Hygroscopic Properties of Internally Mixed Particles of Ammonium Sulfate and Succinic Acid Studied by Infrared Spectroscopy

Abstract

Atmospheric aerosols typically consist of inorganic and organic material. Although the organic fraction can affect the behavior of mixed organic/inorganic particles, their physical properties are not well-understood. In this work, infrared spectra of internally mixed submicrometer particles of ammonium sulfate and succinic acid have been studied at ambient temperature in an aerosol flow cell. The spectra of dried particles show distinct features relative to the pure components, as a result of ion-molecule interactions between the inorganic and organic species. The hygroscopic behavior of the particles has been followed for several organic/inorganic mass ratios, showing that around equimolar composition, the mixed particles uptake water in a broad range of relative humidities (30-80%), substantially lower than the deliquescence relative humidity of the mixed system near 80%. Infrared spectra at predeliquescence relative humidities reveal that succinic acid is partially or completely in the liquid phase at much higher concentrations that those corresponding to a saturated solution of succinic acid. This behavior is proposed to arise from the ion-molecule interactions between the organic and inorganic components, which unstabilize the crystal structure relative to the pure solids and cause loss of translational order in the crystal, bringing about an increase in the Gibbs energy of the solid particles and allowing the uptake of water molecules prior to the deliquescence point. The obtained results show that water absorption prior to full deliquescence in this system has to be taken into account because it extends the range of relative humidities at which particles are partially or completely liquid.

The effect of low solubility organic acids on the hygroscopicity of sodium halide aerosols

“…The configuration of the experimental setup used in this work is based on a previously described system (Minambres et al, 2010) that has been modified for the present study. The main elements are depicted in Fig.…”

An analysis of diurnal cycles in the mass of ambient aerosols derived from biomass burning and agro‐industry

“…[40] A final consideration is that the hygroscopic behavior of particles of mixed composition, containing inorganic species together with soluble organic compounds, can differ from that of single-component aerosols. There is no clear consensus in the literature, with both increases and decreases in DRH values having been reported for mixed aerosols, compared to those containing inorganic substances alone [Choi and Chan, 2002;Miñambres et al, 2010;Wu et al, 2011;Zhang et al, 2011]. The chemical measurements (Table 2) showed that WSOC contributed 66.5%, on average, to the total mass of the soluble aerosol species measured, so that the existence of internal mixtures of inorganic compounds and WSOC could potentially affect aerosol growth rates.…”

Chemical and thermal profile of Plectranthus amboinicus essential oil for its application as a bioherbicide

“…Furthermore, the authors demonstrated a higher productivity in the cultivation of P. sativum using 25% P. amboinicus leaf extract. Several biological activities have previously been attributed to the isomeric chemotypes thymol and carvacrol, such as antifungal activity [33][34][35][36], insecticide, phytotoxic among others [33,37].…”