PHOTOCATALYTIC SANITATION REACTOR

Description

[0001] The present invention relates to a sanitizing photocatalytic reactor suitable for air liquid or liquid fluids.

[0002] Photocatalysis is a catalytic process that can be used in different applications such as the abatement of pollutants and bacteria from liquid and gaseous streams, the purification of water and air, the synthesis of chemical compounds of interest and the conversion of the solar energy into chemical energy.

[0003] A typical photocatalyst is a semiconductor that, by absorbing one photon having higher energy than the gap, between valence band and conduction band, modifies the structure of its molecular orbitals with electrons, defined photoelectrons, of the valence band passing to the conduction band, with the formation of positive photo-gaps in the same valence band.

[0004] These charge carriers have short life: they can, by means of different mechanisms, recombine and return to the original configuration of the semiconductor i.e. generate a flow of surface current, because of the potential gradient that was created at the band level. The lowest energy level of the conduction band defines the reduction potential of the photoelectrons whereas the higher energy level of the valence band determines the oxidizing power of the photo-gaps, respectively.

[0005] When the reagents diffuse on the catalyst surface, they are chemisorbed on an active site and can participate to redox reactions. The absorbed species can be photo-reduced if its reduction standard potential is higher than that of the photoelectrons. Otherwise the photo-gaps can cause the oxidation, if their potential is higher than that of the subject molecules.

[0006] The reaction mechanisms are not yet exactly known: it is believed that the molecules are directly oxidized or reduced or else they react, in an adsorbed phase or in solution, by means of very reactive radical intermediates. These radicals are the result of the interaction effect of the charge photo-carriers with, for example, oxygen and water, contained in a solution.

[0007] The photocatalytic effectiveness depends on different parameters: the number and stability over time of the charge carriers that have been photogenerated, the absorption / desorption balance and the type of reaction considered.

[0008] The photocatalyst is a semiconductor photocatalyst material, such as for example WO 3 , that can be activated with white light basically with an emission temperature in the range from 5500°K to 6500°K, that can intervene in the redox processes thanks to its particular electronic structure. The applications are multiple: degradation of atmospheric pollutants (nitrogen oxides, volatile organic molecules), antimicrobial action, coating of building materials with self-cleaning, anti-fogging properties, and properties of degradation of pollutants in water.

[0009] Currently novel photocatalytic reactors are being studied and designed that allow sanitizing liquid and gaseous streams and in particular purifying water and air by means of the abatement of pollutants and bacteria. An example is disclosed by document US2011142725 which covers a photocatalytic air purification apparatus including a light source surrounded by one or more porous plate substrates coated with a photocatalyst material with a light source to activate the photocatalyst coating.

[0010] We have made novel, relatively simple photocatalytic reactors that allow achieving significant abatements both of pollutants and bacteria to be used directly or to be mounted on suction systems.

[0011] It is an object of the invention a sanitizing photocatalytic reactor as defined in claim 1

[0012] As it will be seen later, in particular in the field of the fluid treatment, the claimed feature of said light sources being mounted on supports that can be coupled in a fixable and separable way to the mantle wall of the tube segment allows obviating the need to have specialized personnel who knows both the technology of the fluid supply circuits and the technology related to the illumination systems with electric power supply. Thus, in particular, for what concerns the water treatment for domestic use both for food and disposal, it is possible to leave the installation of the hydraulic circuit to the person specialized in these circuits and intervene later with the assembly of the light sources by using an electrician or lighting technician.

[0013] As photocatalyst different substances are known, such as for example TiO 2 , ZnO, Fe 2 O 3 , CdS, CdSe, WO 3 , MoO 3 , V 2 O 5 , SnO 2 .

[0014] The photocatalyst preferably used in the state of the art is TiO 2 . This preferably requires the use of ultraviolet radiation for activating it. However, by subjecting this material to doping with Fe, Cr, Co, Mo, V, B, C, N, S and F, it is possible to modify the same and make it activable also by use of light with a wavelength in the spectral region of the visible light radiation.

[0015] A first problem for spreading these devices and the related treatment methods consists in being able to increase efficiency both from the point of view of the effect of purification and sanitizing, and from the point of view of energy efficiency and flow rate of the treated fluid. Maximizing these parameters constitutes a trade-off condition among them as an increase of the flow rate through the reactor requires an increase of the reaction efficiency and usually an increase in radiation energy for the activation of the photocatalyst.

