Purely Inorganic Highly Efficient Ice Nucleating Particle

Abstract

To evaluate the role of atmospheric heterogeneous reactions on the ice nucleation ability of airborne dust particles, we investigated the systematic study of ice nucleation microphysics with a suite of atmospherically relevant metals (10), halides (4), and oxyhalides (2). Within a minute, a kaolin–iron oxide composite (KaFe) showed efficient reactions with aqueous mercury salts. Among the different mercury salts tested, only HgCl 2 reacting with KaFe generated HgKaFe, a highly efficient ice nucleating particle (HEIN). When added to water, HgKaFe caused water to freeze at much warmer temperatures, within a narrow range of −6.6 to −4.7 °C. Using a suite of optical spectroscopy, mass spectrometry, and microscopy techniques, we performed various experiments to decipher the physical and chemical properties of surface and bulk. KaFe was identified as a mixture of different iron oxides, namely, goethite, hematite, magnetite, and ε-Fe 2 O 3 , with kaolin. In HgKaFe, HgCl 2 was reduced to Hg 2 Cl 2 and iron was predominantly in maghemite form. Reduction of Fe 2+ by NaBH 4 , followed by aerial oxidation, helped KaFe to be an exact precursor for the synthesis of HEIN HgKaFe. Kaolin served as a template for synthesizing iron oxide, opposing unwanted aggregation. No other metal or metal halide was found to have more efficient nucleating particles than HgCl 2 with KaFe composite. The chelation of Hg(II) hindered the formation of HEIN. This study is useful for investigating the role of morphology and how inorganic chemical reactions on the surface of dust change morphology and thus ice nucleation activity. The understanding of the fundamentals of what makes a particle to be a good ice nucleating particle is valuable to further understand and predict the amount and types of atmospheric ice nucleating particles.

Natural Kaolin: Sustainable Technology for the Instantaneous and Energy‐Neutral Recycling of Anthropogenic Mercury Emissions

“…Solutions were sonicated for 20 min for ice nucleation for drop–freezing experiments. For each sample, 10 μL droplets were placed on a Pelletier cooling plate (in‐house‐made copper plate) and the plate (which started at approximately 0 °C) was cooled at a rate of 1 °C min −1 . The temperature at which each droplet froze was observed by the naked eye and recorded.…”

“…Kaolin contaminated with CuCl 2 was a highly efficient adsorbent, able to take up gaseous elemental Hg within seconds at room temperature (16.33 mg g −1 of Cu from inductively coupled plasma mass spectrometry analysis). Previously, we synthesized Fe composite BHFe from the reduction of FeCl 2 by NaBH 4 followed by aerial oxidation. BHFe is an efficient Hg II adsorbent and produced a highly efficient ice‐nucleating particle HgBHFe (maghemite@Hg 2 Cl 2 ) after the uptake of HgCl 2 .…”

“…Microphysics of ice nucleation to obtain furtherinsightso n potential reaction mechanism(s) Kaolin contaminated with CuCl 2 was ah ighly efficient adsorbent, able to take up gaseous elemental Hg within seconds at room temperature (16.33 mg g À1 of Cu from inductively coupled plasma mass spectrometry analysis). Previously, [27,28] we synthesized Fe composite BHFe from the reductiono fF eCl 2 by NaBH 4 followed by aerial oxidation. BHFe is an efficient Hg II adsorbenta nd produced ah ighly efficient ice-nucleating particle HgBHFe (maghemite@Hg 2 Cl 2 )a fter the uptake of HgCl 2 .I th as www.chemsuschem.org thus been shown that ionic Hg (in associationw ith Cl À )e nhanced the ice nucleation efficiency of BHFe significantly.…”

“…For each sample, 10 mLd roplets were placed on aP elletier cooling plate (in-house-made copper plate) and the plate (which started at approximately 0 8C) was cooled at ar ate of 1 8Cmin À1 . [27] The temperature at which each droplet froze was observed by the naked eye and recorded. Before the addition of the droplets, at hin layer of petroleum jelly was spread on the copper plate to minimize the reaction between the copper plate and the drops and to maintain hydrophobicity.…”

Using spectra characteristics to identify ice nucleating particle populations during winter storms in the Alps

“…Plant bacteria such as Pseudomonas syringae are deemed omnipresent in the atmosphere and precipitation (Despres et al, 2012;Stopelli et al, 2017;Morris et al, 2014), and facilitate cloud ice formation up to −1 °C (Despres et al, 2012). While, only a few laboratory-based studies have reported known inorganic or mineral materials that ice nucleation activity at such temperatures (Ganguly et al, 2018;Atkinson et al, 2013). Mineral and soil dust serving as atmospheric shuttles for organic microbial fragments can be transported thousands of kilometres and serve as effective INPs, even from highly arid regions such as the Sahara (Kellogg and Griffin, 2006), yet the exact origin of the ice nucleation germ forming at the warmest temperatures is speculated to be due to the ice binding proteins or macromolecules of the biological components (O'Sullivan et al, 2014;O'Sullivan et al, 2016;Conen and Yakutin, 2018).…”