Indoor and outdoor environmental photocatalysis with Tio2 une2
Photo-catalyst is a general term for photocatalytic photo-semiconductor materials represented by nano-scale titanium dioxide.
This, under the action of light, will produce a photocatalytic reaction similar to photosynthesis, producing a free hydroxyl radical and active oxygen with a strong oxidizing capacity. It has a strong function of photo-oxidation and reduction and can thus oxidize.
It decomposes several organic compounds and some inorganic substances and causes the bacterial cell membranes and virus proteins to be destroyed. Kills bacteria and breaks down organic pollutants. It also disrupts organic pollutants in non-polluting water [H2O] and carbon dioxide [CO2].
Therefore, it has strong sterilization, deodorization, mold resistance, anti-fouling, self-cleaning, strong 90% formaldehyde removal, air purification and strong catalytic degradation; effectively reducing toxic and harmful gases in the air and can kill a variety of bacteria. It decomposes and damages the toxins released by bacteria or fungi. It also has the functions of deodorization and anti-fouling.
The nano-titanium dioxide photocatalyst, in contact with carbon dioxide and water, through the use of oxygen molecules and water molecules in the air, converts organic matter.
It is a substance that does not change by itself. But it promotes chemical reactions.
It is theoretically valid for a long period of time and has low maintenance costs.
- Amplitude : the nano-TiO2 photocatalyst effectively degrades 90% formaldehyde, benzene, toluene, xylene, ammonia, VOCs and other pollutants. It has a broad spectrum and high efficiency disinfection performance that can decompose and eliminate toxins released by bacteria or fungi. In general it has a harmful treatment.
- Sustainability : During the reaction, the nano-titanium dioxide photocatalyst itself does not change or is lost. The pollutants can be purified continuously under the illumination of the light. This favors a lasting and sustained action.
- Security : it is not toxic. It is harmless, safe and reliable for the human body. The final reaction products are carbon dioxide, water and other harmless substances, and will not cause secondary contamination.
- High efficiency : the nano-titanium dioxide photocatalyst uses the inexhaustible solar energy and other light energy to eliminate and purify diffuse environmental pollutants in a low concentration state, results can be easily measured .
A. Purification function of the air: It affects harmful organic substances such as formaldehyde, benzene, ammonia, sulfur dioxide, carbon monoxide and oxides of nitrogen: These are reduced to harmless substances. In particular, it has a good effect on the solution of the deterioration of the atmospheric environment, the influence of chemical substances on new construction materials and furniture in the indoor environment.
B. Sterilization function: has a bactericidal effect on Escherichia coli and Staphylococcus aureus. It also breaks down the harmful compounds released by the dead bodies of bacteria during sterilization. Cell membranes that destroy cells with the superoxidative capacity of TIO2 use cytoplasmic loss to cause bacterial death. It coagulates the viral proteins and prints the viral activity, capturing and killing the floating bacteria in the air.
C. Deodorization function: deodorizing effect on cigarette smell, odor of toilet, smell of garbage, body odor of the animal, the smell of mud and the smell of life. Photocatalyst titanium dioxide has a stronger oxidant capacity than ozone anion (O3) and a stronger absorption power than activated carbon.
D. Anti-fouling function: Photocatalyst titanium dioxide will produce ultra-aqueous characteristics by the treated surface of the object. Simply spraying water on the surface of the object will cause dust and dirt to fall. Thus having an anti-fouling function of self-cleaning for treated surfaces or substrates.
The field of application in the dispersion of titanium dioxide of the photocatalyst and market prospects are very broad, not only for air purification, but also for automotive transport facilities, ceramics, building materials, food appliances and beverages, medical equipment, household appliances, environmental protection, degradable plastics, water purification processing, daily necessities and other fields.
E. Anti-mildew and antibacterial: prevents the formation of mold and algae and prevents the adherence of scale.
A. Places of life and work: living room, office, conference room, computer room, conference room, banquet room, apartment, car, etc.
