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Superparamagnetic iron oxides nanoparticles from municipal solid waste incinerators

Funari, V., Mantovani, L., Vigliotti, L., Tribaudino, M., Dinelli, E., Braga, R.
The Science of the total environment 2018 v.621 pp. 687-696
X-ray diffraction, biosphere, combustion, electron microscopy, environmental assessment, incinerators, magnetism, magnetite, municipal solid waste, nanoparticles, sulfides, waste incineration
During their production, management, and landfilling, bottom (BA) and fly (FA) ashes from municipal solid waste incineration may liberate Fe-bearing, ultrafine particles and easily enter different environmental sinks of the biosphere. We aim to explore a collection of BA and FA samples from Italian incinerators to probe magnetic mineralogy and the fraction of harmful superparamagnetic (SP) nanoparticles (d<30nm). X-ray diffraction, electron microscopy observation, temperature- and frequency-dependent magnetometry, and Mossbauer analysis are performed. The integration of information from our rock magnetic and non-magnetic techniques leads us to conclude that the dominant magnetic carrier in our samples is magnetite and its intermediate/impure forms, while sulphides (i.e., monoclinic pyrrhotite) are important ancillary magnetic phases. The SP fraction fluxing from the BA and FA outputs of a single incinerator is detected and estimated in 103tons/year. This work stresses the need to calibrate the current technologies towards a safer management of combustion ashes and certainly to inform the environmental impact assessment by using a combination of different methods.