I was trying to synthesise Fe/Fe oxide naoparticle through green rout ( plant mediated). On adding and stirring the plant extract to precursor the solution changed colour to dark red and fine precipitate settled at the bottom. should I centrifuge the solution for nanoparticle? Some papers report that the fine precipitate was collected and washed for isolating nanoparticle. I am confused?
The formation of Fe/Fe-oxide nanoparticles depends on the redox ability of your plant extract. Generally iron precursors are formed color solutions and in slightly basic medium formed color precipitate of Fe-hydroxides, goethite's etc. It is very difficult to predict the product by seeing the color change during reactions without FTIR, EDX, and XRD analysis.
Extracts of plants containing reductants flavonoids and others are used for the reduction of copper ions, silver platinum, gold, standing in a series of redox potentials after hydrogen. These are weak reducing agents and they do not reduce iron ions. I have not seen articles on this topic. You get iron oxide. They are obtained by the action of ammonium hydroxide on iron salts. Why do you need a plant extract? in this case it can only perform the role of the suspension stabilizer.
There is a good chance of getting iron oxide nano-particles most probably as FeOOH. You need to age the precipitate for several days and then remove supernatant occasionally and rinse with water several times to remove any dissolve materials. Finally, dry the precipitate well and characterize with XRD to see which phase of iron oxide is formed. Good luck!
Thank you for the suggestion Md. Abdur Rahman , Yuri Mirgorod & Md. Aminul Islam .
I have come across a few papers were zero valent Fe was synthesised by plant mediated synthesis (http://www.ijpsonline.com/articles/green-synthesis-of-iron-nanoparticles-using-aqueous-extract-of-musa-ornata-flower-sheath-against-pathogenic-bacteria.pdf) though synthesis of Fe oxide is reported more often.
Most of them do seem to vary pH so may be the role of plant extract is more as a capping agent?
Will age, rinse and dry the precipitate and check the phase with XRD . Is there any probability that if I centrifuge the supernatant I might find Nanoparticle?
I agree with Prof. Mirgorod. It is unlikely that plant extract can reduce iron cation to metallic iron.Even if you use stronger reducing agent than the plant extract, it is difficult to keep Fe(0) nanoparticles in solution without some protection.
Perhaps some extracts, for example nicotine in a tobacco extract, have basic properties and can react with salts to form hydroxides. Hydroxides are then converted to oxides.
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