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Properties analysis of Dextrane magnetic carrier compounds used for wastewaters treatment

Andra Mihaela Predescu1, a, Ecaterina Matei2,b, Cristian Pantilimon3,c, Claudia Drăgan4,d, Cristian Predescu5,e

1[anonimizat], nr. 313, building J, room JF002, Sector 6, Bucuresti, 060042 Romania

[anonimizat], [anonimizat] (corresponding author), [anonimizat], [anonimizat], [anonimizat]

Keywords: [anonimizat], [anonimizat].

Abstract

The paper describes the results obtained by synthesis and characterization of iron oxides nanoparticles coated with dextran for environmental applications. [anonimizat]. [anonimizat], [anonimizat], X-Ray diffraction spectrometry and Fourier transform infrared spectroscopy.

The morphology experiments certified the obtaining of iron oxide nanoparticles covered with an organic compound (dextran) with an agglomeration tendency. Also, the nano dimensions of the analyzed sample were confirmed.

Introduction

Discharge and disposal of hazardous pollutants is governed by strict regulations that nowadays undergo fundamental changes. [anonimizat]. Therefore, [anonimizat], paper, batteries, pesticides and fertilizer industries. Nanotechnology proved recently to be an effective way to treat wastewaters [Babes et. al., 1999, Bee et. al 1995]. Nanomaterials possess high adsorptive capabilities and may be used effectively for the removal of heavy metal ions from wastewaters. [anonimizat]. [anonimizat], [anonimizat]. [anonimizat].

The concern for the environment has become more and more considerable and it is the researchers’ responsibility to find applicable solutions for enhancing its condition. [anonimizat], granted the resolving of many concerns by applying advanced technologies. The removal of heavy metals from wastewaters by help of iron nanoparticles has been a good solution due to their easiness appliance and efficiency. They can be introduced into solutions (wastewaters) with heavy metals content and because of their magnetism and nanosize they easily adsorb onto their surface the heavy metals. The recovery of these nanoparticles from waters can be handled by applying an extern magnetic field.

[anonimizat] without their agglomeration or precipitation is a very important problem. A solution to that seems to be coating of iron nanoparticles with an impermeable cover for assuring that oxygen does not reach the nanoparticles surface [Mihai et. al, 2015]. Organic compounds, including surfactants and polymers represent a proper choice for coating the magnetic iron nanoparticles. Among them, dextran has the advantage of being a biocompatible, biodegradable and water soluble material.

The aim of this paper is to synthesize iron oxide nanoparticles, coat them with dextran and characterize these afterwards for their identification in wastewaters from biomedical field. In fig. 1 are shortly presented the objectives of this study.

Fig. 1: Short description of paper’s objectives

Materials and methods

The synthesis of the iron oxide nanoparticles was carried out using co-precipitation method, by mixing ferrous ion (Fe2+) and ferric ion (Fe3+) with NaOH solution. After mixing up the solutions, the precipitate separation took place by magnetic decantation followed by washing it with distilled water and ethanol. The iron salts and sodium hydroxide were mixed at a molar ratio of 1:2 at room temperature. The pH reaction was settled for three hours at 9. It resulted a precipitate (fig. 2) that was detached by centrifugation, being then washed with distilled water. The formed particles were dried at 60oC and had the final pH 7.

Covering the iron nanoparticles with dextran was achieved by mixing 50% (w/v) dextran and iron salt solutions. The literature indicates that the carboxyl group of dextran forms bond with iron atoms at 11 pH (Kawaguchi et. al., 2001). The pH was after stabilized at 7 and the resulting solution was boiled for one hour at 100oC. After cooling the solution at room temperature, methanol was added and the mixture was centrifuged for 15 minutes. The formed particles had the final pH 8.

