Photocatalyst (2)
product description
The negative ion photocatalyst is a high-performance, multi-functional air purification product made of natural polar mineral materials,
nanomaterials, inorganic antibacterial materials and other materials. This product can absorb various energies such as light energy, heat
energy and electromagnetic waves in the natural environment by itself, and generate electron-hole pairs with strong oxidizing ability on
the surface of the product, thereby effectively decomposing and eliminating indoor formaldehyde, benzene, ammonia and other harmful
substances. Gases and pathogenic bacteria, the powerful microscopic electric field can ionize water molecules in the air to produce a large
number of hydroxyl negative ions, which can wrap and settle harmful substances to achieve the purpose of thoroughly purifying the air
and benefiting human health.
Photocatalyst technology has been applied to products such as furniture odor absorbers. At present, the perfect combination of high
adsorption efficiency photocatalyst loading technology and refined bamboo charcoal has been achieved. This technology has super
activity and can efficiently absorb and decompose formaldehyde, benzene series and other VOC substances released by furniture. Under
the irradiation of sunlight (ultraviolet light), its regeneration is achieved. After regeneration, it still has high adsorption efficiency. If you
repeat this process, it can generally be used for one year.
Principle of action
When the photocatalyst is irradiated with light of a specific wavelength (388nm), it will produce a series of energy conversion processes
similar to chlorophyll photosynthesis in plants. It converts light energy into chemical energy and gives the photocatalyst surface a strong
oxidizing ability, which can oxidize and decompose various organic matter. Compounds and mineralized parts of inorganic substances, and
have antibacterial effects. Under light irradiation, the photocatalyst can absorb light energy equivalent to the band gap energy, causing its
surface to be excited to generate electrons (e-) and holes (h+). These electrons and holes have strong reducing and oxidizing abilities and
can react with water or stored oxygen to produce hydroxyl radicals (·OH) and super anion ions (·O). As shown in Table 1, the oxidation energy
of these holes and hydroxyl radicals is greater than 120kcal/mol. They have strong oxidizing ability and can cut and decompose almost all the
chemical bonds that constitute organic molecules. Therefore, various harmful chemicals and odorous substances can be decomposed or treated harmlessly to achieve the functions of air purification, anti-pollution and deodorization.
Table 1: Oxidation energy of various chemical bonds
Chemical Bonding Positive pores and hydroxyl radicals Carbon-carbon bonds Carbon-hydrogen bonds Carbon-nitrogen bonds Carbon-oxygen
bonds Oxygen-hydrogen bonds Nitrogen-hydrogen bonds
Oxidation energy (kcal/mol) >120 83 99 73 84 111 93 In addition, as shown in Table 2, hydroxyl radicals have stronger oxidizing power than
hypochlorous acid, hydrogen peroxide, and ozone, which are widely used as disinfectants. Ability, through this oxidation ability, titanium dioxide
destroys coenzymes such as coenzyme A and respiratory enzymes in cells to exert antibacterial effects and stop the reproduction of bacteria or
fungi; at the same time, when positively charged holes contact negatively charged microbial cells Then, based on Coulomb gravity, they adsorb
each other and effectively penetrate the cell membrane, denaturing the cell proteins and making them unable to breathe, metabolize and r
eproduce until the cells die, completing sterilization; and can decompose toxins released by bacteria or fungi. Table 2: Oxidation potential of
various oxidants
Oxidizing agent Oxidation potential (volts) Relative oxidation potential (log value)
hydroxyl radical 2.80 2.05
Oxygen atom 2.42 1.78
Ozone 2.07 1.52
Hydrogen peroxide 1.77 1.30
Dioxygen radical 1.70 1.25
Hypochlorous acid 1.49 1.10
Chlorine 1.36 1.00
Classification
Photocatalyst is a type of special-purpose catalyst with many types, including titanium oxide (TiO2), zinc oxide (ZnO), tin oxide (SnO2), zirconium
dioxide (ZrO2), cadmium sulfide (CdS) and other oxide sulfides Semiconductors, they usually appear as powdery solids or liquid sols. Let’s learn
about these metal oxides respectively.
Nanoscale titanium dioxide (TiO2) is a semiconductor with three crystal structures: Anatase, Rutile and Brookite. Only the anatase structure has
photocatalytic properties. It is generally used as a toner, physical sunscreen agent, photocatalyst, etc. in the fields of cosmetics, coatings, indoor
environmental protection, food additives, etc. Titanium dioxide is the whitest substance on earth. When the average particle diameter is less than
10nm, it has very valuable optical properties. Due to its highly unified transparency and UV protection capabilities, it has been widely used in sun
protection and skin care, car topcoats, high-end coatings, inks, plastics, fine ceramics, etc.
