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ITS » PhD Theses » Program Doktoral Teknik Kimia
Posted by tondoindra@gmail.com at 07/03/2012 12:22:52  •  2340 Views


SINTESIS NANOPARTIKEL MAGNETITE DENGAN KEMURNIAN TINGGI DAN UKURAN SERAGAM MELALUI ELEKTRO-OKSIDASI BESI DALAM AIR

Synthesis of High Purity and monodispersed Magnetite nanoparticles by Iron Electro-oxidation in Water

Author :
FAJAROH, FAUZIATUL ( 2308301003 )




ABSTRAK

Pada dekade terakhir pengembangan nanopartikel magnetite Fe3O4 semakin intensif dilakukan. Daya tarik material berskala nanometer ini terletak pada sifat-sifat uniknya antara lain kemagnetannya yang berbeda dengan bulk. Sifat superparamagnetis yang dimilikinya memungkinkan nanopartikel magnetite dikontrol oleh suatu medan magnet eksternal untuk aplikasi tertentu pada banyak bidang. Permasalahan dalam sintesis magnetite adalah bagaimana memperoleh partikel berukuran nanometer dengan kemurnian tinggi dan ukuran seragam. Berbagai metode sintesis telah dikembangkan. Penelitian ini bertujuan mem- pelajari cara sintesis nanopartikel magnetite dengan metode elektrokimia. Sintesis mula-mula dilakukan dengan elektro-oksidasi besi dalam air pada rapat arus dan jarak antar elektrode bervariasi pada suhu kamar dengan sumber arus Continuous Direct Current CDC. Sintesis magnetite selanjutnya dilakukan dengan penambahan sodium silikat dalam konsentrasi bervariasi untuk men- dapatkan magnetite dengan kemurnian tinggi. Upaya untuk mendapatkan mag- netite dengan kemurnian tinggi juga dilakukan dengan cara lain yaitu sintesis dengan Pulsed Direct Current PDC. Produk yang diperoleh pada berbagai kondisi sintesis tersebut berupa powder hitam yang terpresipitasi di anoda yang selanjutnya dikarakterisasi dengan X-ray diffraction XRD dan Fourier Trans- form Infrared Spectrophotometry FTIR untuk identifikasi komponen Brunauer- Emmet-Teller BET untuk penentuan ukuran partikel Scanning Electron Micros- copy SEM untuk mengetahui morfologi partikel dan Vibrating Sample Magne- tometry VSM untuk mengetahui kemagnetan partikel. Hasil karakterisasi dengan XRD dan FTIR menunjukkan produk tersebut sebagai magnetite. Dari sintesis dengan air sebagai elektrolit diperoleh magnetite dengan ukuran seragam berkisar antara 1030 nm bergantung kondisi sintesis bermorfologi bola dan bersifat feromagnetis dengan magnetisasi saturasi relatif tinggi 70 emug. Namun hasil sintesis ini mengandung FeOOH yang diduga sebagai senyawa antara pada pembentukan magnetite. Dari fenomena yang teramati selama proses sintesis serta berdasarkan hasil analisis XRD dan FTIR mekanisme pembentukan magnetite dalam proses elektrokimia ini kemudian disusun. Berdasarkan mekanisme ini dilakukan upaya untuk mendapatkan magnetite tanpa FeOOH dengan dua cara. Cara pertama disebut cara isolasi berupa penambahan sodium silikat. Sintesis dengan larutan encer sodium silikat 150200 ppm menghasilkan magnetite dengan kemurnian tinggi yang monodisperse dan berukuran 610 nm serta bersifat superparamagnetis. Lapisan silika dari sodium silikat telah mengisolasi magnetite dari sistem reaksi sehingga pembentukan magnetite dari FeOOH berlangsung sempurna dan tak menyisakan FeOOH di akhir proses. Pada cara kedua yakni cara osilasi berupa penerapan PDC yang diperkirakan mengganggu difusi ion OH- hasil reduksi air di katoda. Padahal ion ini berperanan pada pembentukan FeOOH. Hasil sintesis dengan PDC berupa nanopartikel magnetite dengan kemurnian tinggi dan ukuran seragam serta bersifat feromagnetis dengan Ms relatif tinggi.


