WO2022101620A2

WO2022101620A2 - Air treatment unit

Info

Publication number: WO2022101620A2
Application number: PCT/GB2021/052906
Authority: WO
Inventors: David Thomas
Original assignee: Environmental control coatings Limited
Priority date: 2020-11-11
Filing date: 2021-11-10
Publication date: 2022-05-19
Also published as: WO2022101620A3; GB202017783D0; GB2600935A

Abstract

A component (3) for an air-treatment unit ( 1) : is provided, the component,(3) comprising a solid body (15) composing longitudinal channels (22) extending between first and second end faces of the body, a first set of channels extending; from a perimeter face (26) of the body towards an opposite side of the body (15) and a second set of channels (24),. which also extend from a perimeter face (26) towards an opposite side of the body. The first set of channels (23) orthogonally intersect the longitudinal channels (22) The second set of channels (24) tangentially Intersects the longitudinal channels (22), A third set of channels (37) may, optionally, also be provided. The third set of channels (37) extends from a perimeter face (26) and orthogonally intersects both the longitudinal channels (22) and the channels from the second set of channels (24), An air-treatment unit (1) comprising a housing (2) end a component (3) is also provided The use of the component (3) in an air treatment system is also disclosed.

Description

Air Treatment Unit

Field of the Invention

[0001] The present invention relates to a component far an air treatment unit, to a housing configured to receive the component and to air treatment units including said componentand housing. The invention also relates to air-treatment systems comprising the air-treatment units. The components of the invention can be used to support photocatalytic materials: used to degrade environmental: pollutants, particularly nitrogen oxides (NO_x) , sulfur oxides (SO_x), volatile organic compounds (VOC), polycyclic aromatic hydrocarbons(PAH), ozone (O₃), particulate pollutants having a size ranging from under 1μm to 10μm, including bacteria, mould, fungus and viral particles. In this respect the invention provides a method far removing toxic gases and pollutants from an environment.

[0002] Background to the Invention

[0003] Several studies have recognised the detrimental effect that environmental pollution has on human health and the ecosystem. Eomet al (Environmental Health and Technology, 33(1) , article ID: e-2018004) observed that there was a greater prevalence of acute eye disorders, respiratory problems, cardiovascular disease and lung and uterine cancers in residents of industrial areas, where the levels of environmental pollutants such as particulate pollutants, sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), ozone (O₃), volatile organic compounds (VOC), polycyclic aromatic hydrocarbons (PAH) and heavy metals are high.

[0004] Particle pollutants (commonly referred to as PM) comprise a mixture of particles having diameters in the range from under 1μm to 10μm (PM₁ to PM₁₀), which are found in air. They are significant contributors to environmental pollutants and are linked to conditions such as pulmonary and cardiovascular diseases, lung cancer and dementia. Ozone (O₃). sulfur dioxide (SO₂) and nitrous oxides, including nitrogen dioxide (NO₂) are believed to be responsible for an increased risk of asthma and for damage to the eyes, skin and respiratory tract. PAHs and VOCs have been associated with skin aging and the formation of pigmented spots on the face. Other effects of air pollution include changes in white blood cell count, hypertension, neurological complications and psychiatric disorders (Ghorani-Azam, J. Res Med Sci. 2006: 21(65); doi: 10.4103/1735-1995.189646). Other airborne species: that have detrimental effects on health include pathogens such as bacteria and viruses, which can be transmitted via particles or droplets, particularly in enclosed spaces.

[0005] A photocatalyst is a material that helps to accelerate and enhance a light induced reaction without being consumed in the process. In most instances the catalytic activity of the photocatalyst is dependent on each of the frequency and the intensity of the light to which the photocatalyst is exposed. The useof photocatalyststo degrade environmental pollutants is known. US 6,221,259 teaches silica catalysts comprising titanium and zirconium dopants for degrading volatile organic compounds (VOCs) and toxic air pollutants at UV wavelengths of less than 400nm. Photocatalysis have also been found to exhibit anti- bacterial and anti-viral properties. Ramesh et al, Food Bioprocess Technol. 11, 2242-2252; doi:10.1007/s11947-018-2182-6, reported that the use of a titania-silica photocatalyst reduced the light energy needed to decompose Escherichia coli in white grape juice . The bacterium could be degraded by UVA light in the presence of the photocatalyst, but only by UVC light when the photacatalyst was absent. GB 2012145.5 teaches zirconium cerium photocatalysts capable of removing toxic gases and pollutants, including particulate matter from an environment.

[0006] Machines and vehicles powered by an internal combustion engine are often fitted with a catalytic convertor to reduce the concentration of toxic gases and pollutants produced in the exhaust gasses. Catalytic convertors comprise a high surface area support, an adhesive and a catalyst bound to the support via the adhesive. Suitable catalytic materials include platinum, rhodium and palladium. Oxides of cerium and zirconium are often included in the adhesive to increase the surface area of the substrate an which the catalyst is supported. It is essential that the support structure has a high surface area; this has the dual function of maximising the amount of catalyst supported in the structure and the efficiency of the catalytic conversion. Furthermore, the catalytic conversion of toxic gases and pollutants requires heat and a high surface area improves heat distribution within the structure. Examples of high surface area supports include alumina beads, metal meshes and substrates comprising surfaces defined by a triply periodic minimal surface (TPMS) as described in WO 2017/192508. The substrates of WO 2017/192508 include a plurality of cells arranged in three dimensions . Each of the plurality of unit cells includes a cavity defined by a triply periodic minimal surface (TPMS) and the cavities of the unit ceils may be interconnected to allow a fluid to pass through. Examples of triply periodic minimal surfaces that have been used in the manufacture of catalytic convertors include a Schwartz Primitive surface, a Schwarz crossed layers of parallels (CLP), a Schoen's Gyroid surface, a Schoen's l-WP surface, a Schwartz diamond surface, a Fischer-Kich PMY surface, a FRD surface, a Fischer-Koch CY surface, a Fischer-Koch S surface or a Neovius surface. Other TPMS surfaces known to a skilled person include Diamond, Split P and Lidinoid surfaces. TPMS are often designed to create turbulent flow through the structure to increase residence timeof exhaust gases in the convertor and maximise their conversion to less harmful substances. This is ideal in situations where the conversion reaction requires heat, but is unsuitable for conversion reactions that are light catalysed as the TPMS structure tends to impede the transmission of light through the support. [0007] A need exists for a component comprising a high surface area support that is capable of supporting a photocatalyst and which facilitates the effective transmission of light throughout the component body without a significant loss of intensity. The present invention addresses those needs.

[0008] In a first aspect of the invention there is provided a component For an air-treatment unit, the component comprising a photocatalytic material and a solid body, the solid body comprising: a. an inlet defined by a first end including a first end face, an outlet defined by a second end including a second end face and one or more perimeter walls defining one or more perimeter faces extending between the first end and the second end; b. a plurality of longitudinal channels extending through the body from the first end face to the second end face, the longitudinal channels defining a longitudinal direction for the flow of air through the body, the channels extending substantially parallel to each other along the longitudinal direction over at least part of the length of the body; c. a first set of channels comprising a plurality of rows of channels provided over at least part of a perimeter wall or over at least one of the perimeter walls, said rows extending laterally andbeing aligned in a longitudinal direction over said at least part of a perimeter wall or over each or the at least one perimeter wall, each of the channels of the first set extending radially from a perimeter face of said part or said at least one of the perimeter walls through the body in a direction substantially perpendicular to the direction of the longitudinal channels, each channel of the first set of channels being configured to orthogonally intersect one or more adjacent channels in a radially extending row of longitudinal channels, the row of longitudinal channels extending in a direction substantially parallel to the direction in which the channels of the first set extend; d: a second set of channels provided over at least part of a perimeter wall or over at least one of the perimeter walls and comprising a plurality of rows of channels, said rows extending laterally and being aligned in a longitudinal direction over a perimeter face of said part or said at least one perimeter wall, each channel of said second set extending from said perimeter face of the perimeter wall through the body in a direction substantially perpendicular to the direction of the longitudinal channels, each of the rows of the second set of channels being dispersed between the rows of the first setof channels and laterally off-set therefrom, each channel of the second set being configured to tangentially intersect two laterally adjacent radially extending rows of longitudinal channels, the first set of channels, second set of channels and perimeter wall defining a substantially continuous surface having the photocatalytic material supported thereon; and e. a recess for receiving a light source within the body.

[0009] The solid body may also comprise a third set of channels, each channels of the third set of channels being configured to orthogonally intersect both one or more longitudinal channels and one or two channels from the second set of channels. Preferably the point at which each channel from the third set orthogonally intersects a longitudinal channel is offset from the point at which the respective channel of the third set orthogonally intersects a channel from the second set of channels. Preferably the offset is lateral or radial, depending on the configuration of the longitudinal channels.

