Synthesis and characterization of new modified silica coated magnetite nanoparticles with bisaldehyde as selective adsorbents of Ag(i) from aqueous samples

Article abstract of DOI:10.1039/c5ra11765h

In this study, new silica-coated magnetic nanoparticles modified with bisaldehyde (BISA-APTSCMNPs) were synthesized using a normal method and a vice versa method. The crystal structure of the newly obtained nanoparticles was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Vibrating Sample Magnetometry (VSM), thermogravimetric analysis (TGA) and ultra-violet visible spectroscopy (UV-vis). The surface of the nanoparticles was modified with bisaldehyde (BISA-APTSCMNPs), and these were used for the highly selective removal of Ag(i) ion from an aqueous mixed metal ion solution containing Cu(ii), Co(ii), Ni(ii), Zn(ii) and Pb(ii) using the syringe and batch techniques. Moreover, the silver ion desorption was most efficient in HCl.

Full text of DOI:10.1039/c5ra11765h

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Synthesis and Characterization of new modified silica coated magnetite nanoparticles
with bisaldeheyde as selective adsorption of Ag (I) from aqueous samples
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Alireza Banaei, Hossein Vojoudi, Soheyla Karimi, Shahriyar Bahar, Eslam Pourbasheer
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Department of Chemistry, Payame Noor University, Tehran, Iran, P.O. Box 19395-4697; Tel: +984533515004; E-mail:
banaei@pnu.ac.ir
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Abstract
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In this paper, new silicaꢀcoated magnetic nanoparticles modified with bisaldeheyde (BISAꢀAPTSCMNPs) was synthesized using a
normal method and a vice versa method. The crystal structure of newly obtained nanoparticles was characterized by Fourier Transform
Infrared (FTꢀIR), Xꢀray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Vibrating
Sample Magnetometry (VSM), Thermogravimetric Analyzes (TGA) and UltraꢀViolet Visible (UVꢀVis). The surface modification of
nanoparticles with bisaldeheyde (BISAꢀAPTSCMNPs) were used to excellent selective removal Ag (I) ion from aqueous mixed metal
ion solution containing Cu (II), Co (II), Ni (II), Zn (II) and Pb (II) by syringe and batch techniques. Also, the silver ion desorption
efficiency was in HCl.
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Keywords: Modified silica coated magnetite nanoparticles, Bisaldehyde, Selective silver adsorption
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1. Introduction
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Nanotechnology is one of the most important branches of modern science in the preparation and usage of nanoparticles [1]. In recent
years, nanomaterials have attracted much interest in the research community due to their large specific surface area and high reactivities
[2]. Magnetic nanoparticles are a class of nanoparticle which is commonly composed of magnetic elements such as iron, cobalt, nickel
and their respective oxides [3, 4]. Among the various nanostructure materials, iron oxides with many important and diverse applications
play a major role in many areas of chemistry, physics and materials science. In particular, various derivatives these nanoparticles such
3 4 2 3 2 3
as magnetite (Fe O ), maghemite (γꢀFe O ), and hematite (αꢀFe O ) have been investigated intensively for environmental and bioꢀ
applications [5]. In addition to convenient magnetic properties and low toxicity and price, iron oxide nanoparticles show high surface to
volume ratios, depending on the particle size, shape, and well dispersed in a solvent [6]. The size and shape of magnetite particles are
generally controlled by the synthesis methods [7]. To date, numerous chemical methods have been developed to produce magnetite
nanoparticles, such as the microemulsion, the chemical coꢀprecipitation, the hydrolysis, the thermal decomposition and the sol–gel
technique [8]. Recently, several researchers have used of Schiff base moiety for anchoring different catalytic species on the magnetic
nanoparticles [9ꢀ13].
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Magnetic solid phase extraction developed rapidly in recent years due to its unique advantages, such as easy operation, high extraction
efficiency and reusability of sorbent [14]. At present, magnetic nanoparticles (MNPs) have been studied as the solid phase extraction
(SPE) sorbents with high magnetic characteristic for the separation and removal of chemical species such as metals, dyes and gases
[15]. In many cases, nanoparticles surface functionality with special functional ligands can improve the sorption capacity and efficiency
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of the extraction [16, 17]. Recently, the number of functionalized Fe O nanoparticles has been employed as solid phase extraction
(SPE) adsorbents for the removal of metal ions from aqueous solutions. For example, silicaꢀcoated magnetic nanoparticles modified
with imidazole and quercetin was used for removal of iodine and uranyl ions from aqueous solutions, respectively [18, 19].
In this paper we report the synthesis silicaꢀcoated magnetic nanoparticles modified with bisaldeheyde (BISAꢀAPTSCMNPs) by a
normal method and a vice versa method. The resulted nanoparticles were employed for selective adsorption Ag (I) ion from aqueous
solution in the presence of equal amounts of Cu (II), Co (II), Ag (I), Ni (II), Zn (II) and Pb (II) ions using syringe and batch techniques.