[0016] Despite all the examples of implementation of these photocatalytic reactors use TiO 2 , it has surprisingly been found that the efficiency, in terms of the effect of the sanitizing treatment, is significantly higher using WO 3 as a photocatalyst.

[0017] As it will appear from the following description, the best results were obtained by combining the photocatalyst made of, or comprising, WO 3 with an activating light radiation having an intensity of at least 300 Lux and a wavelength in the visible light.

[0018] Preferably, said light radiation has an intensity of at least 300 Lux and a white color with a gradation from 5300°K to 10000°K.

[0019] Preferably, LED type lamps are suitable as light sources.

[0020] In combination with the aforementioned features, the parameter optimization is also achieved thanks to a constructive configuration of the supports for the photocatalyst and lamps or light sources emitting the radiation activating the same, in combination with the elements for conveying the flows of gaseous and / or liquid fluid to be treated.

[0021] As already highlighted earlier, it is a feature to separate one from the other, in operating units that can be mounted independently and can be aggregated, the interface part with the fluid flow of the reactor and the generation part of the activating radiation.

[0022] Preferably, the light radiation is emitted with a propagation direction incident on the surfaces of the supporting elements of the photocatalyst and with an opening angle ranging from 100 to 120°.

[0023] A reactor according to one or more of the preceding features can be part of machines or equipment conveying fluid flows in particular gaseous flows, such as for example conditioners or aerators, or other similar devices.

[0024] In a preferred embodiment, the sanitizing photocatalytic reactor is particularly suitable for the sanitizing treatment of liquid fluids and is constituted by a tubular element, preferably having a cylindrical shape, constituting a tube segment through which the liquid fluid is passing and inside which the supporting elements for the photocatalyst are provided, whereas the light source or sources are provided externally to said tubular element, the latter being made.

[0025] Preferably one or more strips of adjacent LED lamps is mounted on a band made of flexible material, which band can be wound around the mantle surface of the tubular segment or container, the strips of LED lamps being oriented parallel to the winding axis, i.e. the axis of the tubular segment or container.

[0026] Preferably, the inner wall of said band is made of reflective material for the activating radiation emitted by the LED lamps.

[0027] Still according to a feature, the outer tubular segment has, at the terminal ends, connection fittings sealing to further parts of the feeding pipe of the fluid, such as for example clamping flanges, terminals coupled by screwing or the like.

[0028] According to the preferred embodiment, a device for sanitizing fluids comprises a tubular pipe segment made of transparent material, whose ends are provided with connection fittings sealing to further elements of a feeding circuit of said fluid, a supporting element for the photocatalyst being housed inside said tubular segment, which element has at least one surface facing the mantle wall of the tubular segment and on which surface the photocatalyst is provided, said surface being in contact with the fluid flow in said tubular segment, and one or more light sources arranged outside the mantle wall of the tubular segment and orientated with one or more LED lamps in the direction of the central axis of the tubular segment i.e. in the direction of the supporting element of the photocatalyst, i.e. the surface of the same on which said photocatalyst is provided, one or more power supply units of said light source or sources, said light sources being mounted on supports that can be coupled in a fixable and separable way to the mantle wall of the tube segment.

[0029] In Figures 1 to 6 different constructive variations of a photocatalytic reactor is built inside a common water filter.

[0030] Figure 7 shows a preferred embodiment variation of a filtering unit of fluids according to the present invention.

[0031] Figure 8 shows a preferred embodiment of the present invention for the treatment of flows of passing liquid fluids.

[0032] Figure 9 shows the supporting element of the photocatalytic material and the band for fixing the sources of the activating light radiation provided for the embodiments of Figures 7 to 8.

[0033] Figures 1 to 6 show, for illustrative purpose only and not forming part of the invention a photocatalytic reactor built inside a common water filter of which Figure 1 shows the external view. The water filter comprises an external socket 31 and a net 32 adhering to the inner surface of the socket. The net is treated, i.e. covered with the photocatalyst. A cartridge 33 made of plastic material and covered by nylon fabric with micro-holes of 60 microns is coaxially supported inside the socket. Inside said cartridge the photocatalytic reactor 133 is inserted on a laminar support or yarn support or other structure on a support and forming channels, all of the construction being transparent to light. The illumination with the necessary LEDs will be placed outside depending on the type of hydraulic assembly as depicted in the example of Figures 2 and 6 and 7. The strips 22 of LEDs 23 are in the form of annular elements inserted on the external wall of the socket and distributed along the axial extension thereof, with the LED sources 23 facing the inside of the socket relative to the emission direction. Other alternatives can also be provided, possibly in combination to each other as arrangements of the rectilinear strips oriented parallel to the axis of the socket and / or one or more helical strips that wind on the outer surface of the socket.