[0010] The solid body in which the channels are contained suitably comprises one or more materials selected from the group comprising a polyamide, a ceramic, a metal including a metal alloy. The solid body may be derived from any suitable shape, such as a cuboid, a cylinder, a sphere or a cone, but is preferably in the form of a cylinder. By the term "cylinder" it should be understood to include a circular cylinder, an elliptic cylinder, a square cylinder, a rectangular cylinder, a triangular cylinder, a pentagonal cylinder, a hexagonal cylinder or the like. Each cylinder is characterised by first and second end faces and one or more perimeter walls extending from and between the or each respective edge or edges of the first and second end faces. Suitably, the one or more perimeter walls extend in a direction that is substantially parallel with the longitudinal axis of the body. Circular and elliptical cylinders comprise a single perimeter wall and a single perimeter face. Square, rectangular, triangular, hexagonal and other polygonal cylinders comprise at least three perimeter walls, the number of perimeter walls being determined by the number of sides of the polygon defining the cylinder; in this case the solid body is characterised by one or more perimeter faces extending over the one or more respective perimeter walls, the one or more perimeter faces being defined by an exterior surface area. Each of the longitudinal channels and the first, second and optimally third sets of channels together are interlinked to define an internal surface within the solid body , the internal surface being defined by an internal surface area and an internal volume for containing air passing through the body. The longitudinal channels terminate at each of the first and second end faces. The first and second sets of channels are terminated over part of or the entirety of the perimeter face when the body is a circular or elliptical cylinder or over one or more perimeter faces when the body is derived from a polygonal cylinder as defined above. The nature of the termination of the first and second sets of channels at the perimeter face depends upon the configuration of the longitudinal channels. Where the component comprises a square array of longitudinal channels in a circular cylindrical body, the first and second sets of channels terminate on one or two parts of the perimeter face. Where the component comprises a circular array of longitudinal channels in a circular cylindrical body, the first and second sets of channels extend radially towards the central axis of the body and terminate over the entirety of the perimeter face. Where the component comprises a square array of channels in a square cylinder, the first and second sets of channels extend between and terminate on two opposite faces of the square cylinder. The third set of channels extends through the body. Depending on the configuration of the longitudinal channels, the third set of channels may terminate at a perimeter face. Where the third set of channels also terminates at a perimeter face, it terminates at a perimeter face or part of a perimeter face orthogonal the perimeter face at which the second set of channels terminate. Together, the longitudinal channels and the first, second and optionally third set of channels and the perimeter faces define a continuous surface having total surface area characteristic of the configuration of the body. The body may also be defined in terms of the ratio of its surface area to internal air volume, the internal air volume being the volume occupied by the longitudinal, first, second and optionally third set of channels within the body. The body is suitably defined by a total surface area to internal air volume in the range of 0.4 to 0.8. Preferably the ratio of the total surface area to internal air volume ratio is in the range 0.45 to 0.75 and is especially 0.48. [0011] Where the body is a cylinder the longitudinal channels extend through the body between the first end face and the second end face of the cylinder. The longitudinal channels are preferably provided in the form of an array extending over each of the first and second and faces. Preferably each longitudinal channel in the array is aligned with at least one other longitudinal channel in the array. A central axis defined by each longitudinal channel may be parallel with a central longitudinal axis of the cylindrical body. Preferably the central axis of each of the longitudinal channels in the array is parallel to the central axis of each of the other longitudinal channels. The array of longitudinal channels is suitably configured to define a regular pattern of longitudinal channels extending across each of the first and second end faces. Each end face may, therefore, be characterised by a square array of channels comprising parallel rows of channels extending across each of the first and second end faces; each channel in one row of the array is suitably aligned with a corresponding channel in the previous row. It will be appreciated that other arrangements of longitudinal channels are possible within the body. For example, each end face may further be characterised by an array of channels having different geometrical configurations: triangular, circular, pentagonal or hexagonal rows of channels may be arranged concentrically over each end face. Where the longitudinal channels are arranged as concentric raws over each end face, the rows are also preferably aligned to also define radial rows of channels extending in a direction from the longitudinal axis of the body towards the perimeter wall. It should be understood that in the context of the present invention, the term ''circular row" includes rows of other geometric shapes, for example triangular, pentagonal, hexagonal, heptagonal and octagonal rows and the like as well as circular or elliptical rows. The configuration of the array of longitudinal channels across each end face may reflect the shape of the body containing the array, but itmight also be different. For example, a right circular cylindrical body may be characterised by a square array of channels at each of the first and second end faces.

[0012] Suitable light sources include UV lamps configured to emit light in the range 100nm to 400nm and daylight lamps configured to emit light in the range 320nm to 700nm. The light source may be augmented by a thermal source of energy, either in the form of a heating element or an infrared lamp. Preferably the light source is a UV light source.

[0013] By the term "component for an air-treatment system" it should be understood to mean a device that, when installed into an air-treatment unit in an air-treatment system, is able to remove toxic gases or pollutants such as those referred to above from an environment such as the interior of a building or a vehicle, a roadside, an airport, a railway station, a marine port, a vehicle exhaust system outlet, a flue or a chimney. The term "remove" includes retention of the toxic species or pollutants in an unaltered form within the component as well as conversion of the toxic gases or pollutants to a less harmful form that is not damaging to the environment or ecosystem.

[0014] By the term "air-treatment unit'' it is to be understood to mean a component according to the first aspect of the invention together with the housing into which it is received.

[0015] By the term "air-treatment system” it is to be understood to mean a system including an air-treatment unit.

[0016] By the term "toxic gases and pollutants" it should be understood to mean nitrogen oxides carbon dioxide (CO₂), sulfur oxides (SO_X), volatile organic compounds (VOC). polycyclic aromatic hydrocarbons (PAH), ozone (O₃), particulate pollutants having a size ranging from under 1μm to 10μm, including bacteria and viral particles.

[0017] By the term "orthogonal intersection” it should be understood to mean that any channel in any one of a set of channels passes directly through a channel of a different setof channels in a substantially perpendicular direction such that a central axis defining the direction of any one channel in a set of channels intersects or crosses a central axis defining the direction of any one of the channels from the other set in a substantially perpendicular direction. In relation to the longitudinal channels and the first set of channels, orthogonal intersection occurs if any one channel of the first set of channels passes directly through a respective longitudinal channel in a substantially perpendicular direction such that a central axis defining the direction of any one of the longitudinal axis intersects with or crosses a central axis defining the direction of any one of channels from the first set with which it is configured to intersect in a substantially perpendicular fashion. In relation to the longitudinal channels and the third set of channels, orthogonal intersection occurs if one channel of the third set of channels passes directly through a respective longitudinal channel in a substantially perpendicular direction such that a central axis defining the direction of any one of the longitudinalaxis intersects or crosses a central axis defining the direction of any one of channels from the third set with which it is configured to intersect in a substantially perpendicular fashion. By the term "tangential intersection" It should be understood to mean that any one channel of one set of channels merges with one or more channels of a different set at their perimeter or circumferential edges. In particular tangential intersection occurs in relation to the longitudinal channels when at least one channel of the second set of channels merges or intersects with a one or more longitudinal channels at their respective perimeter or circumferential edges, such that a central axis defining the direction of any one of the longitudinal channels extends in a direction that is substantially perpendicular to a central, axis defining the direction of any of channels from the second set, but does not intersect there with; instead the perpendicularly extending axes defined by the channels are spatially offset from each other. Tangential intersection could further be defined by the perpendicular intersection of a virtual arc defined in relation to the circular cross-section of a longitudinal channel with an arc defined in relation to the circularcross-section of one of the second set of channels.

[0018] By the term "substantially perpendicular" it should be understood to mean that any of the channels in one set of channels intersect or bypass one or more channels in another set of channels at an angle of between 90° and 109°. By the term “substantially perpendicular" in relation to the longitudinal channels and the first set of channels it should be understood to mean that each of the first set of channels intersects or passes through the longitudinal channels at an angle of between 90° and 109°, preferably at an angle of between 90° and 102° , more preferably, at an angle of between 90 to 95° and especially at an angle of between 90 and 92°. The term should also be interpreted in relation to the relative orientationof the second set of channels . Thus an axis defining each of the second set of channels extends at an angle of between 90° and 109° , preferably at an angle of between 90° and 102° , more preferably, at an angle of between 90 to 95° and especially at an angle of between 90 and 92° relative to an axis defining the longitudinal channels.

[0019] By the term "longitudinal direction" it is to be understood to mean a direction defined between the first and second end faces of the body. This is typically the largest dimension of the body. [0020] By the term "longitudinal axis of the body" or "central axis of the body" it should be understood to mean an artificial line passing through the centre of each of the first and second end faces and extending there between.

[0021] By the term "lateral direction", "extending laterally" or “extending circumferentially” it should be understood to mean a direction which follows a line or part of a line defining the perimeter or circumference of the body. The term “rows extending laterally" means that the channel openings constituting the rows are arranged in a line which follows at least part of the perimeter line of the body. Generally, this direction is also substantially perpendicular to the longitudinal axis of the body. For example, where the body is a right square cylinder, the lateral direction extends across all the perimeter walls. Where the body is a circular cylinder, the lateral direction extends around the circumference of the cylinder. If a cylindrical body includes a square array of longitudinal channels extending between first and second end faces, the laterally extending first, secondand optimally third set of rows may only extend around part of the perimeter.

[0022] By the term “laterally adjacent” it should be understood to mean next to each other ina lateral direction.

[0023] By the term "radially adjacent” it should be understood to mean next to each other in a direction extending from part of the perimeter face or from a perimeter face on one side of the body towards a different part of the perimeter face or a different perimeter face on another part or opposite side of the body. Where the body is a square cylinder and comprises a square array of longitudinal channels, two channels would be considered radially adjacent if they were next to each other in a direction extending from one perimeter wall to the opposite perimeter wall. Where the body is a circular cylinder and composes a circular array of longitudinal channels, two channels would he considered radially adjacent if they were next to each other in a direction extending from one perimeter face towards the longitudinal axis of the body. Where the body is a cicular cylinder and comprises a square array of longitudinal channels, two channels would be considered radially adjacent if they were next to each other in a direction extending either parallel to a diameter of the circular end face of the cylinder or extending parallel with a virtual chord defined relative to the circular end face of the cylinder; a square array of longitudinal channels in a circular cylinder essentially comprises rows of channels extending in a direction parallel to a set of parallel chords defined relative to the circular end face of the cylinder in this respect tod terms

"radially extending” and " extendingradially" should be interpreted accordingly.

