The commonly used methods for treating exhaust gas in painting workshops include direct combustion, liquid absorption, and activated carbon adsorption. Due to the demand for resource recycling, activated carbon adsorption and liquid absorption methods have received more research and application. The liquid absorption method uses water or mineral oil (such as silicone oil) as absorbents depending on whether the coating is water-based or solvent based, to improve absorption efficiency. The most promising method for activated carbon adsorption is to use activated carbon fiber felt (ACFC) as the adsorption medium, which is electrically heated to desorb and recover organic solvents. Activated carbon adsorption method has strong economic applicability, safety and reliability, and is not prone to secondary pollution, making it one of the most commonly used methods currently.
There have been many years of application experience in using activated carbon as an adsorbent for exhaust gas in painting workshops. Activated carbon is inexpensive, with a hydrophobic surface and a large specific surface area (500-1200m2/g), thus possessing excellent adsorption performance. It can adsorb organic solvent vapors on its surface. When the adsorbent is heated and dried, the adsorbed gas is released and cooled into a liquid state, thereby achieving the goal of solvent recovery. Molecular sieves with hydrophobic surfaces are expensive. Activated carbon is the most suitable adsorbent for the purpose of removing organic solvents.
Painting is the most basic technical means used for surface protection and decoration of products, and painting operations cover various sectors of the national economy. However, painting workshops are one of the main production sites for environmental pollution. In air spraying operations, 50% to 70% of solvent based coatings are dispersed as paint mist during the coating process. The vast majority of organic solvents in coatings evaporate and are released into the atmosphere. Harmful exhaust gases emitted during painting are mainly concentrated on the painting production line, among which the painting room, drying room, and drying room are the main sources of exhaust gases. These exhaust gases not only pose a serious threat to the environment, but also make it easy for workers to develop skin cancer and emphysema in an environment with exhaust gases for a long time, seriously affecting their physical health. The toxicity of exhaust gases is also very strong, such as xylene, toluene, methyl ethyl ketone, etc.
https://www.naturecarbon.com/wood-based-activated-carbon/granular-activated-carbon.html
