Optimization of microwave-solvothermal synthesis of Fe3O4 nanoparticles. Coating, modification, and characterization

Accepted Manuscript Optimization of microwave-solvothermal synthesis of Fe3O4 nanoparticles. Coating, modification, and characterization Aldahir Alberto Hernández-Hernández, Giaan Arturo Álvarez-Romero, Araceli Castañeda-Ovando, Yucundo Mendoza-Tolentino, Elizabeth Contreras-López, Carlos A. Galán-Vidal, María E. Páez-Hernández PII:

S0254-0584(17)30879-9

DOI:

10.1016/j.matchemphys.2017.11.009

Reference:

MAC 20129

To appear in:

Materials Chemistry and Physics

Received Date: 29 August 2017 Revised Date:

28 October 2017

Accepted Date: 5 November 2017

Please cite this article as: A.A. Hernández-Hernández, G.A. Álvarez-Romero, A. Castañeda-Ovando, Y. Mendoza-Tolentino, E. Contreras-López, C.A. Galán-Vidal, Marí.E. Páez-Hernández, Optimization of microwave-solvothermal synthesis of Fe3O4 nanoparticles. Coating, modification, and characterization, Materials Chemistry and Physics (2017), doi: 10.1016/j.matchemphys.2017.11.009. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Optimization of microwave-solvothermal synthesis of Fe3O4 nanoparticles. Coating, modification, and characterization Aldahir Alberto Hernández-Hernándeza, Giaan Arturo Álvarez-Romeroa, Araceli

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Castañeda-Ovandoa*, Yucundo Mendoza-Tolentinoa, Elizabeth Contreras-Lópeza, Carlos A. Galán-Vidala, María E. Páez-Hernándeza. a

Universidad Autonoma del Estado de Hidalgo, Chemistry Academic Area. Carr. Pachuca-

2512

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*Corresponding author: [email protected]

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Tulancingo km. 4.5, Mineral de la Reforma, Hgo. 42184. Tel: +52 (771) 7172000. Ext.

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Abstract In this research, magnetite nanoparticles were synthetized by the microwave-solvothermal method. The parameters related to this method were evaluated with: 1) the Plackett-Burman

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design, in order to evaluate the influence of the holding time [th] and the gradient time [tg] (reaction times) in the synthesis percent yield; and 2) the Box-Behnken design (BBD), selected in order to reduce the number of experimental experiences. In this last, the

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ammonium acetate amount (mmol) [th], and the microwave system temperature were optimized in order to achieve the smallest magnetite nanoparticles. Microwave assisted

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coating and modification with TMSPT/AMT were performed to the synthetized nanoparticles, in order to avoid degradation. The response variable considered for optimization of the synthesis was the nanoparticle’s size, which was estimated by X-ray diffraction. Temperature and th resulted to be the most important parameters affecting the

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nanoparticle’s size. The BBD allowed to obtain nanoparticle sizes between 10 and 32 nm. Polynomial validation was performed with confirmatory experiments considering the following conditions: T=255°C, th=10 min, tg=7 min, ammonium acetate amount=4.55

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mmol, Fe(III)=2 mmol, sodium citrate amount=1.55 mmol and ethylene glycol=6 mL. The obtained nanoparticles, with a size of 14 nm, were characterized by FT-IR, X-RD, SEM,

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and STEM.

Keywords: optimization, nanoparticles, coating, microwave-solvothermal synthesis, magnetite.

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1. Introduction There exist several methods for the synthesis of ferrite nanomaterials, such as sonochemical, non-hydrolytic, solvothermal, coprecipitation, sol-gel, and microwave

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assisted [1,2]. From these, the solvothermal method has been used for the synthesis of many types of nanoparticles by means of a liquid-solid reaction. This methodology was suggested by Wang et al. [3] where a metal linolate (solid), a liquid phase (ethanol/linoleic

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acid), and a methanol-water solution is mixed and treated under different hydrothermal conditions [4].

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A modification of this method has been reported by Deng et al. [5] for the synthesis of microspherical ferrites, this is based on the mixture of ferric chloride (FeCl3), ethylene glycol (reducing agent), sodium acetate (agglomeration inhibitor) and poly-ethylene glycol (surfactant), obtaining a clear solution which is heated inside an autoclave at 200°C for 8-

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72 h.

