A closer look at air purification using photocatalysis

If you want to make right choice when buying an air purifier in a store or online, you will need to take your time. Time to understand what it does, how it works, all the , different options and which ones are right for you. This article by AIRVIA Medical will shed light on the purification function of "photocatalysis", also known asd "photo catalytic degradation".

What is photocatalysis?

To understand photocatalysis, you first need to learn what "catalysis" is. In the chemical world, a catalyst is a chemical substance that accelerates the speed of a reaction, without taking a direct part in the final reaction itself. Catalysts are always used in smaller quantities than the reactive products.

Une main tenant une molécule schématisé

Industrials use catalysis to achieve energy savings, and financial savings since they serve to speed up manufacturing processes. All of us use catalysis in our daily lives without even realizing it: in our gas-boilers, our car engines (which often use the famous "catalytic converters") or even when we use yeast for baking.

Photocatalysis is a form of catalysis that uses the energy of light.

A closer look at photocatalysis

Cleaning the air throuh photocatalysis is the promise made by many air purifiers. In ancient Greek, κατάλυσις (katalysis) means "dissolution" while φωτός (photos) means "light".

For the more scientific-minded, here is a graph showing photocatalysis in greater detail:

Photocatalysis is "the absorption of a photon, whose energy is greater than the gap between the valence band and the conduction band, resulting in the formation of an electron-hole pair in the semiconductor." An electron is therefore emitted by the conduction band and causes the formation of a hole in the valence band. Together they form an electron-hole "pair" which leads to the formation of free radicals. These free radicals will either react with compounds present around them, or recombine internally. In both cases the initial particle is modified, degraded.

This is referred to as "photocatalysis" or "photo catalytic degradation".

Photocatalysis in air purifiers

Photocatalysis is used in the UK to purify air, treat water, for medical therapy and more recently in the industrial world. Photocatalysis can eliminate all Volatile Organic Compounds (VOCs).

Un tunnel

Its effectiveness is long proven and it is even used by some governments, such as Belgium. In Brussels for example they use particles of titanium dioxide (TiO2) mixed with cement to clean the air of the Leopold II tunnel. The process is kick-started by UV rays. Gases such as formaldehyde and benzene are easily degraded by the process of photocatalysis. This particular application has been used for over 7 years now and always with solid results.

At AIRVIA Medical, we also use UV rays to make our photocatalysis more powerful and more efficient. Air purification using photocatalysis can break down all sort of harmful particles present in our indoor air such as VOCs, non-organic pollutants produced by combustion devices such as cars for example, and microorganisms such as bacteria, fungi, viruses, etc.

Photocatalysis produces mostly water and small amounts of charcoal dioxide. AIRVIA Medical Air Purifiers have been tested to show safe figures and clear benefits to the cleanliness of the air. Photocatalysis results in better, safer air.

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