10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Generation of Iron Oxide Nanoparticles for Follow-up Exposure Studies by MOCVD
PAVEL MORAVEC, Jaroslav Schwarz, Petr Vodička, Jaroslav Kupčík, Jaroslav Švehla, Institute of Chemical Process Fundamentals of the CAS, v.v.i
Abstract Number: 464 Working Group: Materials Synthesis
Abstract Iron oxide nanoparticles (NPs) are industrially produced and commercially available and they are also frequently emitted into the environment by iron making plants. In the human body, iron is maintained at homeostatic fairly low level. However, freshly generated iron oxide NPs cause febrile and inflammatory response known as metal fume fever, but the potential in vivo consequences of inhalation of iron oxide NPs from the atmosphere has not yet been investigated. In this study we tested a method of long lasting generation of iron oxide NPs by pyrolysis and oxidation of ironIII acetylacetonate (FeAA3).
Experiments were performed in an externally heated work tube with i.d. 25 mm and 1 m long heated zone. A stream of nitrogen carrier gas, saturated by precursor vapours in a saturator (QS), was fed into the reactor, where it was mixed either with a stream of nitrogen (pyrolysis) or a mixture of nitrogen and air (oxidation). A stream of NPs laden gas (QR) was diluted in the outlet part of the work tube by a diluting stream (QDil) of nitrogen (pyrolysis) or air (oxidation). The particle production was studied in dependence on reactor (TR) and saturator temperature (TS), and on flowrates QS, QR and QDil, and NPs production was monitored using SMPS (TSI model 3936L75). Samples for NPs characterization were deposited onto TEM grids, using a nanometer aerosol sampler (TSI model 3089) and on cellulose, quartz, and Sterlitech Ag filters. The particle characteristics were studied using HRTEM (JEOL 3010), energy dispersive spectroscopy (INCA/Oxford connected to JEOL 3010), selected area electron diffraction (JEOL 3010), inductively coupled plasma – optical emission spectrometry (Agilent 4200 MP-AES), elemental and organic carbon analysis (EC/OC, Model 4, Sunset Laboratory) and X-ray diffraction (Bruker D8 Discover diffractometer).
Two experimental campaigns in total duration 100 and 80 hours were performed. The NPs production was studied in the range of TR: 500-800 °C, TS: 134-141 °C, QR: 1400-1500 cm3/min, QS: 120-200 cm3/min and QDil: 1600-1700 cm3/min. Results have shown that NPs generation by oxidation of FeAA3 at TR 700 or 800 °C suits for long term inhalation exposure experiments. The generation provides NPs production rate sufficiently high (up to 2400 μg/m3, i.e. 7.7 μg/min) and can be further increased by an increase of TS or/and QS, and it is stable at steady state conditions for sufficiently long time. Primary particle size is typically between 10-20 nm, the content of Fe varies from 58.7 to 59.6 wt. %, which corresponds to 84.0 – 84.7 wt. % of Fe2O3. NPs are free of EC and contain only 3.6 – 5.2 wt. % of OC. Both XRD and SAED method identified cubic Fe2O3 crystalline phase, Pdf 32-0469. On the other hand, NPs generation by pyrolysis does not seem to be perspective method for exposure experiments due to poorly defined characteristics of NPs. They contain a lot of EC (32.2 – 37.7 wt. %), the content of Fe varies between 22 and 52 wt. % and because the NPs are amorphous, it is very difficult to identify the form of Fe in NPs.
This work was supported by the Czech Science Foundation under grant P503/12/G147. XRD analyses were performed by Mgr. Petr Mikysek, Geological Institute of the CAS, and EC/OC analyses by Mgr. Věra Procházková, Institute of Chemical Process Fundamentals of the CAS.