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2. Experimantal
2.1. Chemicals and reagents
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Ferric chloride hexahydrate (FeCl
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. 6H
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O) with 98% purity, Ferrous chloride tetrahydrate (FeCl
2 2
. 4H O) with 98% purity, Absolute
ethanol, Glycerol with 99% purity and Ammonia (NH
3
) with 25% purity, were purchased from Merck, Germany. Tetraethyl
orthosilicate (TEOS) with 99.8% purity, 3ꢀaminopropyltrimethoxysilane (APTS) with 97% purity and 2ꢀhydroxybenzaldehyde with
99.9% purity were purchased from SigmaꢀAldrich, USA. Toluene was bought from Shanghai Experiment Reagent Co., Ltd (Shanghai,
China). 1, 3ꢀdibromopropane with 98% purity was purchased from fluka chemicals, Switzerland.
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2.2. Instrumentation
FTꢀIR spectra (Shimadzu prestigeꢀ21) were used to determine the identity of the as prepared nanoparticles and to characterize the
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coated Fe O nanoparticles. Xꢀray powder diffraction measurements were performed using a Xꢀray diffractometer (XRD) (Perkin
Elmer) at ambient temperature. The surface morphology of the silicaꢀsupported ligands was identified with a scanning electron
microscope (LECO SEM, Michigan, USA). TEM images of the nanoparticles were obtained with an Hꢀ912 transmission electron
microscope. Magnetic measurements were performed by means of the vibrating sample magnetometery method, using a VSM 7407
magnetometer, at room temperature. Thermogravimetric analysis (TGA) was performed suing a Perkin Elmer thermogravimetric
analyzer. UV–Visible spectra in the 200–1000 nm range were obtained in DMF solvent on a Perkin Elmer Lambda 45
spectrophotometer. The concentration of metal ions in the solution was measured by using a flame atomic absorption spectrophotometer
(FAAS, GBC 932 AA, Victoria, Australia). A Jenway model 4510 pHꢀmeter was used for pH measurements by use of a combined
electrode. An Ultrasonicaton probe (Karl Deutsch, Germany) was used to disperse the nanoparticles in solution.
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2.3. Synthesis of 2, 2'-(propane-1, 3-diylbis (oxy)) bisbenzaldehyde (BISA)
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A solution of 1.22 g (0.01 mol) salicyldehyde in hot ethanolic KOH (prepared by dissolving 0.56 g (0.01 mol) KOH in 100 ml of
absolute ethanol) was stirred until a clear solution was obtained, which was then evaporated under vacuum. The residue was dissolved
in DMF (25 ml) and 0.005 mol of 1, 3ꢀdibromopropan was added. The reaction mixture was refluxed for 5 h, during which KBr was
separated out. The solvent was then removed in vacuo and the remaining solid was washed with water and crystallized from ethanol to
give high quality crystals (Mp. 393 K) suitable for Xꢀray analysis in good yield (84%) [20].
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2.4. Synthesis of modified magnetite nanoparticles
2.4.1. Synthesis of magnetite nanoparticles (MNPs)
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The magnetic nanoparticles (MNPs) were prepared according to Ref. [14] with some little modifications. Briefly, FeCl
3 2
·6H O (11.68 g)
and FeCl ·4H O (4.30 g) were dissolved in 200 mL deionized water under nitrogen gas with vigorous stirring at 85 °C. Then, 20 mL of
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30% aqueous ammonia was added to the solution. The color of bulk solution changed from orange to black immediately. The magnetic
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precipitates were washed twice with deionized water and once with 0.02 mol L sodium chloride. The washed magnetite was stored in
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deionized water at a concentration of 40 g L .
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2.4.2. Synthesis of silica-coated magnetic nanoparticles (SCMNPs)
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The silicaꢀcoated magnetic nanoparticles were synthesized according to previous reported methods with a minor modification [14]. The
magnetite suspension prepared above (20 mL) was placed in a 250 mL roundꢀbottom flask and allowed to settle. The supernatant was
removed, and an aqueous solution of tetraethylorthosilicate (TEOS, 10% (v/v), 80 mL) was added, followed by glycerol (60 mL). The
pH of the suspension was adjusted to 4.6 using glacial acetic acid, and the mixture was then stirred and heated at 90 °C for 2 h under a
nitrogen atmosphere. After cooling to room temperature, the suspension was washed sequentially with deionized water (3×500 mL),
methanol (3×500 mL), and deionized water (5×500 mL). The silica magnetite composite was stored in deionized water at a
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2.4.3. Synthesis of amine-modified silica magnetite (APTSCMNPs)
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These nanoparticles were synthesized with some little modifications [14]. The silica coated magnetite nanoparticles was first dispersed
with technique of sonication in ethanol (100 ml) and then a solution of 3ꢀaminopropyltrimethoxysilane (APTS, 10% in ethanol) was
added to above mixture. After heating at 333 K for 6 h and stir for 12 h at room temperature under dry nitrogen atmosphere, the
resulted solid was magnetically separated, washed with ethanol several times to remove the unreacted residue of silylating reagent and
then vacuum dried at 353 K.