ABSTRACT

In the last decade development of magnetite Fe3O4 nanoparticles have been done intensively. The attractiveness of this nanoscale material is caused by its unique properties that different from its corresponding bulk especially in magnetic aspect. By its superparamagnetic behavior the nanoparticles may be controlled by an external magnetic field for special purpose in many applications. The usual problem in any synthesis method is how to create high purity of monodisperse magnetite nanoparticles. For this reason many magnetite synthesis methods have been developed. The purpose of this research is to study the synthesis of magnetite nanoparticles by electrochemical method. First of all the synthesis was conducted by electro-oxidation of iron in plain water under various of current densities and inter-electrodes distances by Continuous Direct Current CDC. All of the synthesis were conducted at room temperature. However some impurities were detected. In order to enhance purity of magnetite the preparation was carried out in dilute solution of sodium silicate under CDC. Another innovative way to improve the purity of magnetite nano- particles was also done using Pulsed Direct Current PDC in plain water. The nanoparticles generated by the above methods were black powder precipitated around the anode. The particles were then characterized by X-ray diffraction XRD and Fourier Transform Infrared Spectrophotometry FTIR for component identification Brunauer-Emmet-Teller BET for indirectly measured particle size Scanning Electron Microscopy SEM to observe the morphology and Vibrating Sample Magnetometry VSM for evaluating its magnetic properties. Both XRD pattern and FTIR spectra of the particles show that the particles are mainly magnetite. The generated particles are nearly spherical and mono- dispersed with a mean size between 1030 nm depending on synthesis conditions. They show a ferromagnetic behavior with a relativey high saturation magneti- zation 70 emug. However some impurities in the form of FeOOH still remain in the particles. FeOOH was assumed to be an intermediate product during magnetite formation. Based on magnetite formation mechanism deduced two methods were proposed to enhance the purity of magnetite. In the first method the impurities were reduced by isolating the magnetite via in-situ silica coating with sodium silicate as the source of silica that causes the transformation of FeOOH to magnetite proceeds completely. High purity magnetite with sizes ranging from 610 nm were succesfully prepared by this method using sodium silicate solution with concentration of about 150200 ppm. In the second way FeOOH was eliminated by applying PDC that was assumed to interfere diffusion of OH- produced by water reduction in cathode. The OH- ion has a very important role in FeOOH formation. High purity magnetite nanoparticles having ferromagnetic properties with high Ms were successfully synthesized by PDC. This study demonstrated that magnetite nanoparticles can be prepared using a simple electrochemical method. These results also demonstrate the possibility of using this technique as an environmentally friendly synthetic route to producing the very applicable magnetite nanoparticles.



Keywordsmagnetite; electrochemical;silica; pulsed
 
Subject:  Elektrolisis
Contributor
  1. Prof. Dr. ir. Sugeng Winardi, M.Eng
  2. Prof. Dr. Ir. Heru Setyawan, M.Eng
Date Create: 13/09/2011
Type: Text
Format: pdf
Language: Indonesian
Identifier: ITS-PhD-3100012045564
Collection ID: 3100012045564
Call Number: RDK 620.5 Faj s


Source
Phd Theses,Chemical Engineering,RDK 620.5 Faj s, 2012

Coverage
ITS Community

Rights
Copyright @2011 by ITS Library. This publication is protected by copyright and per obtained from the ITS Library prior to any prohibited reproduction, storage in a re transmission in any form or by any means, electronic, mechanical, photocopying, reco For information regarding permission(s), write to ITS Library




[ Download - Open Access ]

  1.  ITS-PhD-18012-synthesis-of-high-purity-and-monodispersed-magnetite-nanoparticles-by-iron-electro-oxidation-in-wate.pdf - 204 KB
  2.  ITS-PhD-18012-2308301003-abstract-idpdf.pdf - 306 KB
  3.  ITS-PhD-18012-2308301003-abstract-enpdf.pdf - 305 KB
  4.  ITS-PhD-18012-2308301003-conclusionpdf.pdf - 275 KB
  5.  ITS-PhD-18012-2308301003-paperpdf.pdf - 1148 KB




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