B. Community of medical attention and public entertainment: hospital waiting room, reproductive health center, kindergarten, pet hospital, nursing home, hotel, public bath, smoking room, karaoke room, restaurant, etc.
C. Specific places: schools, restaurants, laboratories, food processing plants, poultry and livestock farms, etc.
D. Standing areas and appliances: family kitchen, toilet table, dining room, crockery, bathroom, bathtub, toilet, curtains, curtains, toilet, living room, curtains, walls, ceilings, toys, storage tanks, garbage, study, area for smokers and other living areas.
Sterilization mechanism with nano photocatalysis Tio2 une2 .
Products for the heterogeneous photocatalysis of nano titanium dioxide (Tio2) have a strong photocatalytic bactericidal effect.
Comparing the lethal curves of photocatalytic destruction with Gram-negative and positive bacteria TiO2, the verification of conventional cultures and the transmission electron microscopy, it is concluded that the photocatalytic nano-TiO2 sterilization starts from the bacterial cell wall and produces radicals free Destroy the structure of the cell wall and break the cell wall, disintegrate the plasma membrane and then enter the cell body to destroy the intima and cellular components, causing the cytoplasm to adhere, which causes the overflow of cellular content and the phenomenon of bacterial cavitation.
It is confirmed that the bacteriostatic mechanism of nano-TiO2 is that, during photocatalysis, the electrons in the band gap of the nano-TiO2 transition from the valence band to the conduction band, form highly active electron pairs. on the surface and later forming · OHˉ, O2ˉ, · OOHˉ destroying the bacterial cells through a series of physical and chemical reactions, thus killing the bacteria.
Titanium dioxide dispersion principle Tio2 photocatalytic nanometer
The electrons in the valence band (eˉ), under & nbsp; the action of sunlight or ultraviolet light, are excited to pass to the conduction band and the corresponding holes (h +) are generated in the valence band . Then, h + and eˉ interact with H2O, O2, etc., adsorbed on the surface of the nano-TiO2 to form high activity groups such as · OHˉ, · O2ˉ, · OOHˉ, superoxide ion radicals, hydroxyl radicals, super oxidation strong. The hydroxyl hydroxyl radicals oxidize and decompose harmful organic compounds such as formaldehyde, benzene, toluene, xylene, ammonia, TVOC, contaminants, bacteria, viruses, etc., in harmless CO2 and H2O.
In the course of the reaction, the photocatalyst product only acts as a catalyst and does not change or lose and can continuously decompose the pollutants under the irradiation of light.
a) The size of the particle is very small: The titanium dioxide in the photocatalyst titanium dioxide dispersion is approximately 5-8 nm in average size and does not agglomerate.
b) Good dispersion: the photocatalyst titanium dioxide dispersion has a very good dispersion performance. It is a transparent liquid that is sprayed on the surface of the furniture and the wall to form a uniform nano coating to purify the indoor air.
c) High catalytic activity: the titanium dioxide photocatalyst will produce positive light. In negative electrons, positrons combine with water molecules in the air to produce hydroxyl radicals. It has been shown that hydroxyl radicals have a strong capacity for oxidative decomposition, which can decompose almost all organic compounds and some inorganic substances, and do not decompose. Poisonous carbon dioxide and water and negative electrons combined with oxygen in the air to produce active oxygen, superoxide ions, super oxidized ions also have a strong capacity for oxidative decomposition. They destroy the membrane of the bacterial cell and solidify the virus protein in the sterilization, decomposing, at the same time, the harmful compounds released in the corpses of the bacteria.
A) Do not spray on the human body. If it is sprayed over the eyes, rinse immediately with clean water.
B) The base material 1 # uses a spray gun with a nozzle diameter of 1 mm. The titanium dioxide photocatalyst is sprayed with a spray nozzle with a diameter of 0.5 mm or less. The spray gun should be cleaned immediately after spraying to prevent clogging and corrosion of the nozzle.
