Deliquescence and efflorescence behavior of individual NaCl and KCl mixture aerosol particles

Li, Xue; Gupta, Dhrubajyoti; Eom, Hyo J.; Kim, Hyekyeong; Ro, Chul-Un

doi:10.1016/j.atmosenv.2013.10.011

Cited by 70 publications

(80 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The characteristic OH vibration signatures from in situ RMS indicated the formation of MgCl 2 q 4H 2 O, rather than thermodynamically stable MgCl 2 q 6H 2 O, due to a kinetic barrier to nucleation and structural growth with limited condensed water during the dehydration process. The NaCl-MgCl 2 mixture particles with NaCl-rich compositions of 0.05 ≤ X NaCl ≤ 0.9 mostly showed two-stage deliquescence: first, with the dissolution of eutonic components, and second, with the complete dissolution of NaCl, typical for two-component salt systems (Gupta et al, 2015;Li et al, 2014). The second DRH values approach the pure NaCl limit as the mole fraction of NaCl increases.…”

Section: Discussionmentioning

confidence: 83%

“…For particles of X NaCl = 0.1 and 0.2, the encountering frequencies of the type B particles are 29 and 45 %, respectively, and type C are 47 and 18 %, respectively, indicating that the formation of MgCl 2 q 6H 2 O-containing crystals is easier at these mixing ratios. Aqueous moieties in particles were reported to effloresce more easily by heterogeneous nucleation in the presence of seeds (Schlenker and Martin, 2005;Li et al, 2014;Gupta et al, 2015). For type C particles, the crystallization of MgCl 2 q 6H 2 O takes place at an ERH range of 23.7-11.9 % during dehydration (e.g., see Fig.…”

Section: Nacl-rich Particles Of Xmentioning

confidence: 99%

See 1 more Smart Citation

Hygroscopic behavior of NaCl–MgCl2 mixture particles as nascent sea-spray aerosol surrogates and observation of efflorescence during humidification

et al. 2015

View full text Add to dashboard Cite

Abstract. As Na + , Mg 2+ , and Cl − are major ionic constituents of seawater, NaCl-MgCl 2 mixture particles might represent sea-spray aerosols (SSAs) better than pure NaCl. However, there have been very few hygroscopic studies of pure MgCl 2 and NaCl-MgCl 2 mixture aerosol particles despite the MgCl 2 moiety playing a major role in the hygroscopic behavior of nascent SSAs. Laboratorygenerated pure MgCl 2 and NaCl-MgCl 2 mixture aerosol particles with 12 mixing ratios (0.01 ≤ mole fraction of NaCl (X NaCl ) ≤ 0.9) were examined systematically by optical microscopy (OM), in situ Raman micro-spectrometry (RMS), and scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDX) elemental X-ray mapping to observe their hygroscopic behavior, derive the experimental phase diagrams, and obtain the chemical micro-structures. Dry-deposited MgCl 2 q 6H 2 O particles exhibited a deliquescence relative humidity (DRH) of ∼ 33.0 % and an efflorescence RH (ERH) of 10.8-9.1 %, whereas the nebulized pure MgCl 2 and MgCl 2 -dominant particles of X NaCl = 0.026 (eutonic) and 0.01 showed single-stage transitions at DRH of ∼ 15.9 % and ERH of 10.1-3.2 %. The characteristic OHstretching Raman signatures indicated the crystallization of MgCl 2 q 4H 2 O at low relative humidities (RHs), suggesting that the kinetic barrier to MgCl 2 q 6H 2 O crystallization is not overcome in the timescale of the dehydration measurements. The NaCl-MgCl 2 mixture particles of 0.05 ≤ X NaCl ≤ 0.9 generally showed two-stage deliquescence: first at the mutual DRH (MDRH) of ∼ 15.9 %; and second with the complete dissolution of NaCl at the second DRHs depending on the mixing ratios, resulting in a phase diagram composed of three distinct phases. During dehydration, most particles of 0.05 ≤ X NaCl ≤ 0.9 exhibited two-stage efflorescence: first, by the homogeneous nucleation of NaCl; and second, at mutual ERH (MERH) of ∼ 10.4-2.9 %, by the crystallization of the MgCl 2 q 4H 2 O moiety, also resulting in three distinct phases. Interestingly, particles of X NaCl = 0.1 and 0.2 frequently showed three different types of mutual deliquescence behaviors. The first type exhibited an MDRH at ∼ 15.9 %. The second exhibited the first MDRH at ∼ 15.9 %, efflorescence to MgCl 2 q 6H 2 O (confirmed by in situ RMS) at RH of ∼ 16.1-25.0 %, and a second MDRH at ∼ 33.0 %. The third showed an MDRH at ∼ 33.0 %. Some particles of X NaCl = 0.1 and 0.2 also exhibited higher MERHs = 15.2-11.9 % and 23.7-15.3 %, respectively, forming MgCl 2 q 6H 2 O. These observations suggest that the presence of sufficient condensed water and optimally sized crystalline NaCl (X NaCl = 0.1 and 0.2) acting as heterogeneous nucleation seeds helps overcome the kinetic barrier, leading to the structural growth and crystallization of MgCl 2 q 6H 2 O. SEM/EDX elemental X-ray mapping showed that the effloresced NaCl-rich particles contain homogeneously crystallized NaCl in the center, surrounded by MgCl 2 q 4H 2 O. The observation of an aqueous phase over a wider RH range for NaCl-MgCl 2 mixture ...

