Synthesis of magnetite-porphyrin nanocomposite and its application as a novel magnetic adsorbent for removing heavy cations

Article abstract of DOI:10.1016/j.materresbull.2013.03.019

Magnetite-porphyrin nanocomposite (MPNC) was synthesized as a novel magnetic adsorbent for removing heavy cations. Firstly, we prepared nano-sized magnetite using a simple hydrothermal route. The synthesis of nanoscaled magnetite was carried out through reaction between iron source and various amines. In this paper, we studied effective parameters in controlling shape and size of nanoscaled magnetite. These parameters were presence of alkaline, reaction time, kind of amine and iron salt. Morphology, particle size and magnetic properties of the nanoscaled magnetite were obtained by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared (FT-IR), diffuse reflectance spectra (DRS) and vibrating sample magnetometer (VSM). Our study showed that the synthesized magnetite from reaction between FeSO₄ and hydrazinum hydrate has spherical shape. The synthesized magnetite was a nanosized compound and used for preparation of magnetite-porphyrin nanocomposite. The synthesized magnetite-porphyrin hybrid material had magnetic property and was used as magnetic adsorbent for removing heavy cations of water. Satisfactory separation from solutions in the order of Pb²⁺ > Cd²⁺ > Hg ²⁺ was obtained.

Full text of DOI:10.1016/j.materresbull.2013.03.019

Materials Research Bulletin 48 (2013) 2614–2624
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Materials Research Bulletin
journal homepage: www.elsevier.com/locate/matresbu
Synthesis of magnetite-porphyrin nanocomposite and its application
as a novel magnetic adsorbent for removing heavy cations
*
Sara Bakhshayesh, Hossein Dehghani
Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, P.O. Box 87317-51167, Kashan, Iran
A R T I C L E I N F O
A B S T R A C T
Article history:
Magnetite-porphyrin nanocomposite (MPNC) was synthesized as a novel magnetic adsorbent for
removing heavy cations. Firstly, we prepared nano-sized magnetite using a simple hydrothermal route.
The synthesis of nanoscaled magnetite was carried out through reaction between iron source and
various amines. In this paper, we studied effective parameters in controlling shape and size of
nanoscaled magnetite. These parameters were presence of alkaline, reaction time, kind of amine and iron
salt. Morphology, particle size and magnetic properties of the nanoscaled magnetite were obtained by X-
ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM),
Fourier transform infrared (FT-IR), diffuse reflectance spectra (DRS) and vibrating sample magnetometer
(VSM). Our study showed that the synthesized magnetite from reaction between FeSO4 and hydrazinum
hydrate has spherical shape. The synthesized magnetite was a nanosized compound and used for
preparation of magnetite-porphyrin nanocomposite. The synthesized magnetite-porphyrin hybrid
material had magnetic property and was used as magnetic adsorbent for removing heavy cations of
water. Satisfactory separation from solutions in the order of Pb2+ > Cd2+ > Hg2+ was obtained.
ß 2013 Elsevier Ltd. All rights reserved.
Received 29 November 2012
Received in revised form 13 February 2013
Accepted 15 March 2013
Available online 25 March 2013
Keywords:
Nanocomposite
Magnetite
Porphyrin
Heavy cations
Adsorbent
1. Introduction
example, it has been reported that porohyrin-silica hybrid material
can be act as sensor for Ni2+, Cu2+, Pb2+ and Zn2+ions [4].
There is a very serious threat from the heavy metal pollution for
the environment and all the life forms on the earth. This concern is
because of rapid industrialization and increasing the world
population. Research on heavy metal deposition and accumulation
in the environment is the current attention of the most
environmental scientists. The most studies focus on heavy metal
concentrations in foods, vegetables, water, hematological param-
eters, atmosphere and soil [1,2]. Porphyrin derivatives play highly
important roles in various fields of science, including chemistry,
physics, geology, and biology. Researchers around the world have
been studied porphyrins intensively from diverse viewpoints. The
research conducted for many years proved versatility of porphyrin
applications in the different areas of life [3]. The porphyrin
derivatives can be used as sensitive indicator dyes for spectropho-
tometric determination of metal ions. There is an interest growing
in the development of new sensing materials and the immobiliza-
tion method to obtain sensors with improved characteristics. For
Iron oxide nanostructures play an important role in science
from technology to biotechnology. Iron oxides were widespread in
nature. These compounds are ubiquitous in soils and sediments
and have a profound influence on the water chemistry of aquifers
and subsurface waters. Moreover, the formation of various iron
oxides is dependent on abundance of water [5–7]. The iron oxides
have been known for millennia. Such minerals were used originally
as pigments for paints during the Paleolithic, since the uses of iron
oxides have been expanded. Nowadays, iron oxides are used vastly
in different fields; not only as pigments in paint but also as
catalysts, sensors, recording media material and ferrofluids [8–17].
Magnetic nanoparticles have many unique magnetic properties
such as supraparamagnetic, low Curie temperature, high magnetic
susceptibility, high coercivity, etc. Magnetic nanoparticles are
great interest to researchers in a wide range of fields, including
magnetic fluids, data storage, catalysis, and biological applications
such as MRI (magnetic resonance image) and targeted drug
delivery. It has been reported various methods for synthesis and
control of shape, size, stability and dispersibility of nanoparticles.
For example, hydrothermal synthesis, thermal decomposition,
co-precipitation, sol–gel processes, sonochemical synthesis and
microemulsion methods have been reported in literature [18–25].
Magnetite is nonporous and its specific surface area ranges relative
* Corresponding author. Tel.: +98 361 591 2386; fax: +98 361 591 2397.
E-mail addresses: s_bakhshayesh@yahoo.com (S. Bakhshayesh),
dehghani@kashanu.ac.ir (H. Dehghani).
0025-5408/$ – see front matter ß 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.materresbull.2013.03.019

