PCO vs. PECO Air Purifier

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Written By Jamila W.

PCO and PECO are emerging air-cleaning technologies that use catalytic oxidation to destroy particulate and gaseous air pollution. But there are notable differences between these two powerful air purifiers that affect the air quality they achieve. In this article, we compare PCO vs PECO air purifiers to help you evaluate which type of air purifier is the better investment for clean air.

PCO vs PECO air purifier: Side-by-Side Comparison

PCO Air PurifierPECO Air Purifier
Full namePhotocatalytic Oxidation (PCO) air purifierPhotoelectrochemical oxidation (PECO) air purifier
What is it:An air cleaner that uses UV-activated catalytic oxidation to destroy indoor air pollutantsAn air cleaner that uses UV-activated catalytic oxidation and an applied electric current to degrade indoor air pollutants
Initial release:The 2000s2014
Developers:Doodeve and Kitchener (1930s),Akira Fujishima and Kenichi Honda (1970),Genesis Air,Ultravation,Air OasisProfessor Dharendra Yogi Goswami,Clean Energy Research Center, University of South FloridaMolekule
Filter/catalyst:A high surface-area media/titanium dioxide catalystFibrous corrugated filter/proprietary nanocatalyst 
Type of UVUV-A light (365nm)UV-C light (254 nm) UV-C light (220 nm) 
Minimum particle size filtered:0.3 micrometers0.3 micrometers
Percentage of particles removed:Unknown efficiency of the catalytic filter.99.97% minimum (via HEPA pre-filter). Unknown efficiency of the catalytic filter.
Types of particles removed:Volatile organic chemicals (VOCs)FormaldehydeParticulate Matter (PM 1, PM2.5, PM10)BacteriaVirusesMoldCigarette smokeVolatile organic chemicals (VOCs)Particulate Matter (PM 1, PM2.5, PM10)FormaldehydeOzoneNitrogen dioxideVirusesBacteriaCigarette smokeMold
Cleaning/replacementCatalyst and filter adsorption mediums have a finite lifespan. PECO catalytic filters are changed every six months. HEPA pre-filters are changed when saturated.
Applications: Commercial and industrial air cleaningAir purification in hospitality settingsAir pollutant reduction in domestic environments (consumer)Air purification in commercial and hospitality settingsAir purification in high-cleanliness settingsAllergy reduction in domestic environments (consumer)

What is PCO air purification? 

PCO stands for photocatalytic oxidation. It is a powerful air purification technology that can completely degrade a wide range of indoor air contaminants leaving only water, carbon dioxide, and harmless detritus. PCO-based air cleaning technology was developed in the 2000s and has since shown promise as a solution for efficiently reducing indoor air pollution. 

Unlike filters, adsorbent media, and other air-cleaning technologies, PCO can eliminate air pollutants rather than just trap them. It is also not just limited to removing particle pollutants but can also destroy gaseous pollutants too. 

How do PCO air purifiers work?

Photocatalytic oxidation uses a UV light-activated titanium dioxide (TiO2) catalyst to drive its powerful air-cleaning effect. In the presence of UV-A or UV-C light, the TiO2 catalyst transforms into a powerful oxidant, creating hydroxyl free radicals from water vapor in indoor air. 

These free radicals react with any organic air pollutants they come into contact with. The oxidation reaction destroys the pollutants leaving carbon dioxide, water, and mineral residues. In PCO air purifiers contain a high surface area adsorbent medium that is coated in this special catalyst, along with UV bulbs or LEDs to activate it. 

Which air contaminants do PCO air purifiers remove?

person smoking

PCO air purifiers are capable of reducing or removing carbon-containing pollutants. Unlike many competitor air cleaners, PCO air purifiers are also effective at eliminating odors. The oxidative action works equally on organic particulates and gasses including

  • Volatile organic chemicals (VOCs)
  • Aldehydes
  • Olefins
  • Aromatics
  • Alkanes
  • Halogenated hydrocarbons
  • Cigarette smoke
  • Biological aerosols including viruses, bacteria, mold, and pollen
  • PM1, PM2.5, and PM10 particulates
  • Pet dander and dust

However, PCO cannot remove all pollutants present in indoor air. It cannot eliminate radon gas, carbon monoxide, ozone, or nitrogen dioxide.

PCO air purifier formats

PCO air cleaners come in a range of formats spanning industrial, commercial, and residential use. The exact specifications and performance of these air cleaners will vary by manufacturer.

Some PCO air purifiers may include a pre-filter to remove particulates from the intake air. The addition of a MERV or HEPA filter reduces the concentration of pollutants to be treated in the catalytic chamber so the device can work more thoroughly. 

PCO air purifiers may also pass exhaust air over an adsorbent media before it leaves the device. This prevents the release of any pollutants that remain unconverted in the catalytic chamber. 

What is a PECO air purifier? 

PECO stands for photoelectrochemical oxidation. It is a proprietary variant of PCO owned by Molekule and used in their line of air purifiers. Professor Dharendra Yogi Goswami, of the Clean Energy Research Center of the University of South Florida, invented PECO. 

