Benefits and Applications of Photocatalytic Oxidation Coatings

Transcription

1 Provider Number: K244 Benefits and Applications of Photocatalytic Oxidation Coatings Course Number: K244-AIACESK24401 April 6th, 2016

2 Presented by: New England distributor of Agrob Buchtal Ceramics. Architectural Sales since 1984, specializing in terracotta ceramic rainscreens, marble & granite facades, and Division 4 Masonry. In New England since LEARNING OBJECTIVES: 1. Understand chemisty & physics of photocatalytic oxidation coatings on ceramic facade surfaces, exterior & interior. 2. Understand how titanium dioxide POC facilitates self-cleaning through hydrophylic tile effect. 3. Understand how POC on tile surface improves exterior & interior air quality through pollution degradation.

3 Credit(s) earned on completion of this course will be reported to AIA CES for AIA members. Certificates of Completion for both AIA members and non-aia members are available upon request. This course is registered with AIA CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.

4 Copyright Materials This presentation is protected by US and International Copyright laws. Reproduction, distribution, display and use of the presentation without written permission of the speaker is prohibited. DSA, Inc. 2015

5 Course Description This course provides an overview of photocatalytic oxidation coatings and includes discussions on the chemistry behind the reaction, properties of photocatalytic oxidizers (PCOs), air quality, and the benefits and applications of photocatalytic oxidation coatings.

6 Learning Objectives At the end of the this course, participants will be able to: 1.Summarize the chemical process of photocatalytic oxidation and state how this process contributes to keeping surfaces clean and microbe free 2. List the properties of PCOs and the environmental and economic factors associated with each property 3. Explain how photocatalytic oxidation contributes to enhanced air quality in terms of odor and VOC decomposition, and NO x removal 4. Identify the applications and environmental benefits of using PCOs in order to specify them for appropriate projects.

7 Photocatalytic Oxidation

8 Photocatalytic Oxidation Environment and Health Issues Environmental issues facing today s population include: Maintaining healthy environments Pollutants from industry and vehicles Poor indoor air quality Contracting infections from health service areas Creating an environmentally-friendly workplace

9 Photocatalytic Oxidation Environment and Health Issues Due to the increasing human population, more areas are becoming increasingly urbanized, which leads to increased pollution caused by industries and fossil fuel-burning vehicles. The increasing population also needs housing, which requires materials manufactured and constructed with products that emit harmful vapors and fumes. Along with the increasing human population, viruses and bacteria can spread more rapidly and be widespread. Hospitals and assisted living facilities have been struggling to control nosocomial infections (infections that are a result of treatment in a hospital or a healthcare service unit), which cost the healthcare community in the U.S. alone millions of dollars annually. Cleaning and maintaining surfaces is very costly for businesses and individuals and increases over time.

10 Photocatalytic Oxidation The Solution Photocatalytic oxidizing nano-sized coatings which, along with light and water, have ability to keep surfaces clean and microbe-free. What is photocatalytic oxidation? Photocatalytic oxidation can be described as the event of using light as a catalyst to create superoxide and hydroxyl radicals from oxygen and water (air humidity). Semiconductor metals, such as TiO2 (titanium dioxide) in nano-sized particles, use light and water as catalysts to activate movement of electrons, freeing them for secondary reactions with harmful microbes and organic compounds such as those found in VOCs, fossil fuel emissions, and bioaerosols. Titanium dioxide molecules are a form of nanotechnology. Due to this small size, titanium dioxide can be easily mixed and bonded with paints, glazes, and surface pores on various building materials, making it functional and commercially viable.