S. Bakhshayesh, H. Dehghani / Materials Research Bulletin 48 (2013) 2614–2624
2615
to preparation manner from is 4 m2 gꢀ1to 100 m2 gꢀ1 [5]. Due to
2.2. Physical measurements
their high surface area, iron oxides are used as sorbent for control
the aqueous concentration of dissolved species, for example:
arsenate, phosphate and heavy metals [26–31]. Magnetite (Fe3O4),
as one of the basic magnetic materials has great potential for
applications such as magnetic resonance imaging (MRI), magnetic
bioseparation, magnetic drug targeting and gene delivery [32–36].
Magnetite is synthesized by hydrothermal decomposition of
FeII or FeIII chelates. The mixed oxides are more stable than pure
FeIII oxides [5]. There are some studies for synthesis of Fe3O4
nanoparticles with hydrothermal method. For example, Li et al.
reported preparation of Fe3O4 nanoparticles at 150 8C in the
presence of hydrazine [37]. Also, similar synthesis of magnetite
nanoparticles has been reported by other researchers [38–45].
Using iron oxides for adsorption and recovery of metal ions from
industrial waste or natural stream is an attractive subject.
Magnetite separation method is a useful method for separation
in solid-solid or liquid–solid phases. But there is aggregation
problem due to interaction of magnetite particle with each
other. Thus, providing a suitable surface coating to preserve the
stability of magnetic iron oxide is very important. This coating
can be done with small organic molecules, surfactants, poly-
mers, and metal oxides or metal sulfide. Furthermore, in many
cases, protecting shells not only to stabilize the magnetic iron
oxide nanoparticles, but also can be used for further functio-
nalization.
X-ray diffraction (XRD) patterns were obtained on a Phillips
˚
a radiation (l = 1.54178 A). The morphol-
X’Pert PRO with a Cu K
ogies of the synthesized products were observed with a Philips XL-
30ESEM scanning electron microscope (SEM). Fourier transform
infrared (FT-IR) spectra were recorded with a Magna 550 Nicolet
instrument (using KBr pellets). In addition, magnetic characteri-
zation of the samples was performed to measure the magnetic
properties of them at room temperature by BHV-55, Riken, Japan
vibrating sample magnetometer (VSM). The TEM image was
obtained on a Zeiss EM10C transmission electron microscope with
an accelerating voltage of 80 kV. Concentrations of Pb(II) and Cd(II)
were determined using an atomic absorption spectrometer
(Spectra AA 220, Varian) and the concentration of mercury ion
was determined by UV–vis spectrophotometer (Spectronic 20D,
Milton Roy Company). DRS spectra were obtained on a UV
spectrophotometer 1800 Shimadzu within the wavelength 300–
800 nm.
2.3. Methods
2.3.1. Synthesis of the nanosized magnetite
In a typical procedure, 1.0 mmol of FeSO4 was dissolved in 5 ml
of deionized water. Then, 5 ml of sodium hydroxide (0.4 M) was
slowly dropped with steady stirring. Jadegreen colloid was
immediately appeared in aqueous solution. The resulting mixture
was stirred at room temperature for 10 min. Then,