Many advantages for the solvothermal method have been already reported in literature, however, it has a very low reaction rate. In this way, Sreeja & Joy [6] proposed a

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modification using microwave heating in order to increase the crystal formation; in fact, they synthetized γ-Fe2O3 nanoparticles at 150°C for 25 min.

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The microwave-assisted method is considered fast, simple, with lower reaction times and with high-energy efficiency [1]; it has been used for preparing magnetic nanoparticles by different processes, such as sintering [7], solvothermal [6] and combustion [8]. On the other hand, coating and modification are processes used to prevent degradation of magnetic nanoparticles (MNPs). Among the many precursors used for this purpose, MNPs coated with 3-(trimethoxysilyl)-1-propanethiol (TMSPT) and subsequently modified with 2-amino-5-mercapto-1,3,4-thiadiazole (AMT) have been recently applied for magnetic

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solid-phase extraction of several analytes, such as heavy metals, aflatoxins, and polycyclic aromatic hydrocarbons (PAHs) in numerous matrices (biological, food and environmental) [9].

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Despite many methodologies have been reported for the microwave assisted synthesis of MNPs [10-12], robust optimization of these has not been considered, in order to make them more efficient. Additionally, coating and modification of MNPs by microwave assisted

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heating has not yet been reported in literature. This work describes a new approach for the synthesis, coating, and modification of magnetic nanoparticles by a microwave-

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solvothermal method, so nanomaterials can be obtained in less time. X-RD, FT-IR, SEM, and STEM were used for MNP characterization. A Box-Behnken design (BBD) was used to optimize and evaluate the effects of the synthesis parameters (temperature, ammonium acetate amount, and holding time) on the nanoparticle’s size (response), in order to reduce

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the number of experiments. The synthetized nanomaterials can be used as sorbents for extraction, preconcentration, and/or determination of several analytes in trace levels, including heavy metals and organic contaminants.

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2. Materials and methods 2.1. Reagents

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All reagents and chemicals used were analytical grade. TMSPT and AMT were purchased from Sigma-Aldrich (St. Louis, MO, USA). Ferric chloride hexahydrate (FeCl3·6H2O), trisodium citrate, ammonium acetate, ethylene glycol, dimethylformamide (DMF), and ethanol were acquired from J.T. Baker (Center Valley, PA, USA). 2.2. Instrumentation A Microwave Synthesis Monowave 300 from Anton-Paar (Graz, Austria) was used for the nanoparticles synthesis. X-ray powder diffraction (XRD, Equinox 2000) was used to

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estimate the MNPs size (coated and modified). MNPs were characterized using a Perkin Elmer FT-IR spectrometer model Spectrum GX (Shelton, CT, USA). SEM images were obtained using a JSM-6300 field emission scanning electron microscope (JEOL, Japan).

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STEM micrographs were registered with a field emission scanning electron microscope JSM-74101F (JEOL, Japan) equipped with a secondary electron detector (SEI) operating at 30.0 kV. Increases of 100,000 and 300,000x were made. STEM analysis was done to

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confirm the shape and final size of the synthesized MNPs (coated and modified) under the optimum conditions.

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2.3. Synthesis

Two experimental designs were used: 1) a factorial 22 design, to evaluate the effect of reaction times (gradient and holding); and 2) a Box-Behnken design (BBD) for optimizing the synthesis process. From both designs, the fixed factors were the amount of FeCl3·6H2O

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(2 mmol), trisodium citrate (1.55 mmol), and ethylene glycol (6 mL). 2.4. Reaction time effect

For evaluating the effect of the reaction times, a Plackett-Burman factorial design (22) was

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performed before the synthesis optimization. According with the experimental design, gradient time (tg, time required to increase temperature from Troom to Treaction), and holding

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time (th, time where the reaction temperature is maintained constant) can affect the synthesis process. Both tg and th were evaluated at 3 and 7 min. The synthesis yield percentage was considered as response factor. The experimental design matrix is shown in Table 1.

