Green synthesis of iron oxide nanoparticles using aqueous extract of cabbage leaves

Abstract

It is proposed a simple, reliable, inexpensive and environmentally friendly technological method of synthesis of nanoparticles of iron oxide – food additive E172. The use of the principles of green chemistry for the controlled synthesis of nanoparticles with different dispersions is based on the use of plant extracts. White cabbage was chosen as a vegetable raw material for the production of iron oxide nanopowder due to its availability, ease of processing, and cheapness. It is shown that the presence of substances in the aqueous extract of cabbage leaves that exhibit regenerative properties, in particular polysaccharides, organic acids, phenolic compounds, flavonoids, has a positive effect on the processes of phase formation and the particle size of the final product. It was established that the process of synthesis of pigment iron oxide in solution is initiated not only by temperature, but also by the redox reaction that occurs between the nitrate anion of iron salt and organic components in the extract of cabbage leaves. The analysis of the dry residue after evaporation and the powder after additional heat treatment at 650 °С was carried out by the methods of thermogravimetry (TG) and differential thermal analysis (DTA), IR spectroscopy and X-ray diffraction. According to the results of the differential thermal analysis of the dry residue after evaporation of a solution of iron (III) nitrate in the presence of an aqueous extract of white cabbage, the transition Fe₃O₄ → γ-Fe₂O₃ → α-Fe₂O₃ was recorded. The methods of X-ray powder diffraction and IR spectroscopy confirmed that the studied sample after calcination at 650 °C is α-modified iron oxide with a hematite structure. It was established that, depending on the amount (volume) of the extract taken, it is possible to adjust the dispersity of the iron oxide powder and, as a result, to controlled change the shade of the pigment.