Characterisation of Nanomagnetites Co-Precipitated in Inert Gas Atmosphere for Plant Nutrition
A. Lengyel 1,2, Z. Homonnay 1, K. Kovács 1, Z. Klencsár 3, Sz. Németh 1, R. Szalay 1, V. Kis 3, Á. Solti 4, F. Fodor 4, M. Ristić 5, S. Musić 5 and E. Kuzmann 1
1 Institute of Chemistry, Eötvös University, Budapest, Hungary
2 Wigner Research Centre for Physics, HAS, Budapest, Hungary
3 Centre for Energy Research, HAS, Budapest, Hungary
4 Institute of Biology, Eötvös University, Budapest, Hungary
5 Ruđer Bošković Institute, Zagreb, Croatia
(homonnay@caesar.elte.hu)
Our future aim is to ascertain the effects of selected nanoparticles on plants of agricultural importance. In the future study we intend (a) to prepare the nanoparticles containing iron and (b) to obtain data about iron metabolism in the plant(s) and (c) to propose different iron utilization strategies in agriculture. In this sense the experiments involving the plants grown in hydroponics or soil conditions will be conducted. In our previous work [1] we reported about iron(III)-oxyhydroxide and non-stoichiometric magnetite nanoparticles with the aim to use them as possible nutrition source for plants. 57Fe Mössbauer spectra of magnetite nanoparticles synthesized under different preparation conditions at ambient atmosphere showed that the magnetite nanoparticles are highly oxidized. In order to obtain more efficient magnetite nanoparticles with higher FeII content, magnetite nanoparticles were prepared in N2 gas atmosphere. The chemical co-precipitation method was utilized, starting with stoichiometric ratio of FeSO4 and FeCl3 solutions for magnetite formation. Then, ammonia solution was slowly and continuously added to the iron salts solution. After the reaction was completed, the precipitates were filtered, washed several times with deionized water and lyophilized. Citric acid coated nanoparticles were also prepared similarly, but adding the citric acid dissolved in deionized water before the addition of ammonia solution. 57Fe Mössbauer spectra (Fig. 1) of washed and lyophilized nanomagnetite prepared in inert gas atmosphere undoubtedly indicated the presence of considerable fraction of FeII, close to the stoichiometric magnetite composition, both at room temperature (RT) and at 80K. XRD pattern of the same sample corresponded to nanomagnetite crystal structure. Mössbauer spectra in Fig. 1 also showed that after lyophilization the unwashed citric acid coated samples contained some FeII which disappeared when the sample was washed before lyophilisation. The washed samples, however, showed a poorly crystalline character.
Fig. 1 57Fe Mössbauer spectra of liophylized washed nano magnetite recorded at 80K (a) and at 295 K (b) and liophylized non-washed (c) and washed (d) citric acid coated nano iron oxides recorded at 80 K.
The samples are intended to be subject to tests using them as possible nutrition source for plants.
Financial support from the National Research, Development and Innovation Office - NKFIH/OTKA (K115913 and K115784) and Hungarian-Croatian Intergovernmental S & T (No. TET 16-1-2016-0002) is gratefully acknowledged.
[1] Z. Homonnay, Gy. Tolnai. F. Fodor, A. Solti, K. Kovács, E. Kuzmann, A. Ábrahám. E. Gy. Szabo, P. Németh, L. Szabo, Z. Klencsár, Hyperfine Interact (2016) 237:127