Observations on the unique phase transitions of inorganics relevant due to gluconic acid in particles

Zhu, Yue; Pang, Shu-Feng; Zhang, Yunhong

doi:10.1016/j.atmosenv.2022.119313

Cited by 2 publications

(1 citation statement)

References 62 publications

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“…As the RH further increases, the IR features of solid Na2SO4 weaken, almost disappears at 84.6% RH, indicating the deliquescence of Na2SO4. Similar unconventional behavior of "crystallization on hydration" was also observed for mixed 320 gluconic acid/(NH4)2SO4 and gluconic acid/NaCl aerosols using optical images, where solid (NH4)2SO4 and NaCl formed upon hydration (Zhu et al, 2022). Likewise, optical images of ST/(NH4)2SO4 were monitored to verify the phase and morphologies during an RH cycle.…”

Section: The Effect Of Molar Ratio To the Replacement Reaction And Ph...supporting

confidence: 56%

The Impact of Aqueous Phase Replacement Reaction on the Phase State of Internally Mixed Organic/ammonium Aerosols

Yang,

Dong,

Xia

et al. 2024

Preprint

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Abstract. Aerosol phase state is crucial for air quality, climate, and human health. Atmospheric secondary aerosols are often internally mixed with organic and inorganic components, particularly dicarboxylic acids, ammonium, sulfate, nitrate, and chloride. These complex compositions enable aqueous reaction between organic and inorganic species, significantly complicating aerosol phase behaviour during aging and making phase predictions challenging. We investigated carboxylate/ammonium salt mixtures using in-situ infrared spectroscopy. The di- and tri- carboxylates included sodium pyruvate (SP), sodium tartrate (ST), and sodium citrate (SC), while the ammonium salts included NH4NO3, NH4Cl, and (NH4)2SO4. Our results demonstrated that aqueous replacement reactions between carboxylates and ammonium salts was promoted by the formation and depletion of NH3 as relative humidity (RH) changed. Solid NaNO3, SP, and Na2SO4 formed in SP/ammonium aerosol at 35.7 %~12.7 %, 64 % and 65.5 %~60.1 % RH, respectively. In contrast, reactions between ST or SC and (NH4)2SO4 was incomplete due to the gel structure of SC or ST at low RH. Upon hydration, the deliquescence RH of Na2SO4 in SP/(NH4)2SO4 (88.8 %–95.2 %) and NaNO3 in SP/NH4NO3 (76.5–81.9 %) are higher than those of pure inorganic aerosols. Unexpectedly, aqueous Na2SO4 crystallized upon humidification in ST/(NH4)2SO4 particles at 43.6 % RH and then deliquesced with increasing RH. This is attributed to decreased viscosity and increased ion mobility, which overcome the kinetic inhibition of ion movement, leading to nucleation and growth of Na2SO4 crystal. Our findings highlight the intricate interplay between chemical components within organic/inorganic aerosol, the impact of replacement reactions on aerosol aging and phase state, and subsequently on atmospheric processes.

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Section: The Effect Of Molar Ratio To the Replacement Reaction And Ph...supporting

confidence: 56%

The Impact of Aqueous Phase Replacement Reaction on the Phase State of Internally Mixed Organic/ammonium Aerosols

Yang,

Dong,

Xia

et al. 2024

Preprint

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Direct observation for relative-humidity-dependent mixing states of submicron particles containing organic surfactants and inorganic salts

Xiong,

Kuang,

Zhang

et al. 2023

Atmos. Chem. Phys.

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Abstract. Aerosol mixing state plays an important role in heterogeneous reactions and cloud condensation nuclei (CCN) activity. Organic surfactants could affect aerosol mixing state through bulk–surface partitioning. However, the mixing state of surfactant-containing particles remains unclear due to the lack of direct measurements. Here, direct characterizations of the mixing state for 20 kinds of submicron particles containing inorganic salts (NaCl and (NH4)2SO4) and atmospheric organic surfactants (organosulfates, organosulfonates, and dicarboxylic acids) were conducted upon relative humidity (RH) cycling by environmental scanning electron microscopy (ESEM). As the RH increased, the surfactant shells inhibited water diffusion being exposed to the inorganic core, leading to notably increased inorganic deliquescence RH (88.3 %–99.5 %) when compared with pure inorganic aerosol. Meanwhile, we directly observed an obvious Ostwald ripening process (that is, the growth of larger crystals at the expense of smaller ones) in 6 out of 10 NaCl–organic surfactant systems. As a result of water inhibition by the organic surfactant shell, Ostwald ripening in all systems occurred at RH above 90 %, which were higher than the reported RH range for pure NaCl measured at 27 ∘C (75 %–77 %). As RH decreased, eight systems underwent liquid–liquid-phase separation (LLPS) before efflorescence, showing a strong dependence on the organic molecular oxygen-to-carbon ratio (O:C). Quantitatively, LLPS was always observed when O:C≤0.43 and was never observed when O:C>∼0.57. Separation RH (SRH) of inorganic salt–organic surfactant mixtures generally followed the trend of (NH4)2SO4 < NaCl, which is consistent with their salting-out efficiencies reported in previous studies. Solid-phase separations were observed after efflorescence for systems without LLPS. Our results provide a unique insight into the consecutive mixing processes of the inorganic salt–organic surfactant particles, which would help improve our fundamental knowledge of model development on radiative effect.

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Observations on the unique phase transitions of inorganics relevant due to gluconic acid in particles

Cited by 2 publications

References 62 publications

The Impact of Aqueous Phase Replacement Reaction on the Phase State of Internally Mixed Organic/ammonium Aerosols

The Impact of Aqueous Phase Replacement Reaction on the Phase State of Internally Mixed Organic/ammonium Aerosols

Direct observation for relative-humidity-dependent mixing states of submicron particles containing organic surfactants and inorganic salts

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