Filtration performance on ultrafine particles of activated carbon granules

Ultrafine particles (UFPs) can result in serious damage to human health, and they cannot be easily removed from the atmospheric environment. A granular bed filter with activated carbon granules (ACs) can observably improve the filtration efficiency of UFPs removal due to their porosity. In order to study the relationship of pore size distribution of ACs and experimental conditions with the purification efficiency of UFPs removal, ACs were used as filtration materials, and the effects of granular size, bed thickness and superficial velocity on the removal efficiency were investigated in detail in this study. The experimental results showed that the average filtration efficiency could be enhanced from 41.87% to 86.27%, from 68.24% to 83.04% and from 49.39% to 89.29%, when the ACs sizes decreased from 2.50 mm to 0.45 mm, the superficial velocity decreased from 4.25 cm/s to 0.84 cm/s, and the filtration bed thickness increased from 20 mm to 100 mm. Moreover, a single ACs particle worked more robustly with bigger ACs, less thickness and lower velocity. There was thermal bounce when the particle size was smaller than 14.3 nm, which was mainly a result of the diffusion effect. However, the interception and inertial impaction played larger roles in filtration efficiency when the size of UFPs increased. Furthermore, the purification of UFPs was greatly influenced by the ACs pores below 500 nm, therefore it is favorable for porous materials with more of these pores to collect UFPs. © 2015, Editorial Board, Research of Environmental Sciences. All right reserved.