The effect of surface coatings on the dustiness of a calcium carbonate nanopowder
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Six calcium carbonate nanopowders that had been functionalized (coated) to enhance their use in a range of industrial applications were compared to the uncoated nanopowder (15–30-nm size range) from which they were made. The nanopowders were first characterized using the standard gravimetric rotating drum dustiness test (EN 15051 2006). All the functionalized powders showed a substantial increase in dustiness compared with the uncoated sample. The largest increase was some ×45, ×90 and ×331 higher for the inhalable, thoracic and respirable fractions, respectively, and would potentially give rise to much higher exposures to workers handling these powders. This article also investigated a range of additional measurement methods to extend the standard dustiness test to measure the particle size distribution and particle number concentrations. Several online instruments were compared in two sets of tests, as well as, offline transmission electron microscopy analysis. The results of these tests are discussed to assess the suitability and limitations of the measurement methods and to assess the best approach for extending the current gravimetric standard to include number concentration and size distribution measurements. It was concluded that questions remain over the performance characteristics of online charge detection instruments such as the FMPS and ELPI for dustiness testing, and such issues need to be resolved before a standardized test can be finalized.
KeywordsDustiness testing Nanopowder Nanoparticles Functionalization Calcium carbonate
The study was carried out as part of the EU-funded NANODEVICE Project and describes the results collected at HSL. The study forms part of a sub-project of WP3 carried out in collaboration with a number of partners including: Keld Alstrup Jensen and Ismo Kalevi Koponen at Arbejdsmiljoforskning, Copenhagen, Denmark; Timo Tumoni and Tomi Kanerva Finish Institute of Occupational Health, Helsinki, Finland; Minamari Vippola at Tampere University, Tampere, Finland; Christoph Asbach and Burkhard Stahlmecke of the Institute for Energy and Environmental Technology (IUTA), Germany; Oliver Witcher and co-workers at Instiute der National de Recherche et de Securite, Nancy France; and Elsbieta Jankowska, Cenral Instytut Ochrony Pracy—Panstwowy Instyttut Badawczy, Poland. A special thanks are due to Michel Barker and Diane Ciaparra at Tata Steel Europe, Swinden Technology Centre for the loan and support for the ELPI measurements. This publication and the study it describes were funded by the GB Health and Safety Executive, the Health and Safety Laboratory and the EU 7th Framework programme grant agreement no. CP-IP 211464-2. Its contents, including any opinions and/or conclusions expressed, are those of the authors alone, and do not necessarily reflect HSE or EU policy. © British Crown copyright (2011).
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