Nano-zinc oxide (ZnO) has a particle size between 1-100 nm. It is a new high-functional fine inorganic product for the 21st century. It exhibits many
special properties, such as non-migration, fluorescence, piezoelectricity, The ability to absorb and scatter ultraviolet rays, etc., and use its wonderful
properties in light, electricity, magnetism, sensitivity, etc. to manufacture gas sensors, phosphors, varistors, ultraviolet shielding materials, image
recording materials, piezoelectric materials, varistors, high-efficiency Catalysts, magnetic materials and plastic films, etc. It is widely used in the
fields of rubber, ceramics, textile, printing and dyeing, and national defense industries.
Nano-zirconium dioxide (ZrO2) is in the form of high-purity white powder, odorless and tasteless. It is monoclinic at low temperatures and tetragonal
at high temperatures. It has high refractive index (refractive index 2.2) and high temperature resistance. It has good thermochemical stability, high
temperature conductivity, high high temperature strength and toughness, and has good mechanical, thermal, electrical and optical properties.
Among them, HT-ZrO-01 is a monoclinic crystal form, and HT-ZrO-02 is a tetragonal crystal form. Nano-zirconia particles are small in size and
are very stable oxides. They are acid-resistant, alkali-resistant, corrosion-resistant, and high-temperature resistant. They can be used in functional
ceramics, structural ceramics, and gemstone materials.
Nano-cadmium sulfide (CdS) yellow or slightly yellow, widely used in solar cells, semiconductor materials, visible light band optoelectronic devices,
automatic camera control illuminance meters, photoconductor drums, laser modulation cells, visible light detectors, laser window materials, infrared
two-color detectors , Manufacturing of photoluminescence, electroluminescence, cathode luminescence materials and pigments, etc.
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Specific features
(1) Comprehensiveness
Photocatalyst can effectively degrade formaldehyde, benzene, toluene, xylene, ammonia, TVOC and other pollutants, and has efficient and extensive
disinfection performance, and can decompose and harmlessly treat toxins released by bacteria or fungi.
(2) Continuity
During the reaction process, the photocatalyst itself will not change or be lost, and it can continuously purify pollutants under the irradiation of light,
which has the advantage of long-lasting and continuous effect.
(3)Safety
Non-toxic, harmless, safe and reliable for the human body; the final reaction products are carbon dioxide, water and other harmless substances, and
will not produce secondary pollution.
(4) Efficiency
Photocatalysts use inexhaustible solar energy and other light energy to remove and purify diffused environmental pollutants at low concentrations.
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Specific role
As an emerging air purification product, photocatalyst mainly has the following functions:
A. Air purification function: It purifies formaldehyde, benzene, ammonia, sulfur dioxide, carbon monoxide, nitrogen oxides and other harmful organic
substances that affect human health.
B. Bactericidal function: It has bactericidal effect on Escherichia coli, Staphylococcus aureus, etc. While sterilizing, it can also decompose harmful
compounds released from dead bacteria.
C. Deodorizing function: It has deodorizing effect on cigarette odor, toilet odor, garbage odor, animal odor, etc.
D. Anti-fouling function: Prevent the generation of oil, dust, etc. It also has the effect of preventing mold, rust, yellow alkali and rust in the toilet
and fading of painted surfaces in the bathroom.
E. Purification function: It has the function of purifying water pollution and organic harmful substances in the water, and the surface is super
hydrophilic, anti-fogging, easy to wash, and easy to dry.
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Application areas
1. Public places: schools (school classrooms, dormitories, training centers, auditoriums, canteens, science museums, libraries, computer rooms),
office areas (offices, conference rooms), hotels, restaurants, hostels, Internet cafes, cinemas, KTV, lecture halls, banquet halls, public restrooms
and other public or crowded places;
2. Personal residence: living room, kitchen, dining room, study room, living room, smoking area, bathroom, toilet, furniture, toys, tableware,
dressing table, bathtub, toilet, trash can;
3. Medical places: outpatient departments, emergency centers, waiting rooms, wards, reproductive health care centers, health clinics, health
centers, epidemic prevention stations, nursing homes, pet hospitals;
4. Specific places: laboratories, food processing plants, poultry and livestock farms;
5. Transportation: cars, trains, subways, airplanes, ships, elevators, etc.;
6. Industrial products: new products developed using photocatalysts as raw materials and combined with other processes;
7. Building materials: ceramics, coatings, glass;
8. Household appliances: air conditioners, refrigerators, telephones, washing machines, lighting appliances, air purifiers, etc.;
9. Textile technology: curtains, cotton fabrics, fibers, masks, handicrafts, etc.
