The present invention relates to an air sanitisation device and to a process for producing the same.

State of the art

The disinfection of air and surfaces is necessary to reduce the risk of infections by pathogenic microorganisms in indoor environments such as hospitals, food processing plants, public places (schools, offices, etc.) and inside homes.

Since we spend a lot of time indoors (homes, offices, schools, etc.), the indoor air quality becomes a crucial aspect for protecting the health and well-being of living beings.

Air pollution inside buildings is determined in particular by microorganisms such as bacteria, viruses and moulds. Air pollution by these organisms affects the respiratory system causing allergies and asthma. Also not to be underestimated, is the accumulation of dust and pollutants present in the atmosphere as they too can enter the pulmonary alveoli and damage the lungs and the organism as a whole. It is therefore advisable to reduce them as much as possible.

Indoor environments such as homes, offices, schools, workplaces show the presence of chemical, physical contaminants and microorganisms (bacteria, fungi, moulds, viruses, etc.); these must be kept under control in order to guarantee a healthy environment that does not cause damage to the health of individuals.

As is known, air pollution in indoor environments can be higher than in outdoor environments. Since most people spend their time indoors, controlling air quality plays a crucial role that should not be underestimated for health.

The air we breathe in indoor environments is treated and distributed by systems which often become a place of air contamination.

The surfaces of the aeraulic ducts can be contaminated not only by the dust released into the atmosphere, but also by microbial and bacterial colonies; in order to not pollute the rooms to which the air they bring is intended, it is therefore necessary to carry out periodic sanitisations.

The proliferation of microorganisms must be kept under strict surveillance to protect the health of those who are in environments such as schools, hospitals, kindergartens, treatment centres, etc.

It is known that the ducts used to convey air in indoor environments represent a source of vehicle for spreading airborne contaminants; therefore it is necessary to properly clean and carefully sanitise such ducts.

In indoor environments and in particular in ducts, bacterial infections can be generated due to humidity and high temperatures which promote the proliferation of microbial colonies.

A wide variety of air treatment devices and methods are known, in particular one of these approaches uses HEPA filters (High Efficiency Particulate Air, European reference standard EN 1822-1 :2019) capable of collecting almost 100% of airborne particles having a diameter larger than 0.3 pm.

Another approach involves electrostatic precipitators which use electrostatic forces to remove particles present in the air and capturing particles having a diameter of 0.01 pm.

However, neither the HEPA filters nor the electrostatic precipitators have shown the ability to remove the volatile organic compounds (VOCs) from the air, so they are unable to reduce odours and the microbial load.

One of the most methods used to sanitise surfaces and indoor environments is based on the use of paints added to substances with biocidal properties in order to eliminate viruses, bacteria, fungi, algae, etc. In particular, there are sanitisation methods based on the use of paints or polymeric materials which, as biocidal products, contain heavy metal ions inserted using oxides or salts. Despite their effectiveness, biocidal coatings containing heavy metal ions show some drawbacks: the lack of stability of the ions bound to the polymeric matrix and the leaching of metal ions from the polymeric coating. Although the use of these paints or biocidal materials decreases the bacterial load, the toxicity of the heavy metals released in an indoor environment by these paints and materials must be taken into account, in fact these heavy metals can be harmful to individuals who come into contact with them.

Furthermore, heavy metals derived from paints can pollute water and the atmosphere and have deleterious effects on plants, animals and people.

As known to those skilled in the art, a well-known approach for treating air provides using the photocatalytic oxidation process (PCO) based on the use of titanium dioxide. Using the photocatalytic oxidation is a very effective approach as it is able to break down the microbial load and the volatile organic compounds (VOCs) present in the air.

The photocatalytic oxidation process provides for using one or more sources of ultraviolet energy (UV) irradiating a substrate which the titanium dioxide adhered to. The titanium dioxide, when photo-excited by radiation, creates oxidising molecules capable of damaging the microorganisms present in the air surrounding the titanium dioxide.

