Large Variations in Hygroscopic Properties of Unconventional Mineral Dust

Abstract

Unconventional mineral dust, such as fly ash, road dust, and industrial dust, could significantly contribute to fine particulate matters; however, their hygroscopicity remains largely unexplored. In this work, a vapor sorption analyzer and a diffusion reflectance infrared Fourier transform spectroscopy (DRIFTS) were used to examine hygroscopic properties of 11 unconventional mineral dust samples as a function of relative humidity (RH) at 25 °C, including two municipal waste fly ash, one oil fly ash, one road dust, and seven coal fly ash. Large variations in hygroscopicity were observed for the 11 samples, and mass ratios of adsorbed water to the dry samples at 90% RH were found to vary from 0.0003 to 0.7340, showing positive dependence on both water-soluble ion contents and BET surface areas. In addition, hygroscopicity of the 11 unconventional mineral dust samples examined could be well described by the Freundlich adsorption isotherm model, with A F and B F parameters found to be in the range of 3.5 × 10–4–1.29 and 0.12–1.58, respectively. Our study would significantly improve our knowledge of hygroscopicity properties of unconventional mineral dust.

Water Adsorption on Hydroxyapatite and Struvite as a Function of Relative Humidity: Application of BET and Freundlich Adsorption Models

“…The terms x and m denote the mass change (in mg) and the total dry sample mass (in mg), while P / P 0 denotes the relative pressure of the adsorbate gas. The Freundlich equation has been applied over a wide variety of adsorption reactions, and it is applicable for both solid–liquid and solid–gas interfaces. ,,, The Freundlich equation was applied to the two linear regions in the low RH region (0–20%) and high RH range (25–60%).…”

“…The Freundlich equation has been applied over a wide variety of adsorption reactions, and it is applicable for both solid−liquid and solid−gas interfaces. 1,5,76,77 The Freundlich equation was applied to the two linear regions in the low RH region (0− 20%) and high RH range (25−60%). Water as Relative Humidity Adsorption Thermodynamics.…”

“…The understanding of environmental water vapor uptake as a function of relative humidity (RH) on the crystalline materials of anthropogenic origin containing nitrogen (N) and phosphorus (P) in the form of NH 4 + and/or PO 4 3– ions remains very low compared to that on the natural minerals, which are chiefly comprised of oxides/hydroxides or carbonates. − Recent studies investigated water uptake as relative humidity on certain complex anthropogenically derived combustion products, such as fly ash, − that can become incorporated into mineral dust and affect the atmospheric environment, climate, and hydrological cycles. Emission flux and atmospheric loading of these combustion process-generated particles, chiefly coal fly ash, account for ∼300 million U.S. tons annually, while natural minerals have been estimated to reach some 2 billion U.S. tons annually. ,, Importantly, both natural and anthropogenic particles have been shown to undergo environmental processing, such as atmospheric transport and aging, and contribute significant sources of nutrients to the environment . For example, mineral dust was shown to be an important external source of phosphorus to the ocean or Amazon rainforest .…”

“…Emission flux and atmospheric loading of these combustion processgenerated particles, chiefly coal fly ash, account for ∼300 million U.S. tons annually, while natural minerals have been estimated to reach some 2 billion U.S. tons annually. 5,8,9 Importantly, both natural and anthropogenic particles have been shown to undergo environmental processing, such as atmospheric transport and aging, and contribute significant sources of nutrients to the environment. 10 For example, mineral dust was shown to be an important external source of phosphorus to the ocean 11 or Amazon rainforest.…”

Contrasting effects of secondary organic aerosol formations on organic aerosol hygroscopicity

“…Note that the hygroscopicity parameter was (Luo et al, 2020;Jing et al, 2018), and those of potassium chloride and ammonium bisulfate were consistent with Liu et al (2014) Note that Cl − was coupled with K + due to the fact that biomass burning events prevailed during this field campaign. The simple volume mixing rule called Zdanovskii-Stokes-Robinson (ZSR) was usually used for κ chem calculations; that is, bulk κ chem of PM 1 can be calculated on the basis of volume fractions of different compounds (Petters and Kreidenweis, 2007) using the following equation:…”