Content

This knowledge base presents information about the Products which have been approved by our legal consultants (for those with content that could generate legal contestation by third parties) or after internal review to ensure that they are consistent with our communication policy and sales and marketing strategy. Information is provided on Vitesy photocatalytic technology. Information is also provided on plants suitable for Natede Smart and Natede Basic for both home and office use, and all the precautions to be taken for their maintenance.

Use Cases and Context

• The product information in this section is very specific, covering technical and scientific topics, and is designed to provide the user with a technical-scientific answer to questions about the efficacy of product technology, and thus serves users who are interested in learning more about certain aspects of the product and educating themselves about it. It also serves as support in conversations with B2B partners who express doubts or disbelief about the technology or downplay its effectiveness.

• If a user has doubts about which type of plant to use and in which part of the environment to place it, here you will find the appropriate information with all the specifications of plants suitable for Natede and its characteristics, including how to install and maintain it.

• Answering specific questions about the technology of Vitesy products

• Answering specific questions on which plants work best with Natede

• Answering specific questions about Vitesy photocatalytic technology and its security

• Answering specific questions about the performance of air purifiers with photocatalytic technology

Restrictions

• Never extrapolate test report results to infer the efficacy or efficiency of our products in contexts other than those tested. Do not make assumptions about performance in different settings based on these results.

• If a user requests information about the product or technology's efficacy against an untested substance or pollutant, avoid drawing conclusions, even if they seem scientifically sound. Primarily, state that the product or technology has not been officially tested against the substance or pollutant in question. Only if, according to openly available information coming from trusted sources, this substance is chemically similar to a pollutant that the product has successfully been tested against, you can draw a parallel between the two.

Examples of Questions

• What is photocatalysis?

• How does photocatalysis remove pollutants?

• What is the performance of photocatalysis?

• Can photocatalysis be harmful to health?

• Are Vitesy products classified as biocidal products?

• Which plant should I use for Natede?

• How should I install the plant in Natede?

• Where should I place Natede with [Plant Name]?

• What’s the best room for [Plant Name]?

• Can I use Natede with [Plant Name] in [room name]?

Resources (rev. 2024/12/13)

LINKS TO TECHNICAL INFO PDF DOCS

TECHNICAL INFORMATION ABOUT SPECIFIC PRODUCTS

TECHNOLOGY

WO3 (Tungsten Trioxide)-based Photocatalysis &
viruses

Tungsten Trioxyde (WO3) is considered one of the most promising semi-conductive photocatalyst for the degradation of organic compounds, mainly thanks to its small bandgap (which varies between 2,4 and 2,8 eV), allowing thus to activate the photocatalytic reaction with a lower energy input. Furthermore, compared to other photocatalysts, Tungsten Trioxide presents other advantages:
- It’s a very stable material in water-based solutions in acid conditions;
- It’s activated by visible light and thus avoids the problems associated with the use of
UltraViolet (UV) light sources, such as those needed for ex. with Titanium Dioxide
(TiO2), one of the most widely used photocatalysts;
- Much more energy efficient (up to 90% less energy consumption);
- Totally safe, since there’s NO ozone emission (irritating for lungs) and it’s NOT
dangerous for the eyes if observed directly.

The main applications of WO3-based are photo-degradation of organic substances, air
purification, virus & bacteria disinfection, self-cleaning, CO2 photo-reduction, treatment with
heavy metal ions and hydrogen production from water scission.
For these reasons, in the last years the research is focusing on this new photocatalyst for
the disinfection of surfaces, air and water: researchers have indeed proved that WO3-based
photocatalysis can kill a wide range of viruses, Gram-negative and Gram-positive bacteria,
filamentous unicellular fungi, algae and protozoa. The elimination mechanism is based on the degradation of the cell wall and of the cytoplasmic membrane through the Reactive Oxygen Species (ROS) created by the photocatalysis, such as hydroxyl radicals and hydrogen peroxide. The collision between bacteria, viruses and the Reactive Oxygen Species causes cell lysis and can result in the complete mineralization of the microorganism. Of course, the closer the contact between the microorganisms and the WO3 catalyst, the more efficient the elimination. Lastly, WO3-based photocatalytic filters can be enriched through the addition of platinum, gold
and silver, in order to maximize the photocatalysis effectiveness.