[0034] A header 38 locks said concentric tubes, containing at least two openings, at least one for the inlet 39 of the fluid to be sanitized, at least one for the outlet 40 of the sanitized fluid. The fluid enters through the inlet 39, crosses all of the set of parts described and adheres first to the net and then crosses the micro-holes of the coating of the cartridge and, finally, adheres to the photocatalytic reactor inside the cartridge itself. Thus the sanitized liquid exits at 40. The strips 22 of LED lights 23 are placed outside the tube according to the construction.

[0035] In the light of the results achieved, it is evident that the photocatalytic reactor used for sanitizing the air in one passage only works, although in a differentiated way, based on the type of bacteria and throughput in the treatment system.

[0036] Figure 7 shows an embodiment of the present invention. The filtering unit comprises a tubular container 140 closed at one end thereof, coaxially housing a cylindrical filtering cartridge 141 inside it.

[0037] The filtering cartridge 141 has a mantle wall constituted by a grid or a porous material having size of the meshes or pores of the type usually used for example for the water filtration or the like. The cartridge is closed at one head end that is on a side thereof corresponding to the closed end of the container 140. Both the filtering cartridge 141 and the container 140 are open at the opposite end and this end is linked to an inlet union 142 and an outlet union 143, respectively.

[0038] As it is evident, the mantle wall shaped as a grid of the cartridge can be stiffened by a combination of axial and circumferential ribs on which the grid-like wall rests.

[0039] Both the wall of the container 140 and the wall of the cartridge have transmissibility to the light radiation activating a photocatalyst.

[0040] The photocatalyst material is applied on a supporting element, not visible in Figure 7, that is made as depicted in Figure 9 and is denoted by 150. This supporting element of the photocatalyst material is constituted by a plurality of axial fins 151 radially oriented and arranged so as to form a crown along a circumference. The outer diameter of the crown of radial fins 151 is smaller than the inner diameter of the cylindrical filtering cartridge 141.

[0041] The radial fins 151, in pairs of diametrically opposite fins, are coincident with a diametrical plane of said element 150.

[0042] The fins are kept in position at their ends by rings 152.

[0043] According to a further feature that can be provided alternatively or in combination with the supporting element 151, the photocatalytic material is provided on the mantle wall and / or reinforcing ribs of the filtering cartridge 141.

[0044] The illumination source emitting the light radiation activating the photocatalyst is constituted by a band made of flexible material 144 on which the LED strips 145, that are oriented parallel to the winding axis of said band around the mantle wall of the container 140, are fixed with predetermined distances to each other.

[0045] The extent of said band perpendicularly to the longitudinal extent of the LED strips 145 is substantially equal to that of the development on the plane of the mantle wall of the container 140, i.e. the maximum diameter thereof, if the shape of said container is slightly a truncated cone.

[0046] According to a possible feature, the arrangement of the LED strips on the band 144 made of flexible material is such that the LED strips are placed in intermediates points of the succession of adjacent radial fins, by orientating the beam emitted in the angular region generated by the same and by illuminating the facing surfaces of the adjacent fins of the column of fins 151.

[0047] The band can be formed by two layers coupled to each other and covering the sides of the LED strips to which the conductors for the power supply are connected, thus a common power supply wire 146 branching to the various LED strips 145 inside the pocket formed by at least two layers coupled to each other of the flexible band being exited sealingly from said band.

[0048] Still according to a feature, the inner surface of the band made of flexible material 144 is made of, or coated by, a layer of reflective material whose reflectivity parameters are optimized on the wavelengths of the light radiation activating the photocatalytic material.

[0049] As it is evident, the band 144 is wound around the container 140, whereas on a terminal edge parallel to the axis of the container, means fixing to the corresponding opposite edge of said band 144, allowing to tighten the band in position on the container 140, are provided.