For each experiment (Table 1), FeCl3·6H2O (2 mmol), trisodium citrate (1.55 mmol), ammonium acetate (5 mmol), and ethylene glycol (6 mL) were mixed in a 30 mL reaction

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vial, and placed in the microwave equipment. The reaction was carried out under the experimental conditions described in Table 1. Once the reaction time is achieved, the obtained solid was separated with a neodymium

yield was obtained by stoichiometric calculations. 2.5. Synthesis optimization

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magnet (30000 Gauss), washed with ethanol (70% v/v), dried at 60°C, and weighted. The

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The methodology described by Li et al. [8] was used with some modifications. A BBD was used in order to optimize the particle size. The control factors were: ammonium acetate

reaction kinetics); and th (Factor C).

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quantity (Factor A, agglomeration inhibitor); reaction temperature (Factor B, favors the

Control factors levels are presented in Table 2. The fixed factors were the amounts of FeCl3·6H2O (2 mmol), trisodium citrate (1.55 mmol), ethylene glycol (6 mL), and tg (7

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min).

Once the experimental conditions were defined (Table 3), reagents were mixed, added into a reaction vial, and put in the carousel of the microwave synthesis equipment. When the

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synthesis is finished, the obtained solid was treated as previously described. Two replicates for each experiment were performed.

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2.6. Coating and modification

The magnetic solids were coated using the methodology reported by Mashhadizadeh et al. [13] with a modification. Magnetic solids were dispersed in 6 mL of TMSPT 10% (v/v) in ethanol. The mixture was microwave-heated at 135°C for 5 min. Then, the suspension was cooled to room temperature and washed with deionised water. The washing-decantation procedure was repeated five times to remove the excess of TMSPT.

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The coated magnetic particles were dispersed in 1 mL of AMT 1% (v/v) in DMF and sonicated for 5 min. Then, the magnetic solids were washed with 70% ethanol in water, and

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dried at 60°C.

2.7. Characterization

X-ray diffraction analysis was performed considering a Co Ka radiation source

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(Kα1=1.789010 Å) at 30 kV and 20 mA. A continuous scan mode was used to collect 2θ

Scherrer equation (Eq. 1): =

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data from 10° to 90°. The average crystallite size (τ) was calculated using the Debye–

(1)

where K is a shape factor (spherical) with value of 0.9, λ is the X-ray wavelength (Kα1=0.178 nm), β is the full width at half maximum (FWHM) of the diffraction peak in

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radians, and θ is the Bragg’s angle [14].

For SEM analysis, the MNPs were dispersed by sonication, using acetonitrile as dispersant

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to reduce the agglomeration due to strong magnetic interactions between particles. An elemental semi-quantitative analysis was done by Energy Dispersive Spectroscopy (EDS).

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For the STEM analysis, 1 mg of MNPs and 4 mL of acetone were mixed in a 5mL vial, and sonicated for 10 min to deagglomerate them. This dispersion was kept at rest for 15 min, then a sample was placed on a LC300-Cu grid (Lacey carbon support film on copper, 300 mesh).

Fourier Transform Infrared Spectroscopy (FT-IR) is used to obtain the absorption spectra with KBr discs (1:100) in the region 4000–400 cm−1. 3. Results and discussion

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3.1. Effect of reaction times A Plackett-Burman design was used for screening the microwave-solvothermal magnetite synthesis (without coating and/or modification) and for assessing the main effects of

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synthesis times (tg and th).

Table 1 shows the results of the design, in which, the response factor was the yield percentage. Subsequently, the appropriate statistical analysis was done and a Pareto chart of

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the standardized effects (Figure 1A) can be obtained. According with the Pareto chart, tg2 (Factor B) has a positive effect on the reaction yield; for this reason, it was fixed at 7 min

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for the microwave synthesis (Box-Behnken design).

Demazeau [15] considers that temperature is the most important factor in solvothermal processes since this parameter modifies the oxidation state of metals and helps to obtain specific structure and size for a particular material.

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In the same way, the assisted-microwave synthesis has an efficient energy transformation and a uniform heat distribution in the system [16]. Consequently, when the temperature was increased in a longer gradient time (tg), a higher yield percentage was obtained; this can be

synthesis.

