Mittag–Leffler Function as an Approximant to the Concentrated Ferrofluid’s Magnetization Curve

2021 ◽  
Vol 5 (4) ◽  
pp. 147
Author(s):  
Petr A. Ryapolov ◽  
Eugene B. Postnikov

In this work, we show that the static magnetization curve of high-concentrated ferrofluids can be accurately approximated by the Mittag–Leffler function of the inverse external magnetic field. The dependence of the Mittag–Leffler function’s fractional index on physical characteristics of samples is analysed and its growth with the growing degree of system’s dilution is revealed. These results provide a certain background for revealing mechanisms of hindered fluctuations in concentrated solutions of strongly interacting of the magnetic nanoparticles as well as a simple tool for an explicit specification of macroscopic force fields in ferrofluid-based technical systems.

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1870
Author(s):  
Dmitry Borin ◽  
Robert Müller ◽  
Stefan Odenbach

This paper presents the results of an experimental study of the influence of an external magnetic field on the shear flow behaviour of a magnetic fluid based on barium hexaferrite nanoplates. With the use of rheometry, the magnetoviscosity and field-dependent yield-stress in the fluid are evaluated. The observed fluid behaviour is compared to that of ferrofluids with magnetic nanoparticles having high dipole interaction. The results obtained supplement the so-far poorly studied topic of the influence of magnetic nanoparticles’ shape on magnetoviscous effects. It is concluded that the parameter determining the observed magnetoviscous effects in the fluid under study is the ratio V2/l3, where V is the volume of the nanoparticle and l is the size of the nanoparticle in the direction corresponding to its orientation in the externally applied magnetic field.


Nanomaterials ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 1238 ◽  
Author(s):  
Irena Ban ◽  
Sabina Markuš ◽  
Sašo Gyergyek ◽  
Miha Drofenik ◽  
Jasmina Korenak ◽  
...  

The synthesis of magnetic nanoparticles (MNPs) coated with hydrophilic poly-sodium-acrylate (PSA) ligands was studied to assess PSA-MNP complexes as draw solution (DS) solutes in forward osmosis (FO). For MNP-based DS, the surface modification and the size of the MNPs are two crucial factors to achieve a high osmolality. Superparamagnetic nanoparticles (NP) with functional groups attached may represent the ideal DS where chemical modifications of the NPs can be used in optimizing the DS osmolality and the magnetic properties allows for efficient recovery (DS re-concentration) using an external magnetic field. In this study MNPs with diameters of 4 nm have been prepared by controlled chemical co-precipitation of magnetite phase from aqueous solutions containing suitable salts of Fe2+ and Fe3+ under inert atmosphere and a pure magnetite phase could be verified by X-ray diffraction. Magnetic colloid suspensions containing PSA-coated MNPs with three different molar ratios of PSA:MNP = 1:1, 1:2 and 1:3 were prepared and assessed in terms of osmotic pressure, aggregation propensity and magnetization. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the presence of PSA on coated MNPs and pristine PSA-MNPs with a molar ratio PSA:MNP = 1:1 exhibited an osmotic pressure of 30 bar. Molar ratios of PSA:MNP = 1:2 and 1:3 lead to the formation of less stabile magnetic colloid solutions, which led to the formation of aggregates with larger average hydrodynamic sizes and modest osmotic pressures (5.5 bar and 0.2 bar, respectively). After purification with ultrafiltration, the 1:1 nanoparticles exhibited an osmotic pressure of 9 bar with no aggregation and a sufficient magnetization of 25 emu/g to allow for DS regeneration using an external magnetic field. However, it was observed that the amount of PSA molecules attached to the MNPs decreased during DS recycling steps, leaving only strong chelate-bonded core-shell PSA as coating on the MNPs. This demonstrates the crucial role of MNP coating robustness in designing an efficient MNP-based DS for FO.


2015 ◽  
Vol 16 (1) ◽  
pp. 229-236 ◽  
Author(s):  
Tripti Mishra ◽  
Sudipta Ramola ◽  
Anil Kumar Shankhwar ◽  
R. K. Srivastava