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2.4.4. Synthesis of silica-coated magnetic nanoparticles modified with bisaldeheyde (BISA-
APTSCMNPs) using normal method
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The amineꢀmodified silica magnetite (APTSCMNPs) (3 g) was dispersed with technique of sonication into 50 mL of distilled water,
and 2, 2'ꢀ(propaneꢀ1, 3ꢀdiylbis (oxy)) bisbenzaldehyde (BISA) (1 g, 3.5 mmol) dissolved in to 50 mL absolute ethanol, was added. The
resulting mixture was left for stirring for 24 h at room temperature, and was refluxed for 12 h. Then, the formed magnetite
nanoparticles was washed with dichloromethane, methanol and chloroform thoroughly and dried under vacuum at 60 °C.
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2.4.5. Synthesis of BISA- AP with Schiff base reaction
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BISAꢀAP ligand were synthesized by the reaction of 2, 2'ꢀ(propaneꢀ1, 3ꢀdiylbis (oxy)) bisbenzaldehyde (BISA) (1 g, 3.5 mmol) in 30
ml dry toluene and 3ꢀ aminopropyltrimethoxysilane (APTS) (1.26 mL, 7.0 mmol) in 50 ml dry toluene in the presence of 3ꢀ4 drops
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formic acid as a catalyst. The mixtures were stirred for 6 h under N ꢀatmosphere at room temperature. The crystals were filtered in
vacuum.
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2.4.6. Synthesis of silica-coated magnetic nanoparticles modified with bisaldeheyde (BISA-
APTSCMNPs) using vice versa method
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1 g of the silica coated magnetite nanoparticles (SCMNPs) was first dispersed with technique of sonication in water (100 ml) and
BISAꢀAP ligand (2.13 g, 3.5 mmol) dispersed in water (100 mL) was added to above mixture. After heating at 373 K for 2 h and stir for
24 h at room temperature under dry nitrogen atmosphere, prepared to modified magnetite nanoparticles as “on water reaction” and the
resulted solid was magnetically separated, washed with hot ethanol several times to remove the unreacted ligands and then vacuum
dried at 353 K.
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2.5. Solid phase extraction techniques
2.5.1 Batch method
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All adsorption experiments were carried out at room temperature in a gas bath shaker. To determine the sorption capacity, 20 ml of
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aqueous solution containing 10 mol/lit mixture of metal nitrate salts (Pb (NO
3 2 3 2 3 2 3 2 3 2
) , Co (NO ) , Zn (NO ) , Cu (NO ) , Ni (NO ) and Ag
(NO )) were added to 0.05 gr sorbent (BISAꢀAPTSCMNPs synthesized with a normal method and a vice versa method). The mixtures
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were shaked at 300 rpm and allowed to complete the extraction process for 1 h. subsequently, an NdꢀFeꢀB strong magnet (5 cm × 4 cm
× 2 cm, 1.4 T) was placed at the bottom of the beakers and the BISAꢀAPTSCMNPs were isolated from the solution. The upper aqueous
phase was taken out to measure the remaining metal ion concentration by AAS.
To determine the adsorption capacity, the magnetic adsorbents were separated from the solution washed with 10 ml deionized water.
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Then, 5 ml eluent solution containing 0.5 M HNO
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, 0.5 M HCl and 0.5 M S
2
O
(as prepared in the methanol) was added to the
solution and agitation for 15 min by Ultrasonicꢀ50 Hz to separate metal ions from the sorbent. Again, the nanoparticles was isolated
from the solution with an NdꢀFeꢀB strong magnet was placed at the bottom of the beaker and the upper aqueous phase was taken out to
measure the remaining metal ion concentration by AAS. The studies of metal ions (Pb (II), Co (II), Zn (II), Cu (II), Ni (II) and Ag (I))
were performed by varying the amount of sorbents BISAꢀAPTSCMNPs (0.01 g and 0.1 g) which produced by normal and vice versa
methods. To check the reproducibility, all experimental were done at least in triplicates.