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associated with a better temperature distribution in the system, improving the magnetite

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3.2. Optimization

Magnetite was coated with TMSPT and modified with ATM; particle size (response factor in the BBD used for the synthesis optimization) was measured in the obtained material. The functionalization of the magnetic particles with TMSPT/ATM has been already used for the magnetic dispersive microsolid-phase extraction (MDMSPE) of Ag, Cd, Cu, and Zn in environmental samples; [13] and aflatoxins B1 and B2 in cereal products [17].

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The synthesis mechanism of the modified coated Fe3O4-TMSPT-ATM was proposed by Mashhadizadeh and Karami [13], this is described in Figure 2. In the present work, the coating and modification processes were changed in order to reduce the synthesis time.

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Microwave and sonication were used to improve the process efficiency (less time). Also, DMF was used as solvent in the modification process (ATM solution) in order to improve the available amount of ATM to modify the surface of coated magnetite.

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According to Figure 2, amino (-NH2) and thiol (-SH) functional groups can interact with organic molecules or metal ions.

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XRD was used to identify the crystalline structure of the coated modified magnetic nanoparticles, the XRD pattern is shown in Figure 3A. Particle sizes were calculated using the Debye-Scherrer equation (Eq. 1) and used as response factor for the BBD (Table 3). When performing the BBD experiments, proper statistical analysis was carried out and a

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polynomial equation was obtained (Eq. 2), which represents the effect of each control factor on the response (particle size). Control factors were: A, mmol of ammonium acetate; B, temperature (°C); and C, holding time (th). An R2=0.7993 is obtained, which is relatively

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high, indicating good correlation between the experimental and the theoretical models. = 1643 + 0.244 − 12.7 + 1.8 + 0.000436

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− 0.00207

+ 0.00041

+ 0.0252

+ 0.0248

− 0.563 (2)

In accordance to Eq. 2, temperature (Factor B) has the main negative effect on the response, while th (Factor C) has the main positive effect. Demazeau [15] has already reported that temperature is the most important factor in solvothermal synthesis, since this parameter controls nucleation and helps the formation of a specific structure. Response surface and contour plots shown in Figures 1F and 1G show that the smallest particle sizes were obtained when temperature was kept in the central level

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(265°C), no matter the amount of ammonium acetate (Factor A). Therefore, temperature influences nucleation and nanoparticle’s size. On the other hand, Wei et al. [18] suggested that increasing the temperature or the reaction

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time, nanoparticles size and shape can be optimized. Considering that the solvothermal synthesis requires high temperatures and long reaction times, these can be decreased by microwave heating [19].

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Particle sizes were reduced at 265°C (temperature central level) and with times lower than 7 min, this was attributed to the temperature-time interaction effect. BBD experiments

3.3. Confirmatory experiments

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allowed to obtain particle sizes of coated and modified magnetite between 10 and 32 nm.

In order to evaluate the reliability of the theoretical polynomial model (Eq. 2), confirmatory experiments were performed by triplicate. The optimal synthesis conditions found were:

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T=255°C, tg=7 min, th=10 min, 4.55 mmol of ammonium acetate, 2 mmol of ferric chloride hexahydrate, 1.55 mmol of sodium citrate, and 6mL of ethylene glycol. Under these conditions, the coated and modified magnetite obtained had a particle size of 14.19 nm

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(%RSD=0.04). According with the statistical analysis, the predictive interval ranges between 5.71-26.72 nm (P=0.05); therefore, confirmatory experiments were considered

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within that range.

Solvothermal synthesis assisted by microwave has many advantages, for example: the kinetic reaction increases, the desired temperature is rapidly attained, selective crystallization and good reliability [10,20]. MNPs synthesis by the microwave-solvothermal method and the use of ammonium acetate as precursor had being reported by Kozakova et al. [19], however, the obtained particle size was of approximately 60 nm. With the proposed method, particle sizes lower than those

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reported previously can be achieved, and the synthesis, coating, and modification processes

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are carried out in lesser times (30 min, approximately).

3.4. Characterization 3.4.1. FT-IR

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A FT-IR spectrum for the TMSPT-AMT-Fe3O4 nanoparticles (Figure 3B) was obtained to confirm that nanoparticles are successfully coated and modified. The Fe–O characteristic

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band can be observed with a strong absorption at 581 cm-1 [21], while the two absorption peaks around 525 cm-1 and 450 cm-1 corresponding to the Fe–O bond for hematite are absent, [22]. These results corroborate that α-Fe2O3 is not present in the synthetized nanoparticles.

