Development and characterization of a Thermal Denuder for estimation of Volatility Parameters of laboratory generated organic aerosols

In this study, detailed design and characterization of the KNU thermal denuder in the laboratory was presented. The effective heating length was approximately 70 cm with uniform centerline temperature profile. Temperature ramping rate was ~14.3^oC min^-1 for a set value in the range of 25^oC-150^oC. Experiments showed that aerosols reached equilibrium at residence time of approximately 24 s for adipic acid, succinic acid, and pimelic acid. Furthermore, integrated volume method was used to determine saturation vapor pressure (P⁰_sat) at 25^oC and enthalpy of vaporization (ΔH_v) of dicarboxylic acids such as adipic acid, succinic acid, and pimelic acid, aromatic compounds such as phthalic acid, and commercially available α-pinene SOA products such as cis-pinonic acid, keto-pinic acid using volatility profile data generated by coupling thermal denuder and scanning mobility particle sizer. Replicate experiments were performed for succinic acid and pinic acid. The experimental certainty was less than 5%. For adipic acid, succinic acid, pimelic acid, phthalic acid, pinic acid, and keto-pinic acid the determined values of ΔH_v and P⁰_sat were 146.1 kJ mol^-1, 86.5 ± 2.5 kJ mol^-1, 139.2 kJ mol^-1, 135.1 kJ mol^-1, 93.8 ± 1.8, and 136.6 kJ mol^-1 and 1.98 x 10^-5 Pa, 4.7 ± 0.7 x 10^-4 Pa, 8.91 x 10^-5 Pa, 8.15 x 10^-5 Pa, 1.6 ± 0.7 x 10^-4 Pa, and 5.81 x 10^-5 Pa, respectively. The estimated values of ΔH_v and P⁰_sat were comparable to the values reported in the literature