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According to the obtained results in the batch method, we have designed a column which checked the rate of adsorption and sorption of
Ag (I) ion solution as mobile phase by BISAꢀAPTSCMNPs. For the construction of homeꢀmade solid phase extraction syringes, some
glass wool was placed at the bottom of the syringe. Afterwards, 0.05 , 0.1 and 0.2 g of BISAꢀAPTSCMNPs were weighed and placed
into the syringe and then finally another glass wool was placed at the top of the syringe. The syring with plastic stopper was placed in
the mouth of a vacuum flask so that fully coupled with the opening of the Meyer flask to prevent air infiltration. Then, 50 ml burette
was placed on top of the column so that the opening is placed on top of the column. The pump was turned on and then the syringes
were conditioned with 50 mL water before introducing the sample through the syringes. An aliquot of 50 mL of silver nitrate solution
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(10 mol/lit) was applied through the syringe with the flow rates at 1, 3 and 5 ml/min. After completion of the extraction process, the
pump was turned off and the resulting solution was analyzed by AAS. The adsorption of the Ag (I) on the BISAꢀAPTSCMNPs was
performed by 5 ml HCl (0.5 M), with a flow rate of (1 ml/min). After completed each cycle the eluent directly injected into the
nebulizer of the AAS.
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3.1. Preparation of the modified magnetite nanoparticles
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In this paper BISAꢀAPTSCMNPs nanoparticles were synthesized by a normal method and a vice versa method and were successfully
used as a sorbent for excellent selective removal Ag (I) ion from aqueous mixed metal ion solution containing Cu (II), Co (II), Ni (II),
Zn (II) and Pb (II) by syringe and batch techniques. Compared with normal method, the highest sorption percentage of metal ions was
obtained with synthesized nanoparticles using vice versa method. In addition, the FTꢀIR peak of the organic compound was clearer in
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these nanoparticles. Therefore, it can be concluded that more organic compound onto the surface of these nanoparticles attached. The
synthetic procedures of the modified magnetite nanoparticles have been shown in Scheme 1. In normal method, the external surface of
magnetite nanoparticles (MNPs) was coated with silica shell to obtain SCMNPs. Reaction of silicaꢀcoated magnetic nanoparticles
(SCMNPs) with 3ꢀaminopropyltrimethoxysilane (APTS) afforded amineꢀmodified silica magnetite (APTSCMNPs). The next step
involves reaction of APTSCMNPs amine groups with bisaldehyde (BISA) to yield the modified magnetite nanoparticles BISAꢀ
APTSCMNPs. In vice versa method, the BISAꢀAP ligands were synthesized from the reaction of bisaldehyde (BISA) and 3ꢀ
aminopropyltrimethoxysilane (APTS). Then, the reaction of the resulted ligands with silica coated magnetite nanoparticles (SCMNPs)
produced nanomaterials, BISAꢀAPTSCMNPs. The crystal structure of newly obtained nanoparticles was characterized by FTꢀIR, XRD,
SEM, TEM, VSM, TGA and UVꢀVis.
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Scheme 1.
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3.2. Characterization of the modified magnetite nanoparticles
3.2.1. FT-IR analysis
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Figure 1 shows the FTꢀIR spectra of all nanoparticles prepared in this work. The presence of magnetite core nanomaterials was
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confirmed by observation of two broad band's at around 459 cm and 573cm which correspond to the FeꢀO stretching and Fe
2 3
O
stretching, respectively (Fig. 1a). The IR spectrum of the silica coating of magnetite nanoparticles (SCMNPs) shows absorption peaks
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at 1103 and 949 cm are due to the SiꢀOꢀSi and SiꢀOH stretching vibration respectively (Fig. 1b). In addition the presence of the
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anchored propyl groups were confirmed by stretching vibrations appeared at about 2933 cm in the FTꢀIR spectrum of 2, 2'ꢀ(propaneꢀ
ꢀ
1
1, 3ꢀdiylbis (oxy)) bisbenzaldehyde (BISA). The peak corresponding to the CH stretching vibration of ring 2933 cm has appeared in
the area [13]. In addition, the absorption bands of stretching vibrations of CꢀO (ether groups) and C = N (imini) bands are observed at
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ꢀ1
1293 cm and 1640 cm , respectively. The peak at 1599 cm characteristic of bending vibrations of the C=C aromatic ring. The peak
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1
at 3427 cm belongs to the stretching vibration OꢀH adsorbed on the surface of the Fe O nanoparticles. The broad absorption bands
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at 3440 cm and 1600 cm was due to OH stretching vibration, which corresponds to OH groups on the surface of iron oxide and this
band can be attributed to the adsorbed water molecules (Fig. 1d and 1e).
Figure 1.
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3.2.2. XRD analysis
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The crystallinity of asꢀmade magnetic nanoparticles was determined by Xꢀray diffraction (XRD) using a diffractometer with Cu K_
radiation (40 kV/30 mA). Fig. 2 shows the XRD profiles of the BISAꢀAPTSCMNPs nanoparticles prepared in this work. As shown in
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figure, the presence of diffraction peaks located at 2θ = 30.2 , 35.4 , 37.1 , 43.1 , 53.3 , 57 , and 62.5 corresponded to (2 2 0), (3 1 1), (2
2 2), (4 0 0), (4 2 2), (5 1 1) and (4 4 0), respectively. These results indicated that magnetite (Fe ) have a faceꢀcentered cubic (fcc)
structure. Also, we did not observation other iron oxides such as αꢀFe , βꢀFe and γꢀFe , which indicate that the Fe was not
3
O
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O
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O
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O
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O
oxidized to other forms in the synthetic steps. This pattern indicates that organic species are well dispersed on the surface of SCMNPs
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and there is no any crystalline phase of organic in components the resulted nanomaterials.