[0024] The photocatalytic material may be supported on the substantially continuous surface as a coating using an adhesive or other suitable binder. Alternatively, it may be self adherent or comprise an integral part of the surface. Suitably , the photocatalytic material comprises a mixture of zirconium and cerium oxides. Photocatalytic compositions comprising 40 to 99.5mol% zirconium oxide and 0.5 to 60mol% cerium oxide may be used. Preferably the composition comprises 50 to 99.5 mol % zirconium oxide and 0.5 to 50mol% cerium oxide. More preferred compositions include compositions comprising 50mol% of each of zirconium oxide and cerium oxide and compositions comprising 94mol% zirconium oxide and 6mol% cerium oxide. Another preferred photocatalytic material comprises 85 to 99.6 mol% zirconium oxide and 0.5 to 15mol% cerium oxide. The zirconium oxide preferably comprises a zirconsum (IV) oxide. The cerium oxide preferably comprises a mixture of cerium (Ill) oxideand cerium (IV) oxide. Preferably the photo-catalytic material is a material of the type disclosed in United Kingdom patent application GB 2012145.5. Alternatively, or in addition, the coating comprises quaternary ammonium polymer, silver nano-particles, copper nano- particles, gold nano-particles and particles of oxides of metals of iron, tin, zinc and titanium, [0025] The solid body including the channels can fee formed from any suitable methods known to a skilled person. Suitably, the body can be moulded using techniques known to a person skilled in the art. Methods such as those disclosed in WO 2017/192508 can also be employed. Alternatively, the body can be manufactured using three-dimensional printing techniques (3D printing).

[0026] A part of a perimeter face or at least one of the perimeter faces includes a first set of channels, each channel being defined by a central axis, which channel and axis extend from said part of or said perimeter face radially through the body in a direction that is substantially perpendicular to the direction of a central axis of a longitudinal channel with which it is configured to intersect. In this way a central axis defining any one of the channels of the first set of channels orthogonally intersects the central axes of one or more radially adjacent longitudinal channels extending between the first and second end faces. The first set of channels is further characterised by an array of channels, the array comprising rows of channels extending both laterally and longitudinally over part of or at least one perimeter face. Preferably the rows constituting the first set of channels are aligned over a perimeter face so that any one channel in a row is aligned with an adjacent channel in the preceding row so that the array comprises parallel rows of channels extending laterally and longitudinally over a perimeter face of its respective perimeter wall. Preferably the central axis of each of the channels of the first set of channels extends substantially parallel to each of the first and second and faces of the body. In a preferred first embodiment, a longitudinally aligned row of channels of the first set of channels is configured to orthogonally intersect with one or more channels in a respective row of radially aligned longitudinal channels. Where the body is a circular or elliptical cylinder and the longitudinal channels are provided in a circular array, including radially aligned rows of longitudinal channels, the first set of channels extend radlaliy through the body from the perimeter face towards the longitudinal axis in a direction that is substantially perpendicular to the direction of the longitudinal channel and along the radial rows defined by the circular array of longitudinal channels.

[0027] One or more of the perimeter faces referred to above, also includes a second set of channels, each channel of said second set being defined by a central axis, which channel and axis extend radially from a perimeter face through the body in a direction that is substantially perpendicular to the direction of a central axis of a longitudinal channel with which it tangentially intersects. The second set of channels is further characterised by an array of channels, the array comprising rows of channels extending both laterally and longitudinally over the perimeter face. Preferably the rows constituting the second set of channels are aligned so that any one channel in a row is aligned with an adjacent channel in the preceding row so that the array comprises parallel row of channels extending laterallyand longitudinally over the perimeter face of the perimeter wall on which the second set of channels are provided. Preferably the central axis of each of the channels of the second setof channels extends substantially parallel to each of the firstrand second end faces of the body and substantially perpendicular to the longitudinal axis of the body In a preferred embodiment, the second set of channels comprises sets of substantially parallel longitudinal rows of channels laterally aligned over the perimeter face, each channel in the longitudinally aligned row of the second set of channels being configured to tangentially intersect with one or more channels in the laterally adjacent radially extending rows of longitudinal channels. Where the longitudinal channels are arranged as a circular array, the channels of the second set may be arranged so that they tangentially intersect with one or more channels in the laterally adjacent, radially extending rows of longitudinal channels. Thus, each channel of the second set of channels is characterised by an intersection with two laterally adjacent, radially extending rows of longitudinal channels between which it passes . The second set of channels may be provided on the same or same part of the perimeter face as the face or part of the face bearing the first set of channels or it may be provided on a different part of the perimeter face or on a different perimeter face. Preferably the first set of channels and the second set of channels are provided on the same part of the perimeter face, same perimeter face or faces. Where the first set of channels are provided on different parts of the perimeter face or different perimeter faces to the second set, the first set of channels is provided on a perimeter face or part of a perimeter face that is substantially orthogonal to the perimeter face or part of the perimeter face on which the second set is provided. Where a perimeter face or part of a perimeter face includes both a first and second set of channels, the perimeter face or part of the perimeter face is characterised by two interspersed arrays of channels in which each of the rows of the array defining the second set of channels is positioned between adjacent rows of an array defining the first set of channels. Each of the rows of the second set of channels is suitably offset from the adjacent aligned rows of the first set of channels, so that each channel of the second set is essentially surrounded by four channels of the first set and vice versa.

[0028] The advantages of a configuration in which a perimeter face or part of a perimeter face includes first and second sets of channels is that it provides a body having a continuous surface with a high surface area. Further the configuration facilitates the efficient transmission of light emitted by a light source located in the recess throughout the body. Because the solid body provides a high surface area for supporting the photocatalytic material the component of the present invention can support extensive and efficient light catalysed conversion of toxic gases and pollutants to less harmful substances.

[0029] Where the first and second sets of channels are provided on the same perimeter face or same part of the perimeter face, the body may preferably further comprise a third set of channels, which extends throughout the body in a direction that is orthogonal to both the longitudinal channels and the first and second set of channels. If the longitudinal channels are provided as a square array over each of the first and second end faces of a square cylindrical body, the third set of channels may be provided over a perimeter face that is orthogonal to a perimeter face on which the first and second sets of channels are provided. In such a case the channels of the third set are characterised by an array of channels, the array comprising rows of channels extending both laterally and longitudinally over its respective perimeter face. Preferably the rows constituting the third set of channels are aligned so that any one channel in a row is aligned with an adjacent channel in the preceding row so that the array comprises parallel rows of channels extending laterally and longitudinally over the perimeter face of the perimeter wall on which the third set of channels are provided. Where the longitudinal channels are provided as a square array in a circular cylindrical body, the body is characterised by a single perimeter wall and a single perimeter face. In such a case, the first and second sets of channels are provided as first and second arrays over part of the perimeter face. The channels of the first and second set do not necessarily pass through the central axis of the body, but instead extend substantially parallel to each other in a direction defined by parallel virtual chords to the circular end face of the circular cylinder and substantially parallel to a plane passing through the longitudinal axis of the cylindrical body. The third set of channels extends substantially orthogonal to the first and second set of channels. Consequently, the third set of channels extends from a different part of the perimeter face to the part from which the first and second set of channels extends. In contrast, where the longitudinal channels are provided as a circular array of channels within a circular cylindrical body, the circular array comprising concentric circular rows of channels, the third set of channels extends in a direction substantially parallel to the direction of said circular rows and does not necessarily terminate at a perimeter face. In preferred embodiment of the first aspect, the component comprises a body derived from a square cylinder which comprises a square array of longitudinal channels over each of said first and second end faces.

[0030] In a preferred embodiment of the first aspect, the component comprises a body derived from a square cylinder which comprises a square array of longitudinal channels over each of said first and second end faces. The square cylinder is further characterised by first and second sets of opposing perimeter faces extending between the first end face and the second end face, a first set of channels extending between a first set of opposing faces and a second set of channels, offset from the first set and configured to extend between the first set of opposite faces only. Preferably the channels of the second set are both laterally and longitudinally offset from the channels of the first set. The component may be configured as a right square cylinder. Alternatively, it may be shaped or cut into a right circular cylinder having a square array of channels over each of the first and second end faces. In a particularly preferred embodiment, the component comprises a third set of channels extending between a second set of opposing faces of a right square cylinder, each channel of the third set being configured to orthogonally intersect one or more adjacent longitudinal channels in a row of longitudinal channels and to also orthogonally intersect one or more channels in a laterally extending row of the second set of channels. The channels of the third set preferably have a diameter that is substantially the same as the diameter of the channels of the second set.

[0031] In a fourth embodiment of the first aspect of the invention, the solid body is configured as a circular or elliptical cylinder. Preferably, the solid body is derived from a circular cylinder and the longitudinal channels are configured as sets of radially aligned substantially circular rows of channels arranged substantially concentrically about the longitudinal axis. The longitudinal channels are also configured as rows of radial channels, the number of radial rows corresponding to the number of longitudinal channels in any one of the circular rows of channels. Preferably the diameter of each of the longitudinal channels is uniform across the array. Alternatively, the diameter of the individual channels in an array may increase in a direction extending from the longitudinal axis of the body towards the perimeter. This ensures, particularly for pentagonal, hexagonal, right circular cylinders and the like that the continuous surface has a high surface area.

