Horizontal low gradient magnetophoresis behaviour of iron oxide nanoclusters at the different steps of the synthesis route

Abstract

In this work the use of Horizontal Low Gradient Magnetic Field (HLGMF) (<100T/m) for filtration, control and separation of synthesized magnetic nanoparticles (NPs) is investigated. The characteristics of the suspension, size and type of the NPs are considered and discussed. For these purposes, Fe 2 O 3 silica coated nanoclusters of about 150 nm are synthesized by co-precipitation, monodispersion and silica coating. SQUID, TEM, XRD, and ζ potential techniques were used to characterize the synthesized nanoclusters. An extensive magnetophoresis study was performed at different magnetophoretical conditions. Different reversible aggregation times were observed at different HLGMF, at each step of the synthesis route. In particular, differences of several orders of magnitude were observed when comparing citric acid modified NPs with silica coated nanoclusters . Reversible aggregation times are correlated to the properties of the NPs at different steps of synthesis route.

Simple analytical model for the magnetophoretic separation of superparamagnetic dispersions in a uniform magnetic gradient

“…We consider here the case of a radial magnetic gradient, as in the experiments reported in Refs. [12,23,24]. In these experiments, an initially homogeneous dispersion of magnetic particles is placed inside a cylindrical cavity (of radius L) containing a uniform magnetic gradient pointing toward the walls of the vessel.…”

“…As explained in previous works [12,23], the experimental conditions consist of a dispersion of superparamagnetic particles (nanocrystals or composites) with radius R and magnetization per unit mass M(H ) that are immersed in a fluid with viscosity η at temperature T . Let us assume that, under these experimental conditions, the magnetophoretic separation is driven by the motion of the individual particles under the external magnetic field.…”

“…In all cases, our magnetophoretic separation experiments were performed using precision magnetophoresis systems from SEPMAG [33], the SEPMAG LAB 1 × 25 ml 2042 and 2042 plus (in both cases, L = 1.5 cm). The magnetophoresis kinetics is monitored by measuring the opacity of the sample, as in previous works [12,23,24] (we also describe again the full experimental methodology in the accompanying supplemental material). Here it suffices to say that the measured opacity (after appropriate normalization) provides a good estimate of the fraction f of particles remaining in solution.…”

“…In previous works [12,[22][23][24] we have made use of a new concept of magnetic separation (so-called precision magnetophoresis) to effectively remove different types of superparamagnetic nanoparticles from solution. The key aspect here is that the separation process is based on the application of a homogeneous magnetic gradient to drive the removal of the particles, enhancing the control of the experimental conditions.…”

Preparation of immobilized hexamine on Fe3O4/SiO2 core/shell nanoparticles: a novel catalyst for solvent-free synthesis of bis(indolyl)methanes

“…MNPs were prepared by co-precipitation method [17]. Therefore, a solution of FeCl 2 Á4H 2 O (1.27 g) in deionized water (25 mL) was added to a solution of FeCl 3 Á6H 2 O (3.80 g) in deionized water (25 mL), and the resulting solution was vigorously stirred.…”