0.18 ml N2H4.H2O (80%) was slowly added and the solution stirred
for 10 min. The formed solution was transferred into a 25 ml
autoclave. The autoclave was placed in an oven and kept at 150 8C
for 15 h. At the end of the reaction, the product was cooled to room
temperature, and the black precipitate was separated from
solution and washed with distilled water and ethanol for several
times. Then the obtained product was dried at 80 8C.
In attention to this background, we decided to synthesis of
nanosized magnetite by a facile hydrothermal method, and so its
application for preparation of magnetite-porphyrin nanocompo-
site. Furthermore, for the first time, we used the synthesized
magnetite-porphyrin hybrid material as a magnetic adsorbent for
removing heavy metals.
2. Experimental
To study the effect of amine, all the reactions were repeated
using PDA and NDA instead of hydrazinum hydrate. The effect of
precursor was considered using FeCl2, FeCl3 and Fe2(SO4)3 instead
FeSO4. The other factors were examined: the presence of NaOH,
kind of amine and reaction time. Table 1 shows all synthesized
samples under different conditions.
2.1. Material
Chemicals for the synthesis of magnetite nanoparticles were
FeSO4, FeCl2, FeCl3, Fe2(SO4)3, hydrazinum hydrate (N2H4.H2O,
80%), 1,2-phenylenediamine (PDA), 1,8-naphthalenediamine
(NDA) and NaOH that were purchased from Merck. The other
used
chemicals
were
ammonia,
tetraethylorthosilicate
2.3.2. Synthesis of magnetite nanoparticles coated with silica (Fe3O4/
SiO2)
(TEOS), ethanol, 4-methyl-4-(formylbenzoate) (96%), propionic
acid, pyrrole (97%), nitrobenzene, tetrahydrofuran (THF),
3-aminopropyltrimethoxysilane (APTS) (98%), hydrochloric acid
(32%), potassium hydroxide, N,N-dicyclohexylcarbodiimide (98%),
triethylamine (98%), lead(II) nitrate, cadmium(II) nitrate, mercur-
y(II) chloride. THF was dried and distilled over benzoic acid and
sodium metal. Pyrrole was distilled before use too. Other chemicals
were used as received and without additional purification.
Deionized water was used throughout the experiments.
The magnetite nanoparticles coated with silica was synthesized
by a reported method in the literature [46]. Firstly, the magnetite
nanoparticles (0.1 g) were dispersed in a mixture of ethanol
(10 ml) and deionized water (2 ml) by sonication for 10 min. After
adding ammonia (0.25 ml) tetraethylorthosilicate (TEOS, 0.2 ml)
was added to the reaction solution. The produced solution was
stirred at room temperature. After 20 h, the magnetic product was
collected and washed with ethanol and deionized water.
Table 1
Experimental parameters for the synthesized samples.
Sample
Precursor
Mineralizer
Temperature/8C
Time/h
Solvent
S1
S2
S3
S4
S5
S6
S7
S8
S9
S10
S11
FeSO4
FeSO4
FeSO4
FeSO4
FeSO4
Fe2(SO4)3
FeCl2
NaOH + N2H4.H2O
NaOH + N2H4.H2O
NaOH + N2H4.H2O
NaOH
150
150
150
150
150
150
150
150
150
150
150
4
12
15
15
15
15
15
15
15
15
15
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
C2H5OH
N2H4.H2O
NaOH + N2H4.H2O
NaOH + N2H4.H2O
NaOH + N2H4.H2O
NaOH + PDA
FeCl3
FeSO4
FeSO4
FeSO4
NaOH + NDA
NaOH + N2H4.H2O