C) The distance from the spray surface to the nozzle of the gun should be moderate, otherwise the spray effect will be uneven.
D) Avoid construction in confined spaces and ventilate completely after spraying.
E) The titanium dioxide dispersion of the photocatalyst is weakly corrosive. If used to decorate the home, spray it on a stainless steel metal box and wipe it with a damp towel.
1. What is the function of the photocatalyst?
The photocatalyst degrades formaldehyde, benzene series and VOCs and other pollutants in the interior and automobile under the action of light, antibacterials and mold and releases negative oxygen ions.
It is the most excellent indoor air pollution control product.
2. What is the photocatalyst?
Nano-TiO2 is stable, non-toxic and has a wide range of sources. It is the first option for photocatalyst materials and is currently the only option. Although nano-zinc oxide has visible light activity, its photocatalytic efficiency is low and poor stability does not last long.
3. What is the concentration for photocatalysis?
Photocatalysis is a photocatalyst. In theory, the higher the concentration, the better. However, if the concentration is too high, a multilayer nano film will form on the surface of the object and traces will be formed, and the adhesion of the outer film will deteriorate. Studies have shown that 1% is the upper limit of concentration for good photocatalysis.
4. What is the pH of the photocatalyst?
The nano-titanium dioxide particles in the photocatalyst are in the form of colloids. Because the surface is positively charged, mutual repulsion can stabilize the dispersion in the water without causing sedimentation. The isoelectric point of the colloidal particles of nano-titanium dioxide is 6.25. When the pH of the system approaches the isoelectric point, the charge of the particles decreases, the stability weakens and the system will be unstable than the 6.25 system and the product will settle. Therefore, a stable photocatalyst solution requires an acidic environment, but too high acidity corrodes the surface of the metal or object. Therefore, the photocatalyst should be weakly acidic, such as: pH = 5, at which time the acid concentration in the system is 0.00001, which is safe.
5. What is the appearance of the photocatalyst? Is it wrong?
The 1% concentration is an important indicator of high quality photocatalyst products. It is milky white and has no smell. When the photocatalyst is diluted several times or tens of times, a pale blue liquid is obtained. This light blue color is not a chemical change, but a phenomenon of light scattering. When the nano-titanium dioxide particles are in a very dilute aqueous solution (such as 0.001-0.01%), blue light is emitted when exposed to light. When the concentration is large, the astigmatism will darken and appear milky white. Because it is a nano material, the photocatalyst will leave no traces after being sprayed on a film.
6. What is the mechanism by which the photocatalyst works?
After spraying the photocatalyst onto the surface of the object, it dries naturally to form a transparent titanium dioxide film. The nano-particles of titanium dioxide in the film generate hydroxyl radicals under the action of light. This free radical degrades the internal contaminants selectively. Kills bacteria and mold and releases negative oxygen ions. Because the electronic transition band of nano-titanium dioxide determines that it can only absorb ultraviolet light below 387.5 nm, there is no ultraviolet light in the interior car, only a large amount of visible light. Therefore, the product for photocatalysis must be doped with a minimum amount of precious metal elements so that it has a visible light effect, so that it has a practical importance in the application.
Field of application in exteriors
It is often used in glass for self-cleaning, anti-fogging and anti-glare treatment.
When we talk about the self-cleaning treatment involves the activation of TiO2 by the effect of UV sunlight, rain and humidity.
Another area where photo-catalytic technologies can be very useful is in the degradation of pollutants in indoor environments due to the long time that people spend in the industrialized world indoors (offices, factories, shopping centers, housing , etc.).
The performance of photo-catalysis in urban applications can be affected by environmental factors such as the intensity of incident radiation, relative humidity, temperature and wind. But it also depends on other intrinsic factors such as when associated with a supporting cement such as porosity, type and size of aggregates, the method of application, applied quantity and aging.
The way in which we use it to apply depends on the place or material that you want the photocatalysis process to take effect. For example: in the factories, it is normally applied at the end of the production line through spraying, coating or printing methods; in the built environment, it is applied by trained and certified applicators using specialized spray equipment.
