Photocatalyst is a nano-scale metal oxide material (titanium dioxide is more commonly used). It is coated on the surface of the substrate and produces a strong catalytic degradation function under the action of light: it can effectively degrade toxic and harmful gases in the air; it can effectively kill It can kill a variety of bacteria, decompose and harmlessly treat toxins released by bacteria or fungi; it also has deodorizing, anti-fouling and other functions.
Introduction
Photocatalyst [Photocatalyst] is a compound word of light [Photo=Light] + catalyst (catalyst) [catalyst]. Photocatalyst is a general term for optical semiconductor materials with photocatalytic functions represented by nanoscale titanium dioxide. It is currently the most ideal material for controlling indoor environmental pollution in the world.
Under the irradiation of light, the photocatalyst will produce a photocatalytic reaction similar to photosynthesis, producing free hydroxyl radicals and reactive oxygen species with extremely strong oxidizing ability. It has a strong photoredox function and can oxidatively decompose various organic compounds and parts. Inorganic substances can destroy bacterial cell membranes and solidify virus proteins, kill bacteria and decompose organic pollutants, and decompose organic pollutants into pollution-free water (H2O) and carbon dioxide (CO2), so they have extremely strong sterilization and Deodorizing, anti-mildew, anti-fouling, self-cleaning, and air purifying functions. The characteristic of photocatalyst is that it uses oxygen molecules and water molecules in the air to convert the organic matter it comes into contact into carbon dioxide and water. It does not change itself but can promote chemical reactions. In theory, it has a very long validity period and low maintenance costs. At the same time, titanium dioxide itself is non-toxic and harmless, and has been widely used in various fields such as food, medicine, and cosmetics.
Identification of the pros and cons of photocatalyst spray liquid
1. Is it layered? Use a high-speed centrifuge (speed 15,000 rpm) for 30 minutes and observe the liquid after standing still for 60 minutes. If the photocatalyst appears to be stratified, it does not contain dispersant, while the photocatalyst that is not stratified must contain dispersant. The reason is that Van der Waals force research shows that after the photocatalyst is milled in a ball mill and then a dispersant is added, there is no stratification.
2. Is there any residue? Put a small amount of photocatalyst into the crucible and fully heat it with an alcohol lamp. If the residue is black and ash-like, it contains a binder; otherwise, there is no binder. High quality photocatalyst without binder.
3. Is there a smell? If you open the bottle cap of the photocatalyst package and there is an odor of alcohol, resin, or other organic matter, it is a low-quality photocatalyst. High-quality photocatalyst is an odorless aqueous solution.
4. Is it neutral? Measure the pH value. If the PH value of the photocatalyst is below 5 or above 9, the corrosion effect will be obvious and the surface of the wall, furniture, or fabric may become discolored. High-quality photocatalyst products are neutral, with a pH value close to 7, generally within 6-9, and will not corrode objects.
5. Will it change color? Inferior photocatalysts will turn black within a few hours under direct sunlight. This is because titanium dioxide will undergo a photocatalytic reaction under light and oxidize the organic components in its solution. High quality photocatalyst will not change color under light.
6. Is there any testing? Before choosing a photocatalyst product, you must require the photocatalyst manufacturer to issue three test reports from an authoritative testing agency, namely a sterilization effect test report, a harmful substance degradation effect test report and a product non-toxic test report. Moreover, all three reports must be printed with the CMA logo. (National Measurement Certification Unit Mark).
Among these three reports, the non-toxic test report is the most important. If the manufacturer cannot provide a non-toxic test report when consumers choose photocatalyst products, it means that other harmful substances have been added to the photocatalyst products during the processing, and the non-toxic characteristics of the products have been destroyed. The use of inferior photocatalysts has environmental and health risks. Hidden danger.
7. Concentration identification. The commonly used photocatalyst spray concentration is 0.5-0.8%, and the photocatalyst with additives can reach more than 3%. However, the surface of the photocatalyst with additives will be partially covered by the additives, affecting the photocatalytic performance. Without additives, the performance is already excellent when the photocatalyst concentration reaches 1%. High quality photocatalyst without additives.
8. Particle size identification. The performance of the photocatalyst is related to the particle size of titanium dioxide. The smaller the particles, the better the photocatalytic effect. At present, there are domestic manufacturers that can produce photocatalysts smaller than 5 nanometers.
9. Attachment identification. High-quality photocatalysts have good adhesion and can form a strong film after spraying and drying. It is through this film that titanium dioxide absorbs ultraviolet rays from sunlight and produces photocatalysis. Whether a film can be formed after spraying directly affects the degradation effect, and whether the film layer is firm affects whether the product can last long. A type of inferior photocatalyst cannot form a film layer after spraying and quickly pulverizes after drying. Although another type of photocatalyst can form a film after spraying, it disappears immediately after being wiped with a damp cloth. Both types of products are unable to properly perform the role of photocatalysts in degrading pollution and sterilizing. Before purchasing, consumers can apply a small amount of photocatalyst with their fingers evenly on a dark desktop. After drying, observe the film formation state, and wipe it with a damp cloth to observe its adhesion. If the product is powdery or fails to adhere, you can conclude that the product is of poor quality.