[0032] The longitudinal channels may be characterised by a diameter that is uniform along its length. Alternatively, the diameter of one or more of the longitudinal channels may vary along their length as required to either improve airflow through the body or to improve light transmission; in this respect, the diameter of a longitudinal channel may decrease in a direction going from each of the end faces towards a centre of the body; in this case the channel is characterised by a slight restriction along its length followed by an increase in the channel diameter adjacent the outlet of the component. This has the effect of increasing residence time of a gas passing through the component up to the point of the constriction and then increasing the flow of gas exiting the component via the outlet. Alternatively, the diameters of the longitudinal channels may increase in a direction along the longitudinal axis of the body going from the inlet to the outlet. In a preferred embodiment, the longitudinal channels are all characterised by a uniform diameter along their length. Suitably, each of the longitudinal channels has a diameter in the range 3mm to 7mm, preferably 4mm to 6mm and especially 5mm. The spacing between the centres of each of the longitudinal channels is chosen to provide a balance between ensuring the component body is sufficiently rigid to function as a catalyst support and providing a support surface with a sufficiently high surface area to maximise the amount of photocatalyst located on or in the surface. Suitably, the spacing between the centres of each of the longitudinal channels is in the range 5mm to 10mm, preferably 6mm to 9mm, especially 7.5mm.

[0033] Where, in accordance with the fourth aspect of the invention, the longitudinal channels are provided as a circular or elliptical array in a right circular or an elliptical cylindrical body respectively, the body comprises a single perimeter face and the first set of channels extends radially from the perimeter face towards the longitudinal axis of the body, each channel of the first set of channels being configured to orthogonally intersect at least one longitudinal channel in a radial row of longitudinal channels with which the channel of the first set is aligned. The diameter of each channel of the first set of channels may be uniform along its length. Alternatively, the diameter of each channel of the first set of channels may increase in a direction extending from the longitudinal axis of the body to the perimeter face. This will also be true for pentagonal and hexagonal cylinders. This increase in diameter in a radial direction extending from the longitudinal axis towards the perimeter of the body also helps to maintain the high surface area of the continuous surface. A second set of channels is also provided over the perimeter face and each channel of the second set also extends radially in a direction from the longitudinal axis of the body to the perimeter face, each channel of the second set of channels being configured to tangentially intersect two adjacent radial rows of longitudinal channels. As before all the channels within the second set may have a uniform diameter along their length. Alternatively, the diameter of each channel of said second set may increase in a radial direction extending from the longitudinal axis of the body to the perimeter face. Suitably, all of the channels of the first set of channels are characterised by a uniform diameter along their length. Where the body further comprises a third set of channels, these channels extend in a direction defined by the circular rows of longitudinal channels within the circular array. The channels of the third set orthogonally intersect each longitudinal channel in a radial row of longitudinal channels. Furthermore, the third set of channels orthogonally intersects each channel of a radially extending row of channels of the second set of channels. In this respect each channel of the third set of channels has a diameter that is substantially identical with the diameter of the channels of the second set of channels with which it intersects.

[0034] Where the longitudinal channels are provided as a square array in a circular or elliptical cylinder the body comprises a single perimeter face and the first and optionally second set of channels extends from a first part of the perimeter face through the body in a direction parallel to a row of parallel virtual chords to the circular or elliptical end face of the cylindrical body. As such the channels of the first and optionally second set emerge on a second part of a perimeter face. Where the body further comprises a third set of channels these extend between a third and fourth part of the perimeter face in a direction orthogonal to that of the first and second sets of channels.

[0035] Suitably, each of the channels of the third set are defined by a central axis, which channel and axis extend through the body in a direction that is substantially perpendicular to both the direction of a central axis (L) and also to the direction of the second set of channels with which it intersects. Where the longitudinal channels are provided in the form of a square array, the third set of channels are preferably characterised by an array of channels, the array comprising rows of channels extending both laterally and longitudinally over part of the perimeter face where the body is a circular cylinder and over one or more perimeter faces where the body is a square cylinder. Preferably the rows constituting the third set of channels are aligned so that any one channel in a row is aligned with an adjacent channel in the preceding row so that the array comprises parallel rows of channels extending laterally and longitudinally over the perimeter face or part of the perimeter face of the perimeter wall or part of the perimeter wall on which the third set of channels are provided. Preferably the central axis of each of the channels of the third set of channels extends substantially parallel to each of the first and second end faces of the body and substantially perpendicular to the longitudinal axis of the body. In a particularly preferred embodiment, the body comprises a circular cylinder, the longitudinal channels are provided in a square array and the third set of channels comprises sets of substantially parallel longitudinal rows of channels laterally aligned over part of the perimeter face, each channel in the longitudinally aligned row of the third set of channels being configured to orthogonally intersect with one or more channels in a row of longitudinal channels and to orthogonally intersect with one or more channels in a laterally extending row of channels of the second set of channels. Thus, each channel of the third set of channels is characterised by an intersection with one or more adjacent longitudinal channels and also with one or more channels of the second set of channels.

[0036] Preferably, for all embodiments, each channel in said first set has a diameter in the range 2mm to 6mm, preferably 3mm to 5mm and especially 4mm. Suitably, the spacing between the centre of each of the channels of said first set is in the range 5mm to 10mm, preferably 6mm to 9mm, especially 7.5mm. Suitably, all of the channels of the second set of channels are characterised by a uniform diameter along their length. Suitably, each channel in said second set has a diameter in the range 3mm to 7mm, preferably 4mm to 6mm and especially 5mm. Suitably, the spacing between the centre of each of the channels of said second set is in the range 5mm to 10mm, preferably 6mm to 9mm, especially 7.5mm. Suitably, all of the channels of the third set of channels are characterised by a uniform diameter along their length. Suitably, each channel in said third set has a diameter in the range 3mm to 7mm, preferably 4mm to 6mm and especially 5mm. Suitably, the spacing between the centre of each of the channels of said third set is in the range 5mm to 10mm, preferably 6mm to 9mm, especially 7.5mm.

[0037] The recess for receiving a light source is suitably located at and extends along the longitudinal axis of the body. The recess is preferably located at the inlet of the body, but may also be located along the longitudinal axis of the body extending from the body outlet towards the inlet. In an alternative arrangement, the body may comprise a plurality of small recesses distributed evenly over the first end face and around the longitudinal axis of the body each recess being configured to receive a light source such as a strip of light emitting diodes (LEDs). The body may further comprise a helical recess extending from the first end face to the second end face, the helical recess configured to receive a light source, such as a strip of LEDs.

[0038] The component suitably further comprises an end piece configured to be positioned at an end face distal to the recess for receiving a light source, to prevent transmission of light through the distal end face of the body. The end piece is configured to facilitate air flow through the body and as such it may be provided with baffles and/or angled channels to support airflow through the body whilst obscuring the emission of the light at an end face. Where the recess extends from the first end face, the end piece is suitably attached to the second end face and comprises peripheral concentrically arranged rows of angular channels extending from the inner surface of the end piece to the outer surface, the inner portion of the inner surface includes one or more baffles configured to direct the flow of air out of the matrix and block leakage of light from the body. Although daylight lamps can be used, the light source is preferably a UV light source, including both UVA and UVC light sources. In addition to light sources, a source of heat may also be provided to augment the light source; suitable heat sources include heating elements and IR lamps.

[0039] A second aspect of the invention provides a housing for receiving a component according to the first aspect of the invention, the housing comprising an inlet and an outlet, a housing wall extending between the inlet and the outlet, the housing wall defining (i) an enclosure for receiving a component according to the first aspect of the invention (ii) an air passage between the inlet and the outlet and (iii) a longitudinal direction between said inlet and said outlet for defining the flow of air through the housing and means for facilitating airflow between said inlet and said outlet. The housing wall comprises an outer surface and an inner surface configured to face the enclosure. A photocatalytic coating may be provided on the inner surface of the housing. Alternatively, or in addition the inner surface comprises a reflective material. A filter may also be provided on the inlet to remove particulate material having a diameter greater than 15 microns.

[0040] The inner surface of the housing may be configured to improve the efficiency of the catalytic conversion or augment the airflow throughout the air-treatment unit. In addition to the coatings referred to above, the inner surface may comprise one or more recesses for receiving a source of light.

[0041] The inner surface of the housing may be configured to control turbulent airflow between the housing inlet and the housing outlet. The housing may also be configured to support a light source for receipt into the recess of a component body according to the first aspect of the invention. Suitably, the inner surface is characterised by an undulating profile along the longitudinal direction of the housing. Alternatively, the inner surface is characterised by a circumferentially extending undulating profile transverse the longitudinal direction of the housing. The undulating shape may be a twisted undulating shape.

Preferably, the inner surface comprises an undulating shape with a sinusoidal profile having peaks extending into the enclosure and troughs adjacent the housing wall. The toughs may be configured as recesses for receiving a light source.

[0042] Air-treatment units including the housing and the component of the first aspect of the invention may be installed in a variety of locations. The units may suitably be installed in the exhaust system of a car, lorry, ship, aircraft or other similar vehicle. Alternatively, the units may be installed in shops, flues, chimneys, roadside locations, airports, railway stations, ports, schools, homes, theatres, cinemas, restaurants, public houses or other public buildings. The units may also be integrally formed with or installed on the roof or another horizontal surface of a vehicle such as a car, a train or a lorry.