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2.3.3. Synthesis of meso-tetrakis(4-carboxyphenyl)porphyrin
Porphyrin was synthesized according to the literature [47,48].
Freshly distilled pyrrole (1.42 ml, 20 mmol) and 3.42 g (20 mmol)
of 4-methyl-4-(formylbenzoate) was added to a mixture of 15 ml
nitrobenzene and 70 ml propionic acid. The solution was refluxed
for 3.5 h, and was cooled to room temperature and filtered. The
produced solid was washed with distilled water.
Meso-tetrakis(4-carboxymethylphenyl)porphyrin (0.085 g,
0.1 mmol) was dissolved in 100 ml of tetrahydrofuran (THF)-
ethanol (1:1). Potassium hydroxide (0.513 g) in water (5 ml) was
added and refluxed for 8 h. After cooling and removal of solvent,
the residue was diluted with water (100 ml) and desired
porphyrin tetrapotassium salt was filtered. Acidification
(pH = 2) of an aqueous suspension of the porphyrin tetrapotas-
sium salt with concentrated hydrochloric acid and subsequent
filtration gave meso-tetrakis (4-carboxyphenyl)porphyrin as a
purple powder. UV–vis (nm): 421.0, 514.5, 549.0, 590.1, 645.0, 1H
washed with THF (5 ꢁ 10 ml) to remove any un-reacted porphyrin
or unwanted side-products. The particles of magnetite-porphyrin
nanocomposite (MPNC) were finally washed with water. Scheme 1
shows the schematic representation of the formation steps of
magnetite-porphyrin nanocomposite (MPNC).
2.3.5. Investigation of magnetite-porphyrin nanocomposite (MPNC)
as magnetic adsorbent for removing heavy cations
A known amount of MPNC was added to the 1 M solution of
lead(II) nitrate in water. After 2 days, the solid phase was separated
by magnetic separation. The concentration of lead in the sample
was determined by atomic absorption method. The investigations
of adsorption behavior of the MPNC for cadmium and mercury ion
were repeated as mentioned above with solutions of cadmium(II)
nitrate and mercury(II) chloride in water. The concentration of
cadmium and mercury in the samples were determined by atomic
absorption and dithizone methods, respectively [50]. Scheme 2
shows a schematic representation of the magnetic adsorbent for
removal of heavy cations.
NMR (ppm): ꢀ2.98 (s, 2H, NH), 8.37 (s, 16H, o, m), 8.85(d, 8H,
b),
FT-IR (cmꢀ1): 1703, 3430
2.3.4. Modification of porphyrin and attachment to magnetic
nanoparticles
3. Results and discussion
Magnetite-porphyrin nanocomposite was obtained by modified
method in the literature [49]. N,N-dicyclohexylcarbodiimide
(0.18 g; 0.887 mmol) was added to a solution of Meso-tetra-
kis(4-carboxyphenyl)porphyrin (0.07 g; 0.0885 mmol) in dry THF
(10 mL) and the reaction mixture was stirred for 3 h at 0 8C. To
prevent any possible photobleaching of the porphryin, the reaction
was carried out in the dark. 3-Aminopropyltrimethoxysilane
The crystallinity and phase purity of the as-prepared products
were examined by XRD measurements. Fig. 1 shows the XRD
patterns of the obtained samples at various times for the reaction.
As shown in this figure, the suitable time for the preparation of
pure Fe3O4 is 15 h. For shorter times than 15 h, the product was not
pure. The synthesized sample at 4 h (S1) was containing Fe3O4,
Fe2O3 and FeS, and so the produced sample at 12 h (S2) was
containing Fe3O4 and Fe2O3 as impurities. The XRD patterns of the
obtained products in presence of NaOH (S4) and N2H4.H2O (S5) are
shown in Fig. 2. This figure shows that S4 and S5 are not pure. The
XRD patterns are shown that the S4 sample is containing
impurities of Fe2O3 and FeOOH. Furthermore, the S5 is magnetite
with impurities of Fe2O3 and Fe(OH)3. Therefore, for preparation of
(63
ml, 0.355 mmol) in 1 ml dry THF was added to the porphyrin
solution at 0 8C. The reaction mixture was brought to room
temperature and allowed to react overnight. The magnetite
nanoparticles coated with silica (0.05 g) and triethylamine
(300
ml) were added to the reaction vessel and allowed to react
for 24 h. The mixture was centrifuged and the particles were
Scheme 1. Preparation of the MPNC: (i) magnetite nanoparticles is synthesized from FeSO4 with N2H4.OH (15 h, 150 8C) (ii) a thin silica layer is introduced on the magnetite
nanoparticle surface by employing tetraorthosilicate (TEOS). (iii) an amide coupling reaction is performed between the carboxylic acid groups of porphyrin and 3-APTS. (iv)
magnetite-porphyrin nanocomposite is result of a base hydrolysis between the modified porphyrin and the magnetite nanoparticles coated with silica.

