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    Home > Coatings News > Paints and Coatings Market > The research status and application and performance detection method of environmental purification coating

    The research status and application and performance detection method of environmental purification coating

    • Last Update: 2020-11-28
    • Source: Internet
    • Author: User
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    With the improvement of people's material living standards, interior decoration, a variety of daily chemicals, a large number of electrical products and air conditioning use, resulting in an increase in the degree of room closure and indoor production of a large number of physical, chemical, biological and radioactive pollution factors, resulting in a serious decline in indoor air quality. Pollution factors include irritating harmful gases (formaldehyde, ammonia), carcinogenic substances (benzene, radon), volatile organic compounds and microorganisms that are sensitive, long-term exposure of the human body to these pollution factors will have adverse effects, and even the occurrence of various diseases, indoor air pollution and health has become an important environmental issue of concern to governments and the public around the world. NanoTiO2 photocatalytic technology, which has emerged in the past 30 years, has high chemical stability, resistance to light corrosion, deeper price band energy level, can make some heat-absorbing chemical reactions in the nanoTiO2 surface of light radiation to be realized and accelerated, and non-toxic to human body characteristics, has become a hot topic in environmental purification coating research, by the attention of materials and environmental researchers
    China
    .
    1 Status of environmental purification coatings
    The research and application of environmental purification coatings developed rapidly in the 1980s, especially in photo-catalytic environmental purification coatings. In Japan, for example, photo-catalytic environmental purification coatings are used in almost any application, especially in bathrooms where self-cleaning coatings are used more widely. Over the years, the domestic research mainly on nanoTiO2 photocatalytic technology, in the development of photocatalytic environmental purification coating research and industrial applications have achieved remarkable and fruitful results.
    1. 1 The workings of environmental purification coatings
    TiO2 is an N-type semiconductor material whose energy band structure is not continuous and is usually composed of a low-energy-grade price band (VB) filled with electrons and an empty high-energy-grade guide belt (CB), which are separated by a prohibited band. When the energy of the incoming light is greater than or equal to 3. When the 2eV's band width (wavelength is less than or equal to 387.5nm), the electrons on the price band are stimulated over the band, forming a highly charged high-activity electron e-with negative charge on the guide belt, and at the same time producing a positively charged hole h-plus on the price band. Under the effect of the electric field, photoelectronics and photoresist holes are separated and migrated to different positions on the surface of the T iO2 particle, so that the material adsorbed on the surface of the T iO2 particle is oxidized or reduced.
    1. 2 Problems with environmental purification coatings
    Although the application of nanoT iO2 in environmental purification coatings has achieved remarkable and fruitful results, there are still some problems that are not conducive to practical promotion, which need to be studied and solved by the majority of scientific researchers.
    (1) special requirements for light sources. NanoTiO2 has certain dependence and limitations on the environment in its use, and is inefficient and inefficient for common visible light sources such as sunlight. For the corresponding effect of ultraviolet light source is good, the utilization rate is very high, but in daily life, the proportion of ultraviolet light source is less than 6%, which greatly limits the use of nanoT iO2 environmental purification coatings.
    (2) catalytic environment. According to the study of the optical catalytic structure of nanoT iO2, the concentration of O2, H2O and OH adsorbed on the catalyst surface directly affects photogenic electron photogenic cavities, especially in the conversion of photogenic electron photogenic cavities into OH with high oxidative activity and free-based reactive oxygen (O2- , O2, H O2). However, the concentrations of O2, H 2O and OH - vary considerably under liquid-phase and gas-phase conditions, and the current technology used in nanoT iO2 environmental purification coatings under liquid-phase conditions is more mature than that used under gas-phase conditions.
    (3) degrades the physicochemical properties of the target pollutant. Most of the target degradation pollutants are complex organic matter, such as phenol, methyl orange, rodinming B, etc. Because of the molecular structure, the energy of the chemical bonds between atoms varies from target to target to pollutant molecule, so the energy required by nanoT iO2 in the process of degradation varies, such as C H in phenol, which is much higher than the energy of C H in formaldehyde. While nanoTiO2 is non-selective in the process of photocatalysis, how to improve the oxidation and degradation ability of nanoT iO2 environmental purification coatings to different target degradation pollutants is a focus of current research.
    2 Environmental purification coatings are used in
    2. 1 Antibacterial anti-mold material
    The current market of anti-mold coatings, mainly organic arsenic and phenolic compounds as anti-mold agents, although the anti-mold effect is good, but toxic, unsafe to use. NanoTiO2 has a strong redox ability, with clean air, deodorization and other functions, can be made into antibacterial anti-mold interior wall coating, using chlorination synthesis nanoTiO2 technology, according to the needs of sterilization function efficiency, surface doping and treatment, to make a unique antibacterial nanoTiO2, it is fully mixed in water-based latex paint developed into non-polluting, anti-mold indoor environmental protection materials. At present, antibacterial anti-mold inner wall coating is mainly used in a variety of food industry production workshops, warehouses and underground buildings, such as vulnerable to mold contamination of the inner wall coating.