Figure 2.
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3.2.3. SEM analysis
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A scanning electron microscope (SEM) is extremely useful for characterizing the morphological structure and size of the magnetite
nanoparticles. The SEM image of the prepared BISAꢀAPTSCMNPs nanomaterials is shown in Fig. 3. SEM images of synthesized
nanoparticles clearly show the BISAꢀAPTSCMNPs nanoparticles are spheroidal in shape. As shown in Figure 3a, the diameter of
BISAꢀAPTSCMNPs (prepared using normal method) is about 30ꢀ45 nm. While, the diameter of synthesized BISAꢀAPTSCMNPs using
vice versa method are about 35ꢀ50 nm, which is slightly larger than the value of average particle size obtained from normal method
(Figure 3b). Also, the SEM images clearly indicate that the sizes of the particles with add of organic compound very slightly changed
so that is not sensible.
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Figure 3.
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3.2.4. TEM analysis
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In order to obtain more direct information on particle size and morphology, transmission electron microscopy (TEM) micrographs of
the obtained nanoparticles were used. Fig. 4a and 4b illustrates the TEM images of the synthesized BISAꢀAPTSCMNPs. TEM analysis
of the nanoparticles indicated that the both BISAꢀAPTSCMNPs (normal method) and BISAꢀAPTSCMNPs (vice versa method) are
spherical morphologies. According to TEM images, the mean particle size, is about 45 nm for BISAꢀAPTSCMNPs (normal method)
and 50 nm for BISAꢀAPTSCMNPs (vice versa method), which indicate particle size in the vice versa method is slightly larger than the
normal method.
Figure 4.
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3.2.5. VSM analysis
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To study the magnetic properties of magnetite nanoparticles before and after silica coating, we investigated the hysteresis loops of
magnetite and functionalized magnetite nanoparticles at room temperature using vibrating sample magnetometry (VSM). Fig. 5 shows
the room temperature magnetic hysteresis loops of the prepared magnetite nanoparticles. The VSM results indicate that all the prepared
magnetite nanoparticles possess superparamagnetism properties at room temperature, which this is because their small size. On the
other hand, surface coating of the magnetite nanoparticles with silica and bisaldehyde (BISA) compunds results in decreasing of the
saturation magnetizations (Ms), which this decrease may be due to the superparamagnetic property and the screening effect of the silica
layer, since the magnetic silica nanocomposites could be readily and stably dispersed in water and remained in suspension in the
absence of an external magnetic field. The saturation magnetization values for the Fe O particles, SCMNPs and BISAꢀAPTSCMNPs
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nanomaterial are 67, 59 and 18 emu/g, respectively. Compared to the Fe O microspheres, the slow decrease in the saturation
magnetization for the BISAꢀAPTSCMNPs nanoparticles can be attributed to the silica shell.
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Figure 5.
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3.2.6. TGA analysis
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A thermogravimetric analyzer (TGA) was used to confirm the coating formation and to estimate the binding efficacy of bisaldehyde
(BISA) on the surface of magnetite nanoparticles. The TGA measurements were carried out by weighting a powder sample of 5–10 mg
◦
and loaded into a platinum pan. The mass change under the temperature scan from 30 to 800 °C at a heating rate 20 C/min and under a
nitrogen flow was monitored and recorded.
Fig. 6 shows the result of TGA on nanoparticles at the range of 30−800 °C. The TGA curve of the prepared nanoparticles gave two
mass loss processes before 600 °C. The mass loss rates are about 1.5% and 10.7%, respectively. The first weight loss rates are about
1.5% with the temperatures below 260 °C is due to the evaporation of water in magnetite BISAꢀAPTSCMNPs nanoparticales, and the
second weight loss is about 10.7% between 260 and 450 °C is attributed to the thermal decomposition of the organic species, i.e.
aminopropyl groups and bisaldehyde in the nanomaterial. The TGA curve above 600 °C indicates that organic species magnetic
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composite nanoparticles have completely been decomposed and that the remnant is Fe O nanoparticles.
Figure 6.
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3.2.7. UV-vis analysis
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Light absorption properties of all the synthesized nanomaterials were measured using a UV–vis spectrophotometer (Perkin Elmer
Lambda 45) with a wavelength range of 200–700 nm. As shown in Fig. 7, the UV–vis absorption spectrum indicated the absorption
peak of bisaldehyde (BISA) in the range 210ꢀ285 nm due to πꢀπ* transitions of the (C=C) aromatic ring and imine (C=N) group.
