Is photocatalysis useful for purifying indoor air?

It seems that most of the photocatalysis is used to degrade organic waste in sewage, such as methyl orange or rhodamine b, which is not heard of in the air.

Haha, deceitful! Or use the traditional ventilation or activated carbon adsorption method!

Photocatalyst can indeed remove organic matter in the air, but the speed is not fast, it is best to keep the high temperature and humidity in the house now, increase ventilation, so that all harmful substances are discharged.

The disadvantages of photocatalytic technology applied to air purification are mainly reflected in the following aspects: imitation stalls.

1. The removal efficiency of photocatalysis for pollutants is low.

2. Photocatalyst.

Generally, ultraviolet light is required, and when there is no light at night or insufficient indoor light, some harmful gases will be decomposed incompletely.

3. The residence time of the lead contaminant on the surface of the photocatalyst is too short, which can not be completely degraded by photocatalytic oxidation, and intermediate products will be produced, and some intermediate products may bring more harm to human health than the target pollutants.

4. At present, most photocatalytic degradation experiments and reactor design are only considered under the condition of low air volume (10 l h), while indoor air purifiers are generally designed with a higher air volume (100 m3 h) to ensure that the clean air volume (CADR) value can meet the requirements of relevant standards, which is bound to reduce the residence time of pollutants on the surface of the photocatalyst and reduce the photocatalytic efficiency.

As an efficient, safe and environment-friendly environmental purification technology, photocatalytic technology has been recognized by the international academic community for improving indoor air quality. In 1967, Professor Fujishima Akira found in an experiment that photocatalytic reaction is a green technology with important application prospects in the field of energy and environment, which can completely degrade organic pollutants into carbon dioxide and water under the irradiation of light, and at the same time, the photocatalytic material itself has no loss, which is considered by the environmental protection community to be a revolutionary breakthrough in the field of environmental purification in the 21st century, and is known as "the most ideal environmental purification technology in the world today". Pros:

Simple operation, low energy consumption, no secondary pollution, high efficiency. Oxygen in the air is directly used as the oxidant, and the reaction conditions are mild (normal temperature and pressure). It can decompose organic pollutants into inorganic small molecules such as carbon dioxide and water, and the purification effect is thorough.

Semiconductor photocatalysts have stable chemical properties, strong redox properties, low cost, no adsorption saturation, and long service life. Photocatalytic purification technology has the advantages of deep oxygen at room temperature, low secondary pollution, low operating cost and is expected to use sunlight as a reaction light source, so photocatalysis is particularly suitable for the purification of indoor volatile organic compounds, and has shown great application potential in deep purification. Most of the common photocatalysts are metal oxides and sulfides, such as TiO2, ZNO, CDS, WO3, etc., among which TiO2 has the best comprehensive performance and is the most widely used.

Since 1972, when Fujishima and Honda discovered that the redox reaction of water can continue to occur on irradiated TiO2 and produce H2, a great deal of research has been done on this catalytic reaction process.

The results show that TiO2 has good photocorrosion resistance and catalytic activity, and is recognized as the best photocatalyst at present. This technology not only has great potential in the purification and treatment of old water in the ear, but also has a broad application prospect in air purification. In fact, there are many types of photocatalysts, including titanium dioxide (TiO2), zinc oxide (ZNO), tin oxide (SNO2), zirconium dioxide (ZRO2), cadmium sulfide (CDS) and other oxide sulfide semiconductors, in addition to some silver salts, porphyrins, etc. also have catalytic effects, but they basically have a disadvantage--- there is loss, that is, before and after the reaction, it will be consumed, and most of them have a certain toxicity to the human body.

Therefore, the most valuable photocatalytic material known at present is TiO2

When the semiconductor oxide TiO2 nanoparticles are irradiated by photons with energy greater than the band gap, the electrons transition from the valence band to the conduction band, resulting in electron-hole pairs, the electrons are reductive, the holes are oxidizing, and the holes react with the -OH on the surface of the oxide semiconductor nanoparticles to form OH free radicals with high oxidation, and the active OH free radicals can oxidize many refractory organic substances into inorganic substances such as CO2 and H2O.

Photocatalysis is a portmantease of photo=light + catalyst. Photocatalyst is a kind of substance that does not change under the irradiation of light, but can promote chemical reactions, and the vertical side of the photocatalyst is to use the light energy existing in nature to convert the energy required for the reaction of the residual clear aluminum, so as to produce a catalytic effect, so that the surrounding oxygen and water molecules are excited into free negative ions with great positive oxidation force. It can decompose almost all organic substances and some inorganic substances that are harmful to the human body and the environment, which can not only accelerate the reaction, but also use the fixed substances of nature without causing waste of resources and additional pollution.

The most representative example is that of plants"Photosynthesis"It absorbs carbon dioxide, which is toxic to animals, and converts it into oxygen and water using light energy.

Photocatalytic products for indoor air pollution control.

Catalytic technology for air pollution control has the characteristics of broad-spectrum, economy, and sterilization, so it has attracted more and more attention, and has become a hot spot for air pollution control technology research and development.

1) Broad-spectrum: Studies so far have shown that photocatalysis has the ability to treat almost all pollutants.

2) Economy: Photocatalysis is carried out at room temperature, and O2 in the air is directly used as an oxidant, and low-energy ultraviolet lamps can be used for gas-shielded photocatalysis, and even sunlight can be used directly.

3) Sterilization and disinfection: the use of ultraviolet light to control the prosperity of microorganisms has been widely used in life.