Japanese patent document No. 2000 152983 A filed by JUJO PAPER CO LTD on 07/06/2000 describes an air purifier comprising a UV light source and a photocatalyst comprising titanium oxide and an organic polymer binder. However, the yield of electron transfer in a photocatalyst comprising titanium oxide is not high enough.

The scientific publication entitled “Photocatalytic inactivation of airborne bacteria in a polyurethane foam reactor loaded with a hybrid of MXene and anatase TiC exposing {001 } facets” describes the characterisation and use as a photocatalyst of a monolayer TiC and TiaC2Tx hybrid nanosheet (MXene). The introduction of MXene (3.4% by weight) helped to reduce the recombination of photoinduced electrons and holes, thus improving the photocatalytic activity by 30%. However, an overload of MXene (more than 3.4% by weight) may cause the reduction of the photocatalytic active sites and therefore reduce the degradation efficiency.

The need for an air sanitisation system not causing the above- mentioned side effects is therefore a need felt in this field.

Summary of the invention

An objective of the present invention is therefore to provide an air sanitisation device not causing the above-mentioned side effects. An objective of the present invention is in fact to provide a device capable of actively sanitising the air in order to improve the hygienic conditions of indoor environments, surfaces, fabrics and aeraulic ducts in order to control, inhibit and prevent, by an adequate microbicidal and microbiostatic action, the development and spread of potentially pathogenic contaminants harmful to human health, of VOCs, of pathogens and of particulate matter.

A further objective of the present invention is to provide an air sanitisation device which is simple, cheap to produce and completely reliable from an operational perspective.

Such objective is achieved by an air sanitisation device as outlined in the attached claims, which are integral part of the present description.

Therefore, a specific object of the present invention is an air sanitisation device comprising a casing which itself contains an internal chamber fluidically connected both to an inlet port for entering air and to an outlet port for exiting air, wherein the inlet port comprises at least one particulate filter arranged so that the air entering through the inlet port passes through the particulate filter, the outlet port comprises at least one fan adapted to allow the air to easily exit the internal chamber; at least one UV lamp is included inside the internal chamber between the inlet port and the outlet port; wherein inside the internal chamber between the inlet port and the outlet port it is also included at least one photocatalytic cell coated with a mixture comprising an epoxy polymer and a compound according to formula (I):

Ti ₃ C ₂ Tx (I) where Tx is chosen from: F, OH.

According to the invention, said particulate filter may comprise an electrostatic filter according to the European standard EN ISO 29463- 5:2018, Annex C and/or a HEPA filter according to the European standard EN 1822-1 :2019.

Again, according to the invention, said UV lamp can be a UV-C lamp. In particular, according to the invention the fans can be two.

Always according to the invention, the photocatalytic cell can have a honeycomb structure.

Still according to the invention, the photocatalytic cells coated with a mixture comprising an epoxy polymer and a compound according to formula (I):

Ti ₃ C ₂ Tx (I) where Tx is chosen from: F, OH can be two and wherein one of the two photocatalytic cells can be arranged between the inlet port and the UV lamp and the other of the two photocatalytic cells can be arranged between the UV lamp and the outlet port.

A further object of the present invention is a process for producing a photocatalytic cell comprising the steps of: a) providing a cell; b) mixing together an epoxy polymer and a compound according to formula (I):

Ti ₃ C ₂ Tx (I) where Tx is chosen from: F, OH c) evenly spreading the mixture obtained in step b) on the cell of step a).

In particular according to the invention, said cell can have a honeycomb structure.

Always according to the invention, the epoxy polymer of step b) can be epoxy resin.

Brief description of the figures

The invention will be better understood from the following detailed description of its preferred embodiments, made by way of example and therefore in a non-limiting way with reference to the attached Figures, wherein:

Figure 1 is a side view of a device according to the present invention;

Figure 2 is a top view of the device of Fig. 1 ;

Figure 3 is a rear view of the device of Fig. 1 . In the annexed figures, identical or similar parts will be indicated by the same reference numbers.