Goswami worked on his air purification technology for more than two decades before bringing the PECO air purifier to market with his company, Molekule. In 2017 his PECO air purifier was one of TIME Magazine’s best inventions of 2017.  In 2018, it received Class II medical device clearance from the FDA.

PECO filters also use UV-driven photocatalysis to oxidize and eliminate airborne organic particulates from indoor air. Goswami’s design also uses an electric current to enhance the generation of the free radicals that oxidize air pollutants.

How does the PECO air purifier work?

PECO air cleaners purify room air in two stages. First, the room air intake passes through a HEPA pre-filter which traps the particulates present. Secondly, the mechanically filtered intake air passes into a central, cylindrical catalytic chamber, where photoelectrochemical oxidation takes place. 

The photocatalyst material coats the PECO filter which traps and absorbs pollutants. Continual radiation of the catalyst with UV-C light (222 nm wavelength) and electrical current ensure that pollutants within the chamber are completely broken down. Harmless exhaust air is released back into the room.

Which air pollutants are removed by PECO air purifiers?

flame

PECO air filters reduce or remove an extensive range of organic air pollutants. For PECO air purifiers to work, the pollutant must contain carbon. The hydroxyl free radicals in the catalytic chamber of the devices attack carbon-based molecular bonds, breaking them to create carbon dioxide and water. Here are some of the key air pollutants that PECO air purifiers eliminate:

  • Volatile organic chemicals (VOCs)
  • Nitrogen dioxide 
  • Ozone
  • Formaldehyde
  • Aldehydes
  • Olefins
  • Aromatics
  • Alkanes
  • PM1, PM2.5, and PM10 particulates
  • Cigarette smoke
  • Biological aerosols including viruses, bacteria, mold, and pollen
  • Pet dander and dust [1]

However, like PCO air purifiers, a PECO air cleaner cannot eliminate carbon monoxide (CO) or radon gas. 

PECO air purifier formats

PECO air purifier technology is only available from Molekule. The company currently produces Air Mini+, Air Pro, and Pūrgo™ air purifiers for consumer and professional use. Each PECO air purifier contains a HEPA pre-filter and PECO filter that must be replaced at least every six months. 

PCO vs PECO air purifier: What’s the difference?

PCO and PECO work in a very similar way to clean indoor air. But PECO air purifiers innovate the older PCO technology to make it more efficient. Here are five key differences between these two types of catalytic oxidation air cleaners

1. Photocatalysis

Though both types of air purifiers use UV-activated photocatalysis to break down air pollution, the PECO air purifier has an important enhancement. Goswami’s invention introduces an electrical current that increases the generation of free radicals in the catalytic chamber. The increased concentration of radicals makes the destruction of organic air pollutants thorough. 

PCO has the potential for incomplete conversion of pollutants, generating harmful intermediate chemicals like formaldehyde, carbon monoxide, and nitrogen dioxide. Studies of the performance of PCO have found variability of between 20% and 80% in the efficiency of pollutant destruction. 

2. Pollutants filtered

The efficiency of the photoelectric catalytic oxidation of a PECO air purifier makes it able to eliminate a wider range of pollutants than conventional PCO. Laboratory testing has found that PECO catalytic air filters can degrade nitrogen oxide and ozone in addition to the pollutants eliminated by  PCO. 

3. Potential hazards

PCO potentially generates hazardous intermediate chemicals due to the inconsistency of its oxidative action. This safety concern has been recognized by the Environmental Protection Agency and state air quality bodies like the California Air Resources Board (CARB).

If the oxidative breakdown of VOCs is incomplete, PCO air purifiers may release

  • Acetone
  • Ozone 
  • Acetaldehyde 
  • Nitrogen dioxide
  • Formaldehyde 
  • Carbon monoxide

Factors that increase the generation of these harmful intermediates in exhaust air include 

  1. The concentration of pollutants in the device’s intake air
  2. The suboptimal wavelength of UV light that doesn’t fully activate the catalyst
  3. UV-C light frequencies that can generate ozone

PECO air purifiers achieve efficient and consistent conversion of pollutants through enhanced free radical generation. The elevated concentration of radicals can even break down ozone and nitrogen dioxide. The California Air Resources Board has independently verified that PECO air purifiers do not release ozone in their exhaust air. 

4. Filters

PCO air purifiers are made by a range of manufacturers. Catalytic oxidation air purifiers. Currently, there is no nationally agreed efficiency standard or performance rating for them. The catalyst of PCO filters also has a finite lifespan. Adsorbent media can become saturated, causing pollutants to escape in exhaust air. 

PECO air purifiers use disposable PECO filters that are changed every six months to maintain the device’s performance. 

Closing thoughts

person at home

PECO is a refinement of PCO air cleaning technology. It improves the efficiency of PCO and addresses its potential hazards. Though evidence and standards for both types of air purifiers are limited, PECO has already been approved by the FDA and certified by the California Air Resources Board for its ozone-free performance. These considerations make PECO air purifiers the safer and more reliable solution for improving air quality in your indoor space.