Preparation, Characterization and its Application for Energy Production

Preparation, Characterization and its Application for Energy Production

Priyanka, Simran, Adarsh Singh, Vivek Verma*

Department of Physics, Hindu College, University of Delhi, Delhi, India

Ferro fluids are colloidal suspensions of magnetic particles which respond to external magnetic field enabling the possibility of changing the magnetic flux by moving an external magnet about it. In the present work Fe3O4 nano magnetic particles are first synthesized in lab using co-precipitation technique followed by ferrofluid preparation. Structural and magnetic properties are characterized by using XRD, TEM, FTIR and VSM. Their ability to produce a fluid phase of magnetic material is used to demonstrate the generation of energy using a simple energy harvester setup and this energy is demonstrated to produce useful work eg, glowing of a LED.

1. Although non stable magnetic fluids were being prepared as early as, the first successful synthesis of magnetic fluids was reported by in 1965. The study of magnetic fluids has since then become an ever- growing area of multi disciplinary interest with chemists, physicists, biologists and engineers en- gaged in the synthesis and characterization and evolving technological applications for these won- der materials [1-3]. The ability of a ferro fluid to produce patterns of nano scale magnetic particles in liquid phase which can be monitored by an external magnetic field has made it a viable option for appli- cation in many technological areas. The most prom- inent being memory storage, drug delivery, energy production etc [4-6].

   In the present work, the magnetic particles are prepared by co-precipitation technique. The ferro- magnetic particles of fe3O4 are suspended in the car- rier fluid and coated with a surfactant as shown in Fig. 1, to ensure they do not clump together. A simple experimental set up is designed of a vibrato- ry energy harvester utilizing a ferrofluid sloshing in a cylindrical plastic tank. Mechanical vibrations change the orientational order of the magnetic di-

   poles creating a varying magnetic flux thus produc- ing electric current as per Faradays laws. The fer- rofluid was successfully synthesised and the expe- rimental results show generation of voltage drop of around 2V at vibratory frequencies as low as 4-5 Hz

2. 1. The co-precipitation method was used to synthesize ferrofluid. The process for the Fe3O4 nucleation from the salt solution occurs in accordance with the reaction:

      2FeCl3.6H2O + FeCl2.4H2O + 8NH4OH Fe3O4+ 8NH4Cl+20H2O

      A solution of FeCl3 .6H2O (0.5 M i.e 10.35mL in 110mL water) and FeCl2.4H2O (0.5 M i.e 6.85g in 60mL water) mixed in a molar ratio of 2:1 was prepared in contact with air. An ammonia aqueous solution (25%) of 15 ml was then quickly charged into the solution with vigorous stirring using a mechanical stirrer, followed by adding more ammonia aqueous solution into the mixture ( app. 10mL) while stirring. The solution was stirred for

      about one hour. A black precipitate was obtained. Oleic acid (5% v/v) about 30mL was added slowly and intensely stirred at 60 0C for 30 min. The precipitate was separated using a magnet and washed with deionised water and methanol several times. The ferrofluid solution was centrifuged at low rpm for ten minutes .precipitate was dried at 70 0C for 3 hours and the appropriate amount (7% v/v) of solid phase was dispersed in kerosene oil.

      Fig. 1- The ferromagnetic particles of fe3O4 are suspended in the carrier fluid and coated with a surfactant

   2. The structural characterization of samples was carried out by the X-ray diffraction (XRD Rigaku Miniflex II, step size = 0.02) technique using CuK radiation ( = 1.5406 Ã…). The average crystalline size was determined from the measured width of their diffraction curves using the Debye Scherrers relation: D = 0.9/ cos, where is the wavelength (= 1.5406 Ã…) of the CuK radiation and is the full width half maximum (FWHM) in radians calculated using Gaussian fitting. Particle size of the nano Fe3O4 samples was evaluated by using TEM. FTIR spectra of sample was recorded in KBr medium in the wave number range 400 4000cm1 using a PerkinElmer FTIR (spectrum BX).

      Magnetic measurements were performed at room temperature by plotting M-H curve for the samples using vibrating sample magnetometer for all samples. The magnetic properties such as satura- tion magnetization (Ms), Coercivity (Hc) and rema- nence (Mr) were determined from M-H curves.

   3. A simple experimental setup was designed to show the ability of a changing magnetic flux produced by the ferro fluid to produce useful energy that can be made to do work eg, lighting of an LED. The setup

      LED

      is shown in Fig. 2. The vibratory energy harvester consists of a conducting copper coil wound around an insulating plastic container tank filled with the ferro fluid. Rare earth magnet fillets were put in the ferrofluid so that on starting the vibratory motion, a changing magnetic flux is produced. The two ends of the coil are connected first to a bridge rectifier supplemented with a capacitor of sufficiently high value to render the ac voltage produced to a non fluctuating dc voltage. The output of the capacitor filter is then connected to a measuring device like digital multimeter or LED.

      C

      rectifie Cylinder with

      ferrofluid and rare earth magnet filets

3. 1. Fig. 3 exhibit the XRD patterns of nano Fe3O4 prepared by co-precipitation techniques. It is evident that the as-prepared powder of Fe3O4 is in single phases confirming all the peaks in the pattern matching well with JCPDS card [7]. The average crystallite size of Fe3O4 sample was found about 12nm calculated from Debye Scherrers relation which is supported by the TEM analysis. Maximum numbers of the particles were found in the range of the 9-12 nm, as shown in the fig. 4. Distribution of the particles size and selected area electron diffrac- tion pattern is shown in the in-set of fig. 4.