S. Bakhshayesh, H. Dehghani / Materials Research Bulletin 48 (2013) 2614–2624
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Scheme 2. Removing heavy ion from solution with magnetic adsorbent.
Fig. 1. XRD patterns of obtained samples at various times: (a) S1, (b) S2, and (c) S3.

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S. Bakhshayesh, H. Dehghani / Materials Research Bulletin 48 (2013) 2614–2624
Fig. 2. XRD patterns of the synthesized samples at presence of different mineralizers: (a) S4, (b) S5.
the pure nanoscaled magnetite, the presence of both NaOH and
N2H4.H2O is necessary.
plane (3 1 1). Respondent with index, Fe3O4 was identified by the
diffraction peaks at 30.368, 35.748, 37.348, 43.368, 53.718, 57.218,
62.778, 66.128, 71.188, 74.178 and 75.188. These peaks indexed
planes (2 2 0), (3 1 1), (2 2 2), (4 0 0), (4 2 2), (5 1 1), (4 4 0),
(5 3 1), (6 2 0) (5 3 3) and (6 2 2) of the cubic magnetite with the
At subsequent step, precursor effect was investigated. When
FeCl2 or FeCl3 was used instead of FeSO4, was produced the pure
magnetite. But the prepared sample (S6) with precursor of
Fe2(SO4)3 was containing Fe2O3 and other impurities. For
comparison, the XRD pattern of S6 is shown in Fig. 3. The
studies were continued by changing N2H4.H2O with diamines of
1,2-phenylenediamine (PDA) and 1,8-naphthalenediamine
(NDA). The pure magnetite was obtained with both diamines.
For example, the XRD pattern of the prepared magnetite in
presence of PDA (S9) is shown in Fig. 4. This diffraction pattern
shows that the main peaks match to standard diffraction peaks of
bulk material (Card No. 88-0315) and its characteristic peak with
˚
crystallographical parameter of a = 8.38 A. This pattern shows
that the synthesized magnetite is completely pure.
Further information for the nanoscaled magnetite was obtained
by scanning electron microscope (SEM). Fig. 5 shows SEM images
of the prepared samples at presence of hydrazine (S3), PDA (S9)
and NDA (S10) as reductant reagents. As can be observed, the
spherical morphology for S3 (Fig. 5a and b) changed to nanosheet
or aggregated nanoparticles morphologies in S9 (Fig. 5c and d) and
S10 (Fig. 5e and f), respectively. In result, we selected the
optimized conditions as S3.
100% intensity at 2 = 35.748 is correspondence to the reflection
θ
Fig. 3. XRD pattern of the prepared sample with Fe2(SO4)3 (S6).

S. Bakhshayesh, H. Dehghani / Materials Research Bulletin 48 (2013) 2614–2624
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Fig. 4. XRD pattern of prepared magnetite sample with 1,2-phenylenediamine (S9).
Fig. 5. SEM images of obtained magnetite products with various amines: (a, b) N2H4.H2O (S3), (c, d) PDA (S9), and (e, f) NDA (S10).