[0043] The housing may also comprise one or more means to direct the flow of air entering the body around a light source, through and over the body. Examples of suitable structures, which direct this air flow, include one or more baffles, a fan or an air funnel. Examples of fans that can be used in this application include an axial fan, a centrifugal fan and a crossflow fan. The means for facilitating the flow of air between the inlet and the outlet may be positioned at the housing inlet or at the outlet. Where the unit is installed in a vehicle exhaust system or at a roadside location, the means for facilitating the flow of air between the inlet and the outlet is preferably positioned at the housing outlet. Where the unit is installed on the roof of a vehicle, the means for facilitating airflow is preferably an air funnel positioned at the housing inlet.

[0044] In one embodiment of the second aspect of the invention the housing may be a box attached to a fixed construction such as a building or a windmill or it may be attached to a vehicle. Preferably the box is integrally attached to a vehicle housing. The housing inlet comprises an air funnel for facilitating air flow, one or more turbine components and one or more electrical generators connected to and driven by respective turbine components thereby to power a source of light within the unit. In this respect the air funnel is configured to direct moving air over the one or more turbine units to generate enough energy to drive a source of light. The air then passes over and through the component body received in the housing, where the toxic gases and pollutants present in the air are converted to less harmful substances. This embodiment makes use of the movement of the vehicle to power the unit to support the catalytic conversion. The roof of the vehicle may also be fitted with solar cells to power the light source when the vehicle is stationary.

[0045] A third aspect of the invention provides an air treatment unit comprising component according to the first aspect and a housing according to the second aspect.

[0046] Further aspects of the invention include the use of a component according to the first aspect or an air treatment unit according to the third aspect for reducing or removing toxic gases or pollutants from an environment. Another aspect of the invention provides a method for removing toxic gasses or pollutants from an environment, said method comprising the steps of passing a composition comprising said toxic gases or pollutants over a component according to the first aspect of the invention or through an air treatment unit according the third aspect.

[0047] The invention will now be described with reference to the following non-limiting figures and drawings in which.

[0048] Figure 1 is a drawing of an air treatment unit comprising the component and housing of the first and second aspects of the invention.

[0049] Figure 2 is a drawing of the component of the first aspect of the invention illustrating the configuration of the longitudinal channels within the body of the component. [0050] Figures 3 and 4 illustrate alternative configurations of the longitudinal channels within the body of the component according to the first aspect.

[0051] Figures 5a and 5b illustrate a component according to the first aspect of the invention.

[0052] Figures 6a, 6b, 7 and 8 illustrate an alternative component according to the first aspect of the invention.

[0053] Figures 9 to 12 illustrate the ways in which the longitudinal channels can be arranged over the first and second end faces.

[0054] Figure 13 is a view of the component of the first aspect of the invention illustrating the intersection of the longitudinal channels with the first set of channels.

[0055] Figures 14a, 14b and 14c are a top-down views illustrating the various arrangements of the first and second sets of channels relative to the longitudinal channels.

[0056] Figure 15 is a longitudinal cross-section through the housing of the second aspect. [0057] Figure 16 is a transverse cross-section through the housing.

[0058] Figure 17 illustrates the helical arrangement of an LED strip light source within the component of the first aspect of the invention.

[0059] Figure 18 is a longitudinal cross-section through the housing illustrating the helical arrangement of an LED strip light source within the housing.

[0060] Figure 19 illustrates the unit according to the third aspect of the invention fitted to the roof of a car.

[0061] Figure 20 illustrates the unit according to the third aspect of the invention fitted to the bonnet of a car.

[0062] Figure 1 illustrates an air-treatment unit (1) comprising a housing (2) and a component (3) retained within the housing (2). In use air flows with the direction of the arrows A_i and A_o in through the inlet (4) of the housing (2), through the component (3) and housing (2) and leaves via housing outlet (5). The component (3) includes or supports a photocatalyst on its surface and further includes a recess (6) configured to receive a light source (7). A fan (8) is optionally provided at one end of the housing (2) to pull air through the component (3). In the present illustration, the fan is located at the outlet (5). However, the fan could equally be positioned at the inlet (4). The component (3) is retained within the housing through the use of positioning pins (9) and the light source (7) is retained in position through the use of bracket (10), which is configured for attachment to the housing (2). A control unit (11 ) provides power to the light source (7) and the fan (8) and may also be used to monitor the state of the component (3). A filter (12) may optionally be positioned at the inlet (4) to prevent large particles from entering the housing (2). An end piece (13) may also be provided; the end piece (13) includes a baffle (14) configured to prevent light from being visible from the outlet (5) of the housing (2).

[0063] The component (3) of the air-treatment unit (1 ) is illustrated in figures 2 to 14. Figures 2, 3 and 4 illustrate the arrangement of the longitudinal channels (22) in the body. The longitudinal channels (22) extend through the body (15) from a first end face (18) to a second end face (21). The channels (22) are provided as an array of channels over each of the end faces (18, 21 ) and are preferably centrally arranged around a central longitudinal axis (L). In figure 2, each of the longitudinal channels (22) extend in a direction that is both substantially parallel to the direction of the central axis (L) and to that of each of the other longitudinal channels (22). The channels (22) extend in a direction that is also substantially parallel to the location of the recess (6) within the body (15). In figure 3 the longitudinal channels (22) curve away from a central axis (L) as they extend along the body (15) from the first end face (18) to the second end face (21). This may improve the flow of the gases being treated through the body (15). In figure 4, the diameter of the longitudinal channels (22) increases as they extend from the first end face (18) to the second end face (21 ). As before this feature may improve the flow of the gases being treated through the body (15). In the embodiments illustrated in figures 5 to 13, the component (3) comprises a solid body (15), the body (15) comprising an inlet (16) comprising a first end (17) including a first end face (18) and an outlet (19) comprising a second end (20) including a second end face (21). One or more perimeter walls (25) extend between the first end face (18) and the second end face (21 ). Each perimeter wall defines a perimeter face (26, 26a, 26b, 26b) (figures 5a, 5b, 6 and 7). A plurality of longitudinal channels (22) extend through the body (15) from the first end face (18) to the second end face (21).

[0064] A first set of channels (23) (figures 5a, 5b, 6a, 7, 8, 13) is provided over one or more perimeter faces (26, 26a, 26b, 26c). The channels of the first set (23) comprise rows of channels (23a) which extend laterally over a respective perimeter face in a direction defined by the perimeter of the body (15) as illustrated by the dotted line in figures 5a, 5b, 6a and 7. Each of the channels in the row of channels (23a) is aligned with a channels in the row above so that the set of channels (23) comprises substantially parallel rows of channels that extend both laterally (23a) and longitudinally (23b) over the perimeter face (as illustrated by the dotted line in figures 5a, 5b, 6a and 7). Each of the channels in the first set of channels (23) extends through the body (15) from a first perimeter face towards another side of the body (15). Where the longitudinal channels are provided on the first and second end faces as a square array (figures 6a and 6b) and the body is in the form of or is derived from a right square cylinder, the first set of channels extend from one perimeter (26a) face through the body to an opposite perimeter face (figure 6a). Where the longitudinal channels are provided on the first and second end faces as a square array and the body is a circular cylinder (figures 5a, 5b, 11, 12 and 13), the first set of channels extend from one part of the perimeter face through the body to another part of the perimeter face substantially opposite the first part. Where the longitudinal channels are provided on the first and second end faces as a circular array and the body is provided in the form of a right circular cylinder (figures 8, 9 and 10) the first set of channels extends from the perimeter face through the body towards the longitudinal axis of the body. Preferably each of the channels of the first set of channels (23) extends in a direction that is substantially parallel to a plane defining a first or second end face. In addition a radially extending longitudinal row of the first set of channels extends perpendicular to the longitudinal axis (L) of the body. Furthermore each of the channels of the first set of channels (23) provided on the perimeter face (26) is aligned with a radially extending row of longitudinal channels (22); consequently each of the channels of the first set of channels (23) orthogonally intersects one or more adjacent longitudinal channels (22) in a radially extending row of longitudinal channels.

[0065] A second set of channels (24) is provided on at least one of the perimeter faces (26, 26a) (Figures 5a, 5b, 6a, 6b, 7, 8). In figures 5a and 5b, the second set of channels (24) is provided on the perimeter face (26) of a right circular cylinder, in which the longitudinal channels (22) are provided as a square array. In figures 6a and 6b the first (23) and second (24) sets of channels are provided on a first perimeter face (26a) of a right square cylinder having a square array of longitudinal channels (22). In figure 6a a third set of channels (37) is provided on a perimeter face (26b) that is orthogonal to the perimeter face (26a) on which the first (23) and second (24) sets of channels are provided. The third set of channels (37) extends in a direction that is orthogonal to both the longitudinal channels (22) and the second set of channels (24). The third set of channels (37) orthogonally intersects with both the longitudinal channels (22) and the second set of channels (24). This is illustrated in figure 6a where the alignment of the second (24) and third (37) set of channels relative to the longitudinal channels (22) and the offset of the first (23) and second (24) set of channels relative to each other is shown. An embodiment in which a right square cylinder is provided with first (23) and second (24) channels only (over the same end face) is illustrated in figure 6b. In figure 7, the first (23) and second (24) rows of channels are provided on at least two faces of a hexagonal cylinder.

