In this work, a stable NiFe2O4 paraffin based FERROFLUID was prepared via high energy milling. The rheological properties of FERROFLUID were studied. Bingham plastic, Herschel-Bulkley and Casson models were used to evaluate the shear stress-shear rate dependency. The FERROFLUID exhibited a shear thinning behaviour for all studied magnetic field. The magneto-viscous effect and thixotropy of FERROFLUID were studied and the role of formation and destruction of magnetically induced structures and the interactions of nanoparticles and aggregates were discussed.

Tri-ethylene glycol (TEG) coated Fe3 O4 nanoparticles FERROFLUID were used for Pb (II) removal from simulated wastewater. The samples were synthesized using a modified co-precipitation method. The prepared samples were characterized by different techniques including X-ray diffraction, Rietveld method, FTIR, FESEM, TEM, VSM, TGA, BET, and atomic adsorption experiments. The crystallinity of nanoparticles with a cubic spinel ferrite structure and absence of impurity phases were verified using X-ray diffraction and the Rietveld method. The presence of TEG was approved by FTIR and thermogravimetric analysis. The VSM results indicated that the bonding between the TEG molecules and ferrite nanoparticles reduces the surface spin disorder, influences the morphology and magnetization, and consequently increases the Pb (II) removal efficiency to a high value of 97%. The obtained high value of adsorption capacity of q=363. 4 mg. g-1 with R= 91 % and q=129. 4 mg. g-1 with R=97 % shows the effective role of TEG coating on Pb (II) adsorption. The interesting results of this study imply that the TEG-coated FERROFLUID sample is a suitable candidate for practical applications.

In the present work, stable FERROFLUIDs containing oleic acid capped magnetite nanoparticles were synthesized via low temperature hydrothermal method. The physical and chemical properties of the synthesized particles were studied using TEM, XRD, AFM, VSM and PCS techniques. Mean particles size of the samples was between 4. 5 and 10 nanometers, depending on experimental conditions. Effect of precursor’ s medium alkalinity was investigated on particle size. Cell culture experiments performed via MTT assay demonstrated that this product was biocompatible. In addition, cellular uptakes were investigated by Prussian blue staining and also measuring Fe concentration by inductively coupled plasma spectroscopy. Finally, the synthesized particles were dispersed in the Ethiodol and the obtained suspension was used as a potential MRI contrast agent. To the best of our knowledge, the mentioned procedure of using a non-aqueous based MRI contrast agent has been done for the first time in the present work and provides good capabilities as opposed to aqueous ones including reduced synthesis process time and increased magnetic properties of the obtained contrast agent.