“Nanocomposites and nanomaterials”

Nanostructured aerosols containing magnetite and -iron 
for low-temperature ozone decomposition
T.L. Rakitskaya1, A.S. Truba1,2, A.A. Ennan2, V.Ya. Volkova1
1Faculty of Chemistry, Odessa I.I. Mechnikov National University.
St. Dvoryanskaya 2, 65082, Odessa, Ukraine. E-mail: tlr@onu.edu.ua
2Physico-Chemical Institute of Environment and Human’ Protection.
 St. Preobrazhenskaya 3, 65086, Odessa, Ukraine. 

Nanostructured compositions containing magnetite (Fe3O4) and -iron (-Fe) were obtained by welding of steel using a bare welding wire of Sv08G2S (ER70S-6) type in CO2 as a shielding gas. The wire had the following composition (wt. %): Fe (97.2), Mn (1.51), Si (0.92), Cu (0.2), and C (0.08). With the help of an electromechanical filter, three fractions of the solid component of welding aerosol were obtained. The first fraction (CD) was picked up from a corona discharge zone, the second fraction (PE) – from a perforated electrode, and the third fraction (GE) – from a grid electrode. The samples of each fraction were characterized by X-ray phase and FT-IR spectroscopy, water vapor adsorption, and pH-metry and also were tested in the reaction of ozone decomposition at the initial ozone concentration,, of 1.0 mg/m3. Table demonstrates values of the time of protective action (MPC) shown by CD, PE, and GE fractions in this testing. The main parameters of Fe3O4 and -Fe phases prevailing in CD, PE, and GE fractions are also presented in Table. The contents of these phases were estimated based on their integral intensities and their crystallite sizes (D) were calculated using the Scherrer equation. From the experimental data, it has been found that magnetite phase is responsible for the activity of the two-component, Fe3O4 + -Fe, composition. 

SCWA fraction	Phase	Phase content, weight %	D, nm	MPC, min	
CD	Fe3O4	61.4	58	80	
	-Fe	31.3	59		
PE	Fe3O4	91.2	58	360	
	-Fe	8.8	28		
GE	Fe3O4	92.2	45	140	
	-Fe	5.0	42