Frequently Asked Question

Photocatalyst is the branch of chemistry concerned with the chemical effects of light. Generally, this term is used to describe a chemical reaction caused by absorption of ultraviolet (wavelength from 100 to 400 nm), visible light (400 – 750 nm) or infrared radiation (750 – 2500 nm). A catalyst does not change in itself or being consumed in the overall chemical reaction. This definition includes photosensitization, a process by which a photochemical alteration occurs in one molecular entity as a result of initial absorption of radiation by another molecular entity called the photosensitized.

There are various materials that show photocatalytic capability, and titanium dioxide (TiO2) is said to be the most effective.

When photocatalyst is exposed to light in the presence of water vapor, two highly reactive substances are formed: hydroxyl radicals [OH] and a superoxide anion [O2-1]. It allows the oxidation of airborne VOCs and toxic organic matter into carbon dioxide and water at room temperature with light source. It does not need a special energy and use only clean energy in ordinary life. Specific titanium dioxide has strong photo catalyst reaction. It has strong oxidation and decomposition strength.

A promising approach for remediating volatile organic compounds or VOCs is to employ photocatalyst that oxidize these compounds. It is a substance that facilitates chemical reactions by photo-irradiation without becoming transformed:

Toxic VOC + Light + Water + Photocatalyst = Non-Toxic inorganic Gas + Photocatalyst

Photocatalyst has the following advantages over any current air/water purification technologies:

• Real destruction of pollutant rather than a simple transfer on a substrate
• Degradation of pollutant at ambient temperature and pressure
• Build with easily available materials and by mean of well-known techniques
• Economical, cheap and low energy consumption
• Adapted for a large range of pollutant (VOC, bacteria, mold)

Titanium dioxide, also known as titanium, is the naturally occurring oxide of titanium, chemical formula TiO2.Approved by the food testing laboratory of the United States Food and Drug Administration (FDA), Titanium Dioxide is considered a safe substance and harmless to human. It is commonly used in paint, printing ink, plastics, paper, synthetic fibers, rubber, condensers, painting colors and crayons, ceramics, electronic components along with food and cosmetics. Many studies have been published on the use of titanium dioxide as a photocatalyst for the decomposition of organic compounds. After illuminated by light, titanium dioxide produces hydroxyl radicals, which react with the organic matters in the air to form non-toxic inorganic matters.

We succeeded in finding a novel phenomenon on the photocatalyst. That is, when the surface of photocatalytic film is exposed to light, the contact angle of the photocatalyst surface with water is reduced gradually. After enough exposure to light, the surface reaches super-hydrophilicity. In other words, it does not repel water at all, so the water cannot exist in the shape of a drop, but spreads flatly on the surface of photocatalyst. The photo-catalytic super-hydrophilicity is important technology, because it has wider applications, including anti-fogging, self-cleaning properties, sterilization, deodorization, antifouling and removal of pollutants can be achieved.

UV rays are part of sunlight and fluorescent light, no special operating costs are required and the reaction can be maintained semi-permanently. Moreover, Green Millennium’s photocatalyst contains no volatile organic compound (VOC) and neutral pH. This supports government’s Green House theory to help create a safe, low emission of VOC, and energy saving house.

Hydroxyl radicals are among the strongest oxidizing species, even much stronger than chlorine, ozone, and peroxide. They act as very powerful disinfecting agents by oxidizing the cells of microorganisms, causing rupture and leakage of vital composition.

Deodorizing.
On the deodorizing application, the hydroxyl radicals accelerate the breakdown of any Volatile Organic Compounds or VOCs by destroying the molecular bonds. This will help combine the organic gases to form a single molecule that is not harmful to humans thus enhance the air cleaning efficiency.  Some of the examples of odor molecules are: Tobacco odor, formaldehyde, nitrogen dioxide, urine and fecal odor, gasoline, and many other hydrocarbon molecules in the atmosphere

Sterilization, Anti-Bacterial and Mold Preventing
Nano photocatalyst titanium dioxide has strong oxidation affects to single-celled organism that includes all bacteria and fungus. The very strong oxidizing power of Titanium Dioxide can destroy bacteria’s cell membrane, causing leakage of the cytoplasm, which inhibits bacteria’s activity and ultimately results in the death and decomposition of bacteria. Generally speaking, disinfections by titanium oxide is three times stronger than chlorination, and 1.5 times stronger than ozonation.

Although it is originally water-soluble, it dries quickly after application and becomes water-insoluble. It also becomes as hard as a 4H pencil in ten to fourteen days after application. It does not come off unless the surface is polished. Even a bathroom can be used immediately after application. Because titanium oxide is merely the catalyst and is not changed, its effect is semi-permanent except when walls and ceilings are repainted.

Since photocatalyst TiO2 is only acting as semi-conductor catalyst, it is not consumed during the oxidation process, therefore, completing a long lasting oxidation cycle. Green Millennium is now offering a five years limited product warranty.

Yes, it will be harmless of direct touching the material or having direct contact with it after the coating is dried. The material is totally safe and the titanium dioxide used is FDA approved (refer to EPA certified toxicity lab report).

• Acute Oral Toxicity in Mice
• Microbiological Mutagencity Test
• Primary Toxicity Test Report
• EPA Toxicity Test Report

Green Millennium provides photocatalyst surface coating for long-lasting effects of deodorization, sterilization, and anti-soiling purposes. Using our specialized spray-coating equipments, a fine mist of photocatalyst can be applied on different types of surface material that guarantees the maximum result.

HEPA (High Efficiency Particle Arresting) Filter
Most widely known method for purifying air. Depending on the filter size, it can clean up to 99.99% of particulate in the air with proper ventilation. They are not effective on treating mold, mildew, bacteria, and other fungi.