Detailed description of the invention

With reference to Figures 1 , 2 and 3, a first object of the present invention is shown, i.e. an air sanitisation device comprising a casing 1 1 which itself contains an internal chamber 13 fluidically connected both to an inlet port 15 for entering air and to an outlet port 17 for exiting air, wherein the inlet port 15 comprises at least one particulate filter 5 arranged so that the air entering through the inlet port 15 passes through the particulate filter 5, the outlet port 17 comprises at least one fan 1 , adapted to allow the air to easily exit the internal chamber 13; at least one ultraviolet (UV) lamp 3 is included inside the internal chamber 13 between the inlet port 15 and the outlet port 17; wherein inside the internal chamber 13 between the inlet port 15 and the outlet port 17 it is also included at least one photocatalytic cell 4 coated with a mixture comprising an epoxy polymer, preferably an epoxy resin, and a compound according to formula (I):

Ti ₃ C ₂ Tx (I) where Tx is chosen from: F, OH.

Preferably, the particulate filter 5 comprises an electrostatic filter and/or a HEPA filter. As known to those skilled in the art, the term HEPA filter (High Efficiency Particulate Air filter) indicates a particular filtration system with a high efficiency of fluids (liquids or gases).

Preferably, the UV lamp 3 is a UV-C lamp.

As known to those skilled in the art, a UV-C lamp emits ultraviolet light (UV) with wavelengths included in the UV-C band, i.e. between 100 and 280 nanometres, advantageously capable of modifying the DNA or RNA of microorganisms and thus of preventing them from reproducing or from being harmful to human health. According to a preferred embodiment of the device 10 according to the present invention, the UV-C lamp 3 can emit a light having a wavelength between 100 nm and 280 nm, however it preferably emits a light having a wavelength of 254 nm. According to a preferred embodiment, the fans 1 and 2 of the device 10 are preferably two.

Preferably, always according to an embodiment of the device 10 according to the present invention, the photocatalytic cell 4 has a honeycomb structure.

Preferably, there are two photocatalytic cells 4 coated with a mixture comprising an epoxy polymer and a compound according to formula (I):

Ti ₃ C ₂ Tx (I) where Tx is chosen from: F, OH wherein one of the two photocatalytic cells 4 is placed between the inlet port 15 and the UV lamp 3 and the other of the two photocatalytic cells 4 is placed between the UV lamp 3 and the outlet port 17.

A second object of the present invention relates to a process for producing a photocatalytic cell 4 comprising the steps of: a) providing a cell; b) mixing together an epoxy polymer and a compound according to formula (I):

Ti ₃ C ₂ Tx (I) where Tx is chosen from: F, OH; c) evenly spreading the mixture obtained in step b) on the cell of step a).

Preferably, the cell of step a) has a honeycomb structure.

Furthermore, the epoxy polymer of step b) is preferably epoxy resin.

The compounds belonging to the formula Ti ₃ C ₂ Tx are commonly referred to as “MXene”. The term MXene refers to a class of two- dimensional inorganic compounds. These compounds consist of layers having a thickness of a few atoms of transition metal carbides, nitrides, or carbonitrides.

Advantageously, the device 10 according to the present invention, thanks to the presence of the photocatalytic cell 10 coated with a mixture comprising an epoxy polymer and a compound according to formula (I):

Ti ₃ C ₂ Tx (I) where Tx is chosen from: F, OH; provides a method for sanitising air, fabrics and surfaces, especially ducts and aeraulic components.

The sanitisation method operated by the device 10 according to the present invention can be used for sanitising internal surfaces, aeraulic ducts and components used to convey air such as heating and air conditioning systems both in industrial and civil fields.

Advantageously, the device 10 according to the present invention uses a component, the photocatalytic cell 4, coated with a mixture comprising an epoxy polymer and a compound according to formula (I):

Ti ₃ C ₂ Tx (I) where Tx is chosen from: F, OH.