show abstract

Section: Discussionmentioning

confidence: 83%

Section: Nacl-rich Particles Of Xmentioning

confidence: 99%

Hygroscopic behavior of NaCl–MgCl2 mixture particles as nascent sea-spray aerosol surrogates and observation of efflorescence during humidification

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Thermodynamically, as the phase transition of mixed-salts is governed by the water activity at the eutonic point, the MDRH of the mixed-salt particles is independent of the initial composition of the mixture. Other inorganic mixed particles, such as NaCl-KCl, Na 2 SO 4 -NaNO 3 and NH 4 Cl-NaCl particles, also exhibited a mutual deliquescence transition at RHs, which were independent of the initial dry-salt compositions, and the phase diagram followed the typical pattern for these two-component inorganic salt + water ternary systems (Tang and Munkelwitz, 1994a;Li et al, 2014;Kelly et al, 2008). For the NaCl-rich particles of X NaCl > 0.38, which contain more NaCl than the eutonic composition, the second DRH value approached the DRH of the pure NaCl salt as the NaCl concentration was increased.…”

Section: Deliquescence Phase Diagram Of Mixedmentioning

confidence: 96%

“…After the hygroscopicity measurements of the individual particles, SEM/EDX was performed for the effloresced particles to determine the morphology and spatial distribution of the chemical elements (Ahn et al, 2010;Li et al, 2014). The measurements were carried out using a Jeol JSM-6390 SEM equipped with an Oxford Link SATW ultrathin window EDX detector.…”

Section: Sem/edx Measurementmentioning

confidence: 99%

Hygroscopic properties of NaCl and NaNO3 mixture particles as reacted inorganic sea-salt aerosol surrogates

et al. 2015

View full text Add to dashboard Cite

Abstract. NaCl in fresh sea-salt aerosol (SSA) particles can partially or fully react with atmospheric NO x /HNO 3 , so internally mixed NaCl and NaNO 3 aerosol particles can co-exist over a wide range of mixing ratios. Laboratorygenerated, micrometer-sized NaCl and NaNO 3 mixture particles at 10 mixing ratios (mole fractions of NaCl (X NaCl ) = 0.1 to 0.9) were examined systematically to observe their hygroscopic behavior, derive experimental phase diagrams for deliquescence and efflorescence, and understand the efflorescence mechanism. During the humidifying process, aerosol particles with the eutonic composition (X NaCl = 0.38) showed only one phase transition at their mutual deliquescence relative humidity (MDRH) of 67.9 (±0.5) %. On the other hand, particles with other mixing ratios showed two distinct deliquescence transitions; i.e., the eutonic component dissolved at MDRH, and the remainder in the solid phase dissolved completely at their DRHs depending on the mixing ratios, resulting in a phase diagram composed of four different phases, as predicted thermodynamically. During the dehydration process, NaCl-rich particles (X NaCl > 0.38) showed a two stage efflorescence transition: the first stage was purely driven by the homogeneous nucleation of NaCl and the second stage at the mutual efflorescence RH (MERH) of the eutonic components, with values in the range of 30.0-35.5 %. Interestingly, aerosol particles with the eutonic composition (X NaCl = 0.38) also showed two-stage efflorescence, with NaCl crystallizing first followed by heterogeneous nucleation of the remaining NaNO 3 on the NaCl seeds. NaNO 3 -rich particles (X NaCl ≤ 0.3) underwent singlestage efflorescence transitions at ERHs progressively lower than the MERH because of the homogeneous nucleation of NaCl and the almost simultaneous heterogeneous nucleation of NaNO 3 on the NaCl seeds. SEM/EDX elemental mapping indicated that the effloresced NaCl-NaNO 3 particles at all mixing ratios were composed of a homogeneously crystallized NaCl moiety in the center, surrounded either by the eutonic component (for X NaCl > 0.38) or NaNO 3 (for X NaCl ≤ 0.38). During the humidifying or dehydration process, the amount of eutonic composed part drives particle/droplet growth or shrinkage at the MDRH or MERH (second ERH), respectively, and the amount of pure salts (NaCl or NaNO 3 in NaCl-or NaNO 3 -rich particles, respectively) drives the second DRHs or first ERHs, respectively. Therefore, their behavior can be a precursor to the optical properties and direct radiative forcing for these atmospherically relevant mixture particles representing the coarse, reacted inorganic SSAs. In addition, the NaCl-NaNO 3 mixture aerosol particles can maintain an aqueous phase over a wider RH range than pure NaCl particles as SSA surrogate, making their heterogeneous chemistry more probable.

