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New route for preparation and characterization of magnetite nanoparticles
*Corresponding author. Tel.: +966 4675970 mhjaafar@ksu.edu.sa (M.H. Jaafar)
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Received: ,
Accepted: ,
This article was originally published by Elsevier and was migrated to Scientific Scholar after the change of Publisher.
Peer review under responsibility of King Saud University.
Available online 3 July 2010
Abstract
We report here the synthesis of naked magnetic nanoparticles by using a facile method. Magnetic nanoparticles were prepared by mixing and stirring two equivalents of iron(II) chloride tetrahydrate with three equivalents of iron(III) chloride hexahydrate at room temperature. The mixture was treated by adding 100 ml of 28% ammonium hydroxide. Immediately, the color of the solution turned from orange to black. The magnetite nanoparticles that precipitated were washed three times with 5% NH4OH solution using the magnetic decantation method.
The nanoparticles underwent full characterization. Their surface show a bunch of hydroxyl groups which can be used for further complexion and removal of many hazardous compounds.
Keywords
Magnetite
Nanoparticles
Co-preparation
Characterization
Iron(II) chloride
Iron(III) chloride
1 Introduction
Nanoscale magnetite particles have drawn increasing interest for studying their application in environmental studies. There are different methods described in the literature which are used for their synthesis with a desired size, structure and other surface properties (Cornell and Schwertmann, 1996; Thuman, 1985; Trauth and Xanthopoulos, 1997; Solomons and Fryhle, 2004; Potter and Simmons, 1998; Readman et al., 2002; Anderson et al., 1980). These properties directly influence the chemical behavior of these nanoparticles and hence affect their application in different environmental applications. (Squillace et al., 1999; LaGrega et al., 2001; Rittman, 1987).
Nanoscale magnetite particles are nanoscale materials with a typical size range of 1–100 nm. Recent articles in the literature have shown that many of these particles’ properties depend on their size, which is in the nanoscale size. Besides, it shows that the coercive force in a magnetic material can be changed with the enhancement of their mechanical strength. It is also affects their surface chemistry (Rittman, 1987; Lagwaldt and Puhakka, 2000; Grady, 1986).
There are vast environmental applications of this nano-based material particularly, in cleaning up contaminated soil and ground water. Because these particles have a smaller size, these nanoscale magnetic iron materials are much more reactive than the conventional iron powders. Moreover, they can be suspended in slurry and pumped straight to the contaminated site. Elemental metal iron is known to be non-toxic, and when oxidized in the presence of organic contaminants, these organic contaminants can be broken down into simple carbon compounds that are less toxic. It is also known that oxidizing iron can reduce heavy metals to an insoluble form that tends to stay locked in soil. In this paper, the magnetic fluid containing Fe3O4 nanoparticles was prepared by the chemical co-precipitation of ferric and ferrous salts in an alkaline medium using Reimer’s procedure (Balba et al., 2002; Hou et al., 2003; Al-Khamis et al., 2009).
2 Experimental
2.1 Chemicals and apparatus
All chemicals used in the experiment were of analytical grade. Iron(II) chloride tetrahydrated (99%) and iron(III) chloride hexahydrated (97%), ammonium hydroxide (28%) NH3 in double distilled water, are all from (BDH).
FT-IR spectra were recorded by a prestige -21-FT-IR spectrophotometer (Shimadzo).
SEM spectra were recorded by JSM-6380LA scanning electron X-ray diffraction spectra were recorded by microscope (Jeol) Altima 4 X-ray diffraction (Rigaco).
2.2 Procedure
To prepare Fe3O4 particles add two equivalents of FeCl2·4H2O to three equivalents of FeCl3·6H2O in a 500 ml beaker and add 100 ml of double distilled water and stir the solution continuously at room temperature till complete dissolution is achieved. Then add 200 ml of ammonium hydroxide and allow the reaction to proceed for around 15 min. The resulting particles were then washed three times with a 5% ammonium solution.
The precipitates were then filtered and allowed to dry in air. The dried particles were then ground in a mortar and were then examined with an FT-IR, scanning electron microscope, X-ray diffraction and PPMS (quantum design) measurements to investigate the crystal structure of the particles and for magnetization of the sample material.
3 Results and discussion
Nanoscale magnetic particles were prepared by the chemical co-precipitation of iron(III) and iron(II) chloride salt in an alkaline medium using Reimer’s procedure with a slight modification. Spectral characterizations have proven the formation of super magnetite nanocrystals of Fe3O4.
In Fig. 1 the peak at 576.72 cm−1 is attributed to the vibration of Fe–O band of Fe3O4, the peak at 1402 cm−1 is assigned the Fe–O stretch of the Td. entity and the peak at 3134.33 cm−1 is attributed to the stretching vibration of –OH which is assigned to OH− adsorbed by Fe3O4 nanoparticles.
FTIR Spectra.
Fig. 2 shows the X-ray diffraction pattern of the Fe3O4 nanoparticles. The three main-peaks indicate that the nanoscale magnetite particles can be identified as Fe3O4. The X-ray spectra does not show any other crystalline phases. The use of the X-ray also gave an indication of the crystallite size of Fe3O4 nanoparticles to be approximately 10 nm.
X-Ray Defraction.
Fig. 3 illustrates the SEM micrograph of the nanoscale magnetite particles. The morphology of the particles was uniform, with each particle approximately ranging between 10 and 70 nm in diameter.
SEM of Fe3O4 nanoparticles.
Fig. 4 presents the magnetization of Fe3O4 nanoparticles in a field of 90 Oe on a super conducting quantum interference device magnetometer. The absence of a well-defined maximum in the ZFC curve indicates that Fe3O4 nanoparticles exhibit a blocking temperature above the room temperature. It is known that the maximum of the ZFC curve for a collection of super paramagnetic non-interaction single-domain nanoparticles is dependent on the size of the nanocrystals and their degree of clustering, as well as on the mutual dipolar interaction between them.
Magnetic properties of Fe3O4 nanoparticles.
We conclude from that the efficiency and simplicity of the chemical co-precipitation method for the preparation of nanoscale magnetite with a super para-magnetism from the solution of iron(II)/iron(III)mixed salt-solution in aqueous ammonium hydroxide solution. The results show that Fe3O4 nanoparticles can be prepared in the size range from 10 to 20 nm. The use of these nanoscale particles in the purification of water from organic contaminants is under study and will be reported later. As mentioned previously, Fe3O4 nanoparticles which were prepared by the above mentioned method can of course be promising as potentially good magnetic material that can have good magnetic quality.
Acknowledgment
The authors would like to thank the Research Center, College of Science for the financial support (Project No. (Chem/2009/56).
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