Photocatalytic Disinfection - Detailed Explanation

The photocatalytic disinfection of viruses and other microorganisms happens mainly
through chemical oxidation carried out by
Reactive Oxygen Species (ROS), such as •OH e
H2O2, created by the photocatalyst. The disinfection mechanism entails therefore the creation of ROS and consequent decomposition of the viruses’ cell wall and cytoplasmatic membrane through various steps as described below:

1. The photocatalyst’s excitation electronically charges its surface and thus the couples
   electron/hole (e−/h+) are created.
   

2. The holes in the valence band react with the species OH- o H2O adsorbed on the filter’s
   surface, thus generating the hydroxil radical (•OH), which in turn oxydizes the virus chemical substances (specifically, the envelope and the capsid) adsorbed on the photocatalyst’s surface.
   

3. The electrons in the conduction band react with Oxygen (O2) and as a result produce
   highly efficient radicals (•O2 −, •OH e •OOH). Therefore, the ROS created in this way
   starts the reactions, which culminate in the destruction of the virus adsorbed on the
   photcatalyst’s surface.
   

As explained above, therefore, the various highly efficient ROS produced on the photocatalyst’s surface can oxidize the viruses adsorbed on the same surface, destroying them and thus effectively disinfecting the medium (whether gaseous, liquid or solid). The following image shows the whole process: creation of the couples e−/h+, recombination phase, ROS generation and the viral disinfection. Thus, the more ROS a photocatalyst can generate, the more efficient it will be in terms of virus disinfection (and more in general against all target pollutants).
N.B. The catalyst only acts as accelerator of the process and doesn’t release any substance on
its own. All photocatalysts indeed release/produce ROS: what changes is the reaction kinetics,
that is, the speed of the pollutant’s reduction.

WO3-based photocatalytic technology: safety, ROS (Reactive Oxygen Species) release in the environment, BPR classification

Photocatalytic Technology and Release of Reactive Species: Efficacy and
Safety

Vitesy’s indoor air purifiers use photocatalytic technology, which allow to reduce and degrade in an efficient and safe way gaseous pollutants and airborne microorganisms. Photocatalytic filters clean the air through the creation of Reactive Oxygen Species (ROS) and Radicals, in the immediate proximity of the filter surface. The reactive species, thanks to their very powerful oxidizing action, degrade microorganisms and pollutants in an extremely short timespan and with very high conversion yields. The peculiarity of the photocatalytic technology is precisely the ability to create a layer of ROS on the filter surface (a few mm thick) without releasing the same ROS and Radicals in the purified air and thus preventing their diffusion in the environment.
In this sense, the photocatalytic technology differs from other air purification technologies such
as:
- HEPA filters (effective mainly against dust and other solid particles)
- UV-C rays (which produce ozone as a byproduct -irritating for lungs- and require long
exposition times, making them unsuitable for occupied spaces)
- Ozonizers (which produce great quantities of ozone - irritating for lungs)
- Ionizers (effective in retaining dust but producing ozone as a byproduct -irritating for
lungs)
- Cold Plasma (which has to create a large amount of ROS in order to be effective).
As proof of its safety, many studies in the literature confirm that the purified air released by
photocatalytic filtering machines, has negligible quantities/concentration of active substances such as ROS (ozone, peroxides, radicals and ions): so low, indeed, that they can not even be measured with dedicated, professional instruments. Last but not least, on the website of the California Air Resources Board (CARB), which has become one of the most strict regulators of Air Quality in the world, none of the appliances identified as potential emitters of ozone uses photocatalytic technology.

Tungsten Trioxide (WO3)-based Photocatalytic Technology: the New
Frontier, Even Safer and More Sustainable

Following our Continuous Evolution mantra, at Vitesy we’ve decided to use the most advanced
and innovative version of the photocatalytic technology.
In the first version of Natede we’ve used the more classic implementation of the photocatalytic
technology, with a Titanium Dioxide (TiO2) filter coating that requires a UltraViolet (UV) light
source for activating the photocatalytic reaction. In the product evolution Natede Smart (
www.vitesy.com/natede-smart - launched August 2021) and in our newest product personal air purifier Eteria (www.vitesy.com/eteria - available from January 2022) we’re using instead a filter with a Tungsten Trioxide (WO3)-based coating. The move to such coating allowed us to employ visible light LEDs for the activation of the photocatalytic reaction in place of UV light sources, which is instead needed in the case of TiO2-based coatings. This entails great advantages both in terms of energy consumption (much lower) and lifespan (much higher) of the visible light LEDs that activate the photocatalytic process, compared to UV light LEDs, which perform worse in both respects. The switch to visible light LEDs, in addition, eliminates all risk factors linked to the use of UV light, that is:

• Ozone emission (which was anyway negligible even in the 1st version of Natede) -
  ozone is a lung irritant;
  

• Potentially dangerous for the eyes (only if observed directly and for a long time).

