This paper presents a novel approach for the sensitive detection of Cu(ii) ions in acidic industrial samples, used in the manufacture of printed circuits. The study outlines the synthesis and functionalization of Fe3O4 magnetic nanoparticles, emphasizing the optimization of parameters affecting Cu(ii) concentration measurements. The NPs are surface-modified with APTES and succinic acid and characterized through different methods including TEM imaging and FTIR analysis. A method employing the magnetic NPs for bulk preconcentration of Cu(ii) ions, followed by collection using a simple and home-made magnetic glassy carbon electrode (MGCE), is detailed. The electrochemical analysis showcases the efficiency of the proposed method for rapid and sequential measurements of Cu(ii) ions adequate for industrial matrices. Results demonstrate the potential of this approach for sensitive Cu(ii) sensing, offering a cost-effective and efficient alternative to conventional analytical techniques. Notably, the successful quantification of Cu(ii) concentrations in a real sample obtained from an acid industrial electroplating bath of CuSO4 highlights the practical applicability of the developed methodology.

This paper (part II) is devoted to the effect of molecular adsorption on the surface of magnetic iron oxide nanoparticles (IONP) on the enhancement of their (secondary) field-induced agglomeration and magnetic separation. Experimentally, we use Methylene Blue (MB) cationic dye adsorption on citrate-coated maghemite nanoparticles to provoke primary agglomeration of IONP in the absence of the field. The secondary agglomeration is manifested through the appearance of needlelike micron-sized agglomerates in the presence of an applied magnetic field. With the increasing amount of adsorbed MB molecules, the size of the field-induced agglomerates increases and the magnetic separation on a magnetized micropillar becomes more efficient. These effects are mainly governed by the ratio of magnetic-to-thermal energy α, suspension supersaturation Δ0, and Brownian diffusivity Deff of primary agglomerates. The three parameters (α, Δ0, and Deff) are implicitly related to the surface coverage θ of IONP by MB molecules through the hydrodynamic size of primary agglomerates exponentially increasing with θ. Experiments and developed theoretical models allow quantitative evaluation of the θ effect on the efficiency of the secondary agglomeration and magnetic separation.

Magnetic iron oxide nanoparticles have been recognized for use in various promising biomedical applications, such as detection of biological molecules, contrast agents in magnetic resonance imaging (MRI), vectors in drug delivery and mediators to convert electromagnetic energy to heat (hyperthermia). We reproduce a simple two-step reaction strategy for the synthesis of uniform magnetic iron oxide nanorods with ~50 nm in length and ~5 nm in diameter (Figure 1) and their colloidal stabilization with three different polymers (bisphosphonate polyoxyethylene-Optima 100, polymethacrylate polyoxyethylene-PCP45 and polyacrylic acid sodium salt-PAA) in water. Two-step reaction consists on synthesis of akaganeite followed by its transformation by reduction using hydrazine in microwave to obtain magnetic iron oxide nanorods [1]. The nanorods present the saturation magnetization value of 64 kA/m and residual magnetization of 15 kA/m, thus this material has ferro-or ferrimagnetic behavior. To estimate the iron oxide composition we use the technique of Mossbauer spectroscopy and a mixture of maghemite (strongly magnetic phase) with a quasi-amorphous intermediate phase (weakly magnetic phase) was detected, explaining a relatively low magnetization saturation. The suspensions of MNPs were probed by dynamic light scattering (DLS) and the distribution curve provides the Z-average hydrodynamic diameter equal 70±5 nm for Optima 100, 82±8 nm for PCP45 and 99±8 nm for PAA. We also study the effect of the polymer concentration and of the solution pH on the suspension stability. Figure 1: Transmission electron microscopy image of nanorods stabilized with Optima100 [1] Milosevic, I., Jouni, H., David, C., Warmont, F., Bonnin, D., and Motte, L. Facile microwave process in water for the fabrication of magnetic nanorods.