Advantageously, the coated photocatalytic cell 4 is irradiated by the light emitted by the UV lamp 3, which is preferably a UV-C lamp which emits a light having a wavelength of 254 nm. Advantageously, the two- dimensional material Ti3C2T _x (with T _x = F, OH) is composed of a transition metal (Ti) having a great antimicrobial power, capable of oxidising the membrane of microorganisms and consequently capable of inactivating them.

Therefore, advantageously, the device 10 according to the present invention is intended to be used for the control of the hygienic conditions of the surfaces and indoor environments where people spend 80% of their time.

In particular, the device 10 according to the present invention has the ability to sanitise public and private indoor environments and distribution networks of ventilation systems.

The sanitisation carried out using the device 10 according to the present invention is not based on the use of titanium dioxide, but rather is based on the principle of the photocatalytic oxidation applied to a photocatalytic cell 4 coated with a mixture comprising an epoxy polymer and a compound according to formula (I):

Ti ₃ C ₂ Tx (I) where Tx is chosen from: F, OH.

The advantage of using the compound of formula I is given by the multiple chemical and physical properties it has, including resistance to high temperatures, extreme charging speed, good conductivity and the remarkable ability to reduce the microbial load.

The Ti3C2Tx compound, where Tx is chosen from: F, OH, has the ability to activate the photocatalysis process when it is hit by an ultraviolet light beam having a wavelength of 254 nm.

Advantageously, according to the present invention, the Ti3C2T _x compound (where Tx is chosen from: F, OH), when it is irradiated by the UV light at a wavelength of 254 nm produced by the UV lamp 3, becomes excited. The air, full of relative humidity naturally occurring in our atmosphere and microorganisms, attracted by the mechanical action of at least one valve 1 and 2 present in the outlet port 17, enters the internal chamber 13 through the inlet port 15, passes through the internal chamber 13 interacting first with the particulate filter 5 and then with the photocatalytic cell 4 coated with a mixture comprising an epoxy polymer and a compound according to formula (I):

Ti ₃ C ₂ Tx (I) where Tx is chosen from: F, OH and the UV lamp 3. At this point the TisC2T _x compound (where Tx is chosen from: F, OH) being photo-excited by the ultraviolet light emitted by the UV- C lamp interacts with the water present in the air and starts a redox cascade reaction that leads to form hydroxyl ions and reactive oxygen species (ROS) which sanitise the air as they are able to eliminate the microorganisms they are in contact with.

Advantageously, unlike other purifiers, the device according to the present invention does not simply filter the air present in the environment but sanitises it by using the photocatalytic oxidation technology (PCO) combined with the TisC2Tx compound (where Tx = F, OH).

The device according to the present invention is advantageously based on an air filtration system by means of a photocatalytic cell 4 coated with a mixture comprising an epoxy polymer and a compound according to formula (I):

Ti ₃ C ₂ Tx (I) where Tx is chosen from: F, OH and irradiated by a UV-C lamp which emits an ultraviolet light having a wavelength of 254 nm.

The purpose of using the aforesaid coated and irradiated cell is to produce a high concentration of ROS, hydroxy and hydroxylic radical ions.

The characteristic of coating the cell with a mixture comprising an epoxy polymer and a compound according to formula (I):

Ti ₃ C ₂ Tx (I) where Tx is chosen from: F, OH has the further advantage of providing a more long-lasting device than the current air sanitisation systems, as the coating slows down the wear of the cell caused by atmospheric agents (humidity, precipitations, etc.).

Preferably, the cell has a honeycomb structure and is coated with a powder of the Ti ₃ C ₂ T _x compound (where Tx = F, OH) mixed with an epoxy polymer so as to obtain a liquid phase mixture with a filming action.

The liquid phase mixture thus obtained has a good bonding capacity.

The fine particles of the Ti ₃ C ₂ T _x compound (where Tx = F, OH) are added to an epoxy polymer and fused together when heated.

