Adsorption And Desorption Of Low-concentration Volatile Organic Compounds On Spherical Activated Carbon

Volatile organic compound (VOC) is the third largest air pollutant after particles and oxides of nitrogen and sulphur. People’s health and quality of life would be greatly threatened when they stay in the environment with low-concentration VOC pollutant for too long. In addition, the use and emission of VOC are inevitable recently, and there is little research about the removal of VOC with concentration less than20ppm. Therefore, it is of great significance to investigate the removal of low-concentration VOC.Adsorption technology is widely used in the control of VOC pollution, and the porous carbonaceous material is commonly used as adsorbent because of the large specific surface area and high adsorption capacity. In this research, spherical activated carbons (SAC) were used to investigate the adsorption of four typical VOC (toluene, benzene, n-heptane, and ethyl acetate) with low-concentration (10ppm) through dynamic adsorption on fixed bed. Besides, thermal desorption was used to study the desorption performance of saturated SACs. The main results are as follows:(1) The VOC adsorption capacity of SACs were decreased with the BET specific surface area, while increased with the ultra micropore volume;(2) Air oxidation modification had low-impact on the adsorption capacity of SACs, but had significant influence on the breakthrough point, pore structure characteristics, surface functional groups of the SACs, conbined with the physical properities of the VOCs themselves, influenced the adsorption of VOC with low-concentration;(3) The desorption of adsorbed VOC was relative to the adsorption capacity of the SACs, the more the adsorption capacity was, the more difficult the desorption was;(4) The desorption of different VOCs were related to the effective adsorption sites and the physical properties, the desorption of long-chain alkane n-heptane was the most difficult.