Forward osmosis (FO) is attracting worldwide attention as an emerging technology in the fields of power generation, water reuse, desalination, pharmaceuticals and food processing. Still, the critical challenge of finding a suitable draw solute for FO persists. Therefore the current research focuses on synthesizing hydrophilic magnetic nanoparticles (HMNPs) and systematically investigating their potential as draw solutes. HMNPs were synthesized using functional groups polyethylene glycol (PEG 400) and polyacrylic acid (PAA). These functional groups under different ratios with a metal precursor react by one-pot polyol and thermal decomposition methods respectively to give different diameter HMNPs. In addition the effect of different sizes of synthesized HMNPs was investigated for their recovery under an external magnetic field and reusability in FO performance. The physical properties and chemical compositions of the resultant MNPs are fully characterized. Transmission electron microscopy (TEM) analyses show the characteristics as spherical morphology with a narrow size distribution, and a mean size from 9 to 32.5 nm for PEG and 8 to 30 nm for PAA coated HMNPs depending on the ratio of the functional group and metal precursor. The PEG and PAA layer on the MNPs is confirmed by Fourier transform infrared (FTIR) analysis, and thermogravimetric analysis demonstrates a hydrophilic surface composition. The PEG and PAA coated HMNPs generate high osmotic pressures and exhibit good dispersibility in aqueous solutions. Water fluxes of >13 L m−2 h−1 are achieved across Hydration Technologies Inc. flat sheet membranes at a concentration of 0.05 M of HMNPs using deionized water as the feed solution. The HMNPs can be easily recaptured from draw solutions by applying an external magnetic field and recycling them back as draw solute in the FO process. The MNPs remain active after nine runs of recycling but with a total water flux decrease of 5% in PEG and 3% with each successive recycling due to slight aggregation, and reduced surface to volume ratio is observed. Results of the present study have demonstrated that PEG and PAA coated HMNPs can viewed as promising and potential draw solutes in the FO process.


2018 ◽  
Vol 464 ◽  
pp. 76-90 ◽  
Author(s):  
Anatolij M. Shuty ◽  
Svetlana V. Eliseeva ◽  
Dmitrij I. Sementsov

2012 ◽  
Vol 190 ◽  
pp. 725-728 ◽  
Author(s):  
Mikhail Chuev ◽  
Valery Cherepanov ◽  
Maxim P. Nikitin ◽  
Mikhail Polikarpov

In order to extract a quantitative information about characteristics of the magnetic nanoparticles injected into a living organism one has to define a model of the magnetic dynamics in order to fit self-consistently the whole set of the experimental data, particularly, the evolution of Mössbauer spectral shape with temperature and external magnetic field as well as the magnetization curves. We have developed such a model and performed such an analysis of the temperature-and magnetic field-dependent spectra and magnetization curves of nanoparticles injected into a mice. This allowed us to reliably evaluate changes in the residual nanoparticles characteristics and their chemical transformation to paramagnetic ferritin-like forms in different mouses organs as a function of time after injection of nanoparticles. Actually, the approach allows one to quantitatively characterize biodegradation and biotransformation of magnetic nanoparticles injected into a body.


2016 ◽  
Vol Volume 11 ◽  
pp. 6449-6458 ◽  
Author(s):  
Cynthia A Alvizo-Baez ◽  
Itza E Luna-Cruz ◽  
Natalia Vilches-Cisneros ◽  
Cristina Rodríguez-Padilla ◽  
Juan M Alcocer-González

2019 ◽  
Vol 43 (15) ◽  
pp. 5932-5939
Author(s):  
Marko Perić ◽  
Magdalena Radović ◽  
Marija Mirković ◽  
Aleksandar S. Nikolić ◽  
Predrag Iskrenović ◽  
...  

The advances in nanotechnology are directed towards the development of new theranostic agents based on magnetic nanoparticles that can be used for both cancer detection and treatment.


2021 ◽  
Vol 10 (1) ◽  
pp. 485-498
Author(s):  
Junpeng Tan ◽  
Ting Wang ◽  
Yong Li ◽  
Shenghui Xu ◽  
Simin Chen ◽  
...  

Abstract Organophosphorus pesticides are currently extensively applied on the control of agricultural and forestry pests. The number of poisonings and deaths caused by organophosphorus pesticides are increasing year by year. Because of the complex matrix, numerous interfering substances, and low poison content, pretreatment methods are crucial for the detection and analysis of such cases. As an adsorbent used for pretreatment, magnetic nanoparticles have the advantages of simple preparation, convenient modification, superparamagnetism, and hydrophilicity. Microextraction can be performed with small amount of magnetic nanoparticles in a short time, and the target substances can be separated with an external magnetic field. In this paper, the latest research achievements are reviewed. Based on the introduced characteristics and preparation methods of magnetic nanoparticles, this paper outlines the applications of different functionalized magnetic nanoparticles for the pretreatment of organophosphorus pesticides and predict the potential research prospects.


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