The polymeric coating thus obtained continues to have the same chemical composition once it cools becoming a solid coating.

The step of spreading the mixture in its liquid state on the surface of the cell according to the present invention is carried out so as to obtain an even and continuous film layer.

Advantageously, the irradiation of the UV-C lamp combined with the structure of the photocatalytic cell coated with a mixture comprising an epoxy polymer and a compound according to formula (I):

Ti ₃ C ₂ Tx (I) where Tx is chosen from: F, OH activates the photocatalytic oxidation process. The air full of humidity passes through the coated photocatalytic cell 4; thanks to the action of the UV-C lamp, which irradiates ultraviolet light at a wavelength of 254 nm on the mixture comprising the Ti ₃ C ₂ T _x compound (where Tx is chosen from: F, OH), the photocatalytic oxidation process becomes active leading to the formation of ROS, hydroxy, hydroxylic radical ions which have the ultimate goal of eliminating most of the polluting compounds present in the air such as bacteria, viruses, moulds, allergens and odours.

When the aforesaid ultraviolet light irradiates the photocatalytic cell according to the present invention, there is, advantageously, the adsorption of a photon having an energy higher than the “energy gap” of the electrons of the aforesaid Ti3C2T _x (where Tx is chosen from: F, OH), this causes photoexcitation, i.e. a promotion of electrons from the valence band to the conduction band leaving a positively charged hole in the valence band: an excited state. In the presence of water, this state of excitation transfers energy or electrons to it (to the water) resulting in the production of radical oxygen species (ROS) which have an antimicrobial action.

The ROS spread in the surrounding environment make it possible a safe, effective and complete sanitisation of both the air and, as a consequence, of the surfaces of the ducts conveying the air and of the surfaces in direct contact with the treated air.

Advantageously, according to the present invention, in order to obtain a solid and crosslinked polymeric coating, the Ti3C2T _x compound (where T _x is chosen from: F, OH), is mixed with an epoxy polymer and spread on the surface of the photocatalytic cell. The coating thus created has a filming action.

Advantageously, in the device according to the present invention, thanks to the suction generated by the fans 1 and 2, a first filtration of the air takes place through the electrostatic filter 5 located at the air inlet point: the inlet port 15.

Subsequently, the sanitisation of the air is achieved when it passes the photocatalytic cell 4 coated with a mixture comprising an epoxy polymer and a compound according to formula (I):

Ti ₃ C2T _x (I) where T _x is chosen from: F, OH where the aforesaid compound is photo-excited by irradiation of light at a wavelength of 254 nm produced by the UV-C lamp 3.

Advantageously, as soon as the Ti3C2T _x compound (where T _x is: F, OH) is hit by the light at a wavelength of 254 nm, the photocatalytic oxidation process (PCO) takes place which, in contact with the humidity present in the air, leads to the formation of ROS. ROS are highly unstable molecules capable of mineralising organic substrates and triggering the destruction of a wide range of microorganisms, by attacking vital organic components such as cell membranes, RNA, DNA, proteins and lipids.

The device according to the present invention also has the advantage of remaining stable, guaranteeing many years of constant activity, without releasing any substance which could be considered a polluting source.

The device according to the present invention provides the advantage of eliminating microorganisms such as germs, bacteria and viruses which, by proliferating in the air, cause the spread of diseases and allergies. Furthermore, the device according to the present invention makes it possible to eliminate odours present in the environment and reduces harmful microparticles present in the air, including the particulate matter. As a consequence of this, there is a better air quality and a reduction of the periodic interventions (and of the corresponding costs) provided for the sanitisation and decontamination of indoor environments, surfaces, fabrics and aeraulic ducts.

The present invention has been described for illustrative, but not limitative purposes, according to its preferred embodiments, but it is to be understood that variations and/or modifications can be made by those skilled in the art without thereby departing from the relevant scope of protection, as defined in the attached claims.