[0050] Optionally said fixing means are made of a material of the Velcro ®< type, one of the ribbons being placed along a first edge 146 of two edges of the band parallel to the axis of the container 140 and / or LED strips 145, on the external surface of the band 144, whereas the other ribbon is provided on an extension of the opposite edge 147 of the band 144 intended to overlap with the ribbon on said first edge.

[0051] Still according to a further feature, both the filtering cartridge 141 and the supporting element 150 of the photocatalytic material are made modular, a module being provided with a minimum axial length of both of these elements 141 and 150, which length is defined correspondingly and such that it is possible to generate filtering cartridges 141 and corresponding supporting elements 150 of the photocatalytic material having length equal to multiples of said minimum length by axially aligning to each other the individual modules having minimum length.

[0052] These can be removably fixed to their ends facing head-to-head thanks to any type of fixing member, such as for example screws, bolts, rivets, interlocking means, ring nuts locking the ends of the modules facing to each other and / or also by gluing or welding.

[0053] In Figures 7 and 9 an embodiment is shown wherein both the filtering cartridge 141 and the supporting element of the photocatalytic material 150 are constituted respectively by two modules coupled to each other and having minimum length.

[0054] A further feature can provide that also the band 144 with the LED strips 145 has a length corresponding to said minimum length and that, in case of combination of several modules, the individual bands 144 are mounted one after the other along the longitudinal extent of the set of modules.

[0055] In the example of Figures 7 to 9, the choice has been made by providing a band whose minimum length is corresponding to the length of two modules of filtering cartridge 141 and / or supporting element of the photocatalytic material 150.

[0056] Figure 9 shows an embodiment variation of the filtering unit according to Figure 7, that differentiates because the inlet and the outlet of the filter are not provided on the same end of the container. The latter his has been made in the form of tubular element that is inserted thanks to the nuts of the ends in a feeding pipe of a fluid flow. The construction of the cartridge 141 and supporting element of the photocatalytic material, as well as the construction of the band 144 bearing the LED strips 145, are essentially identical to those described with reference to the previous example.

[0057] As it is evident from Figure 9, the embodiments depicted have the advantage that the support 150 for the photocatalytic material and the illumination source can be made as integration kit for existing filtering structures. In general, such existing filtering unit have standardized sizing, therefore by defining accordingly the diameters of the supporting element 150 of the photocatalytic material and the minimum length of the module when a modular construction is provided, and the size of the band 144 in axial direction and in circumferential direction, it is possible to produce universal kits that adapt to the different configurations of existing filtering units.

[0058] Furthermore as it is evident, the particular implementation of the illumination source in the form of band outside the container of the flow releases the installation of the hydraulic part from the electric one and simplifies the construction and maintenance activities that can thus be given, depending on the type of work, to a plumber or an electrician.

[0059] For what concerns the type of photocatalysts, the embodiments described of the device according to the invention can be provided in combination with any photocatalyst.

[0060] However, the best results in terms of efficiency and effectiveness are obtained by combining the constructions described above with the preferred photocatalyst defined above.

[0061] The above also applies to the features of intensity and / or wavelength and / or color of the activating light radiation and / or to the preferred materials used for the supports of the photocatalyst material.

Claims

1. Sanitizing photocatalytic reactor suitable for gaseous or liquid fluids essentially comprising a reaction region containing a photocatalyst selected among photocatalyst materials activated with sunlight, which photocatalyst is distributed on a support made of inert material or else mixed with a matrix made of plastic material, and an illumination source oriented so as to emit light radiation beams incident on said photocatalyst, i.e. on said support and which illumination source is constituted by one or more white color LED lights, where said reaction region comprises one or more channels through which said fluids to be sanitized flow, said channels being delimited and / or containing said supports for the photocatalyst and in which the device comprises a tubular pipe segment made of transparent material, whose ends are provided with connection fittings sealing to further elements of a feeding circuit of said fluid, the supporting element for the photocatalyst being housed inside said tubular segment, which element has at least one surface facing the mantle wall of the tubular segment and on which surface the photocatalyst is provided, said surface being in contact with the fluid flow in said tubular segment, and one or more light sources arranged outside the mantle wall of the tubular segment and orientated with one or more LED lamps in the direction of the central axis of the tubular segment i.e. in the direction of the supporting element of the photocatalyst, i.e. the surface of the same on which said photocatalyst is provided, one or more power supply units of said light source or sources, said light sources being mounted on supports that can be coupled in a fixable and separable way to the mantle wall of the tube segment.