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S. Bakhshayesh, H. Dehghani / Materials Research Bulletin 48 (2013) 2614–2624
Fig. 6. SEM images of the synthesized magnetite products with the different precursors: (a, b) FeCl2 (S7), (c, d) FeCl3 (S8).
For further comparison, FeCl2 and FeCl3 are used as precursors.
Fig. 6 shows the SEM images of S7 and S8 under the optimized
conditions. The magnetite nanoparticles and nanosheets were
formed using precursors of FeCl2 and FeCl3, respectively. Another
effective reagent was solvent. Changing the solvent from water to
ethanol leads to a slight agglomeration in the product (S11) (Fig. 7).
As a result, the diamine, the solvent and precursor play important
role on the morphology and structure of the synthesized magnetite.
Finally, a possible mechanism for the hydrothermal formation
of the magnetite can be expressed as follow:
N2H4 þ H2O þ 2e ¼ 2NH3 þ 2OHꢀ
(2)
(3)
(4)
2FeðOHÞ2 þ N2H4:H2O ! 2FeðOHÞ3 þ 2NH3
or
2Fe2þ þ N2H4:H2O ! 2Fe3þ þ 2NH3 þ 2OHꢀ
2FeðOHÞ3 þ FeðOHÞ2 ! Fe3O4 # þ 4H2O
or
Fe2þ þ 2OHꢀ ! FeðOHÞ2
(1)
2Fe3þ þ Fe2þ þ 8OHꢀ ! Fe3O4 # þ 4H2O
Fig. 7. SEM images of obtained magnetite with N2H4.H2O in ethanol (S11).

S. Bakhshayesh, H. Dehghani / Materials Research Bulletin 48 (2013) 2614–2624
2621
Fig. 8. TEM image of obtained magnetite with N2H4.H2O (S3).
Fig. 8 presents the TEM image of the synthesized sample of
magnetite with N2H4.H2O (S3). This image shows that the
magnetite has a spherical shape and its particles size is less than
100 nm. Furthermore, SEM images of the S3 (Fig. 5a and b) show
that particles of the sample are uniform and in result we select this
sample as a core for preparation of magnetite-porphyrin nano-
composite (MPNC).
The IR spectra of the synthesized magnetite nanoparticles, the
magnetite coated with silica (Fe3O4/SiO2) and the magnetite-
porphyrin nanocomposite are shown in Fig. 9a. In the spectrum of
magnetite nanoparticles is observed a broad band at ꢂ3400 cmꢀ1
,
which is assigned to stretching vibrations of hydrogen bonding
related to water molecules and hydroxyl groups of the magnetite.
The strong band at 582 cmꢀ1 is attributed to Fe–O vibration of
Fe3O4 (Fig. 9a(i)). In the case of magnetite nanoparticles coated
with silica, the sharp band at 1090 cmꢀ1 is related to Si–O–Si
antisymmetric stretching vibrations. This indicates existence of
SiO2 in the nanoparticles and the band at 3423 cmꢀ1 is related to
O–H stretching vibration of water. Fig. 9a(ii) shows the strong
Fig. 9. (a) FT-IR spectra of magnetite nanoparticles (i), Fe3O4 nanoparticles coated
with SiO2 (ii), magnetite-porphyrin nanocomposite (iii). (b) DRS of magnetite
nanoparticles (i) Fe3O4 nanoparticles coated with SiO2 (ii), magnetite-porphyrin
nanocomposite (iii).
Fig. 10. Room temperature magnetization curve of magnetite nanoparticles and magnetite-porphyrin nanocomposite (MPNC).