      Fig. 3 XRD pattern of the Fe3O4nano-particles prepared by co-precipitation technique.

      1226.66

      1155.61

      1226.66

      1155.61

      1560.61 1429.29

      1560.61 1429.29

      Fig. 4. TEM analysis of the Fe3O4nano-particles prepared by co-precipitation technique

      67.5

      67

      67.5

      67

      891.89

      891.89

      66

      1033.49

      66

      1033.49

      448.51

      65

      448.51

      65

      64

      63

      64

      63

      3421.50

      3421.50

      62

      2852.12

      62

      2852.12

      61

      61

      %T

      %T

      60

      2921.78

      60

      2921.78

      59

      58

      57

      56

      59

      58

      57

      56

      626.91 591.85

      626.91 591.85

      55

      55

      the range of (400-600 cm-1) in the spectra, confirm the formation of Fe3O4 [8]. As prepared samples A, B and C showed the characteristic bands at about 1300 & 2900 cm-1 corresponding to the NO – ion and O-H group respectively. FTIR curve for sample shows the formation of spinel structure.

      3

      3

   2. The hysteresis curves (M-H curves) for the Fe3O4 nano-particles prepared by Co-precipitation is shown in Fig. 5. Due to the applied magnetic field (H), the magnetic induction (B) could be measured according to Faradays law, and the magnetization

      (M) was then obtained by the relationship:

      B = H + 4M

      The applied magnetic field was increased until the saturation magnetization was achieved. Then the applied field was reduced to zero to measure the remanene (residual magnetization). When the ap- plied field was further reversed, the coercivity (the applied field that reduces magnetization to zero) and the saturation magnetization in the reverse direction could be obtained. This increasing and decreasing applied field process was repeated five times to get the magnetization curve (magnetization (M) versus applied magnetic field (H)) and examine the mag- netic properties of the Fe3O4 particles. In addition, the important parameters used to characterize the magnetic properties of solids, magnetic susceptibil- ity (), and magnetic permeability () were also cal- culated using the following equations:

      = M/H = B/M

      Parameters such as saturation magnetization (Ms) and coercivity (Hc) were determined from the hysteresis curves. The saturation magnetization of sample is 48.8 emu/g at room temperature. The area within a M-H loop represents a magnetic energy loss; this energy loss is defined as heat that is capa- ble of rising specimen temperature. It is observed that area of the M-H curve is small, and the loop is thin and narrow which is a specific criteria for soft magnetic material and required for the ferro fluids preparation. The magnetic response of the ferro flu- id in the presence of the external magnetic is shown in the Fig. 7.

      3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400.0

      cm-1

      3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400.0

      cm-1

      54.0

      4000.0

      54.0

      4000.0

      Fig. 5 FTIR spectra of the Fe3O4nano-particles prepared by co-precipitation technique.

      Fig. 5. shows the FTIR spectra of prepared nano Fe3O4 samples prepared by co-precipitation techniques. The presence of wave number bands in

      Fig. 6 – M-H curve of the Fe3O4nano-particles pre- pared by co-precipitation technique.

   3. It was observed that vibrating the ferrofluid filled cylinder with a frequency of as low as 5-10 Hz pro- duced sufficient current in the conducting wire to light up an LED or equivalently to generate a 2V drop across the wire ends.

The authors are grateful to University of Delhi for providing Innovation project HC-104 (funded by Delhi University) to carry out this work. We are thankful to Dr. Anju Srivastava, Dr. Reena Jain and Dr. Devanshi for valuable suggestions rendered time to time. The authors are grateful to Dr. Pradumn Kumar, Principal Hindu College, University of Delhi for constant encouragement and motivation.

1. Magnetic Fluids and Applications Handbook, edited by B. Berkovski and V. Bashtovoy, Begell House, Wallingford (1996)

2. R. A. Buhrman and C. G. Granqvist, J. Appl. Phys. 47, 2220 (1976)

3. C.Scherer and J.A.Miranda, Proceedings of the 10th international conference on magnetic fluids, J. Magn. Mag. Mat. 289, 484 (2005)

4. K. Raj and R. Moskowitz, "Commercial applica- tions of ferrofluids", Journal of Magnetism and Magnetic Materials. 85, 233 (1990)

5. S, J Roger, J,N. Pons, R. Massart, A. Helbriech,

   J. C. Bacri, ome bio medical appluications of fer- ro fluids, The Europian Physical Journal Applied

   Physics /Volume 5/ Issue 03 / Marh 10000, pp 321-325.

6. Sensors and Actuators A: Physical, Volumes 123124, 23 September 2005, Pages 43844, A novel magneto-optic ferrofluid material for sen- sor applications,Luis Martinez, Franjo Cecelja, Ryszard Rakowski.

7. PCPDFWIN CAS Number- 89-0691, ICSD: 082237.

8. Li-Ying Zhang, Hong-Chen Gu, Xu-Man Wang, Journal of Magnetism and Magnetic Materials 311 (2007) 228233.