Computer 10: Lesson 10 - Online Crimes and Hazards
Action photo catalyst
1. ACtion Photocatalytic Coating
Information Manual
Overview
Tio2 Photoctalysis is internationally recognised as one of the most effective materials which can kill almost all
kinds of bacteria including flu and SARS. It has been widely used in the sterilisation of hospitals, institutions,
schools etc. The PROtect ACtion photocatalyst coating, kills almost all kinds of bacteria under the irradiation of
light, which can be maintained long enough to thoroughly decompose bacteria, its cell body and the residual
exdotoxin. Meanwhile the photocatalyst can wipe out indoor allergen and reduce the incidence of respiratory
deseases.
Sterilization Mechanisms of ACtion Photocatalyst
Titanium Dioxide itself has no toxicity, its sterilization function activates after the irradiation of UV light.
When exposed to light, the very strong oxidising power of Titanium Dioxide can destroy the bacteria’s’ cell wall
and membrane and react with the cell components inhibiting growth and ultimately killing and decomposing
the cell structure.
Sterilization by Tio2 photocatalyst presents the following 2 biochemical
mechanisms.
Direct Photocatalysis
The electron-hole can directly react with a cell wall cell membrane and cell component in the sterilizing
process of mycrozymes and bacilli, the CoA inside the cell oxidizes which causes the respiration of the cell to
stop and finally in its death. During this process, the electron shift between the dead cell and Tio2 is passed by
CoA, therefore the content of CoA decreases and CoA dimer increases.
Indirect Sterilization Reaction
When and electron hole dissolves in water it generate Active Oxygen such as Hydroxile Radical. The electronic
structure of Titanium Dioxide is characterised by filled valence band(VB) and an empty conduction band (CB).
The band gap energy is excited and an electron is promoted from the valence band (VB) to the conduction
+
band (CB) then and electron-hole pair is generated (electron e- and hole h ) the positive –hole of Titanium
Dioxide breaks the water molecule apart to form hydrogen gas and hydroxyl radical
-
The negative-electron reacts with the Oxygen molecule to form a super oxide anion (0 2 ) Super oxide anion can
react with water molecules generating hydroxyl radical peroxide ( 00H ) and Hydrogen peroxide (H 2O2)
Moreover, active Hydroxyl Radicals can combine to form Hydrogen Peroxide. This cycle continues when light
is available.
The active Hydroxil radical, super oxide anion, peroxide hydroxyl radical and hydrogen peroxide can react with
biomacromolecules such as protein enzyme and lipid, which will destroy the cell wall membrane and its
components. For example, the oxidation=reduction material is necessary in the formation of Adenosine
Triphosphate insode the hela cell. After reacting with the active Oxygen, the hela cell ( T24)membrane is
2+
oxidised by Titanium Dioxide and leaks, the positive ion Ca enters the cell and reacts with the inner protein
which cvauses the death of the cell
2. R R RC R
C C OH C
R R RH R Typical Redox Potential of Microbes and Cells
(vs, SCE, PH=7)
Microbe Cell Concentration Redox
Take OH for example , it can provide an unsaturated bond Cell / L Potential
N
or take out its atom H as organic matter Microzyme 1 x 1011 0.74
Escherichia Coli 1 x 1011 0.72
R3CH OH R3C H 2 O Lactobacillus 5 x 1011 0.68
Bacillus Subtilis 2 x 1011 0.68
Samonella 6 x 1011 0.70
The new free radical will cause a chain reaction which will lead to Typhimurium
the qualitative change of bacterial proteins and the total Cell Concentration Redox
Component Cell / L Potential
decomposition of lipids. The bacteria is decomposed and killed at N
once. Microzyme - 0.65
Extravasate
Thereforethe electron hole and OH , O2 , HO2 , H 2 O2 CoA
Reductive co-
3.7 x 103
5.0 x 103
0.40
0.68
formed on the surface of Titanium Dioxide can react with a enzyme
cell wall, membrane and its component to kill the cell. Cysteine 2.5 x 103 0.45
Protolasm - .65
Hela Cell - .65
In the sunlight, the Titanium Dioxide particles are absorbed by
the surface of animalcule cells,
( OH , O2 , HO2 , H 2 O2 ) will react directly with cytologic histologocal elements which improves
the sterilization effect. The positive –hole of Titanium Dioxide irradiated by UV light is an extremely
strong oxidation agent, the reactive Oxygen is also extremely active. As a result, Titanium Dioxide
can effectively kill Escherichia Coli, Lactobacillus, Bacillus Subtilis, Hela and Cancer cells T24.
Furthermore it can inhibit or prevent the growth of malignant cells and even kill green algae.As a
result of such effective sterilization, Titanium Dioxide can be used indoors as an antiseptic and
sterilization agent for water treatment, water pollution and Photodynamiotherapy.
Actually, photocatalytic sterilization remains constant when bacteria is exposed to Titanium Dioxide,
as the active hydroxyl radical cannot exist and cannot enter a cell membrane to destroy the cell
structure, therefore the sterilization effect is the result of hydroxyl radical and other active oxygen
( O2 , OOH , H 2 O2 ) since H 2 O2 can enter a cell wall it not only kills the bacteria but also
decomposes lipoids such as Endotoxin released by its death. In addition it can remain stable for as
long time so H 2 O2 can be the most important reaction medium in photocatalytic sterilization. Of
course the reaction also includes other active oxygen and H 2 O2 is not the only reactant. The active
hydroxyl radical performs strong oxidation inside the cell, which greatly improves its sterilization
effect.