    2. 2 Anti-fouling self-cleaning material
    the surface coated with nanoTiO2 film has a high self-cleaning effect, once the surface is contaminated by sewage grease, dust and so on, because its surface is super hydro-hydro, the dirt is not easy to attach to its surface. Ultraviolet rays in sunlight are sufficient to maintain the hydromassive properties of the nanoT iO2 film surface, giving it a long-term anti-fouling self-cleaning effect. Because nanoTiO2 has photocatalytic and ultra-hydro-hydroponic properties, when applied to building materials such as glass and ceramics, it has environmental protection functions such as purifying air, sterilizing deodorization and anti-fouling. But also can save a lot of cleaning agent use, save cleaning time and human maintenance costs, while curbing the growth of a variety of molds, reduce allergen production, maintain a healthy living environment.
    2. 3 Automatic non-toxic material
    adds nanoTiO2 photocatalysts to materials prone to harmful gases, which degrade the harmful gases by nanoT iO2 before entering the atmosphere, thus automatically detoxifying the material. For example: In order to prevent the production of antioxins in waste incineration, nanoTiO2 automatic non-toxic materials can be used in plastic products, when plastic products for waste incineration, nanoT iO2 crystallization, can adsorb a large number of harmful substances produced during incineration, and through the photocatalytic reaction of nanoT iO2 degradation.
    3 Environmental purification coating performance testing
    In recent years, environmental purification coatings in practical applications have achieved exciting results, but for the environmental purification coating performance test is still lack of understanding, the author details scanning electron microscopy, transmission electron microscopy, infrared absorption spectroscopy, X-ray diffraction and other applications in environmental purification coating detection.
    3 1 Scanning Electron Microscopy (SEM)
    Scan electron microscopy is the use of scanning incoming electron beam and sample surface interaction generated by a variety of signals, the use of different signal detectors to observe the sample surface shape and chemical components of the analysis technology, which has a direct observation diameter of 0 to 30mm sample surface structure; Scanning electron microscopy is one of the most effective tools for studying the surface structure of an article, which can be used to examine the breaks, wear surfaces, coating surfaces, cutting surfaces, polishing and etching surfaces of environmental purification coatings, and can also make rapid qualitative and quantitative analysis of the surface of environmental purification coatings.
    3. 2 Transmission electron microscopy (TEM)
    transmission electron microscopy is an imaging signal based on transmission electrons, The microstructure and profiling technology of the observation sample through the magnification imaging of the electronic optical system has high resolution, keen analytical ability of grain direction, homogeneity isomorphic structure, heterogeneity structure and homogeneity homogeneity structure; Transmission electron microscopy is mainly used in the field of new materials in physics and chemistry, and can analyze the structure and particle size distribution of environmental purification coatings.
    3. 3 Infrared absorption spectroscopy (IP)
    Infrared absorption spectroscopy is the study of infrared radiation and sample molecular vibration and rotational energy level interaction, The analysis method of measuring sample composition, molecular structure, etc. by using the wavelength position and absorption strength of the infrared absorption spectral band is not limited by the sample state, high characteristics, the study of unknown components according to the characteristic frequency of the spectral band, the low sensitivity of quantitative analysis, etc., which is particularly suitable for qualitative analysis and structural change analysis of environmental purification coatings composed of organic compounds and some inorganic compounds.
    3. 4 X-ray diffraction (XRD)
    X-ray diffraction method is a kind of non-destructive and non-destructive analysis method used to measure the particles of environmental purification coating according to the X-ray diffraction map characteristics of matter. The X-ray diffraction map carries information on the internal structure of the crystals of environmental purification coatings, including electronic structure, crystal structure, various defect structures, structural strain, grain size, crystallization, crystalline tendency, etc.
    3. 5 Other methods
    In addition to appealing several methods, other methods such as X-ray small-angle scattering method , X-ray diffraction diffraction method , 10 , ultraviolet visible spectroscopy , 11 12 , are often used in the analysis of environmental purification coatings , providing the main parameters of microcrystalline size , crystal structure and optical properties of environmental purification coatings , which play a vital role in detecting the performance of environmental purification coatings .
    4 Conclusions and Prospects
    At present, nanoT iO2 is studied in environmental purification coatings, mainly focusing on the development of new photocatalytic environmental purification coatings with narrow band gaps and the ability to utilize visible light; It can be predicted that, with people pay more and more attention to environmental quality, improve the overall quality of indoor air environment, to meet people's expectations of a healthier living environment has become the direction of development. The continuous improvement of environmental purification coating research by scientific researchers will certainly improve the current problem of restricting the promotion and application of environmental purification coatings, and green, environmental protection and high efficiency will become the future direction of environmental purification coatings.
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