WO3-based Photocatalysts: Safe and Non-Toxic

Speaking of the potential dangerousness (toxicity) of the substances used as photocatalysts,
it is important to note that they are positioned within the device, in the form of hard coating
(anodization) of the photocatalytic filter which is hit with visible light and therefore it is not in
direct contact nor with people or pets during use. In addition, the hard coating won’t release particles in the environment, since it’s applied through an anodization process (creating a very tight bond with the carrier) and, just as important, is NOT subject to any form of mechanical attrition or impact/shock but only to the flow of pre-filtered air.
Therefore, the filter position within the device and the strong bond of the coating to the carrier
are a guarantee of the safety of the photocatalyst even for the use in occupied rooms.
This means that the core purification technologies used by Vitesy Air Purifers are safe and
present no risks for the people staying in the rooms and environments where the devices are
placed.

Photocatalytic Devices & "Biocidal" Classification: State of the Art

Turning specifically to the topic of the biocidal product, which are regulated in the EU area by
the BPR - Biocidal Products Regulation (EU Regulation nr. 528/2012 and following
modifications), the application of such regulation on devices emitting Reactive Species,
such as those using Photocatalytic technology, is still not fully defined and thus not yet
implementable, even though the analysis in this sense is underway.
At present, the BPR regulation defines biocidal substances as follows (Article 3.1.a): “ [...]

• any substance or mixture, in the form in which it is supplied to the user, consisting of,
  containing or generating one or more active substances, with the intention of destroying,
  deterring, rendering harmless, preventing the action of, or otherwise exerting a
  controlling effect on, any harmful organism by any means other than mere physical or
  mechanical action;
  

• any substance or mixture, generated from substances or mixtures which do not
  themselves fall under the first indent, to be used with the intention of destroying,
  deterring, rendering harmless, preventing the action of, or otherwise exerting a
  controlling effect on, any harmful organism by any means other than mere physical or
  mechanical action.
  A treated article that has a primary biocidal function shall be considered a biocidal product.”.
  

At present, only some guidelines have been defined on the information requirements about free radicals generated in situ and for the approval of related substances used as biocides in a document of the Health and Food Safety Directorate General of the European Commission. In such document, treating the topic of product authorization, it is expressly required to take as reference the mixture (in the case of Vitesy filters, the photocatalytic elements) which, applied as coating on a carrier, is able to generate free radicals (also through the use of light). However, it is still unclear how and what information is required to classify these products as biocidal products and to authorize their use.

CADR and purifiers with photocatalytic technology - Application limits

Introduction & key points

Purifiers come in many shapes and sizes, from static ones for entire rooms to portable ones for personal use. Even within these categories there is significant variation - in price, performance, and especially in the type of filter used to break down harmful substances.A typical metric that is taken into account to evaluate the performance of a purifier is CADR: in this article we'll see what it is and why it shouldn't be the most important metric to consider when evaluating the efficiency of a purifier.

KEY POINTS:

• CADR measures the ability to move large volumes of air rather than the effectiveness of purification;

• CADR is only performed on a single category of pollutant, particulate matter, and does not measure abatement effectiveness at all toward other types of pollutants that are widespread in Indoor air;

• Vitesy air purifiers, which use photocatalytic technology, very efficiently break down all types of non-particulate pollutants that are not measured by CADR. The CADR value would therefore not represent their performance;

• In the case of Natede, specifically, the airflow rate must be balanced with the well-being of the plant inside, to maximize the efficiency of the system.

