PMI Titanium Dioxide (TiO2) Photocatalyst

PMITM nano titanium dioxide photocatalyst technology provides a new generation of environmental purification. The process of air purification called photocatalysis makes use of light and a photocatalyst to decompose and neutralize organic matter such as grime, biofilms, bacteria, viruses, mould VOCs (volatile organic compounds) and odours.

Environmental benefits of photocatalysis include:

  • Pollution Control
  • Self-cleaning Surfaces
  • Odour Elimination
  • IAQ Improvement
  • Sustainability Enhancement

Catalysis occurs when UV light (from sunlight or fluorescent lights) energizes titanium dioxide and triggers two chemical reactions that lead to the near instantaneous formation of hydroxyl radicals (OH*) and superoxide anions (O2-). These highly reactive chemical agents then instantly interact at the treated surface to accelerate the environmentally beneficial decomposition of all organic pollutants.


The OH radical is the most important oxidant in the troposphere, the lowest part of the atmosphere (below about10 km). Nobel Prize winner Paul Crutzen coined the phrase “detergent of the atmosphere” to describe this important cleansing role of OH.


PMITM titanium dioxide photocatalytic solution has been applied in MRT toilets throughout the North East Line in Singapore to improve sanitation standard, by killing germs and removing odours. The same technology has also been implemented in the air-conditioning cooling coils in the Khoo Teck Puat Hospital and Tan Tock Seng Hospital for air and surface sterilization and odour removal.

Why Choose PMI Titanium Dioxide (TiO2) Photocatalyst?

PMI Titanium Dioxide Photocatalyst™ has a proven track record around the world as an environmental cleaning technology. By harnessing the power of light, PMI cleans the air simply by reacting with pollutants. A tiny layer of PMI applied on wall surfaces clears the air of carcinogens, biological organisms (e.g. bacteria, viruses, algae, mould and fungi) and odour producing chemicals (e.g. ammonia, hydrogen sulphide). PMI also protects surfaces and inhibits mould and fungal growth. Indoor applications of PMI include hospitals, cooling coils, toilets, smoking rooms, locker rooms, canteens and rubbish bin centres.


The self-cleaning property of PMI, combined with its photocatalytic, pollution consuming abilities makes it an ideal coating for external building façade under polluting urban conditions. Dirt and grime which collect on building surfaces are disintegrated by PMI’s photocatalytic action. Sunshine and rain are all you need to keep external surfaces clean for extended periods of time.

Application of PMI TiO2 Photocatalyst
Application of PMI TiO2 Photocatalyst

E. Coli Bacterium under Microscope

Picture Source: Chemistry World

PMI TiO2 Photocatalyst not only kills bacteria, but also decomposes the cell itself.  Hydroxyl radicals generated by TiO2 photocatalyst are very potent oxidants. When irradiated TiO2 particles are in direct contact with or close to microbes, the microbial surface is the primary target of the initial oxidative attack. Polyunsaturated phospholipids are an integral component of the bacterial cell membrane, and the susceptibility of these compounds to attack by hydroxyl radicals has been well documented (Gutteridge JMC. “Lipid Peroxidation: Some Problems and Concepts”, 1987 & Kappus H. “Lipid Peroxidation: Mchanisms, Analysis, Enzymology and Biological Relevance”, 1987).

The loss of membrane structure and, therefore membrane functions is the root cause of microbe cell death when photocatalytic TiO2 particles are outside the cell. The toxin called endotoxin, produced at the end of cell death is also destroyed by photocatalytic action. Titanium dioxide does not deteriorate. It has a long-term anti-bacterial effect.

Deodourizing Effect

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PMI eliminates odours by generating hydroxyl radicals which accelerate the breakdown of any Volatile Organic Compounds or VOCs by destroying their molecular bonds. Hydroxyl radicals chop these bonds and cut the molecule into smaller compounds which are broken over and over until only carbon dioxide and water are left.

Examples of odour molecules include tobacco odour, garbage odour, formaldehyde, nitrogen dioxide and many other hydro carbon molecules in the atmosphere.

Air Purifying Effect

Picture Source: Fine Art America

The photocatalytic reactivity of PMI can be applied for the reduction or elimination of many harmful pollutants in the air such as nitrogen and sulphur oxides, carbon monoxide and benzene (one of many harmful constituents of cigarette smoke).  The by-products of the photocatalytic reaction vary depending on what substances are involved, but they are relatively benign. Nitrogen oxides are broken down into nitrates, while organic compounds are turned into carbon dioxide and water

In polluted urban environment, atmospheric constituents such as chlorofluorocarbons (CFCs) and CFC substitutes, greenhouse gases, and nitrogenous and sulfurous compounds are removed when they undergo photochemical reactions in the presence of sunlight. Paving blocks treated with TiO2 photocatalyst have been used in cities for such air cleaning purposes.

Self-Cleaning Effect

Most of the exterior walls of buildings become soiled from dust, grime and automotive exhaust fumes which contain oily components. If the building façade walls are coated with titanium dioxide, a protective film of photocatalyst on the wall surfaces provides a ‘self-cleaning’ effect. Sunlight provides the energy to initiate photocatalytic action to decompose and loosen dirt and grime deposited on the wall surfaces.


PMI TiO2 photocatalyst has an interesting super-hydrophilic property. When water comes into contact with a surface coated with PMI and irradiated with sunlight, the contact angle of the droplet of water decreases dramatically to close to zero degree. The treated surface’s affinity for water helps to spread rain drops into a thin film under the dirt. Together with the help of gravity, the dirt just slides down the wall surfaces. The hydrophilic property of PMI also helps to remove and prevent water marks and stains from forming on building surfaces since water always appear as a thin film. The view of the outside from the inside of a building will also be clearer on a rainy day as optical distortion from water droplets on a glass window has been eliminated.

Water Purification

Picture source: Samadoyo

PMI TiO2 Photocatalyst coupled with UV lights can oxidize organic pollutants into nontoxic materials such as CO2 and water and can destroy microbes and their toxins. Pilot projects have demonstrated that photocatalytic detoxification systems could effectively kill faecal coli form bacteria in secondary wastewater treatment.


The combination of sunlight and photocatalyst is a promising option for water treatment in areas with insufficient infrastructure but high yearly sunshine. The use of compound parabolic reactors as an efficient technology to collect and focus diffuse and direct solar radiation onto a transparent pipe containing contaminated water has demonstrated feasibility for water disinfection.