[0066] The second set of channels (24) comprises laterally extending rows of channels (24a) (as illustrated by the dotted line in figures 5a, 5b, 6a, 6b and 7) and longitudinally extending rows channels (24b) (also illustrated by the dotted line in figures 5a, 5b, 6a, 6b and 7). The laterally extending rows of channels (24a) extend over the perimeter face (26, 26a) around the circumference of the body (15). Each of the channels in the laterally extending rows of channels (24a) is aligned with a channel in the row above so that the second set of channels is also defined by longitudinally extending rows of channels (24b), each row extending longitudinally between the first (18) and second (21 ) end faces. Each of the rows of channels of the second set of channels (24) is offset from and interspersed between adjacent rows of the first set of channels (23). Preferably each of the channels in the second set of channels (24) is longitudinally and laterally offset from each of the channels in the first set of channels (23). This is illustrated in each of figures 5a, 5b, 6a, 6b and 7 where it can be seen that where a perimeter face contains two sets of channels (23, 24) each channel of the first set of channels (23) is surrounded by four channels of the second set (24) and each channel of the second set of channels (24) is surrounded by four channels of the first set of channels (23). In figures 5a and 5b each of the rows of the second set of channels extends through the body from one part of the perimeter face in a direction parallel to a virtual chord to a circle defined by the end face of the cylindrical body between adjacent rows of longitudinal channels. As before each row of channels of the second set tangentially intersect laterally adjacent rows of longitudinal channels.

[0067] In figures 8, 9 and 10 each of the channels of the second set of channels (24) extends from one perimeter face (26) through the body (15) to an opposite side of the body (15) in a direction that is both substantially parallel to a plane defining a first (18) or second

(21) end face and substantially perpendicular to the longitudinal axis (L) of the body (15). Each of the channels of the second set of channels (24) essentially passes between the volume occupied by two laterally adjacent radially extending rows of longitudinal channels

(22) (each row extending in a radial direction through the body (15)). Since the diameter of each of the channels in the second set of channels (24) is chosen to be larger than the spacing between the outer edges of adjacent longitudinal channels (22), each channel of the second set of channels (24) intersects each of two laterally adjacent longitudinal channels (22) at their edges. In this way a longitudinally extending row of the second set of channels (24) tangentially intersects with substantially all the channels in the respective laterally adjacent radially extending rows of longitudinal channels (22). This form of intersection is referred to throughout as tangential intersection; each channel of the second set of channels (24) intersects the adjacent orthogonally extending longitudinal channel (22) at opposite edges of its circumference.

[0068] The arrangement of the first (23), second (24) and optionally third (37) set of channels relative to the square array of longitudinal channels (22) is illustrated in figures 14a, 14b and 14c, which is a sectional view in a direction looking down end face (21). Longitudinal channels (22) are viewed from below and extend away from the page. Channels (23) of the first set of channels extend in a direction parallel to the page and pass through or directly intersect adjacent longitudinal channels (22) in an orthogonal direction, so that the angle of intersection between a line defining a central axis of any one of the first set of channels (23) with that of a line defining a central axis of any one of the longitudinal channels (22) is substantially perpendicular. Each of the channels of the second set of channels (24) are laterally and longitudinally offset relative to the first set of channels (23) and extend between the longitudinal channels (22) in a direction substantially parallel to the first set of channels (23) and substantially perpendicular to the longitudinal axis of the body (L). The channels of the second set (24) are wider than the spacing between adjacent longitudinal channels (22'). A lateral offset of the second set of channels (24) relative to the first set of channels (23) within the body (15) means that each longitudinally extending row (24b) of the second set of channels (24) extends between the volume defined between laterally adjacent rows of longitudinal channels (22) and merge or tangentially intersect at their opposite edges with these laterally adjacent rows of longitudinal channels (22). The configuration of the first and second set of channels (23, 24) relative to the longitudinal channels (22) within the body (15) has the advantage that the body (15) is characterised by an internal surface that has a high surface area, which is capable of being substantially fully irradiated by light emitted from a UV or other light source (7) placed within recess (6). A component (3) including a photocatalyst is therefore able to support rapid and high conversion of toxic gases and pollutants exposed to the continuous surface of the body (15) to less harmful species to improve the environment.

[0069] In figure 14a, the first (23) and second (24) sets of channels extend substantially parallel to each other and substantially perpendicular to the longitudinal channels (22); this is essentially the internal arrangement of channels within the body depicted in figure 6b. In figure 14b, the first set of channels extends in a direction that is substantially orthogonal to both the direction in which the second set of channels (24) extends and the direction in which the longitudinal channels (22) extend. In figure 14c, the first (23) and second (24) set of channels extend in a direction that is substantially parallel to each other and which is substantially orthogonal to the direction in which both the longitudinal channels (22) and the third set of channels (37) extend; furthermore the third set of channels (37) extends in a direction that is substantially orthogonal to the direction in which the longitudinal channels (22) extend.

[0070] In a preferred embodiment, the longitudinal channels are provided as a square array and each of the channels in the first, second and third set of channels (23, 24, 37) extend in a direction that is substantially perpendicular to the direction of a respective longitudinal channel having a longitudinal axis (L). That is to say the longitudinal axis (L) of the longitudinal channel intersects or passes the central axis defined along the length of each of the channels of the first (23), second (24) and third (37) sets of channels at 90°. Channels

(23) and (37) and the longitudinal axes defining these channels intersect channels (22) (and the longitudinal axis defining channels (22)) at an angle of substantially 90 . Channels (24) tangentially intersect channels (22) at an angle of substantially 90° the longitudinal axis defining channel (24) passes but does not intersect with the longitudinal channel defining channel (22) at an angle of substantially 90°. However each of the first(23), second (24) and third (37) sets of channels may extend at an angle of greater than 90° relative to the longitudinal channels (22), for example 90 to 109 , preferably 90 to 102 , more preferably 90 to 95° and especially 90 to 92°. This means that if the first end face were considered to be an upper end of the body and the second end face the lower end, the first (23), second (24) and optionally third (37) sets of channels would essentially be configured in a downward direction relative to the longitudinal channels (22). This has the advantage of improving airflow through the body (15).

[0071] An especially preferred embodiment of the invention is illustrated in figure 6a. The body (15) is derived from or is provided in the form of a right square cylinder having opposed perimeter faces (26a, 26b) extending from first and second end faces (18, 21 ) and a square array of longitudinal channels (22) arranged over each of the first (18) and second (21) end faces. A first (23) and second (24) set of channels are provided over perimeter face (26a). The first set of channels (23) are laterally and longitudinally offset from each other so that each channel of the first set (23) is surrounded by four channels of the second set (24) and each channel of the second set (24) is surrounded by four channels of the first set (23). A third set of channels (37) is provided on perimeter face (26b), which is orthogonal to perimeter face (26a). Each of the channels of the third set of channels (37) aligns with one or more longitudinal channels (22) extending between the first (18) and second (21) end face and intersects therewith in a substantially orthogonal fashion. Similarly each channel of the third set of channels (37) aligns with one or more channels of the second set of channels

(24) provided on perimeter face (26a) and intersect therewith in a substantially orthogonal fashion. Preferably the diameter of the channels of the second set is similar to the diameter of the channels of the third set. This component may be shaped or cut to a circular cylinder having a square array of longitudinal channels.

[0072] In an alternative embodiment, the longitudinal channels (22) are provided in the form of a circular array over the end faces (18, 21) of a right circular cylinder in figures 8, 9 and 10. In figure 9 it can be seen that each end face (18, 21 ) comprises both concentric (22a, 22b, 22c) and radial (22x, 22y, 22z) rows of longitudinal channels (22). In figure 8 it can be seen that the first (23) and second (24) sets of channels are provided as rows of channels which extend both laterally and longitudinally over perimeter face (26). Each row of channels of both the first (23) and second (24) set of channels also extends in a radial direction that is substantially perpendicular to the longitudinal axis (L) of the body (15). Each longitudinally extending row of channels of the first set of channels (23) orthogonally intersects a one or more channels (22) in a radially extending row (22x, 22y, 22z) of longitudinal channels (22). Each longitudinally extending row of channels of the second set of channels (24) tangentially intersects one or more channels (22) in two laterally adjacent radially extending rows of longitudinal channels (22x, 22y) at (22w). The third set of channels (37) extends coplanar with the direction in which the second set of channels extends and follows a line (22a, 22b, 22c) defined by a circular row of longitudinal channels. In this way the third set of channels orthogonally intersects one or more longitudinal channels (22) in a circular row and one or more channels from the second set of channels (24).

[0073] The body (15) may be provided in the form of a right circular or elliptical cylinder (figures 5a, 5b, 8, 9, 10, 11 , 12 and 13), a right square or rectangular cylinder (figures 6a and 6b) or a right hexagonal cylinder (figure 7). Other shapes such as a pentagonal or heptagonal prism may also be envisaged. The longitudinal channels (22) are suitably provided as an array over each of the end faces (18, 21). The longitudinal channels may be arranged over each of the end faces (18, 21) as a square array of channels (figures 5a, 5b, 6a, 6b, 11, 12 and 13) or as a radial array (figures 7 to 10).

[0074] Square arrays of channels are best illustrated in figures 5a, 5b, 5c, 6a, 6b, 11 and 12 where each of the channels (22) are arranged as aligned rows over each end face, the longitudinal rows (22) extending in both the x direction and the y-direction. By the term “aligned rows” it should be understood to mean that each of the channels in any one of the rows is positioned immediately adjacent channels in any preceding or subsequent row. [0075] Radial arrays are illustrated in figures 7 to 10. Radial arrays comprise circular rows of channels (22a, 22b, 22c; figure 9) radially distributed about a central axis (L) extending the length of the cylindrical body (15). The circular rows of channels (22a, 22b, 22c) are radially aligned so that each channel in any one of the circular rows is positioned immediately adjacent a channel in any preceding or subsequent row. In this way the radial arrays define both circular rows of channels (22a, 22b, 22c) and radially extending rows of channels (22x, 22y, 22z), each radial row extending from an axis defining the centre of the body (15) towards a perimeter face (26). By the term “circular rows of channels” it is to be understood to include rows of channels of any geometric shape, whose configuration follows the line of the perimeter defined by the shape of the body (15). For example, it can be seen that the component (3) of figure 7 comprises a right hexagonal body (15) comprising aligned hexagonal rows of channels (22) radially distributed about a central axis of the body (15). Radially extending rows of channels similar to channels (22x, 22y, 22z) illustrated in figure 9 can also be seen. All of the longitudinal channels (22) in the radial arrays may have substantially identical diameters at each end face (18, 21 ); figures 7, 8 and 9. Alternatively, and as seen in figure 10, the diameter of the channels of the outer circular rows of channels (closer to the perimeter of the end face) may be larger than those of the channels (22) closer to the middle of the end face. An advantage of this arrangement is that it maximises the surface area available for supporting the catalyst.

