Enhancement of Mn-doped magnetite by mesoporous silica for technological application
- PDF / 1,334,060 Bytes
- 13 Pages / 595.276 x 790.866 pts Page_size
- 48 Downloads / 152 Views
Enhancement of Mn‑doped magnetite by mesoporous silica for technological application Rania Ramadan1 · S. I. El‑Dek2 · M. M. Arman1 Received: 10 April 2020 / Accepted: 5 October 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Mn0.6Fe2.4O4 was synthesized by the co-precipitation method. A simple method was developed for preparing M n0.6Fe2.4O4@ SiO2 nanocomposite via few steps. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) images, BET surface area measurements were used to characterize the physical structures of the investigated samples. The crystal n0.6Fe2.4O4 is lite size of the nanocomposite is greater than that of the parent sample. The dielectric constant (ε/) of the M greater than that of the sample M n0.6Fe2.4O4@SiO2. The investigated samples have a semiconductor-like behavior with two different conduction mechanisms. M-H loops of the samples show ferrimagnetic properties. Mesoporous silica increased the coercive field and decreases the values of both Ms and Mr of M n0.6Fe2.4O4. Mn0.6Fe2.4O4@SiO2 nanocomposite exhibits higher removal efficiency than Mn0.6Fe2.4O3. The maximum removal of the heavy metals is observed for Pb2+ and Cr6+. Keywords Mesoporous silica · Mn0.6Fe2.4O4 · Heavy metal removal · Magnetic properties · Nanoparticles
1 Introduction Magnetite as ( Fe 3O 4) has several applications in water purification [1], microwave absorption [2] and hyperthermia therapy [3]. Crystal structure as well as metal ion distribution affected the magnetic properties of magnetite [4]. Magnetic behavior can be improved by doping Fe3O4 with Mn2+ as the magnetic moment for Mn2+ and Fe2+ is 5µB and 4µB, respectively. Consequently, saturation magnetization is amended [5, 6]. M n xFe 3−xO 4 can exist in two crystal structure forms at room temperature cubic or tetragonal according to the Mn content. Cubic structure exists for x 400 K), a decrease in S was observed with the temperature which indicates that the conduction mechanism is the correlated barrier hopping (CBH) as a result of the presence of the Fe3+ to Fe2+ ions in the investigated sample on octahedral coordination. This could be easily explained by the well-known Verway conduction mechanism in ferrite [45].
Page 7 of 13
Enhancement of Mn‑doped magnetite by mesoporous silica for technological application
-400
Mn0.6Fe2.4O4
60
Mn0.6Fe2.4O4@SiO2
40
20
0
-200
0
200
400
Magnetic field (Oe)
-20
-40
Magnetization (emu/g)
Magnetization (emu/g)
Fig. 8 M-H loop for M n0.6 e2.4O4 and Mn0.6Fe2.4O4@SiO2 F nanocomposite
900
-60
60
40
20
0
-20000 -15000 -10000 -5000
0
5000
10000 15000 20000
Magnetic field (Oe)
-20
-40
-60
3.4 Magnetic properties measurements Figure 8 represents the room temperature hysteresis plot for the samples under investigation. As presented, the saturation magnetization has values of 48.4 (emu/g) and 34.1 (emmu/g) for M n0.6Fe2.4O4 and M n0.6Fe2.4O4@SiO2,
(a)
1340Oe 1660Oe 1990Oe
10 9
respectively. Saturation magnetization i
Data Loading...