show abstract

“…25 For determining the ERH values, dedicated experiments in a RH controlled environment are needed. 27,28 All the accelerated corrosion tests considered in this work, have a salt spray phase. The modeling of this phase is not included into the model, as runoff is a complex phenomenon.…”

Section: Physics and Modelmentioning

confidence: 99%

Comparing Modeled and Experimental Accelerated Corrosion Tests on Steel

Steen

Simillion

Thierry

et al. 2017

J. Electrochem. Soc.

View full text Add to dashboard Cite

Four different accelerated corrosion tests on steel are simulated with a Dynamic Electrolyte Film Corrosion model. Based on the time dependent temperature and humidity, combined with the presence of hygroscopic salts, a time dependent electrolyte thickness is calculated. At every timestep, the modeled film thickness dictates the corrosion current. Focussing on the thickness predictions, an elementary corrosion model is adopted to enable the corrosion depth estimations. The trends of the simulated corrosion depths are compared with experimental data obtained with an electrical resistance corrosion sensing system, demonstrating the importance of the electrolyte thickness and composition for a thorough understanding and modeling of atmospheric corrosion on steel.

show abstract

Deliquescence and efflorescence behavior of individual NaCl and KCl mixture aerosol particles

Cited by 70 publications

References 42 publications

Hygroscopic behavior of NaCl–MgCl<sub>2</sub> mixture particles as nascent sea-spray aerosol surrogates and observation of efflorescence during humidification

Hygroscopic behavior of NaCl–MgCl<sub>2</sub> mixture particles as nascent sea-spray aerosol surrogates and observation of efflorescence during humidification

Hygroscopic properties of NaCl and NaNO<sub>3</sub> mixture particles as reacted inorganic sea-salt aerosol surrogates

Comparing Modeled and Experimental Accelerated Corrosion Tests on Steel

Contact Info

Product

Resources

About

Deliquescence and efflorescence behavior of individual NaCl and KCl mixture aerosol particles

Cited by 70 publications

References 42 publications

Hygroscopic behavior of NaCl–MgCl&lt;sub&gt;2&lt;/sub&gt; mixture particles as nascent sea-spray aerosol surrogates and observation of efflorescence during humidification

Hygroscopic behavior of NaCl–MgCl&lt;sub&gt;2&lt;/sub&gt; mixture particles as nascent sea-spray aerosol surrogates and observation of efflorescence during humidification

Hygroscopic properties of NaCl and NaNO&lt;sub&gt;3&lt;/sub&gt; mixture particles as reacted inorganic sea-salt aerosol surrogates

Comparing Modeled and Experimental Accelerated Corrosion Tests on Steel

Contact Info

Product

Resources

About

Hygroscopic behavior of NaCl–MgCl<sub>2</sub> mixture particles as nascent sea-spray aerosol surrogates and observation of efflorescence during humidification

Hygroscopic behavior of NaCl–MgCl<sub>2</sub> mixture particles as nascent sea-spray aerosol surrogates and observation of efflorescence during humidification

Hygroscopic properties of NaCl and NaNO<sub>3</sub> mixture particles as reacted inorganic sea-salt aerosol surrogates