In this study, magnetic alginate nanoparticles (AlgMNP) were synthesized using a simple and green two-step method, which can be easily developed on an industrial scale. First, coprecipitation of both ferric and ferrous ions in alkaline medium followed by oxidation of magnetite into maghemite leads to a stable colloidal dispersion called ferrofluid. A sodium alginate solution was then added to the ferrofluid in order to obtain the magnetic nanocomposite. This approach combines the advantages of a biopolymer with magnetic properties of the maghemite nanoparticles. The morphology, structure, size and composition of the magnetic nanoparticles were characterized by means of atomic absorption spectrometry, transmission electron microscopy, X-ray diffraction, Fourier-transform-infrared spectroscopy and thermogravimetric analysis. Adsorption is one of the most efficient treatments for the removal of pollutants from wastewater. But the development of efficient and environmental friendly adsorbent still remains challenging. Using AlgMNP as a magnetic adsorbent could be a suitable response to this challenge. Its adsorption efficiency was investigated by using methylene blue as pollutant. The effects of pH, contact time, and initial concentration of the dye on adsorption were investigated. The high adsorption capacity with respect to the dye in a wide pH range (273 mg/g) was explained by the way magnetic nanoparticles bind to the alginate chains. We assumed an organization with alginate strands decorated by the magnetic nanoparticles leaving the adsorption sites of the particles more accessible rather than a configuration with a complete coating of magnetic nanoparticles by alginate. The reusability was successfully demonstrated through 10 adsorption/desorption cycles.

Protein imprinted polymers have received a lot of interest in the past few years because of their applications as tailor-made receptors for biomacromolecules. Generally, the preparation of these polymers requires numerous and time-consuming steps. But their coupling with magnetic nanoparticles simplifies and speeds up the synthesis of these materials. Some recent papers describe the use of protein imprinted polymer (PIP) coupled to magnetic iron oxide nanoparticles (MION) for the design of MION@PIP biosensors. With such systems, a target protein can be specifically and selectively captured from complex media due to exceptional chemical properties of the polymer. Despite such performances, only a limited number of studies address these hybrid nanosystems. This review focuses on the chemistry and preparation of MION@PIP nanocomposites as well as on the metrics used to characterize their performances.

A magnetic composite material composed of magnetic nanoparticles and clay encapsulated in cross-linked chitosan beads was prepared, characterized and used as a magsorbent for the removal of a cationic dye, methylene blue (MB), from aqueous solutions. The magnetic properties of these beads represent an advantage to recover them at the end of the depollution process. The optimal weight ratio R=clay:chitosan for the removal of MB in a large range of pH was determined. For beads without clay, the maximal adsorption capacity of MB occurs in the pH range [9], [10], [11], [12], while for beads with clay, the pH range extends by increasing the amount of clay to reach [3], [4], [5], [6], [7], [8], [9], [10], [11], [12] for R>0.5. Adsorption isotherms show that the adsorption capacity of magnetic beads is equal to 82 mg/g. Moreover, the kinetics of dye adsorption is relatively fast since 50% of the dye is removed in the first 13 min for an initial MB concentration equal to 100 mg/L. The estimation of the number of adsorption sites at a given pH shows that the main driving force for adsorption of MB in a large range of pH is the electrostatic interaction between the positively charged dye and the permanent negative charges of clay.

Wastewater cleaning strategies based on the adsorption of materials are being increasingly considered, but the wide variety of organic pollutants at low concentrations still makes their removal a challenge. The hybrid material proposed here consists of a zwitterionic polyethylenimine polymer coating a magnetic core. Polyethylenimine is phosphonated at different percentages by a one-step process and used to coat maghemite nanoparticles. It selectively extracts high amounts of cationic and anionic contaminants over a wide range of pH values, depending on the adjustable number of phosphonate groups introduced on the polymer. After recovering the nanoparticles with a magnet, pollutants are quantitatively released by repeated washing with low amounts of pH-adjusted water. The material can be reused many times without noticeable loss of efficiency and is designed to resist high temperatures, oxidation and harsh conditions.

We present a structural and a multi-scale rheophysical investigation of magneto-sensitive materials based on biopolymers, namely aqueous solutions of sodium alginate incorporating magnetic maghemite nanoparticles, functionalized with adsorbed negative citrate ions. The large alginate ionic strength impacts the structure and the rheology of these nanocomposites in zero magnetic field. In given physico-chemical conditions, the system is fluid and homogeneous on macroscopic scales while it is diphasic on microscopic ones, containing micro-droplets coming from the demixion of the system. These micro-droplets are liquid and deformable under magnetic field. Their under-field elongation and their zero-field relaxation are directly observed by optical microscopy to determine their interfacial tension, their magnetic susceptibility and their internal viscosity. A structural analysis of the solutions of alginate chains and of the phase-separated mixtures of alginate and nanoparticles by Small Angle Scattering completes the local description of the system.