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The peak located at 3792 cm-1 could be related to the Si–OH bonds [23]. Also, a Si-O vibration band at 1134 cm-1 can be observed. The adsorption bands in 3079 and 2931 cm-1 are associated to the stretching vibration of =C-H and C-H, respectively. Bands near 3260,

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3302, and 1636 cm-1 exhibit the existence of N-H bonds. All these bands are related to the immobilization of TMSPT/AMT in the MNPs surface [24]. The FT-IR spectrum bands is in

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agreement with those bands reported previously for coated and modified magnetite with TMSPT/ATM [17,24,25]. 3.4.2. SEM

SEM micrographs for Fe3O4-TMSPT-ATM are shown in Figures 3B and 3C, at 2700x and 10000x, respectively. In Figure 3C, agglomerates can be observed (particle size ≈25µm), this can be associated to a high magnetic saturation. In Figure 3D, a homogeneous distribution can be observed, with an apparent particle size between 114 and 149 nm. Also,

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from SEM analysis it was possible to determine that the magnetic nanomaterial has cubic shape. Elemental components of the synthesized material were determined by EDS (Figure 3F).

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According with the obtained spectrum, Fe and O distributions were 10.09% and 28.97%, respectively. Si (1.72%), S (6.33%), C (40%), and N (12.88%) were also present, which are components of TMSPT and ATM. EDS analysis allowed to demonstrate that coating and

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modification processes were performed correctly.

On the other hand, elemental distribution analysis was carried out (Figure 3E), which

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demonstrated a homogenous distribution of iron, oxygen, sulfur, and silicon atoms in the magnetic materials. 3.4.3. STEM

STEM analysis was used to test the particle size of the magnetic materials. Micrographs at

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100000 and 300000x are showed in Figures 3G and 3H, respectively. Particle sizes around 10 nm were observed, which is very closed to those calculated by XRD. 4. Conclusions

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Magnetic nanoparticles were synthetized by the microwave-solvothermal method. Optimal conditions were stablished for the synthesis of magnetic materials with nanometric particle

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sizes, which can be used as extraction magnetic supports. The most important factors in the synthesis process were temperature and reaction times (gradient and holding). Synthesis, coating and modification processes were completely performed in 30 min; unlike other methods, which need about 24 h to be completed. FT-IR characterization allowed to test the coating and modification processes. XRD, SEM, and STEM analysis enabled to know some characteristics of magnetic nanomaterials, such as semi-quantitative composition, morphology, and particle size. The synthetized magnetic nanomaterials showed promising

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properties for their use as extraction supports in MDMSPE for a wide variety of chemical

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species, for example: heavy metals, food additives, pollutants, mycotoxins, etc.

Acknowledgements

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A.A.H.H. gratefully acknowledges to the Consejo Nacional de Ciencia y Tecnologia (Mexico) for the scholarship received. G.A.A.R., A.C.O., E.C.L., C.A.G.V., and M.E.P.H.,

Funding

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also thank Sistema Nacional de Investigadores for the stipend received.

This study was funded by the Consejo Nacional de Ciencia y Tecnologia (Mexico) [Project number CB-2013-220163].

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References

[1]. T. Tatarchuk, M. Bououdina, J.J. Vijaya, L.J. Kennedy. Spinel ferrite nanoparticles: Synthesis, crystal structure, properties, and perspective applications, in F. Olena, Y.

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Leonid (Eds.), Nanophysics, nanomaterials, interface studies, and applications, Springer International Publishing, 2016, pp.305-325.

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[2]. A. A. Hernández-Hernández, G.A. Álvarez-Romero, E. Contreras-López, K. AguilarArteaga, A. Castañeda-Ovando, Food analysis by Microextraction Methods Based on the Use of Magnetic Nanoparticles as Supports: Recent Advances. Food Anal. Methods 10 (2017) 2974–2993.

[3]. X. Wang, J. Zhuang, Q. Peng, Y.D. Li, A general strategy for nanocrystal synthesis, Nature. 437 (2005) 121-124.

