Development and performance test of a thermo-denuder for separation of volatile matter from submicron aerosol particles

In this study we designed and evaluated a home-made thermo-denuder (TD) both experimentally and numerically. Sodium chloride (NaCl) particles, toluene gas, and carbon black particles were used for the performance evaluation of the TD. The TD was evaluated for various set-point air temperatures and particle sizes using the following three parameters: the temperature profile, penetration efficiency, and gas adsorption efficiency. At 0.6lmin-1, the temperature was nearly uniform, remaining within ±15∘C of the set-point temperature, in the heating section and decreased to the temperature of ambient air in the cooling section. The particle penetration efficiencies were 93–96% at 20∘C and 58–67% at 300∘C for particle sizes of 20–60 nm. The gas adsorption efficiency was nearly unity until the breakthrough time of 65 h, and the total amount of toluene adsorbed by activated carbon particles was 72 mg-toluene/g-activated carbon particles. From size distribution measurements of dry carbon black and toluene enriched carbon black particles, the mode diameter measured at the set-point temperature of 300∘C was found to be 48.6 nm, which agreed with the one obtained from the dry particle measurements. The overall number concentration obtained after particle losses were compensated was lower than that measured without using the TD by 35.6%, which was caused by gas adsorption in the TD.