11 Photocatalytic Oxidation How Small is a Nano? A nanometer is one billionth of a meter. Photocatalytic oxidation nano particles are about 10 nanometers in length. How does that size compare to other microscopic items? A pinhead has a diameter of one to two millimeters A dust mite has a length around 200 micrometers Red blood cells have a diameter of 7-8 micrometers DNA strands have a diameter of just over two nanometer

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13 Photocatalytic Oxidation Photocatalytic Oxidation Explained Reviewing the concept graphically (animation on a following slide), we find a molecule of a titanium dioxide nano particle has a band gap energy of 3.2 electron volts between its valence band and its conduction band. When the titanium dioxide nano particle is eradiated with light photons of <385 nanometers, the band gap energy is exceeded and an electron is promoted from the valence band to the conduction band. The resultant electron-hole pair has a lifetime in the space charged region that enables its participation in chemical reactions. These chemical reactions include the formation of superoxide ions, caused by the combination of the free election and oxygen found in the air, and the formation of hydroxl radicals caused by the loss of a hydrogen electron from water found in the air.

14 Photocatalytic Oxidation Photocatalytic Oxidation Explained Hydroxl radicals and superoxide ions are highly reactive species that will oxidize volatile organic compounds and pollutants absorbed on the catalyst s surface into primarily carbon dioxide, water, and inert materials. They will also kill and decompose absorbed bioaerosols, making the process a strong candidate for indoor air quality applications. Additionally, hydroxl radicals have a high oxidation potential, meaning it takes less of an effort to donate an electron to microbes and volatile organic compounds, thereby speeding their decomposition. The oxidation potential of hydroxl radicals is much greater than the common disinfectant, chlorine.

15 Photocatalytic Oxidation Oxidation Super Oxide (O 2 -) O 2 CB e - TiO 2 VB 3.2 ev h+ H 2 O Ref.: Hoffmann et al., Chem. Rev., 95, 69 (1995); Mills et al.,j. Photochem.Photobiol.A Chem.,108,1(1997) Blake et al., Sep. Purif.methods, 28, 1(1999) Photo Oxidation Hydroxyl Radical (OH - ) + H 2 O CO 2

16 Properties of Photocatalytic Oxidizers (PCOs)

17 Properties of Photocatalytic Oxidizers (PCOs) Properties of PCOs Surfaces coated with PCOs display the following properties: Anti-microbial Self-cleaning Deodorizing

18 Properties of Photocatalytic Oxidizers (PCOs) Properties of PCOs Anti-Microbial When photocatalytic oxidizers are activated with light, treated surfaces display properties that are both environmentally-friendly and cost-beneficial. Surfaces become antimicrobial. Treated surfaces remove volatile organic compounds, disengaging bioaerosols. Self-Cleaning Treated surfaces create a superhydrophilic surface that allows water to separate dirt, stains, and other foreign particles from the surface, minimizing cleaning time. Deodorizing Odors are caused by bacteria and other microbes; treated surfaces provide natural deodorizing properties by decomposing the microbes as they come in contact with the PCO treated surface.

19 Properties of Photocatalytic Oxidizers (PCOs) Anti-Microbial Properties Comparison of Common Disinfection Methods to Photocatalytic Oxidation Common Disinfection Methods Use toxic chemicals such as Chlorine Cl2 Can result in re-growth of harmful microbes By-products are toxic to humans Some methods can interfere with humans Photocatalytic Oxidation Methods Use no toxic chemicals Deactivate and prevent the re-growth microbes By-products are non-toxic to humans High redox potential doesn t interfere with humans Create environment for healthy living

20 Properties of Photocatalytic Oxidizers (PCOs) Anti-Microbial Properties Comparison of Common Disinfection Methods to Photocatalytic Oxidation To demonstrate the effectiveness of PCOs as an anti-microbial treatment, we can compare PCOs to common disinfection methods many of us use to control microbes such as viruses, bacteria, molds, mildews, and algae. Common disinfection methods include the use of chlorine, which is toxic not only to microbes, but also to animals and plants. Although disinfectants are effective in deactivating microbes, the results are not permanent. Microbes that are not deactivated will again multiply when disinfectants are no longer present. Most disinfectants are also, by their very nature, potentially harmful and even toxic to humans or animals. Because disinfectants are designed to kill, they have great potential to cause DNA damage to animal cells or possibly mutations.