Figure 7.
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3.3. Extraction condition optimization
3.3.1. Effect of extraction time
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The effect of the extraction time was also studied in the range of 5ꢀ60 min for batch method and different flow rates varied from 1.25
ꢀ
1
ꢀ1
ml min to 10 ml min for syringe method in order to find optimum extraction time for maximum adsorption. Mix standard solutions
ꢀ
1
of Cu (II), Co (II), Ag (I), Ni (II), Zn (II) and Pb (II) (1 mg l ) were used for all experiments. The adsorption of Ag (I) increased during
the first 5 min and then level off as an equilibrium (above 95% sorption) was reached in 5 min. Optimum flow rate of all metal ions
ꢀ
1
were found as 3 ml min for syringe method. The rapid adsorption equilibrium indicates the strong affinity between the ligands and the
metal ions. This behavior indicates that these ions have a good accessibility through the chelating sites on the modified silica and the
binding constant between the metal ion, imine and hydroxyl groups immobilized on the silica surface is possibly high. According to
these results, it is suitable for applying the sorbent in a syringe system where shorter extraction time or faster adsorption is required.
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3.3.2. Effect of sorbent amount
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The amount of sorbent is very important parameter that affects the recovery. Nanoparticles have been used as better sorbents for their
high surface areas than conventional sorbents. Therefore, fewer amounts of modified silica coated magnetite nanoparticles (nanoꢀ
sorbents) can achieve satisfactory results. Optimum sorbent was determined by using batch and syringe methods. The influence of the
sorbent amount for the quantitative extraction of Cu (II), Co (II), Ag (I), Ni (II), Zn (II) and Pb (II) from an aqueous sample was tested
in the range 5ꢀ50 mg for batch method and 25ꢀ100 mg for syringe method at pH= 9, respectively. Effect of the adsorbent amount on
extraction of metal ions in batch procedure is shown in Fig. 8 and 9. The results for syringe procedure are shown in Table 1. As it is
seen from the Fig. 7 and 8, the best sorption percentage and the highest adsorption coefficient values were obtained for Ag (I) ion from
water samples with synthesized BISAꢀAPTSCMNPs (0.05 g) using vice versa method. According to results, the synthesized
nanomaterial shows excellent silver (I) ion adsorption selectivity at pH=9 in mixed metal ion solution containing Cu (II), Co (II), Ni
(II), Zn (II) and Pb (II). Furthermore, the experimental results indicated that 0.05 and 0.1 g of the nanoꢀsorbent is enough for the
preconcentration of Ag (I) using the batch and syringe method, respectively. Therefore, 0.05 and 0.1 g of sorbent was used at the
subsequent experimental.
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Figure 8.
Figure 9.
Table 1.
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3.3.3. Effect of elution conditions on recovery
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The effect of various acids were used to identify the best eluent for the adsorbed metal ions on solid phase extraction (SPE) with BISAꢀ
APTSCMNPs produced by normal and vice versa methods is given in Figure 8 and 9. To obtain a high enrichment factor, a suitable
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ꢀ
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eluent should be used. Diluted hydrochloric acid (HCl), nitric acid (HNO ) and thiosulfate (S O ) as prepared in methanol solutions
were used for the maximum elution of Cu (II), Co (II), Ag (I), Ni (II), Zn (II) and Pb (II) ions from the nanoparticleꢀsupported complex
form as in the literature. An acid solution has been widely used for the elution of metal ions from a sorbent due to the protonation at a
chelating site of the sorbent. The experimental results indicated that among of different eluents used, 0.5 M HCl provided higher
recovery and reproducibility. Hydrochloric acid (HCl) is commonly suitable and hence replaces the metal ions from binding sites;
moreover this acid does not interfere with the subsequent determination by AAS.
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3.3.4. Reusability of sorbent
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The reusability of the sorbent is very important in order to evaluate its widespread usage in the laboratory. The stability and potential
reusability of the adsorbent was investigated through several adsorptionꢀelution cycles. In order to test the reusability, it was subjected
to repeated adsorption and desorption operations as follows: 100 mg sorbent was put into the syringe and washed with 0.5 M HCl and
ꢀ
1
water in order to activate the sorbent. 10 ml 1.0 mg l Cu (II), Co (II), Ag (I), Ni (II), Zn (II) and Pb (II) mix standard solution was
drawn at room temperature. The metal adsorbed ligands were washed with 10 ml 0.5 M HNO and the desorbed metal ions were
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detected with AAS. Finally, the eluted sorbent was treated with doubly distilled deionized water repeatedly until the supernatant
reached neutrality. The absorbance and recovery of Cu (II), Co (II), Ag (I), Ni (II), Zn (II) and Pb (II) were calculated from the
adsorption and desorption operations respectively. The results agreed with 95% ± 5 recoveries for all metal ions within 0.1–5% relative
error for metal ions in five cycles which fully demonstrates the nanoparticleꢀsupported ligands have desirable stability and reusability.