An innovative magnetic delivery nanomaterial for triggered cancer therapy showing active control over drug release by using an alternative magnetic field is proposed. In vitro and In vivo release of doxorubicin (DOX) were investigated and showed a massive DOX release under an alternative magnetic field without temperature elevation of the medium.

A new magnetorheological cell is implemented to perform measurements of temperature-controlled flows and determine viscoelastic properties in magnetic complex fluids under applied continuous magnetic fields. The flow properties of water-based and oil-based ferrofluids with volume fractions up to 10 % are investigated here in various situations of interparticle interaction, leading also to various microstructures already known from previous works. Shear flow behaviors under magnetic fields resulting in a competition between magnetic and hydrodynamic forces are directly related to the microscopic structure of the probed magnetic fluids.

The paper focuses on the removal of p-nitrophenol by an adsorption process. A magnetic adsorbent was synthesized by encapsulation of magnetic functionalized nanoparticles using alginate as a green biopolymer matrix. A cationic surfactant, cetylpyridinium chloride (CPyCl), was used to confer a hydrophobic character to the magnetic beads and thus to promote their adsorption efficiency. The effect of different parameters such as initial concentrations of both PNP and CPyCl, contact time and solution pH value on the adsorption of PNP in the presence of CPyCl was investigated. It should be noted that combination of magnetic and adsorption properties in a same material is an interesting challenge which could overcome the recovery problems of pollutant-loaded adsorbent.

Novel partially phosphonated polyethylenimine polymers are developed in order to control the modification of nanoparticle (NP) surfaces. This polymer is built by an accessible one‐step process. The numerous phosphonate functions assume both a strong covalent anchoring on metal oxide NPs and a modulation of electric charges, while amino groups are associated with dispersion preservation and subsequent biofunctionalization. The zwitterionic nanomaterials obtained display a good stability toward pH and ionic strength. According to the selected percentage of phosphonation and the polymer size, zeta potential, and diameter of the particles are controlled.

In this study, magnetic beads were prepared by encapsulation of magnetic nanoparticles in epichlorohydrin cross-linked chitosan beads. Their adsorption characteristics were assessed by using methyl orange (MO) as an adsorbate. MO adsorption onto chitosan beads was found to be optimal in the pH range of 3-5. The adsorption isotherm was well described by the Langmuir model and showed high MO adsorption capacity (2.38 mmol/g, i.e. 779 mg/g). MO adsorption kinetics followed a pseudo-second-order kinetic model, indicating that adsorption was the rate-limiting step. At 0.305 mmol/L, only 19 min was required to reach 90% adsorption and 50% of the MO was adsorbed in 2 min. Desorption studies of MO using NaOH showed the reusability of the magsorbent. No release of iron species was observed at pH > 2.4. (C) 2013 Elsevier Inc. All rights reserved.

Maghemite nanoparticles (γ-Fe2O3 NP) and maghemite/silica nanocomposite microspheres (γ-Fe2O3/SiO2 MS) have been evaluated as magnetic heterogeneous Fenton catalysts. The catalysts were fully characterized by electronic microscopies, magnetometry, XRD, UV–vis–NIR spectroscopy, and sorption volumetry. It was found that the two materials differ in size, morphology, porosity and microstructure, although the maghemite nanoparticles are not modified by their encapsulation into the silica. Both catalysts have a strong magnetic susceptibility, but only the MS catalyst can be easily recovered by magnetic settlement. The mineralization and decolorization of aqueous solutions containing a model pollutant in presence of the catalysts were comparatively studied. Three model pollutants differing in their structure and their electrostatic charge were tested. The obtained reaction rates depend on the nature of the pollutant and catalyst. The results indicate the existence of a correlation between the amount of adsorbed pollutant and the decolorization rate. The free NP are usually more active than the MS catalyst, but larger velocity can also be obtained with the MS catalyst when the pollutant is strongly adsorbed on this material. Moderate mineralization rates were observed for both catalysts illustrating the larger stability towards oxidation of the uncoloured organic intermediates resulting from the primary degradation of the model pollutants. Moreover the efficiency and stability of the MS catalyst were established since this material showed an activity for a pollutant during five consecutive tests. This was also confirmed by characterization of the catalyst after these tests.