21 Properties of Photocatalytic Oxidizers (PCOs) Anti-Microbial Properties Comparison of Common Disinfection Methods to Photocatalytic Oxidation The PCO methods greatly reduce harmful effects to the environment, humans, and animals. PCOs do not use toxic chemical. Products found in PCOs, such as titanium dioxide are also used in common everyday products such as cosmetics and toothpaste. PCOs provide a continual deactivation of microbes on their surfaces; all microbes are deactivated so they cannot re-establish colonies. Because the by-products of PCOs are primarily carbon dioxide, water, and inert materials, they are not toxic to humans or animals. Unlike other disinfection methods, PCOs high redox potential doesn t interfere with human or animal cells. Because they do not produce vapors or fumes, like some common disinfectants, PCOs create a healthier, safer environment.

22 Properties of Photocatalytic Oxidizers (PCOs) Decomposition of Bacteria Decomposition of Bacteria Cells Using Photocatalyst Oxidizers Lab tests indicate the effects that PCO-coated surfaces have on bacteria. E. Coli (escherichia coli) and MRSA (Mersa), the bacteria responsible for secondary staph infections, were applied to PCO-coated ceramic tiles, as well as uncoated ceramic tiles, and were placed under a light source for 24 hours. Results of the test show a high cell count remaining for both types of bacteria on the uncoated surfaces. In contrast, the coated surfaces show bacteria cell counts were reduced to virtually nil. The chart on the following slide illustrates the results of the test.

23 Properties of Photocatalytic Oxidizers (PCOs) Decomposition of Bacteria Decomposition of Bacteria Cells Using Photocatalyst Oxidizers Live bacteria test result on PCO-coated tile, illumination based on an overcast day: Type of Bacteria Material Immediately after illumination (cells/ml) +24 hrs (Group 1) +24 hrs (Group 2) Average E. Coli Coated 3.5 X 10 5 < 10 < 10 < 10 E. Coli Uncoated 3.5 X X X X 10 6 MRSA Coated 3.5 X 10 5 < 10 < 10 < 10 MRSA Uncoated 3.5 X X X X 10 4 Bacteria Decomposition Test - Kyoto Microorganism Research Center, Japan

24 Properties of Photocatalytic Oxidizers (PCOs) Decomposition of Bacteria Bacterial Decomposition on PCO-coated Tiles Additional bacteria and viruses were tested on PCO-coated tiles with the same positive results. When examining images on the following slide, the photos on the left of each picture show the results of coated tiles after 25 minutes of light exposure. The photos on the right of each picture show the results of the uncoated tiles after the same time period.

25 Properties of Photocatalytic Oxidizers (PCOs) Bacterial Decomposition on PCO-coated Tiles

26 Properties of Photocatalytic Oxidizers (PCOs) Properties of Photocatalytic Oxidizers (PCOs) Decomposition of a Bacteria Cell How do PCOs deactivate bacteria and virus cells? PCOs deactivate cells by attacking the cell walls which are composed of sugar molecules, and converting those molecules into carbon dioxide and water. Once the cell wall is compromised, the interior of the cell, the cytoplasm, leaks from the cell rendering it inactive.

27 Properties of Photocatalytic Oxidizers (PCOs) Real-World Surgery Room Results Tests have been performed in real surgery rooms treated with photocatalytic oxidizers on the floors and walls. Samples of bacteria on the walls and floor, as well as airborne samples, were taken in a surgery room prior to the application of PCOs. Both bacteria counts were at a high rate prior to application, but dropped drastically after the installation of PCOs to the walls and floor.

