I have prepared Fe3O4 nanoparticles by co-precipitation method. Now i want to make them well dispersible in water at around neutral pH. They are not so well dispersible, what are the remedies?
Dear Namita
You need an hydrophillic surface. try to functionalize them with a molecule with a terminal OH moiety. Mercapto alcohols could work if they attach to the iron oxide surface, Another issue is the particle size, if they are very large they would precipitate at last. Have you tried for example with an emulsifier/surfactant such as TOPO, or some sulphonates. Let me know if it works! regards
HI , thanks a lot , I will follow the advice. They are simple Fe3O4 particles, I have not functionalised them. I wanted to see their dispersibility. I have used different pH media.
Hi, Instead of using Mercapto alcohols for functionalization, I suggest following silanization approach. e.g. see this paper. This way, you can make the surface hydrophilic, to see if it helps. But again, if the particle size is large, there may definitely be some sedimentation over a period of time.
http://www.sciencedirect.com/science/article/pii/S0304885311005981
pH must be adjusted at about 10 to disperse your particles in aqueous medium by surfactants ! But try ultrasound irradiation to disperse them for a limited time ( about 2 hours)
Once the surface is dry then it is very difficult to disperse the particles in a medium. Only adjusting pH and ultrasonication will not give stable suspension. What you can try is to activate the surface of particles with acidic medium wash, then follow the procedure of coating the surface with hydrophilic surfactant. Then you may have a good suspension. But again, dry magnetic particles has strong dipolar attraction. So it is very critical to separate them apart before coating. If you can make a good suspension then you will really solve a problem persisting from ages.
As Caballero-Briones mentioned, you need to coat your particles with a hydrophilic capping agent. For me, PVP worked very well. You can try the synthesis technique in my paper (see below). PVP provides steric stabilization and many researchers reported that PVP-coated NPs are very stable and will not aggregate.
https://www.researchgate.net/publication/281681716_Oil_Recovery_from_Water_under_Environmentally_Relevant_Conditions_Using_Magnetic_Nanoparticles
Article Oil Recovery from Water under Environmentally Relevant Condi...
Thanks Seyyedali, but I do not want to go for the polymers, instead want to use hydrophilic reagents, like with --COOH or - OH gr.
Stable Fe3O4 nanoparticles can be obtained by laser ablation of an iron target in pure water.
Use this simple method that can give you small particle size as well as good dispersibility in water ..
https://www.researchgate.net/publication/286639591_Water_dispersible_CoFe2O4_nanoparticles_with_improved_colloidal_stability_for_biomedical_applications
Article Water dispersible CoFe2O4 nanoparticles with improved colloi...
You can use this method to get water dispersed magnetic fluid for biomedical application.
J Mater Sci: Mater Med (2015) 26:202
hi ... can i disperse magnetic oxide nanoparticles in distilled water or ethanol
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