3. Comparison with Traditional Antiseptics
Traditional antiseptics are divided into the following three
categories. Organic Antiseptic, Inorganic Antiseptic and Natural
Antiseptic. There are two types of Inorganic Antseptics, one with
a strong oxidant property used to kill bacteria and fungus and the
other with a metal ion that will kill germs, however, the
antiseptics themselves like Chlorine and Chlorine oxide are
potentially bad for health. The metal antiseptics do not continue
to decompose the germ body after killing so the germ body coats
the metal ion, this greatly affects the antibacterial efficiency. The
organic antiseptics compounded by scientific chemical methods
kill germs quickly but the germ can adapt itself to organic
antiseptics easily and the process involves the use of toxic
substances.
Type Advantages Disadvantages Typical Products
Inorganic Heat resistant, wide The silver antiseptics Silver-zeolite/ Phosphate
range of sterilization and change colour easily and and silver silica gel.
no need for light surfaces remain coated
with germ bodies which
reduce the effect
Organic Fast and wide range of Not heat resistant, Phenol
sterilization, low price produces nasty toxins,
and is a pollutant
Natural High effect of Not heat resistant, Chitosan, Sorbic Acid
sterilization, safer to use processing the material
and non pollutant can be difficult
Photocatalyst Wide range of Light required Titanium Dioxide based
sterilization, high and Photocatalysts
everlasting effect,
decomposition of germ
bodies and their
endotoxin, non pollutant,
harmless to humans
4. Advanced Sterilization with ACtion Nanocoat
Anti-bacterial and anti virus treatment of public places and facilities such as hospitals, schools, hotels, offices,
taxis and public transport.
Anti-bacterial and anti virus treatment for face masks, air and water filters, clothes and textiles and domestic
hygiene.
The ACtion nano-photocatalyst kills almost all kinds of bacteria and virus including SARS, H5N1etc and remains
effective for several years. It works by decomposing virus and their cell bodies and the residual endotoxin and
then continues to break down any new mutations of the bacteria. Because the bacteria cell structure is
completely decomposed, the surface remains active and effective unlike standard disinfectants.
The ongoing activity of the ACtion coating eliminates odours such as cigarette smoke, pets and reduces
allergens present in the ambient micro environment.
Benefits
Broad spectrum sterilization feature, killing almost all kinds of
bacteria and virus.
Providing deodorization and anti allergen properties
Long active life ( approx 5 years) depending on conditions
Active photcatalytic decomposition of mould and fungus, self
cleaning.
Safe and environmentally responsible method of killing
bacteria and virus with no toxins or residual pollutant
ACtion Nanocoatng delivers excellent anti
bacterial performance after coating in areas
where hygiene is critical.
Our product has been tested in a Hospital in
high risk areas and the growth rate of
bacteria measured.
8 critical areas of contamination where
measured for bugs and 6 from the 8 were
contaminated at a dangerous level. The
areas were then coated with ACtion and
then re-opened to normal operations for a
period of 24 hours. After this period each
area was re-tested and were either free
from contamination or at a safe level.
Data available on demand
5. Air Purification
ACtion is a next generation air purification technology that will de-activate harmful pollutants in 85% of all
harmful gases such as , Nitrogen Oxide, Formaldehyde,
Benzene, VOC’s.
ACtion nanocoat works by Photocatalysis, in the presence
of light, it produces hydroxyl radicals and holes ( h+). These
react with organic materials and harmful gases to produce
Water and Carbon Dioxide.
Through nano-particulate engineering and modifications in
the reology of the monolayer, the coating can be adapted
to operate in low light conditions without any detrimental
effect to the overall performance.
Pollutant Source Chemical Reaction End Product
H2O CO2 N2, O2
NO3
2
Ammonia Urine, Sweat,
Garbage, Smoke
2 NH 3 6OH N 2 6H 2 O
Acetaldehyde Garbage, Smoke
etc
CH 3CHO 6OH O2 2CO2 4H 2 O
Acetic Acid Garbage, Smoke
etc
CH 3COOH 4OH O2 2CO2 4H 2 O
Methane Gas, Fuel,
Organic CH 4 4OH O2 CO2 4H 2 O
Decomposition
Carbon Exhaust fumes,
Monoxide Smoke
CO 2OH CO2 H 2 O
Nitrogen Exhaust fumes,
Oxide Smoke
" NO 4OH N 2 2O2 2H 2 O
Formaldehyde Resin, Paints etc HCHO 4OH CO2 3H 2 O
The above table shows the chemical reactions initiated by the photocatalytic process and the resulting
products produced in each case. The residual products are non pollutants and are completely harmless.
6. Self Cleaning
Overview
Action self cleaning nanocoat is a special photocatalytic coating that reacts with light to create a hydrophilic
surface or a surface that is super receptive to water.
The washing proess is done by reducing the surface tension of the coated area so that it cannot repell water
but accepts it to spread evenly over the surface. Surface tension is normally measured by establishing the
contact angle of a water droplet on the surface , the diagram shows the angle and how the coating alters the
shape of the droplet.
The coated area eventually becomes completely saturated by water, so that excess water begins to flow by
gravity, “washing” the coated area.
Before and during this washing process the photocatalytic coating has decomposed organic pollutants, lipids
and moulds that may have contaminated the surface, so the combination of the two processes ensures that
all dead and decomposed organic cells are washed free from the surface each time for the ACtion coatings
cycle to continue.
Before After