28 Properties of Photocatalytic Oxidizers (PCOs) Oxidizers (PCOs) Real-World Surgery Room Results Bacteria on and Floor Walls CFU (ml) Time (months) Air-borne Bacteria CFU (ml) *CFU = Colony Forming Unit Time (months)

29 Properties of Photocatalytic Oxidizers (PCOs) Effectiveness Tests eight- Tests have been conducted to show how PCOs decompose existing molds. This week test was conducted on existing mold on the side of a building. As time progresses, the mold is decomposed and is washed away by rain water. After 1 week Initial After 3 weeks After 8 weeks Test Showing the Decomposition of Existing Mold

30 Properties of Photocatalytic Oxidizers (PCOs) Effectiveness Tests Another test performed on organic dye applied to PCO-treated tiles shows how effective PCOs are within a short period of time. After 3 minutes Initial After 5 minutes After 10 minutes Test Showing the Decomposition of Organic Red Ink Exposed to Light Irradiation

31 Self-Cleaning Properties

32 Self-Cleaning Properties Superhydrophilic Properties Another added benefit that PCOs produce is the ability to make surfaces superhydrophilic. Water tends to bead on conventional surfaces. When this happens, beaded water may not drain from the surface, and the standing water collects pollutants. When the water dries, the pollutants remain, leaving dirty spots on the surface. On PCO-treated surfaces, the surface becomes superhydrophilic, meaning that water does not bead, but creates a thin sheet of water that floats across the treated surface. As the water sheet flows, it lifts dirt from the surface, resulting in a clean surface. Oil and grease detach from the surface.

33 Self-Cleaning Properties Superhydrophilic Properties Properties Conventional Surfaces Water drops form and dirt is left on the surface after drying. Treated Surfaces The water spreads as a thin film on the surface and lifts dirt from the surface resulting in a clean surface.

34 Self-Cleaning Properties Superhydrophilic Properties Looking at the surface from a profile perspective, we can see that the PCO allows water to flow under dirt, lifting it away from the surface along with the water to drain. Photocatalytic Oxidation Coating Surface

35 Self-Cleaning Properties Superhydrophilic Properties Photocatalytic oxidizers also work well on glass and mirrors; when water condenses on glass, it forms tiny drops or fog that makes the surface difficult to see through; with the superhydrophilic properties of PCOs, the glass remains fog-free.

36 Air Quality

37 Air Quality Indoor Air Quality (IAQ) Causes of Indoor Air Problems Indoor pollution sources that release gases or particles into the air are the primary cause of indoor air quality problems in buildings. Inadequate ventilation can increase indoor pollutant levels by not bringing in enough outdoor air to dilute emissions from indoor sources, and by not carrying indoor air pollutants out of a building. High temperature and humidity levels can also increase concentrations of some pollutants.

38 Air Quality Quality Indoor Air Quality (IAQ) Sources of Indoor Pollutants There are many sources of indoor air pollution in any building. These include combustion sources such as: oil, gas, wood, tobacco products, building materials and furnishings, asbestoscontaining insulation, wet or damp carpet, cabinetry or furniture made of certain pressed wood products, products for household cleaning and maintenance, personal care products, materials used for hobbies, central heating and cooling systems, humidification devices, and outdoor air pollution.

39 Air Quality Indoor Air Quality (IAQ) Sources of Indoor Pollutants Volatile organic compounds or VOCs, from sources such as building materials and furnishings, release pollutants continuously. Other sources, related to activities carried out in the home, release pollutants intermittently, such as: smoking; the use of unvented or malfunctioning stoves, furnaces or space heaters; paint and paint strippers; and the use of cleaning products and pesticides in housekeeping. VOC concentrations can remain in the air for long periods after some of these activities.

40 Air Quality Indoor Air Quality (IAQ) Health Effects Health effects from indoor air pollutants may be experienced soon after exposure or possibly years later. Immediate effects may show up after single exposure or repeated exposures. These effects may include irritation of the eyes, nose, and throat; headaches; dizziness; and fatigue. Such immediate effects are usually short-term and treatable. Sometimes the treatment is simply eliminating the person s exposure to the source of the pollution, if it can be identified. Symptoms of diseases, including asthma, may also show up soon after exposure to some indoor air pollutants.

