Application of activated carbon for waste gas treatment in painting workshop

At present, the commonly used methods for treating exhaust gas in painting workshops are: direct combustion method, liquid absorption method, and activated carbon adsorption method. Because of the requirement of resource recycling, activated carbon adsorption method and liquid absorption method have been more researched and applied. The liquid absorption method uses water or mineral oil (such as silicone oil) as the absorbent according to whether the coating is water-based or solvent-based to improve the absorption efficiency. The most promising method of activated carbon adsorption is to use activated carbon fiber felt (ACFC) as the adsorption medium, desorption and recovery of organic solvents by electric heating. The activated carbon adsorption method has strong economical applicability, is safe and reliable, and is not easy to cause secondary pollution. It is one of the most used methods at present.

Activated carbon has been used for many years as a paint shop exhaust gas adsorbent. Activated carbon is cheap, has hydrophobic surface, and has a large specific surface area (500-1200m2/g), so it has excellent adsorption performance, which can make organic solvent vapor adsorb on its surface. When the adsorbent is heated and dried, the adsorbed gas It is parsed out and cooled to a liquid state, so as to achieve the purpose of recovering the solvent. Molecular sieves with hydrophobic surfaces are expensive. In the case of removing organic solvents, activated carbon is the most suitable adsorbent.

Coating is the most basic technical means used for product surface protection and decoration. Coating operations cover all sectors of the national economy, but the coating workshop is one of the main production sites for environmental pollution. In the air spray operation, 50% to 70% of the solvent-based paint is scattered in the paint mist during the painting process. Most of the organic solvents in the paint are volatilized and released into the atmosphere. The emission of harmful waste gas in painting is mainly concentrated in the painting production line, among which the painting room, drying room and drying room are the main sources of waste gas. These waste gases are not only harmful to the environment, but also cause skin cancer and emphysema to be easily caused by the long-term exposure of workers in the environment with waste gases, which seriously affects their health. The toxicity of exhaust gas is also very strong, such as xylene, toluene, methyl ethyl ketone, etc.