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S. Bakhshayesh, H. Dehghani / Materials Research Bulletin 48 (2013) 2614–2624
absorption bands at 472 and 578 cmꢀ1 related to Fe–O vibrations.
FT-IR spectrum of the magnetite-porphyrin nanocomposite
showed stretching vibrations for NH and CO (amide) related to
amide groups of the porphyrin at 1472 and 1630 cmꢀ1. Other
aromatic and aliphatic stretching vibrations of the porphyrin are
found at 719, 795, 1583, 1537, 1379 and 2928 cmꢀ1. The presence
of coated silica can be proved by strong bands at 1102 cmꢀ1
(Fig. 9a(iii)).
The diffuse reflectance spectra (DRS) of the magnetic samples
are shown in Fig. 9b. The DRS of Fe3O4 does not show any
significant variation in the measured reflectance with visible and
UV light. This is because of its band gap of about 0.1 eV [51]. Silica
coating around the nanoparticles increases the relative amount of
absorption without the appearance of a characteristic peak in the
UV–vis range. The spectrum of the magnetite-porphyrin nano-
composite is quite similar to the UV–vis spectrum of porphyrin.
This shows that the porphyrin is connected to the magnetite
nanoparticle coated with silica (Fig. 9b(iii)).
Fig. 11. MPNC are attracted to the wall of the vial in presence of a magnet.
The magnetite properties were studied using VSM at room
temperature. Ferromagnetic behavior was observed with an S-
Shaped hystersis loop, typical of magnetite. Fig. 10 shows the
magnetization curve of the nanoscaled magnetite (S3) and the
magnetite-porphyrin nanocomposite. The plot of the magnetiza-
tion versus magnetic field (M-H loop) shows that the magnetite
sample has strong magnetization and small coercivity (HC). The
saturation magnetization value (MS) was calculated from VSM
analysis, which is about 80 emu gꢀ1 and is lower than the bulk
magnetite (90–100 emu gꢀ1) [52]. As shown in Fig. 10, when
applied magnetic field is removed, the synthesized nanoscaled
soft magnetite material. Whereas (MS), (MR) and (HC) values for the
obtained magnetite-porphyrin nanocomposite were 23.5 emu gꢀ1
,
ꢂ2 emu gꢀ1, ꢂ82.5 Oe, respectively. The data show that the
magnetite-porphyrin nanocomposite (MPNC) has magnetic prop-
erty less than the magnetite nanoparticles, but is good candidate
for removal of heavy cations from solutions by magnetic
separation easily. After placing of a magnet besides the vial,
materials was quickly attracted to the wall of the vial, Fig. 11.
The adsorption of lead(II) ion with MPNC can be proved by XRD
and EDS analysis. Fig. 12 shows the XRD patterns of the MPNC. This
Fe3O4 keeps very low remanence magnetic (MR) ꢂ 8 emu gꢀ1
.
Coercivity value is low (ꢂ78 Oe) and indicates that the sample is
Fig. 12. XRD patterns of the magnetite-porphyrin nanocomposite (a) and the sample consist of MPNC and lead (b).

S. Bakhshayesh, H. Dehghani / Materials Research Bulletin 48 (2013) 2614–2624
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Fig. 13. EDS pattern of the sample consist of MPNC and lead.
figure shows that the sample contains both the magnetite related
to MPNC and lead. Furthermore, the EDS pattern of this sample is
containing MPNC and lead (Fig. 13).
water and so is separated from solution by a magnetic power
easily.
The amount of lead ion adsorption by the magnetite sample was
determined from a standard curve according to atomic absorption
method. The data showed that the mass of lead that adsorbed by
the magnetite sample was 2%. Also, the magnetite sample was not
adsorbed cadmium or mercury ions from those solutions. As a
result, with connection of the porphyrin to magnetite, adsorption
of lead increases, and it enables us to remove cadmium and
mercury ions from solutions. When the nanoparticles are modified
to the nanocomposite, both qualitative and quantitative properties
in removal of cations from water are improved. Furthermore, the
amounts of lead and cadmium ions in the magnetite-porphyrin
nanocomposite were determined from a standard curve according
to atomic absorption method. Calculations showed that mass per
cent lead and cadmium in the MPNC samples were 45.2% and
15.2%, respectively. The amount for mercury in the MPNC sample
(with dithizone method) was mass 10%. In result, the MPNC acts as
an effective material in removing heavy cations from water.
Acknowledgements
The authors are grateful to University of Kashan for supporting
this work by Grant No. (159183/8).
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