Characterization of Volatilization of Filter-Sampled PM2.5 Semi-Volatile Inorganic Ions Using a Backup Filter and Denuders

Abstract

The characteristics of the volatilization of semi-volatile inorganic ions sampled on a Teflon filter were investigated using a backup nylon filter and annular denuders. The volatilization ratio (VR) was defined as the fraction of the concentration at the backup filter and denuder to the sum of the concentrations collected at the Teflon filter, backup filter, and denuder. Particles whose aerodynamic diameters are less than or equal to 2.5 µm (PM 2.5 ) were sampled for 24 h each season from summer 2011 to spring 2012 at a site, about 35 km southeast of downtown Seoul. Increase in VR with increasing temperature was evident, but the effects of relative humidity were not clear, because seasonal variation in the two variables was correlated, and the variation in relative humidity was smaller than that in temperature. While VRs generally decreased with the amounts sampled on the Teflon filter, details of the volatilization behaviors varied among ions according to concentrations at the Teflon filter and VR. The removal of gaseous species at the upstream denuders affected VRs of semi-volatile ions by shifting the equilibrium among NH 4 + , NO 3 -, and SO 4 2-.

Effect of PM2.5 chemical constituents on atmospheric visibility impairment

“…Among the ions, sulfate has been found to be the maximum in summer, followed by ammonium and nitrate; however, in winter, ammonium has been found to be the maximum, followed by nitrate and sulfate. This is in accordance with observations from previous studies with sulfate being higher in summer and nitrate in winter, as ammonium nitrate is volatile in nature and thus has been lost in summer due to volatilization (Chatterjee et al 2010;Chow et al 2005;Kim, Choi, and Ghim 2015). In summer, the concentration of ions has been higher in the day than at night as the ionic formation is favored by high temperature and strong solar radiation (Zhang et al 2006).…”

Classification of diurnal patterns of particulate inorganic ions downwind of metropolitan Seoul

“…IC analysis of the extracts was carried out in the same way as for the PILS liquid samples. The detection limits of IC for filter samples, which used a 20-μl sample loop, in μg/m 3 (uncertainties in %) were 0.040 (4.9) for Cl − , 0.058 (4.2) for NO 3 − , 0.057 (3.3) for SO 4 2− , 0.062 (21.4) for Na + , 0.010 (15.5) for NH 4 + , 0.010 (8.8) for K + , 0.007 (10.8) for Mg 2+ , and 0.045 (7.4) for Ca 2+ , determined by seven blank samples (Kim et al, 2015). The 24-h averages of the PILS ion concentrations were compared with the sums of the concentrations from the Teflon filters, backup denuders, and Nylon filters.…”

Estimation of columnar concentrations of absorbing and scattering fine mode aerosol components using AERONET data

“…Sampling was conducted for 24 h, starting at ~10 A.M. The upstream configuration of a sampler for inorganic ions consisted of a PM 2.5 cyclone (URG‐2000‐30EH) followed by sodium carbonate‐ and phosphorous acid‐coated annular denuders (URG‐2000‐30x242‐4CSS) to remove acidic gases and gaseous NH 3 , respectively [ Yu et al ., ; Kim et al ., ]. A two‐stage filter pack (URG‐2000‐22FB) was equipped with a Teflon filter (Zefluor, Pall) to collect particles and a backup Nylon filter (Nylasorb, Pall) to capture acidic gases volatized from the particles.…”