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3.3.5. Effect of Doping of silver ions by column filled with BISA modified nanoparticles
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9
The studies of doping of Ag (I) were performed by varying the concentration of sorbents BISAꢀAPTSCMNPs (0.05 g, 0.1 g and 0.2 g)
produced by normal and vice versa methods with a flow rate of (1 ml/min, 3 ml/min and 5 ml/min). Data Tables 1 and 2 shows the
doping and adsorption of silver ions. As can be seen from the results, 0.1 g of synthesized BISAꢀAPTSCMNPs using vice versa method
are sufficient in the preconcentration of Ag (I) using syringe method and with a flow rate of (3 ml/min).
Table 2.
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4. Conclusion
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In this paper, aromatic bisaldehyde (BISA) was synthesized by coupling salicylaldehyde with 1, 3ꢀdibromopropan and then
nanocomposite material of BISAꢀAPTSCMNPs was synthesized using a normal method and a vice versa method. The newly
synthesized nanoparticles were characterized by FTꢀIR, XRD, SEM, TEM, VSM, TGA and UVꢀVis. These nanoparticles were applied
as a sorbent for excellent selective removal Ag (I) ion from aqueous mixed metal ion solution containing Cu (II), Co (II), Ni (II), Zn (II)
and Pb (II) by syringe and batch techniques. The adsorption mechanism of metal ions onto the surface of BISAꢀAPTSCMNPs is more
likely to be templates effects or interaction between metal ions and aromatic rings [21, 22]. The results indicated that the best sorption
percentage and the highest adsorption coefficient values were obtained in regard to Ag (I) ion from water samples with synthesized
BISAꢀAPTSCMNPs using vice versa method. According to these results, we can say the novel modified magnetite nanoparticles may
be used as an alternative sorbent for the removal of Ag (I) from water sample. Also, it was observed that the silver ion desorption
efficiency was in HCl. XRD results show that the prepared magnetite nanoparticles have good crystal structure with a faceꢀcentered
(fcc) structure. The studies of doping of Ag (I) ion showed that 0.1 g of synthesized BISAꢀAPTSCMNPs using vice versa method are
sufficient in the preconcentration of Ag (I) using the syringe method at flow rate of (3 mL/min).
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Acknowledgements
The authors acknowledge the Payame Noor University, Ardabil, Iran for providing facilities for this work.
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Supplementary information
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FTꢀIR sepectra were recorded on Shimadzu prestigeꢀ21 FTꢀIR spectrophotometer in KBr disc. These spectra were used to determine
3 4
the identity of the as prepared nanoparticles and to characterize the coated Fe O nanoparticles. The magnetic properties of the
synthesized magnetite nanoparticles were performed by means of the vibrating sample magnetometery method, using a VSM 7407
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magnetometer, at room temperature. Light absorption properties of all the synthesized nanomaterials were measured using a UV–Vis
spectrophotometer (Perkin Elmer Lambda 45) with a wavelength range of 200–1000 nm.
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References
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[1] M. Faraji, Y. Yamini, M. Rezaee, J. Iran. Chem. Soc., 2010, 7, 1ꢀ37.
[2] Q. Li, Sh. Mahendra, D.Y. Lyon, L. Brunet, M.V. Liga, D. Li, J. J. Alvarez, P. water research., 2008, 42, 4591ꢀ4602.
[3] R. Kaur, A. Hasan, N. Iqbal, S. Alam, M. K. Saini, S. K. Raza, J. Sep. Sci., 2014, 37, 1805–1825.
[4] T. K. Indira, P. K. Lakshmi, IJPSN, 2010, 3, 1035ꢀ1042.
[5] P. I. Girginova, A. L. DanielꢀdaꢀSilva, C. B. Lopes, P. Figueira, M. Otero, V. S. Amaral, E. Pereira, T. Trindade, J Colloid Interf Sci.,
2010, 345, 234ꢀ240.
[6] N. Nuryono, N. M. Rosiati, B. Rusdiarso, S. C. W. Sakti , Sh. Tanaka, SpringerPlus, 2014, 3:515, 2ꢀ12.
[7] L. Shen, Y. Qiao, Y. Guo, Sh. Meng, G. Yang, M. Wu, J. Zhao, Ceram Int., 2013, 3, 1ꢀ6.
[8] S. Laurent, D. Forge, M. Port, A. Roch, C. Robic, L. V. Elst, R. N. Muller, Chem. Rev., 2008, 108, 2064–2110.
[9] H. Keypour, M. Balali, M. M. Haghdoost, M. Bagherzadeh, RSC Adv., 2015, 5, 53349–53356.
[10] M. Esmaeilpour, A. R. Sardarian, J. Javidi, Applied Catalysis A: General, 2012, 445– 446, 359– 367.
