means of immersion in at least one solvent and it is subject to ultrasound treatment.

9. Modified porous coatings according to claim 8 characterised in that the purified film is rinsed with demineralised water streams, dried and placed in an electrolyte, and later is anodised using a platinum net as a cathode.

10. Modified porous coatings according to claim 9 characterised in that the electrolyte contains ethylene glycol and/ or water and/ or ammonium fluoride.

11. Modified porous coatings according to claim 9 or 10 characterised in that the matrix of Ti0₂ nanotubes formed during the electrochemical process on the surface of the base material is rinsed with demineralised water, dried and exposed to ultrasounds with the view to removal of surface contaminants, after which it is dried and calcined.

12. Modified porous coatings according to claim 7 or 8 or 9 or 10 or 11, characterised in that platinum nanoparticles are deposited on the surface of Ti0₂ nanotubes using a photodeposition method in a photoreactor.

13. Modified porous coatings according to claim 12 characterised in that a titanium board with the formed Ti0₂ nanotubes is immersed in HC1 solution with pH 5, and later in the K₂Ci₆Pt metal precursor solution, after which isopropanol is introduced into the photoreactor and run through N₂ solution for air removal, and then the solutions together with the immersed titanium plate covered with Tio₂ nanotubes are exposed to UV-Vis radiation and dried.

14. Modified porous coatings according to claim 7 or 8 or 9 or 10 or 1 1 or 12 or 13, characterised in that quantum dots are applied to porous surfaces in the form of Ti0₂ or Ti0₂-Pt nanotubes, preferably Ag₂S or Bi₂S_3; using a chemical bath deposition method, consisting in immersing a photocatalyst successively in the cation and anion precursor of the quantum dot.

15. A modular device for air treatment containing modified porous coatings characterised in that it contains a dust removal module (1) for the removal of solid particles, an advanced oxidation module equipped with a chamber for conducting a photocatalytic reaction (2a) with the photocatalytic layer placed on the carrier in the form of a modified porous coating according to claim 1, or 2, or 3, or 4, or 5, or 6, or 7, or 8, or 9, or 10, or 11 and a radiation source as well as a reaction chamber (2b) for contacting ozone with the contaminated gas phase, a residual ozone inactivation module (3) for the removal of ozone remains on the catalytic deposit, and also the adsorption module on activated carbon (4).

16. A modular device according to the claim 15 characterised in that the chamber for conducting a photocatalyst reaction (2a) with a photocatalyst layer and a radiation source operates in the mode of contaminants degradation, corresponding to the radiation intensity scope from the radiation source of between 0.2 and 20 mW/cm² and in the mode of photocatalytic layer treatment, corresponding to the radiation intensity scope from the radiation source of between 10 and 60 mW/cm².

17. A modular device according to the claim 16 characterised in that the time ratio of device operation in the contaminants degradation mode and in the photocatalytic layer treatment mode is between 5: 1 and 50: 1 respectively, preferably between 5: 1 and 15: 1.