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 this research the effects of surfactant concentration and its addition time in the synthesis procedure of kerosene based FERROFLUID were investigated. Magnetite nanoparticles were prepared by co-precipitation method and were dispersed in Kerosene as carrier liquid. Oleic acid was used as surfactant. Powder X-ray diffraction was used to phase identification and crystallite size was calculated via scherrer formula. For investigating of surfactant adhesion on particles Fourrier transform infrared spectroscopy was used. Magnetic properties were studied using alternative gradient force measurement. Size and distribution of agglomerates were studied by dynamic laser scattering. Results show that addition of surfactant before reaction effectively prevents from agglomeration. If oleic acid is added about 10wt% before reaction, hydrodynamic size and particle size will be 21nm and 13nm respectively. It was revealed that the size of agglomerates and their distribution are effectively changed when the concentration and addition time of surfactant is changed.

Here, the sensitivity of the Casimir force in a three-layer microsystem is investigated by considering a FERROFLUID as the middle layer and plates with different optical properties via Lifshitz theory. The plate materials are made of gold (Au), silica (SiO2), and silicon carbide (SiC) to cover a wide range of conductivity. It is observed that by changing the plates from a good conductor to a poor conductor, the magnitude of the Casimir force decreases significantly, and if the gap between the plates is filled with a liquid layer, this decrease is even greater. The results show that the presence of a FERROFLUID, formed by adding ferric oxide (Fe3O4) magnetic nanoparticles to kerosene (C12H26-C15H32), leads to a reduction in the Casimir force. Moreover, increasing the nanoparticle concentration (at a constant diameter) causes a significant decrease in the Casimir force, while increasing the nanoparticle diameter (at a constant concentration) strengthens the Casimir force. The results indicate that the optical properties of the plates have a significant impact on this behavior. It has also been observed that at a fixed distance between the plates, the addition of magnetic nanoparticles with a specific diameter has no effect on the magnitude of the Casimir force compared to the case where the middle layer of fluid is nonmagnetic, and considering this point is very important in the design of microelectromechanical systems (MEMS) that operate under magnetic effects.

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.

This investigation purposes to study the magnetic fluid based squeeze film behavior on transversely rough stepped plates with the influence of couple stress. Using the well-known stochastic model of Christensen and Tonder the roughness effect has been evaluated. The magnetic fluid flow model of Neuringer-Roseinweig has been adopted to obtain the influence of magnetization. The governing Reynolds’ type equation is derived on the basis of stokes microcontinum theory for couple stress fluid. For the expression of pressure distribution, the stochastically averaged Reynolds’ type equation is solved. which results in calculation of load carrying capacity. The graphical outcomes also presented in tabular form suggest that although the bearing suffers on account of roughness, the magnetization and couple stress effect save the situation, as this combination does not allow the load carrying capacity to fall rapidly. However, in the case of negatively skewed roughness the magnetization goes a long way in dropping the adversarial influence of roughness by selecting an appropriate value of couple stress parameter when variance (-ve) is involved. It is found that the couple stress effect, alone may not be sufficient to counter the negative influence of transverse roughness and porosity. However, in almost all situations the FERROFLUID lubrication adds significantly to the positive effect of couple stress to overcome the adversarial outcome of porosity and roughness. Further, the position of step plays a vital role for an all-round enhancement of the bearing performance.