[0076] The recess (6) configured to receive the UV light source (7) is, as illustrated in figures 1 to 4, 5a and 7 to 11 , preferably located along a central axis (L) defined by the body (15). However other configurations are envisaged and, as illustrated in figure 12, the body (16) may be provided with more than one recesses located over the first end face (18) extending from the first end face (18) towards the second end face (21). Alternatively, and as illustrated in figure 17, the body (15) may include a helical recess extending from the first end face (18) towards the second end face (21), the helical recess being configured to receive a strip of LED lights that emit light in the UV range of the spectrum. Alternatively the recess may be configured to house a visible light source configured to emit light in the range 300 to 700nm. [0077] As illustrated in figures 1, 19 and 20, in use the component (3) comprising the body (15) and the photocatalyst is located in a housing (2) to give an air-treatment unit configured for use in an air-treatment system. As illustrated in figures 1 and 15, the housing (2) comprises an inlet (4) and an outlet (5), a housing wall (27) extending between the inlet (4) and the outlet (5), the housing wall comprising an exterior surface (28) and an interior surface (29), the interior surface (29) defining an enclosure (30), the enclosure being configured to receive the component (3) of the first aspect of the invention and to provide an air passage to support the flow of air in a longitudinal direction (defined by arrows A_o, Ai) between the inlet (4) and the outlet (5). Preferably the housing also comprises means (8) (figure 1) for facilitating airflow between said inlet (4) and said outlet (5). The housing may optionally also be provided with a filter (12) (figure 1 ) and a bracket (10) to support a UV light source. The means for facilitating airflow include fans, baffles and air funnels (34). Examples of fans that can be used in this application include an axial fan, a centrifugal fan and a cross- flow fan. Air funnels can be provided in applications of the type illustrated in figures 19 and 20 where the air-treatment unit is incorporated into the roof (figure 19) or bonnet of a car (figure (20)). In both cases the housing (2) includes an air funnel (34) at its inlet. Air entering the housing (2) via the air funnel (34) impinges on turbines (35). The transfer of kinetic energy between the incoming air and the turbines causes generators (36) to produce electrical energy that powers a UV light source (7) located within the recess (6) of component (3). [0078] A photocatalytic coating may be provided on the inner surface (29) of the housing (2). This has the advantage of increasing the amount of photocatalyst that can be supported in the unit (1) to increase the conversion of toxic gases and pollutants passing through the unit (1) to less harmful substances. Alternatively, or in addition, the inner surface (29) comprises a reflective material. This has the advantage of reflecting any light escaping from the perimeter face (26) back towards the interior of the body (15), thereby improving the efficiency of the conversion process.

[0079] The interior surface (29) of the housing (2) may be smooth or may configured to improve the airflow through the housing (2). In this respect the interior (29) of the housing (2) may, as illustrated in figures 15, 16 and 18 include ridges (31 ) and troughs (32). The ridges (31 ) and troughs (32) may be configured to extend in a repeating pattern along the length of the housing (2) between the inlet (4) and the outlet (5) (figure 15) or they may be configured to extend in a repeating pattern around the interior surface (29) of the housing (2).

Alternatively, and as illustrated in figure 18, the housing may comprise a series of ridges (31 ) and troughs (32), which extend in a repeating helical configuration along the length of the housing (2). The troughs (32) may be configured to receive one or more sources of light (33). The sources of UV light (33) may be provided as strips of LED lights that extend laterally (figure 15), longitudinally (figure 16) or helically (figure 18).

[0080] In use air including a source of toxic gases and pollutants passes through the inlet (4) and over and through component (3) where the toxic gases and pollutants are converted to less harmful substances. The improved, conditioned, treated or purified air then passes through outlet (5) and is eventually released from the system. Where the air-treatment unit is installed in a fixed location, such as a vehicle exhaust system, a building, a flue, a chimney or at the side of a road, the means for providing a flow of air through the housing is preferably a fan. The fan may be located at the inlet (4) or outlet (5) but is preferably located at the outlet (5). Where the air-treatment unit is installed in a movable location, such as on the roof or bonnet of a vehicle, the means for providing a flow of air through the housing is suitably an air funnel which directs the airflow generated by the moving vehicle into the housing and over the component.

[0081] Examples

[0082] Example 1

[0083] Comparison of Different Matrix Structures

[0084] A polyamide component having a structure in accordance with the first aspect of the invention coated with a photocatalyst as disclosed in example 5 was located in a housing to form a unit. A UV light source (Osram Puritec UV-C HNS L 24W 2G11) having a dominant wavelength of 254nm was located in the recess of the component. The component is characterised by a square array of longitudinal channels extending from the first end face to the second end face as illustrated in figures 5a, 5b and 11. Each of the channels of the longitudinal channels has a diameter of 5mm and a centre to centre spacing of 7.5mm. The component is derived from a right square cylinder and is shaped to a right circular cylinder. A first set of channels extends from what would have been one face of the right square cylinder to the opposite face such that the first set of channels extends over part of the perimeter face of the right circular cylinder. The channels of the first set orthogonally intersect the longitudinal channels. This is illustrated in figures 6b and 13. Each of the channels of the first set of channels has a diameter of 4mm and a centre to centre distance of 9.7cm. A second set of channels extends from the same face as the first set of channels and extends in a direction that is substantially parallel therewith (as illustrated in figure 6b). The channels of the second set tangentially intersect two laterally adjacent rows of longitudinal channels. Each of the channels of the second set of channels has a diameter of 5mm and a centre to centre spacing of 7.5mm. A third set of channels extends between the part of the perimeter face orthogonal to the part of the perimeter face between which the first and second set of channels extends. Each of the channels of the third set of channels has a diameter of 5mm and a centre to centre spacing of 7.5mm. The component of the first aspect of the invention has a total surface area of 350661mm² and an internal air volume of 735725mm^{3 -}and a total surface area to volume ratio of 0.48. A fan was fitted adjacent the housing outlet (5). A pollution source was created by burning butane gas and cigarettes in a closed room for 150 minutes. Monitors capable of detecting carbon dioxide and particulate materials having a diameter in the range from under 1μm to 10μm (PM1 , PM2.5, PM4 and PM10) were fitted to the inlet and the outlet of the housing. The fan was turned on and the levels of carbon dioxide and particulate matter detected at the outlet were monitored over a period of 135 minutes. The efficacy of the unit including the component (3) at removing carbon dioxide and particulate matter from the air source was calculated. The experiment was repeated using a component as above, which was not coated with a photocatalyst. The experiment was further repeated using a component having a split-P TPMS configuration coated with the photocatalyst; the split-P component is characterised by a total surface area to air volume ratio of 0.75. The results are shown in tables 1 to 5 below and also in figures 22 to 26.

[0085] Table 1: a comparison of the change in CO₂ levels achieved using (1) the photocatalyst-coated polyamide component of the present invention; (2) an uncoated body having a configuration according to the present invention; and (3) a photocatalyst (PCO) coated polyamide body having a split-P TPMS structure.

[0086] Table 2: a comparison of the change in PM₁ levels achieved using (1) the photocatalyst-coated polyamide component of the present invention; (2) an uncoated body having a configuration according to the present invention; and (3) a photocatalyst coated polyamide body having a split-P TPMS structure.

[0087] Table 3: a comparison of the change in PM_2.5 levels achieved using (1 ) the photocatalyst-coated polyamide component of the present invention; (2) an uncoated body having a configuration according to the present invention; and (3) a photocatalyst coated polyamide body having a split-P TPMS structure.

[0088] Table 4: a comparison of the change in PM₄ levels achieved using (1 ) the photocatalyst-coated polyamide component of the present invention; (2) an uncoated body having a configuration according to the present invention; and (3) a photocatalyst coated polyamide body having a split-P TPMS structure.

[0089] Table 5: a comparison of the change in PM₁₀ levels achieved using (1) the photocatalyst-coated polyamide component of the present invention; (2) an uncoated body having a configuration according to the present invention; and (3) a photocatalyst coated polyamide body having a split-P TPMS structure.

[0090] It can be seen from the foregoing that when the component of the first aspect of the invention is included in an air treatment unit, it is able to remove toxic gases such as carbon dioxide and pollutants such as particulates from an air source in many cases more than twice as effectively as the uncoated (control) component and also as the coated component having a TPMS Split-P configuration.

[0091] Example 2

[0092] Comparison of Matrix Structures

[0093] A Proster hand-held anemometer was used to study the pattern of air movement at the inlet and outlet ports of air-treatment units comprising the component of the present invention and a component having a TPMS split-P structure. In a general case air entering the system is relatively laminar, whereas air leaving the system is relatively turbulent as it is forced to mix with an open body of air. It was noted that the air exiting a unit including the component of the present invention was more laminar than air exiting a unit including the TPMS split-P component. The anemometer showed that numerous counter-rotating eddies were formed at the inlet with the split-P matrix, which were entirely absent with the component of the present invention. It would therefore appear that the component of the present invention is characterised by improved airflow compared to the TPMS split-P component.