Fig. 2: Iron oxide nanoparticles synthesis and their covering with dextran

The characterization of the iron nanoparticles covered with dextran was carried out using X-Ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy. For X-Ray diffraction analysis was used a Panalytical X’Pert PRO MPD X-ray diffractometer with high-intensity Cu–Kα radiation (λ = 1.54065 A) and 2θ range from 10 to 90°. For the SEM analysis was used a scanning electron microscope QUANTA INSPECT F type, with field emission gun. The TEM (transmission electron microscopy) analysis were conducted on a TECNAI F30 G2 high resolution electron microscope with 1Å line resolution equipped with an X-ray dispersive energy (EDS) detector with 133 eV resolution.

In order to detect the presence of the organic compound on the surface of the iron nanoparticles, a FT-IR (Fourier transform infrared spectroscopy) spectrometer Thermo Fischer Model Nicolet 50 with 0.09 cm-1 resolution and variable aperture was used.

Results and discussion

The X-Ray diffraction for the two nanomaterials, presented in Fig. 3a, showed differences between the two diffractograms, indicating the presence of two analyzed compounds. In accordance with the ASTM reference code, the indexed peaks are characteristic to the Fe3O4 with crystal orthorhombic system. Comparing the two diffractograms from fig. 3a, it can be noticed lower peaks which can indicate the presence of some particles due to the dextran covering. In image 3b is presented the quantify diagram for Fe3O4 which validate the presence of the magnetite.

(b)

Fig 3: a) XRD Diffractograms for Fe3O4 and Fe3O4 covered with dextran nanoparticles;

b) Quantify diagram for Fe3O4 sample

The iron nanoparticles were also characterized by transmission electron microscopy. In fig. 4a is presented a TEM image of iron nanoparticles agglomeration and the associated SAED (selected area electron diffraction) image. A high resolution transmission electron microscopy (HRTEM) image is spotted in fig. 4b and indicates that the medium size of the analyzed nanoparticles is 10 nm, which confirms the nano dimension of the nanoparticles.

Fig. 4: TEM image for Fe3O4 covered with dextran and the associated SAED image; b) HRTEM image for Fe3O4 covered with dextran

The magnetite nanoparticles covered with dextran were also characterized through scanning electron microscopy at different magnifications. The SEM image obtained at 200 000x is presented in fig. 5a. The image indicates an aggregation tendency, with oval or spherical shape of the nanoparticles. Most of the spheres have an average diameter under 50 nm. The energy dispersive spectrum confirmed the presence of Fe and O as majority elements.

Fig. 5: SEM image for Fe3O4 covered with dextran; b) EDS analysis for Fe3O4

In order to prove the successful synthesis of iron oxide nanoparticles covered with dextran, FT-IR analysis was conducted. The FT-IR spectrum presented in fig. 6a displays the band at 578 cm-1 which is characteristic to the adsorption of ν (Fe-O) and the presence of dextran can be due to the broad absorption peak resulted at about 3423 cm-1 (fig. 6b). Considering fig. 6 a and b, it can be noticed the differences between the adsorption bands which strengthen the covering of the iron nanoparticles with an organic compound (dextran).

Fig. 6 : FTIR spectrum for iron nanoparticles (a) and iron nanoparticles covered with dextran(b)

Conclusions

The paper describes the results obtained by synthesis and characterization of iron oxides nanoparticles coated with dextran for water treatment applications in the environmental field. For the nanoparticles synthesis, the co-precipitation technique was used. For establishing the properties of the analyzed nanoparticles, characterization techniques such as X-Ray diffraction, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy techniques.

The morphology experiments certified the obtaining of iron oxide nanoparticles covered with an organic compound (dextran) with an agglomeration tendency. Also, the nano dimensions of the analyzed sample were confirmed.

The obtained nanoparticles can be used in the environmental engineering, as adsorbent particles for metal ions removal (Bee et. al., 1995), as well as in biomedical field as a matrix in which drugs (Babes et. al., 1999), radionuclides or genetic material can be dissolved or as a site for binding of drugs; thus the magnet-coating system can act as “carrier” to deliver useful material to the targeted region.

Acknowledgement

The work has been funded by the Increase of Economic Competitiveness Program through the Financial Agreement ID Project: 1799 / 2015, SMIS 48589.

The work has been funded through the Romanian-French Bilateral Cooperation Project no. 775/30.06.2014.

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