Particle size distributions and hygroscopic restructuring of ultrafine particles emitted during thermal spraying

Journal article (2020)

Authors

A. Salmatonidis Universitat Politecnica de Catalunya, IDAEA-CSIC
Mar Viana IDAEA-CSIC
G. Biskos Atmospheric Remote Sensing - CEG , The Cyprus Institute
Spyros Bezantakos Universite du Littoral Cote d'Opal, The Cyprus Institute
Research Group
Atmospheric Remote Sensing (CEG) (TU Delft)
Copyright: © 2020 A. Salmatonidis, M. Viana, G. Biskos, S. Bezantakos
DOI
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https://doi.org/10.1080/02786826.2020.1784837
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Published Date

2020

Language

English

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Faculty

Civil Engineering & Geosciences

Department

Geoscience and Remote Sensing

Research Group

Atmospheric Remote Sensing

Abstract

We report measurements of the size, concentration, and hygroscopicity of ultrafine particles (UFPs) emitted during thermal spraying of ceramic coatings in an industrial setting. High concentrations (i.e., higher than 106 cm−3) of fractal-like UFPs were measured inside the spraying booths of the facility. The emitted UFPs were found to take up small amounts of water when exposed to elevated relative humidity (RH = 87%) within a Hygroscopic Tandem Differential Mobility Analyzer (HTDMA) system. The hygroscopicity of the sampled particles was distinguishably lower compared to those of the atmospheric background aerosol particles present in the breathing air. UFPs smaller than 90 nm that are produced by the thermal spraying process, exhibit hygroscopic factors less than unity in a systematic way. This behavior indicates that the particles were irregularly shaped at dry conditions, and that they underwent a shape change (i.e., restructuring) upon humidification inside the HTDMA. The fractal-like structure of process-emitted UFPs was further corroborated by Transmission Electron Microscopy (TEM) conducted on samples collected at dry conditions on site.