Nous présentons la synthèse par chimie verte de nanocomposites magnétiques qui pourraient être utilisés dans le traitement de l’eau. Ils sont constitués par une matrice de silice encapsulant des nanoparticules d’oxyde de fer. Outre les avantages liés à leur faible impact sur l’environnement, les méthodes de synthèse décrites ici ont conduit à des particules structurées sur plusieurs échelles de taille. Deux types de synthèse ont été étudiés. Des billes millimétriques parfaitement monodisperses ont été obtenues par voie sol-gel en utilisant comme agent structurant des biopolymères non-toxiques et biodégradables. Des microsphères ou des nanosphères magnétiques ont été préparées à l’aide de réactions sol-gel dans des émulsions à base d’huile végétale. Nous avons testé ces solides comme adsorbants magnétiques dans des procédés de dépollution des eaux utilisant la séparation magnétique. Nous montrons ici les premiers résultats quant à l’application de ces matériaux comme adsorbants de colorants et de métaux lourds après une éventuelle modification chimique de leur surface.

We present an eco-friendly synthesis of magnetic nanocomposites which may be used in water-treatment. They are composed of iron oxide nanoparticles encapsulated in a silica matrix. In addition to the benefits of their low environmental impact, the synthetic methods described here have led to particles structured on several scales. Two types of synthesis have been studied. Perfectly monodisperse millimetric beads were obtained by a sol-gel method using a non-toxic and biodegradable biopolymer as structuring agent. Microspheres or magnetic nanospheres were prepared using sol-gel reactions in emulsions of vegetable oil. We tested these solids as magnetic adsorbents for water-treatment processes with magnetic separation. Here we show the first results on the application of these materials as adsorbents for dyes and heavy metals after a possible chemical modification of their surface.

In this work, 6–12nm iron oxide nanoparticles were synthesized and coated with poly(acrylic acid) chains of molecular weight 2100gmol−1. Based on a quantitative evaluation of the dispersions, the bare and coated particles were thoroughly characterized. The number densities of polymers adsorbed at the particle surface and of available chargeable groups were found to be 1.9±0.3nm−2 and 26±4nm−2, respectively. Occurring via a multi-site binding mechanism, the electrostatic coupling leads to a solid and resilient anchoring of the chains. To assess the efficacy of the particles for pollutant remediation, the adsorption isotherm of methylene blue molecules, a model of pollutant, was determined. The excellent agreement between the predicted and the measured amounts of adsorbed dyes suggests that most carboxylates participate to the complexation and adsorption mechanisms. An adsorption of 830mgg−1 was obtained. This quantity compares well with the highest values available for this dye.

Magnetic nanoparticles (maghemite gamma-Fe2O3) functionalised with citrate ions were synthesised and characterised. These highly dispersible particles are stable in aqueous media and have a large surface area (170 m(2) g(-1)), which confers them a high number of active sites leading to a large ion loading capacity. The adsorption of Eu3+, La3+, Co2+ and Ni2+ ions from aqueous solution by these citrate-coated magnetic nanoparticles was studied. The maximum adsorption capacities determined by fitting experimental data with Langmuir model were close to 0.5 mmol g(-1) for the 4 cations studied. The kinetic study showed a rapid adsorption due to the presence of active sites on the external surface of the magnetic nanoparticles. The equilibrium time is 15 min at most and at least 83% of cations are adsorbed after 1 min. The effect of pH was also investigated. The adsorbed amount of cations increases drastically with pH from pH 2 to 3.5 and remains constant over pH 3.5. In addition, competitive adsorption was investigated. The adsorption capacity of the citrate-coated magnetic nanoparticles for both cations together (Eu3+/La3+ or Co2+/Ni2+) is similar to those obtained when each type of ion was present alone. These results show that these nanoparticles could be used in water treatment process for removal of pollutants. Indeed, this magnetic adsorbent is efficient and easily removed from the aqueous solution by applying a magnetic field. (C) 2011 Elsevier B.V. All rights reserved.