Electrostatic Filtration
Another filtration system with a negatively charged surface is used to attract particulate. In comparison to most HEPA systems it is more effective in trapping smaller micron particulate and effective in clearing smoke from the air. Low levels of ozone may be produced which can neutralize most mold, mildew, bacteria, and other fungi that comes in contact with the filter.

Ionization
Also uses a negatively charged surface to produce and expels an abundance of negative ions and cause suspended particles to cling to walls, floors, and other surfaces . Most ionizers are effective in settling dust and particulate out of our breathing space.

Ozone
Ozone is a very powerful oxidizer that will neutralize odors, mold, mildew, bacteria, and other fungi. This technology is commonly used in flood and fire restoration. Ozone is found to be effective because it works on the problem at the source and air does not have to be pulled through the unit for treatment.

UV Germicidal Lamps
Commonly used for disinfecting purposes. This technology is effective in sterilizing air and surfaces that come in contact with the UV light. UV has been proven in both air and water applications to inactivate bacteria and viruses to prevent them from reproducing.

Photocatalysis
Using light to react with a catalyst resulting in oxidation. This is found to be effective in destroying mold, mildew, bacteria, other fungi, dust mites, and many odors. This technology is produced with an Ozone/UV lamp set in a variety of combinations. When this type of photocatalysis is combined with the natural humidity in indoor air it creates hydroxyl radicals and super oxide ions that are effective in combating bacteria, fungi and VOC. This method is also a pro-active approach that goes to the source for treatment.

After being dry, photocatalyst forms a very solid film that can’t be wiped off unless strong cleaning chemicals are used.

Light and airflow will have a remarkable influence over the reaction of the photocatalyst. Both factors are needed to maintain the coating effectiveness all the time. From that, the better airflow you have (air circulation which can be obtained by using an ordinary fan or the normal air movement from air conditioner ducts) and the longer light times, the better the results of coating will be achieved.

Research indicates that people spend approximately 80 ~ 90 percent of their time indoors, where they are exposed to polluted indoor air that may cause irritation of the eyes, nose, and throat, headaches, dizziness, fatigue, and even lung cancer or other malignancies. Recent study reveals that bacteria, molds and house dust mites bred inside carpets and air conditioners can be airborne by dust particles, paints, varnishes, harmful chemical fibers and pressed wood products, which are most commonly used in household decoration, may emit formaldehyde, benzene and other hazardous and carcinogenic organic chemicals — all these as well as unwholesome matters produced in the metabolism of human bodies and ammonia inside toilets have made the air within homes and other buildings more seriously polluted than the outdoor air.

People may experience one or more of the following reactions when exposed to indoor air pollution:

Allergic Reactions
Some common signs and symptoms are:

• Watery eyes
• Runny nose and sneezing
• Nasal congestion
• Itching
• Coughing
• Wheezing and difficulty breathing
• Headaches
• Fatigue

Infectious Reactions
Caused by bacteria and viruses, such as influenza, measles, chicken pox, and tuberculosis. Most infectious diseases pass from person to person through physical contact. Crowded conditions with poor air circulation can promote this spread. Some bacteria and viruses thrive in buildings and circulate through indoor ventilation systems.

Toxic Reactions
Some fungi are known to produce toxic substances as a by-product of their metabolism, which can cause a variety of adverse health effects. Short-term symptoms can include dermatitis, respiratory irritation, headaches and fatigue. Long-term health effects can include cancer, damage to the central nervous system, and suppression of the immune system.

The U.S. Environmental Protection Agency ranks poor indoor air quality among the top five environmental risks to public health. Poor indoor air quality can cause or contribute to the development of chronic respiratory diseases such as asthma and hypersensitivity pneumonitis. In addition, it can cause headaches, dry eyes, nasal congestion, nausea and fatigue. People who already have respiratory diseases are at greater risk.

The following have been cited causes of or contributing factors to sick building syndrome:

• Inadequate ventilation
  In an effort to achieve acceptable Indoor Air Quality or IAQ while minimizing energy consumption, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recently revised its ventilation standard to provide a minimum of 15 cfm of outdoor air per person (20 cfm/person in office spaces). Up to 60 cfm/person may be required in some spaces (such as smoking lounges) depending on the activities that normally occur in that space.
• Chemical contaminants from indoors sources
  Most indoor air pollution comes from sources inside the building. For example, adhesives, carpeting, upholstery, manufactured wood products, copy machines, pesticides, and cleaning agents may emit volatile organic compounds (VOCs), including formaldehyde. Environmental tobacco smoke contributes high levels of VOCs, other toxic compounds, and respirable particulate matter. Research shows that some VOCs can cause chronic and acute health effects at high concentrations, and some are known carcinogens. Low to moderate levels of multiple VOCs may also produce acute reactions. Combustion products such as carbon monoxide, nitrogen dioxide, as well as respirable particles, can come from unvented kerosene and gas space heaters, woodstoves, fireplaces and gas stoves.
• Chemical contaminants from outdoor sources
  The outdoor air that enters a building can be a source of indoor air pollution. For example, pollutants from motor vehicle exhausts; plumbing vents, and building exhausts (e.g., bathrooms and kitchens) can enter the building through poorly located air intake vents, windows, and other openings. In addition, combustion products can enter a building from a nearby garage.
• Biological contaminants
  Bacteria, molds, pollen, and viruses are types of biological contaminants. These contaminants may breed in stagnant water that has accumulated in ducts, humidifiers and drain pans, or where water has collected on ceiling tiles, carpeting, or insulation. Physical symptoms related to biological contamination include cough, chest tightness, fever, chills, muscle aches, and allergic responses such as mucous membrane irritation and upper respiratory congestion.