What is photocatalytic oxidation and how does it works

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4 concepts to understand what exactly does and why air purifiers help to improve indoor air quality

Not too long ago, indoor air quality was an unknown subject for most people. The air we breathe was taken for granted, and little was known about how it affects our health.

But why it matters now?

The effects of 2020’s pandemic COVID-19 have pointed at indoor air quality as a matter of concern, and as a principal way of transmission of viruses.

We spend 90% of our time in indoor spaces and approximately 6 to 8 hours in shared spaces like schools and offices.

Public transport, restaurants, healthcare venues and other spaces can become a potential way of transmission of illnesses.

And in highly polluted outdoors, especially in big cities, keeping a clean indoor air quality can be challenging, since indoor and outdoor air are closely connected.

To these problems, we have to ad the fact that HVAC systems usually present problems. In some cases, the air conditioning systems and ductwork do not get proper maintenance and cleaning after installed. Thus, virus and bacteria tend to accumulate dust and mould all through the ventilation channels.

65% of ducts are contaminated, and 10% are infected with pathogenic bacteria

Though experts have called to ventilation as a solution to the excess of indoor pollution and the concentration of bacteria and viruses, this might help just partially. Air exchange it’s important, but this varies depending on the type of ventilation system that the building has, and the proper functioning is not guaranteed. 

there’s a 55% of chemical agents present in the indoor air: perfumes, aerosol, cleaning products, airborne fibreglass particles, between others

To help ventilation in the hard process of keeping indoor air clean, some methods can complement and help to reduce the excess of bacteria. Air purifiers based on the photocatalytic system, far from being a trend, provide a handful solution for air cleaning in residential and industrial ambiences. 

Below you will find 4 concepts you need to know in order to understand how the photocatalytic oxidation technology works, and how can you benefit from its effects. 

1. A definition

Photocatalysis is a technology first used and tested by NASA back in the ’70s. 

The Photocatalytic Oxidation, also known as PCO, it’s a chemical effect produced when a light source penetrates a surface that works as a semiconductor material, best known as a photocatalyst. 

The photocatalyst absorbs the UV lights and creates oxygen particles such: OH•, OH-, O2-•, HO2, thanks to a mix of noble metals, where Titanium Dioxide (TIO2) works as the key element.

Titanium Dioxide it’s a non-toxic substance, and it’s high level of photoactivity, good behaviour and stability, added to its low cost, converts it in a very efficient material.

2. This is how it works

There are two main reactions produced by the photocatalysis:

Oxidation, that derives from the photogenerated holes, and reduction, created due to the presence of electrons that have been photogenerated. 

These 2 processes are key to guarantee the photocatalytic effect.  

Several tests have demonstrated that photocatalytic technology produce by TIO2 can efficiently inactivate the particles of virus and bacteria by degrading their infectious proteins. 

The speed of this degradation will depend on 3 aspects:

  • the UV- A intensity (optimal range: 0.5 – 3.5 mW/cm2)
  • the irradiation time (optimal range: 30 min – 2 hrs) 
  • the amount of Titanium Dioxide concentration solution (optimal range: 0. 5 – 1.0 mg/mL)

3. Applications in everyday life

The photocatalytic system can help to eliminate pollutants present in the air an improve the air quality of a room efficiently. 

It is a safe technology for human use and can start to activate its effects within an hour. It’s generated in a specific place, and then it expands all over the place; its effect it’s like the one of a perfume.

In shared venues, such as schools, offices, public transport, hospitals and hotels, its effects contribute to a better indoor air quality, but air purifiers can also help in:

  • industrial spaces, where it is well known that a percentage of the work absenteeism has to do directly to the quality of the air that the workers breathe. 
  • residential buildings, to reduce odours from the kitchen, smoke and chemical agents.

4. How does it help to improve indoor air quality?

It is scientifically tested that virus and bacteria are reduced in 99% after 24h of usage; according to the latest laboratory results, mould and airborne decrease radically, and the benefits of using air purifiers can make ventilation more efficient. 

The air purifier devices are installed inside the AHU or inside of the duct. Therefore, it guarantees that air purification will start inside the ductwork, and will flow all through the ventilation system.

However, it is important to understand that the effects of the photocatalytic oxidation have to do with disinfection and not sterilisation.

What is the difference between disinfection and sterilisation?

The disinfection process eliminates many potentially pathogenic microorganisms on inanimate objects, except for bacterial spores.

The sterilisation process destroys all forms of microbial life using a very intense chemical method. It is commonly used in health care facilities.

We’ve got the opportunity to improve the air we breathe in 2021. 

Now is the moment. 

Clean air is a human right.

Do you need an extra from our experts? Contact here or write to us: info@dustfree.eu 

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