41 Air Quality Indoor Air Quality (IAQ) Health Effects Other health effects may show up either years after exposure has occurred, or only after long or repeated periods of exposure. These effects, which include some respiratory diseases, heart disease, and cancer, can be severely debilitating or fatal. It is prudent to try to improve the indoor air quality in a building, even if symptoms are not noticeable, as it is one of the top five health concerns in the U.S. according to the Environmental Protection Agency.

42 Air Quality irqu Odor/VOC Decomposition Rates Tests on odor and VOC decomposition rates further show photocatalytic oxidizing. The following common VOCs or tested for decomposition on a PCO-treated surface: the effectiveness of odor-causing chemicals were Ammonia is completely reduced to nitrogen and water over a period of 90 minutes Ethylene is completely reduced to carbon dioxide and water over a period of 160 minutes Formaldehyde is completely reduced to carbon dioxide and water over a period of 90 minutes Vegetable Oil Odor is completely reduced to zero over a period of 10 hours

43 Air Quality Odor/VOC Decomposition Rates Ammonia 100 Ethylene Conc. (ppm) 150 Coated Time (min) 2NH3+1.5O2 N2+3H2O CH2=CH2+6O2 4CO2+4H2O Formaldehyde Coated Uncoated Time (min) 400 Uncoated Conc. (ppm) Coated Uncoated Vegetable Oil Conc. (ppm) Time (min) CoverageofVeg.Oil Time (hr) HCHO+O2 CO2+H2O

44 Air Quality NO x Removal NO x is the generic name for a group of highly reactive gases that contain varying amounts of nitrogen oxide (NO) and nitrogen dioxide (NO 2 ) and are colorless and odorless. The major sources of NO x are motor vehicles, electric utilities, and industrial, commercial, and residential combustion emissions.

45 Air Quality r Quality NO x Removal When NO x and volatile organic compounds react in the presence of sunlight, they form photochemical smog, a significant form of air pollution, especially in the summer. Children, people with lung diseases such as asthma, and people who work or exercise outside, are susceptible to the adverse effects of smog, such as damage to lung tissue and reduction in lung function. Photocatalytic oxidizers degrade NO x on the surface, leaving the surface clean.

46 Air Quality NO x Elimination Effectiveness Test Testing of a photocatalytic oxidizer was performed on a pre-cast building panel in an urbanized area. The right side of the panel was treated once with a PCO, while the left side remained untreated. After a four-year test period, the right side of the test panel remains clean of pollutants, while the left side has become tainted with pollutants from industry and vehicular emissions. Initial condition After 4 years of exposure, the treated side remains clean

47 Air Quality irq NO x Elimination The process by which PCOs eliminate NO x can be air. A treated surface area of 10,000 square feet equivalent to 70 deciduous trees. compared has an air to how trees clean our purification capability

48 Applications and Benefits

49 Applications and Benefits PCOs Installed Directly Into Product Photocatalytic oxidizers can be installed directly into products during the manufacturing process. Currently, PCOs can be applied to ceramic tiles using this method. With this process, the lifespan of the PCO is as long as the lifespan of the tile.

50 Applications and Benefits Applications and Benefits PCOs Installed Onto Product Photocatalytic oxidizers can be installed onto the product after the manufacturing process. PCOs that cannot be installed into products during the manufacturing process may be installed using different techniques, such as spraying and dipping methods. With these processes, the lifespan of the PCO will be temporary, and must be reapplied periodically.

