Strongly and Loosely Bound Water in Ambient Particulate Matter—Qualitative and Quantitative Determination by Karl Fischer Coulometric Method

Abstract

Simple physical characterization of water evaporation can provide detailed information regarding its component distribution in particulate matter (PM) samples. The water presence in PM can greatly influence its polarity and subsequent reaction activity, for example, in secondary inorganic and organic matter formation. In this study, the presence of PM-bound water is detected using the Karl Fischer titration method in a temperature gradient with an aim to quantitatively assess different types of water occurrence. The analyses were initiated by testing two reference materials, namely urban particulate matter 1648a and urban dust 1649b (NIST). Four different types of water were found in both NIST materials, which helped to optimize the temperature ramp program and its adjustment for real PM samples. It was found that water contents in total suspended particles (TSP) are similar to those typically occurring in urban background stations—approximately 7.12–45.13% of the TSP mass, differentiated into the following water mass contributions: 48.5% of the total water found was loosely bound water; 23.3% was attributed to the absorption water; while the missing 20% could be probably attributed to crystal water removed only above 180 °C and artifacts connected with the drift correction problem. By comparing water release curves for single PM-compounds like pure SiO2; Al2O3; NH4NO3; (NH4)2SO4 and NH4Cl with water spectra obtained for real PM samples, it was found that water in particulate matter mainly comes from the dehydration of TSP-bound crystalline like Al2O3, SiO2 and to a lesser extent from salts like NH4NO3; (NH4)2SO4 and NH4Cl. A newly used thermal ramp method was able to assess water contents from Teflon–polypropylene baked filters characterized by low melting points and therefore filter degradation even under temperatures oscillating around 200 °C. The advantage of this new work is the separation of different types of TSP-bound water contributions, facilitating and promoting further research on the origin of PM-bound water and its role in atmospheric chemistry, secondary aerosol formation and visibility.

In-situ Measurement of Aerosol Water Content in an Urban Area Using a Sequential Aerosol-Water Measurement System (SAWMS)

“…Teflon filters were selected for their hydrophobic property, reducing the background water signal in the system. Widziewicz-Rzońca et al (2020) also showed that Teflon filters absorb less water than other filter materials. The flow rate in the sampling system was 16.7 L min -1 .…”

“…Several studies have measured particulate-bound water (PM-bound water) with the offline filter-based Thermal ramp Karl-Fisher (tr-KF) method (Canepari et al, 2013;Perrino et al, 2016;Widziewicz-Rzońca et al, 2020). In that method, Teflon filters are conditioned at 50% RH to investigate the PM-bound water of each chemical component (Perrino et al, 2016) and the characteristic strength (i.e., strongly or loosely) of the bound water (Widziewicz-Rzońca et al, 2020). Dai et al (2021) modified the Dry-Ambient Aerosol Size Spectrometer (DAASS) (Stanier et al, 2004) to estimate the AWC in-situ through the aerosol size change at different RH levels.…”

Fluid Characteristics of Biodiesel Produced from Palm Oil with Various Initial Water Contents

“…The iodine values of the tested biodiesel were determined by titration with 0.01 N sodium thiosulfate compound until the appearance of a light blue color. The water content in the biodiesel was analyzed using volumetric Karl Fischer titration (Model DL-31, Mettler-Toledo Inc., Greifensee, Switzerland), based on the coulometric method [9]. In order to determine the sample's moisture, the Karl Fischer solution was titrated into the biodiesel sample until the first trace of excess iodine appears.…”

“…% did not cause the variation of the yield of fatty acid methyl ester (FAME) at 130 • C. In contrast, some studies found that sufficient water content, such as 2.5 wt. %, in raw oil might enhance hydrolysis of fatty acids, which leads to activation of the transesterification reaction [9]. Sun et al [10] studied the effect of water content in wet Nannochloropsis oceanica on 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim][HSO 4 ])-catalyzed in situ transesterification.…”

Optymalizacja warunków oznaczania wody metodą miareczkowania kulometrycznego z odparowaniem dla olejów smarowych

“…Metodę piecykową stosowano także do analizy zawartości wilgoci w proszkach metali (Mellin et al, 2020), w próbkach 1-oktanolu nasyconego wodą, cementu, węgla i rafinowanego oleju (Margolis et al, 2004a), a także w filtrach cząstek stałych. W tym ostatnim przypadku metoda pozwoliła na ilościową ocenę różnych rodzajów wody (luźno związanej, absorpcyjnej i krystalicznej) (Canepari et al, 2013;Rogula-Kozłowska et al, 2017;Widziewicz-Rzońca et al, 2020). Margolis et al (2004b) wykorzystali metodę z odparowaniem do badania olejów smarowych.…”