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[4]. A. Lu, E.L. Salabas, F. Schuth, Magnetic nanoparticles: synthesis, protection, functionalization, and application, Angew. Chem. Int. Ed. 46 (2007) 1222-1244. [5]. H. Deng, X. Li, Q. Peng, X. Wang, J. Chen, Y. Li, Monodisperse magnetic single-

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crystal ferrite microsphere, Angew. Chem. Int. Ed. 44 (2005) 2782-2785.

[6]. V. Sreeja, P.A. Joy, Microwave-hydrothermal synthesis of γ-Fe2O3 nanoparticles and their magnetic properties, Mater. Res. Bull. 42 (2007) 1570-1576.

SC

[7]. E. Chandra Sekhar, B.R. Babu, K.V. Ramesh,·M. Sreenivasulu, Y. Purushotham, Structural, magnetic, and dielectric properties of conventional- and microwaveNi0.6Zn0.4−xCuxFe2O4.

J.

Supercond.

M AN U

sintered

Nov.

Magn.

(2017).

https://doi.org/10.1007/s10948-017-4264-5

[8]. T. Tatarchuk, M. Bououdina, W. Macyk, O. Shyichuk, N. Paliychuk, I. Yaremiy, B. Al-Najar, M. Pacia, Structural, optical, and magnetic properties of Zn-Doped

TE D

CoFe2O4 nanoparticles. Nanoscale Res. Lett. (2017) 12:141 [9]. M. Wierucka, M. Biziuk, Application of magnetic nanoparticles for magnetic solidphase extraction in preparing biological, environmental and food samples, Trends

EP

Anal. Chem. 59 (2014) 50–58.

[10]. Y. Zhang, R. Liu, Y. Hu, G. Li, Microwave heating in preparation of magnetic

AC C

molecularly imprinted polymer beads for trace triazines analysis in complicated samples, Anal. Chem. 81 (2009) 967–976.

[11]. Y. Hu, Y. Li, R. Liu, W. Tan, G. Li, Magnetic molecularly imprinted polymer beads prepared by microwave heating for selective enrichment of β-agonists in pork and pig

liver samples, Talanta. 84 (2011) 462–470. [12]. C. Li, Y. Wei, A. Liivat, Y. Zhu, J. Zhu, Microwave-solvothermal synthesis of Fe3O4 magnetic nanoparticles, Mater. Lett. 107 (2013) 23-26.

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[13]. M.H. Mashhadizadeh, Z. Karami, Solid phase extraction of trace amounts of Ag, Cd, Cu, and Zn in environmental samples using magnetic nanoparticles coated by 3(trimethoxysilyl)-1-propantiol

and

modified

with

2-amino-5-mercapto-1,3,4-

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thiadiazole and their determination by ICP-OES, J. Hazard. Mater. 190 (2011) 10231029.

[14]. B. Barfi, M. Rajabi, M.M. Zadeh, M. Ghaedi, M. Salvati-Niasari, R. Sahraei,

SC

Extraction of ultra-traces of lead, chromium and copper using ruthenium nanoparticles loaded on activated carbon and modified with N,N-bis-(α-

M AN U

methylsalicylidene)-2,2-dimethylpropane-1,3-diamine, Microchim. Acta. 182 (2015) 1187–1196.

[15]. G. Demazeau, Solvothermal and hydrothermal processes: the main physico-chemical factors involved and new trends, Res. Chem. Intermediat. 37 (2011) 107-123.

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[16]. C.O. Kappe, Controlled microwave heating in modern organic synthesis, Angew. Chem. Int. Ed. 43 (2004) 6250–6284.

[17]. M. Hashemi, Z. Taherimaslak, S. Rashidi, Application of magnetic solid phase

EP

extraction for separation and determination of aflatoxins B1and B2 in cereal products by high performance liquid chromatography-fluorescence detection, J. Chromatogr.

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B. 960 (2014) 200-208.

[18]. Y. Wei, B. Han, X. Hua, Y. Lin, X. Wang, X. Deng, Synthesis of Fe3O4 nanoparticles and their magnetic properties, Procedia Eng. 27 (2012) 632-637.

