Scientific Explanation

For those want more technical information on what Morphic Envirotech’s units can do, we’ve put together this slightly more scientific explanation…

Indoor Air Quality

Indoor air quality (“IAQ”) has become a new branch of chemical and medical science directly related to the presence and accumulation of polluting volatile organic compounds (“VOC”s) and pathogenic and/or allergenic microbial or other particulate species (e.g., molds, bacteria, viruses, and pet dander).  The deterioration of indoor air quality is a direct consequence of increased energy efficiency (“conservation”) measures that restrict fresh air exchange together with the increased use of “synthetic” building, furnishing, solvents, and “cleaning” materials that off-gas VOC’s.  Furthermore, limited air exchange in a warm, humid environment is ideal for mold, bacterial, and viral growth.  Indoor air can be many times more polluted than outdoor air.  “Fresh” outdoor air, in industrialized countries, is affected by automotive exhaust and other “industrial” emissions, in addition to the “natural” loadings of odours, molds, bacteria, viruses, pollens, and animal emissions.

Photocatalysis and IAQ

Photocatalyst technology is receiving world-wide attention as an economic and immediate means of reducing urban air pollution from all sources.  Wide-area applications of photocatalysis are reported to reduce airborne nitrogen oxides (NOx’s) by up to 60% and volatile organic compounds (VOCs) by up to 80% in treated areas.1 A major source of urban air pollution is vehicular exhaust.2 Until there are major changes in automotive engineering and the driving habits of urban dwellers, this will not change (certainly not rapidly).  A 50% reduction in vehicular exhaust pollution is equivalent to an “effective” reduction in vehicular traffic of 50% (with the corresponding improvement in air quality).  With increasing vehicular traffic, urban air quality continues to deteriorate. 2(c)

“Photocatalysis” (the reverse of “photosynthesis” in green plants) is an electro-chemical phenomenon that utilizes ultraviolet light to remove/break-down NOx’s and VOCs (including odours).  These are major components of urban air pollution.  Photocatalysis was first developed and commercialized in Japan, but has been known for decades.  The Photoelectric Effect of light shining on a conductor surface causing emission of electrons was explained by Albert Einstein in the early 1900s.  Certain wavelengths of light shining on a semi-conductor surface can also free electrons from the surface to participate in pollution scavenging (free-radical scavenging).  Titanium dioxide, TiO2, is one such semi-conductor.  Among the many semi-conducting materials, TiO2, is most extensively used because it has the advantages of low cost, abundance, chemical inertness, ease of manufacture and processing, and excellent photocatalytic activity in the UV region of the electromagnetic spectrum.  Titanium is the eighth most abundant element in the earth’s crust.  Annual production of titanium dioxide is approximately 2 million tonnes, for use as a benign colourant in food, cosmetics, tooth paste, paint, paper, and plastics.  The World Health Organization and the US Environmental Protection Agency consider the toxicity and epidemiology of exposure to titanium dioxide to be minimal.4 There are no negative health concerns.

This process is commonly called photocatalytic “oxidation” or “PCO” even though both oxidation and reduction occur.  The efficiency of the PCO process is dependent upon (a) the wavelength and intensity of the UV light, (b) the surface area of semi-conductor exposed to the UV light, and (c) the crystal form of the semi-conductor (e.g., the “anatase” form of TiO2 works the best).

Air supplied to “environmentally sensitive” individuals is usually scrubbed with high efficiency particulate air (“HEPA”) filters in combination with VOC absorbers and/or chemical oxidizers.  These components become saturated or exhausted and are expensive to replace (sometimes as frequently as every two weeks).  A carefully designed photocatalytic reactor system can operate for one to two years with much less operator intervention and expense and equivalent or greater pathogen removal efficiency (both microbes and VOC’s).  In destructive “force”, PCO acts like a “lightning strike” on the “nano-scale”, i.e., devastating to both microbes and VOC’s.

Germicidal UV irradiation alone kills all microbes with sufficient time (dosage).  The lethal UV dosage is reduced (i.e., enhanced) by combination with PCO in a reactor.  VOC’s, on the other hand, require photocatalysis for rapid destruction.  Continuous circulation of indoor air through a PCO reactor will continuously reduce ambient levels of both microbes, VOC’s and many volatile inorganic chemicals (“VICs”).  The efficiency of air scrubbing is strong function of germicidal UV irradiation intensity and the “active”/exposed semiconductor surface area.

VOC’s susceptible to PCO destruction include:

  • Saturated hydrocarbons
  • Un-saturated hydrocarbons
  • Aromatic hydrocarbons
  • Alcohols
  • Aldehydes (including formaldehyde)
  • Ketones
  • Esters
  • Ethers
  • Carboxylic acids
  • Chlorocarbons
  • Amines (ammonia decomposes to N2 and O2, no NOx species)
  • Sulfur-containing materials (usually odoriferous)
  • Carbon monoxide
  • Phosphorous containing compounds (including “nerve” gases)
  • Other volatile halogen (fluorine, chlorine, bromine, and iodine) containing compounds

The limitation of PCO applicability is the susceptibility of the “polluting” or “contaminating” species to energetic (chemical-bond breaking) attack by free radicals.  Very few volatile chemical (and no living) species are immune to such attack.  PCO literally and economically provides a “breath of fresh air”.

MorphAir 36W™

The MorphAir 36W™ (the first unit from Morphic Envirotech) combines the efficiency of (a) MERV 14 (“near HEPA”) filtration, (b) ultraviolet germicidal irradiation (UVGI) provided by two 18 W UV-C lamps, and (c) photocatalysis of VOCs and VICs at the large irradiated surface area (182 sq. feet of photocatalyst-coated quartz wool fibers) of the permanent photocatalytic elements.

References

1.  Photocatalytic Coating on Road Pavements/Structures for NOx Abatement, Lamar University, December 12, 2005 (and references therein).  See http://files.harc.edu/Projects/JointCenter/Meetings/RR200512/ProjectPhotocatalyticCoating.pdf.
2. (a)  Unique project highlights effective ways to reduce vehicle emissions, CASA News Release – vehicle emissions study, October 12, 2006.
2. (b) Don’t Drive and Breathe, Bob Weinhold, Environmental Health Perspectives, V109, n.9, September, 2001.
2. (c) Understanding Air Pollution Near Urban Roadways: A Research Study, EPA research highlights, EM magazine, p. 30, December 2006.
3. See US Patent 6,602,918, Processes of producing a titanium oxide-forming solution and a dispersion with crystalline titanium oxide particles, Hiromichi Ichinose, August 5, 2003.
4. (a)    Titanium Dioxide: Inhalation Toxicology and Epidemiology, Paul M. Hext, John A. Tomenson, and Peter Thompson, Annals of Occupational Hygiene, March 24, 2005, 49(6), 461-472.
4. (b)    Titanium Dioxide: Exemption from the Requirements of a Tolerance, U.S. Environmental Protection Agency, March 25, 1998.