What is CADR

The CADR (Clean Air Delivery Rate) is a value that basically indicates the volume of air free of polluting particles emitted by a purifier in a given period of time. The CADR value is based on a test developed by AHAM (The Association of Home Appliance Manufacturers) and recognized by the EPA (U.S. Environmental Protection Agency) and other U.S. institutions, with the goal of providing a uniform standard by which consumers can compare the performance of different purifiers.
CADR is officially defined as: CADR = ( A - A0 ) * V

A: contaminant reduction rate in a controlled environment with the unit on
A0: natural sedimentation rate when the unit is off
V: volume of the environment measured in cubic feet
The unit of measure for CADR is CFM (cubic foot per minute).

How the CADR test is performed

CADR testing is performed only for the following pollutant categories:

• Dust, 0.5-3 micron diameter (medium size particles)

• Pollen, 5-11 microns in diameter (large particles)

• Smoke, 0.09-1 micron diameter (small particles)

This means that the removal of gases, bacteria and other pollutants is neither considered nor
measured, despite the fact that indoor pollution is known to affect these other categories as well.
The test consists of verifying the filter's ability to remove dust, pollen and smoke from a 1008 cubic foot (28.54 m3) controlled environment, with the purifier turned on at maximum power for twenty minutes. There is also a ceiling fan and a wall fan. Contaminants in the room are measured before, during, and after the test. The remaining contaminants are then compared to those present at the beginning and to the natural sedimentation rate to calculate the CADR value for the three categories of pollutants.

Limitations of CADR for evaluating the efficiency of a purifier

CADR has several limitations that should be kept in mind when using it as a term of comparison:

• The CADR value is strongly influenced by how well the purifier is able to move air, rather than
  by its ability to purify it. This is because the test is very short in duration (20 minutes) and takes place in a room of about 29m3. If the purifier has poor ventilation capabilities ( i. e. it does not move air well in the room), it may receive a lower score because it is not working efficiently according to the CADR standard.
  

• CADR is based on the filter's ability to trap pollen, dust, and smoke, but does not take into account the filter's ability to remove odors, VOCs, gases such as CO, ozone, NOx, or microbiological agents such as viruses and bacteria. These non-particulate contaminants are very common in indoor air and can be eliminated through the use of air purifiers. It is important to emphasize that there is a clear difference between "trapping particles" and "killing substances such as odors, VOCs and bacteria", because in the second case a real irreversible transformation of contaminants into substances harmless to health takes place. The CADR measures how much a purifier is able to trap (and not destroy) particles. Non-particulate compounds by their nature cannot be trapped by a HEPA filter. When a purifier is tested for CADR, only a portion of its filtration capacity is actually measured. So, if gaseous contaminants are part of your home air quality issues, a CADR test shouldn't be the only metric used when choosing an air purifier.

• What's more, with use over time, the typical HEPA filter becomes saturated and its suction
  capacity reduced, thus lowering the CADR value for pollen and dust and potentially improving that for smoke (small particles). So CADR is not a value that remains constant over time. This means that a purifier might get a higher CADR because it has a less efficient filter and therefore allows more airflow, thus penalizing a purifier with a more efficient filter through which air and different particles find it harder to pass.
  

Why it is not worthwhile to evaluate CADR for Vitesy Photocatalytic Purifiers

CADR, as previously discussed, does not indicate a product's ability to capture and remove odors, bacteria, or volatile organic compounds (VOCs). Vitesy air purifiers, through the use of nanomaterial-based photocatalysis, successfully remove these contaminants from indoor air, a capability that CADR does not take into account. The air needs to be stationed inside the photocatalysis chamber for a certain amount of time to allow for total air purification. This performance over time (unlike the CADR evaluation on a generic HEPA) is not altered, as the
photocatalytic filter activates the reaction but does not wear out (as it acts as a catalyst).
And that's not all: in the case of NATEDE, in which the plant (a living system) represents 1 of the 2 stages of air purification, Vitesy's technicians and scientists have maximized the air flow with the same well-being of the plant. In fact, the plant under optimal working conditions is able to participate in air purification through the phenomenon of phytoremediation. An excessively high flow would stress the plant too much and dry out the cultivation substratum too much, causing its death. For these reasons, Vitesy air purifiers are not rated by the CADR system. We believe that higher filtration efficiency is more important than higher airflow rates. Our goal is to help our customers live better lives by removing an effective amount of airborne particles and indoor air contaminants, not moving air to receive a higher CADR.