1. La reducción de las concentraciones de NOx y SOx emitidos por el tráfico de los vehículos y transportes en las ciudades.
2. Reduce el “efecto albedo” porque una vez que el producto se aplica sobre dicho soporte, su tono se vuelve más claro reduciendo así la capacidad de calentamiento de la empresa y por tanto de las ciudades.
3. Reducir la adherencia de partículas extrañas, como pueden ser el polvo o suciedad, en las superficies donde se utilizan estos productos consiguiendo capacidad de limpieza.
4. Capacidad de reducción de olor.
FOTOCATÁLISIS TRATAMIENTOS AGUA
La fotocatálisis está reconocida como una alternativa de desinfección solar. Las investigaciones publicadas en el tema de referencia revelan un resultado de gran potencial para eliminar los microorganismos presentes en el agua. La descontaminación de aguas contaminadas mediante fotocatálisis solar es en la actualidad una de las más exitosas aplicaciones de la fotoquímica solar. La posibilidad de la utilización de la radiación solar como fuente primaria de energía, le otorga un importante y significativo valor medioambiental; el proceso, constituye un claro ejemplo de tecnología sostenible.
La fotocatálisis es un proceso fotoquímico que transforma la energía solar (en algunas aplicaciones es posible usar la luz del día como un recurso para estimular la fotocatálisis y reducir así los costos de operación) en energía química mediante la ayuda o implementación de un fotocatalizador. El catalizador más ampliamente usado es el dióxido de titanio (Tio2). El dióxido de titanio no es tóxico ni genera subproductos cancerígenos. El dióxido de titanio puede cristalizar en forma rutilo y anatasa.
El mecanismo de fotorreacción comienza cuando Tio2 es iluminado con fotones cuya energía es igual o mayor a la separación energética existente entre la banda de valencia y la de conducción. En esta situación, tiene lugar una absorción de esos fotones y la creación en el seno del catalizador de pares electrón-hueco (e- y h+), los cuales disocian en foto-electrones libres en la banda de conducción y foto-huecos en la banda de valencia. Simultáneamente, tiene lugar una adsorción de reactivos y, de acuerdo con el potencial redox (o nivel de energía) del catalizador, un electrón es transferido hacia una molécula aceptora (Ox1) produciendo una reacción de reducción de la misma; al mismo tiempo, un foto-hueco es transferido hacia una molécula donadora (Red2), que se oxidará. Cada ión formado reacciona para formar productos intermedios y finales. El flujo neto de electrones es nulo y el catalizador permanece inalterado. La excitación fotónica del catalizador aparece como el paso inicial de la activación de la totalidad del sistema catalítico.
This photocatalyst is commonly a semiconductor that, when activated by radiation from the electromagnetic spectrum, generates reactions that are highly oxidizing, such reactions destroy contaminants in water.
This disinfection mechanism is based on a physical phenomenon whereby short waves of ultraviolet radiation produce a division between the cell wall and the membrane of the cells. microorganisms and viruses, which deteriorates its cell membrane and inhibits its reproduction, and this causes its elimination without causing physicochemical changes that can alter the treated water.
Some successful applications are the treatment of industrial pollutants, such as phenolic compounds from a wide variety of industries or the degradation of pesticides, which constitute a wide range of chemical products widely used in agriculture. On the other hand, photocatalysis has been used in the treatment of water contaminated with metals of high toxicity, in this sense the photocatalytic process allows the reduction of metallic cations to deposit them on the semiconductor surface, which can later be extracted by mechanical or chemical methods .
Photocatalysis has been applied with excellent acceptance to the elimination of herbicides, pesticides, phenol and its derivatives, halogenated hydrocarbons, alcohols, organic acids, nitrogen oxides, dyes or pharmacological products. One of the main advantages of using photocatalysis to clean water is its ability to decompose even very low concentrations of substances that, for the rest, are difficult to eliminate, such as dioxins.