51 Applications and Benefits Applications and Benefits Overview of Properties of PCOs Air Purification Anti-fogging Photocatalytic Oxidizer Surfaces Self- Cleaning Antimicrobial Odor Removal

52 Applications and Benefits Advantages of PCOs on Tiles Decomposition of bacteria, fungi, algae, Elimination of odors Improvement of room air quality moss and germs The original characteristics of the tile, such as resistance to abrasion, resistance to chemicals, etc., are maintained Requires only minimum care Low cleaning costs Free of irritating substances, Environmentally friendly Long-term guarantee Varied range of products non-toxic

53 Applications and Benefits Applications for PCOs on Tiles Now that the properties of the photocatalytic oxidizers have been reviewed, where can they be applied? Proven application locations for PCOs include these areas: Health and healthcare areas such as hospitals, assisted living facilities, and medical office buildings Transportation and the public sector such as airports, mass transit stations, and tunnels Fitness and wellness areas such as pools, spas, and saunas Building facades including rain screens Shopping and business areas including shopping malls and office buildings Residences in kitchens and baths Application locations of PCOs are virtually unlimited.

54 Applications and Benefits Applications for PCOs on Tiles Catering Trade and Food Processing In kitchens, restaurants, and cafeterias, a hygienic environment can be ensured by the use of PCO-coated tiles, thereby making an odor-free, healthy working environment. Planners and architects can ensure these standards are met by specifying PCO-coated tiles. Medical Areas Absolute hygiene is of utmost importance in hospitals, clinics, doctors practices, operating rooms, and nursing homes. The antibacterial properties of PCO-coated tiles are significant. Germs, bacteria and fungi are decomposed, and the risk of infections in surgical rooms and hospital rooms is reduced.

55 Applications and Benefits Applications for PCOs on Tiles Swimming Pools and Wellness Areas Sports and leisure facilities, pools, fitness centers, whirlpools or Finnish saunas: workout and relaxation are only fun in a clean environment. In all these areas, PCOcoated tiles are essential in every respect. Surfaces are easy to clean, and use of cleaning agents can be restricted, thereby reducing maintenance costs and helping preserve the environment. Reception Areas The first impression is decisive. No matter whether in showrooms, foyers, or in other reception areas, PCO-coated tiles ensure a first-class atmosphere. Ease of maintenance ensures these sophisticated premises are kept appropriately.

56 Applications and Benefits pplatosanee Applications for PCOs on Tiles Facades The photocatalytic oxidation effect has proven to be particularly effective in rain screen cladding projects. Sunlight ensures a particularly intensive photcatalytic reaction. The anti-microbial surface helps decompose algae, fungi and moss. Rain lifts dirt and impurities from the surface. As opposed to normal cladding materials, where maintenance costs increase with time and appearance wears, PCO-coated products ensure an ageless appearance and long-term minimum maintenance. Restrooms With PCO-coated materials, the typical disagreeable odors in sanitary facilities are a thing of the past because the microbes causing the odor are decomposed quickly and thoroughly. The result: perfect cleanliness and fresh air in sanitary areas.

57 Applications and Benefits General Applications for PCOs Because photocatalytic oxidizers act as a UV protectant, they may be applied to exterior surfaces such as paint, concrete, glass, roofs, stone, wood, plastic, metal, and water features. They may be applied to interior surfaces such as walls, tile, fabrics, mirrors, kitchen, and bathrooms. PCOs can be used on the interior of cars; they help keep them odor-free.

58 Summary

59 Summary Key environmental issues facing today s population include: maintaining healthy environments, pollutants from industry and vehicles, poor indoor air quality, contracting infections from health service areas, and creating an environmentallyfriendly workplace. Photocatalytic oxidation addresses these issues. Photocatalytic oxidation can be described as the event of using light as a catalyst to create superoxide and hydroxyl radicals from oxygen and water (air humidity). PCO-treated surfaces are anti-microbial, remove odors, are self-cleaning and airpurifying, and anti-fogging. Advantages of using PCO-treated tiles include: the decomposition of bacteria, fungi, algae, moss and germs; elimination of odor; improvement of room air quality; low cleaning costs; and minimal care requirements.

60 This concludes The American Institute of Architects Continuing Education Systems Course