[0094] Example 3

[0095] Preparation of Coating Solutions

[0096] Three photocatalytic coating solutions were prepared. Each solution comprises a photocatalytic compound suspended in a 2 to 5% by volume solution of (3-glycidyloxypropyl) trimethoxysilane (C₉H₂₀O₅Si; CAS Number 2530-83-8) in a 1:3 ethanokwater solution. Typically between 0.25 and 1.5g of a powder of a photocatalytic compound is added to 100ml of the silane solution and stirred at room temperature for 30 minutes. The solutions were then used to coat the component body. Solutions of the following photocatalytic material were prepared: cerium oxide-zirconium oxide comprising 50% zirconium oxide and 50% cerium oxide; cerium oxide-zirconium oxide comprising 6wt% cerium oxide; and a cerium oxide-zirconium oxide comprising 5wt% cerium oxide manufactured as used in example 1 and set out in example 5 below. [0097] Example 4

[0098] Method for Coating the Component Body

[0099] The component body was washed in a dishwasher at 40C using water only (no detergent) and dried in a warming cabinet. The clean, dry components were then dipped, both ways round, into a bucket containing a coating solution prepared as outlined above and agitated for 30 seconds per dip. The twice-dipped coated components were then dried in the drying cabinet (LEEC LS). The recoating and drying steps were repeated. The coated component was then inserted into a housing and used as an air conditioning unit.

[0100] Example 5

[0101] Preparation of Coating Composition Comprising 5wt% Cerium Oxide

[0102] 200ml of ethanol (CAS Number 64-17-5) was mixed with 100ml of distilled water and 20ml of a 5 to 20% by volume aqueous solution of acetic acid (CAS Number 64-19-7) and stirred for 10 minutes. Cerium nitrate hexahydrate (10.855g; 0.1mole; CAS Number 10294- 41-4) was added to the ethanol water mixture and stirred at room temperature for 20 minutes after which time 157.51g of a 70wt% solution in 1-propanol of zirconium propoxide (CAS Number 23519-77-9) was added and stirred for a further 10 minutes. 175ml of a 3:1 molar ratio solution of water: ethanol was added to the mixture and stirred for a further 10 minutes after which time the resulting mixture is heated to 100C and stirred for 19 hours until an aerogel is formed. The resulting product was in dried in an oven at 200C for an hour, washed in ethanol with stirring for a further hour and then calcined in a vacuum oven at 200C for a further hour. The calcined product was then sintered at 1100C for 4 hours, placed in a furnace at 500C and brought up to 1100C over 2 hours after which time the furnace was turned off and the powder was left in the oven overnight until cooled. The resulting coating composition was then used to prepare a coating solution as described in example 3 and to coat a component as described in example 4.

[0103] Example 6

[0104] Comparing Air Treatment Units including Different Photocatalytic Coating Compositions

[0105] Two components as described in example 1 above were coated with a zirconium oxide-cerium oxide coating composition comprising 50mol% CeO₂ (coating 1 ) and 6mol% CeO₂ (coating 2) respectively instead of the coating described in example 1. Each coated component was placed in a housing including a fan and sensors configured to detect carbon dioxide, PM₁, PM_2.5, PM₁₀, nitrous oxides, volatile organic compounds, ozone and carbon monoxide. Sensors were placed at both the housing inlet and the housing outlet to compare the levels of each of the pollutants as a result of passing through the component. A UV lamp as described herein was secured in the recess of the component, The resulting air treatment units were placed in a sealed room, the fan and the UV lamp were turned on and the average change in pollutant levels observed between the inlet and outlet over the period for which the unit is in place is set out in Table 6 below:

[0106]

Table 6 From table 6 it appears that coatings including the second coating are most efficient at removing pollutants in the presence of UV light.

Example 7

Comparing the effects of UV and Visible light on Component 1

Each coated component was placed in a housing including a fan and sensors configured to detect carbon dioxide, PM₁, PM_2.5, PM₁₀, nitrous oxides, volatile organic compounds, ozone and carbon monoxide. Sensors were placed at both the housing inlet and the housing outlet to compare the levels of each of the pollutants as a result of passing through the component. UV (Osram Puritec UV-C HNS L 24W 2G11) and daylight (Osram Dulux L24 W/8402G11) lamps were respectively secured in the recess of each component, The resulting air treatment units were placed in a sealed room, the fan and the UV lamp were turned on and the average change in pollutant levels observed between the inlet and outlet over the period for which the unit is in place is set out in Table 7

Table 7. From table 7 it appears that where the coating is coating 1, the catalyst is more effective at removing pollutants in the presence of visible light.

Claims

1. A component (3) for an air-treatment unit (1), the component (3) comprising a photocatalytic material and a solid body (15), the solid body (15) comprising: a. an inlet (16) defined by a first end (17) including a first end face (18), an outlet (19) defined by a second end (20) including a second end face (21) and one or more perimeter walls (25) defining one or more perimeter faces (26) extending between the first end (17) and the second end (20); b. a plurality of longitudinal channels (22) extending through the body (15) from the first end face (18) to the second end face (21 ), the longitudinal channels (22) defining a longitudinal direction for the flow of air through the body (15), the channels (22) extending substantially parallel to each other along the longitudinal direction over at least part of the length of the body (15); c. a first set of channels (23) comprising a plurality of rows of channels provided over at least part of a perimeter wall or over at least one of the perimeter walls (25), said rows extending laterally and being aligned in a longitudinal direction over the said at least part of a perimeter wall or over each or said at least one perimeter wall (25), each of the channels (23) of the first set extending radially from a perimeter face of the said part or at least one of the perimeter walls (25) through the body (15) in a direction substantially perpendicular to the direction of the longitudinal channels (22), each channel of the first set of channels (23) being configured to orthogonally intersect a radially extending row of one or more adjacent longitudinal channels (22), the row of longitudinal channels (22) extending in a direction substantially parallel to the direction in which the channels of the first set (23) extend; d. a second set of channels (24) provided over at least part of a perimeter wall or over at least one of the perimeter walls (25) and comprising a plurality of rows of channels, said rows extending laterally and being aligned in a longitudinal direction over a perimeter face of said part of or said at least one perimeter wall (25), each channel of said second set (24) extending from the perimeter face of the at least one perimeter walls (25) through the body in a direction substantially perpendicular to the direction of the longitudinal channels (22), each of the rows of the second set of channels (24) being dispersed between the rows of the first set of channels (23) and laterally off-set therefrom, each channel of the second set (24) being configured to tangentially intersect two laterally adjacent radially extending rows of longitudinal channels (22), the rows of longitudinal channels (22) extending in a direction substantially parallel to the direction in which the channels of the first set (23) extend, the first set of channels (23), second set of channels (24) and perimeter wall (25) defining a substantially continuous surface having a photocatalytic material supported thereon; and e. a recess (6) for receiving a light source (7) within the body.

2. A component (3) according to claim 1, wherein the body (15) further comprises a third set of channels (37), each channel of the third set of channels (37) being configured to orthogonally intersect one or more longitudinal channels (22) and to orthogonally intersect one or more channels from the second set of channels (24).

3. A component (3) according to any one of the preceding claims, wherein the first set of channels (23) comprises substantially parallel rows of channels extending laterally and longitudinally across the perimeter face (26) of the perimeter wall (25).

4. A component (3) according to any one of the preceding claims, wherein the second set of channels (24) comprises substantially parallel rows of channels extending laterally and longitudinally across the perimeter face (26) of the perimeter wall (25).

5. A component (3) according to any one of the preceding claims, wherein the longitudinal channels (22) are preferably provided in the form of an array extending over each of the first (18) and second (21) end faces.

6. A component (3) according to claim 5, wherein the array is a square array.

A component (3) according to claim 5, wherein the array is a circular array.

8. A component (3) according to any one of the preceding claims, wherein the continuous surface is characterised by a surface area and an internal air volume and the ratio of the surface area to the internal air volume is 0.4 to 0.8.

9. A component (3) according to any one of the preceding claims, wherein the photocatalytic material supported on the surface is a mixture of zirconium and cerium oxides.

10. A housing (2) for a component (3), the housing (2) comprising an inlet (4) and an outlet (5), a housing wall (27) extending between the inlet (4) and the outlet (5), the housing wall (27) defining (i) an enclosure (30) for receiving a component (3) according to any one of claims 1 to 11; (ii) an air passage between the inlet (4) and the outlet (5) and (iii) a longitudinal direction defining the flow through the housing (2) between said inlet (4) and said outlet (5), the housing (2) further comprising means for facilitating airflow between said inlet (4) and said outlet (5).

11. A housing (2) according to claim 10, wherein the housing wall (27) comprises an outer surface (28) and an inner surface (29) configured to face the enclosure (30) and a photocatalytic coating is provided on the inner surface (29) of the housing (2).

12. A housing according to claim 11 , wherein the inner surface (29) of the housing (2) comprises a reflective material.

13. A housing (2) according to any one of claim 10 to 12, wherein the surface (29) of the housing (2) comprises ridges (31) and troughs (32).

14. A housing according to claim 13, wherein the troughs (32) are configured to receive a source of light (33).

15. An air treatment unit (1 ) comprising a component (3) according to any one of claims 1 to 9 and a housing according to any one of claims 10 to 14.