[19]. Z. Kozakova, I. Kuritka, N. E. Kazantseva, V. Babayan, M. Pastorek, M. Machovsky, P. Bazant, P. Saha, The formation mechanism of iron oxide nanoparticles within the microwave-assisted solvothermal synthesis and its correlation with the structural and magnetic properties, Dalton Trans. 44 (2015) 21099–21108.

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[20]. Z. Liu, F. Miao, W. Hua, F. Zhao, Fe3O4 nanoparticles: Microwave-assisted synthesis and mechanism, Mater. Lett. 67 (2012) 358–361. [21]. J. Yan, S. Mo, J. Nie,W. Chen, X. Shen, J. Hu, G. Hao, H. Tong, Hydrothermal

RI PT

synthesis of monodisperse Fe3O4 nanoparticles based on modulation of tartaric acid. Colloids and Surfaces A: Physicochem. Eng. Aspects 340 (2009) 109–114.

[22]. F. Davar, H. Hadadzadeh, T. S. Alaedini, Single-phase hematite nanoparticles: Non-

SC

alkoxide sol–gel based preparation, modification and characterization. Ceram. Int. 42 (2016) 19336–19342.

M AN U

[23]. G. Kafili, M.R. Loghman-Estarki, M. Milani, B. Movahedi, The effects of TEOS on the microstructure and phase evolutions of YAG phase by formation of alumina/yttria core-shell structures. J. Am. Ceram. Soc. 100 (2017) 4305–4316. [24]. M.H. Mashhadizadeh, M. Amoli-Diva, K. Pourghazi, Magnetic nanoparticles solid

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phase extraction for determination ofochratoxin A in cereals using high-performance liquid chromatography with fluorescence detection, J. Chromatogr. A. 1320 (2013) 17-26. Hashemi,

Z.

Taherimaslak,

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[25]. M.

S.

Rashidi,

Enhanced

spectrofluorimetric

determination of aflatoxin M1 in liquid milk after magnetic solid phase extraction,

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Spectrochim. Acta A Mol. Biomol. Spectrosc. 128 (2014) 583–590.

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Table 1. Experimental design matrix for Plackett-Burman factorial design (22).

Factors

Yield, B

%

1

3

7

72.01

2

3

3

72.44

3

1

7

4

1

5

1

6

3

7

1 3

74.58

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8

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A

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Experiment

7

56.44

3

90.26

3

93.05

3

81.39

7

82.87

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Factors: A, holding time (th, min); and B, gradient time (tg, min).

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Table 2. Levels of the control factors for Box-Behnken design.

Chosen levels

Control factors Description

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Factor C

1

Amount of CH3COONH4, mmol

3.90

5.20

6.50

Temperature, °C

255

265

275

th, min

5

7.5

10

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Factor B

0

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Factor A

-1

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Table 3. Experimental design matrix for Box-Behnken design.

Factors B

C

Particle size, nm

1

3.9

255

7.5

11.46

2

6.5

255

7.5

31.64

3

3.9

275

7.5

10.90

4

6.5

275

7.5

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5

3.9

265

5

10.71

6

6.5

265

5

12.96

7

3.9

265

10

13.23

8

6.5

265

10

15.89

9

5.2

255

5

12.33

10

5.2

275

5

10.17

5.2

255

10

11.21

5.2

275

10

11.59

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265

7.5

12.94

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265

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13.43

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265

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10.70

12 13 14 15

22.79

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Experiment

Factors: A, ammonium acetate quantity (mmol); B, reaction temperature (°C); C, holding time (min).

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Fig. 1. (A) Pareto chart of the standardized effects (α=0.05), where: Term A is tg1 and Term B is tg2. Reaction temperature vs th : response surface (B) and contour plot (C). Amount of ammonium acetate vs th: response surface (D) and contour plot (E). Amount of ammonium acetate vs reaction temperature: response surface (F) and contour plot (G).

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Fig. 2. Synthesis mechanism of the modified coated Fe3O4-TMSPT-ATM [9].

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Highlights Optimization of microwave-solvothermal synthesis of Fe3O4 nanoparticles was done.

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Coating and modification processes were carried out by microwave-assisted method.

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Synthesis, coating and modification processes were completely performed in 30 min.

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The nanoparticles (14 nm) were characterized by FT-IR, X-RD, SEM, and STEM.

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The nanomaterials showed promising properties for their use as extraction supports.

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