[11] A. GhorbaniꢀChoghamarani, Z. Darvishnejad, M. Norouzi, Appl. Organometal. Chem., 2015, 29,
[12] A. D. Campo, T. Sena, J. P Lellouche, I. J. Bruce, J. Magn. Magn. Mater, 2005, 293, 33–40.
[13] M. H. Ayob, J. Efendi, L. S. Yuan, Sh. Chandren, H. Ch. Siong, H. Nur, Jurnal Teknologi (Sciences & Engineering), 2014, 69,
21–23.
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[14] Ch. Huang, B. Hu, Spectrochim Acta B., 2008, 63, 437–444.
[15] Sh. Shariati, M. Faraji, Y. Yamini, A. A. Rajabi, Desalination, 2011, 270, 160–165.
[16] N. Neyaz, M. S. S. Zarger, W. A Siddiqui, IJES, 2014, 5, 260ꢀ269.
[17] M. Wierucka, M. Biziuk, Trends Anal. Chem., 2014, 59, 50–58.
[18] T. Madrakian, A. Afkhami, M. A. Zolfigol, M. Ahmadi, N. Koukabi, Nano-Micro Lett., 2012, 4 (1), 57ꢀ63.
[19] S. Sadeghi, H. Azhdari, H. Arabi, A. Zeraatkar Moghaddam, J HAZARD MATER, 2012, 215– 216, 208– 216.
[20] A. H. M. Elwahy, A. A. Abbas, Tetrahedron, 2000, 56, 885ꢀ895.
[21] V. K. Ahluwalia, R. Aggarwal, Organic Synthesis: Special Techniques, 2001, ISBN 1ꢀ84265ꢀ058ꢀ0, pp. 65ꢀ89.
[22] Y.Habata, J. Kizaki, Y. Hosoi, M. Ikeda, Sh. Kuwahara, Dalton Transactions, 2014, 44(3), 1170ꢀ7.
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Table 1. Doping of silver metal by nanoparticles modified with bisaldeheyde (BISAꢀ APTSCMNPs)
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Attraction
Ag 10 M
1 mL/minute 3 mL/minute 5 mL/minute
+
ꢀ4
BISAꢀAPTSCMNPs (normal method)
65
97
99
71
H
61
93
95
67
98
54
74
78
55
80
0
.05 gr
BISAꢀAPTSCMNPs (normal method)
.1 gr
BISAꢀAPTSCMNPs (normal method)
.2 gr
BISAꢀAPTSCMNPs (vice versa method)
.05 gr
BISAꢀAPTSCMNPs (vice versa method)
.1 gr
BISAꢀAPTSCMNPs (vice versa method)
.2 gr
Cotton
0
0
0
0
H
H
87
0
1
ND
01
ND
1
1
1
2
ND. Not detected
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Table 2. Desorption of Ag (I) ion from the surface of the nanoparticles modified with bisaldeheyde (BISAꢀ APTSCMNPs)
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Pull
Ag 10 M
5 mL
+
ꢀ4
HCl 0.5 M Condensed
BISAꢀAPTSCMNPs (normal method)
331
356
33.1
35.6
0
.1 gr
BISAꢀAPTSCMNPs (vice versa method)
.1 gr
0
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Figure Captions
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Figure 1. FTIR spectra of the synthesized magnetite nanoparticles: (a) MNPS, (b) SCMNPs, (c) APTSCMNPs (d) BISAꢀ
APTSCMNPs (Normal method) and (e) BISAꢀAPTSCMNPs (Vice versa method).
Figure 2. Xꢀray diffraction pattern of (a) BISAꢀAPTSCMNPs (Normal method) and (b) BISAꢀAPTSCMNPs (Vice versa method).
Figure 3. SEM images of magnetite nanoparticles: (a) BISAꢀAPTSCMNPs (Normal method) and (b) BISAꢀAPTSCMNPs (Vice versa
method).
Figure 4. TEM images of magnetite nanoparticles: (a) BISAꢀAPTSCMNPs (Normal method) and (b) BISAꢀAPTSCMNPs (Vice versa
method).
Figure 5. Hysteresis loops of a) MNPS, (b) SCMNPs, (c) APTSCMNPs, d) BISAꢀAPTSCMNPs (Normal method) and (e) BISAꢀ
APTSCMNPs (Vice versa method).nanoparticles at room temperature using VSM.
Figure 6. TGA curves of magnetite nanoparticles: (a) BISAꢀAPTSCMNPs (Normal method) and (b) BISAꢀAPTSCMNPs (Vice versa
method).
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Figure 7. The Uvꢀvis spectra of MNPS, SCMNPs, APTSCMNPs and BISAꢀAPTSCMNPs nanoparticles
Figure 8. Removal and recovery percentage of metal ions at different amounts of adsorbent obtained with normal method in various
eluent.
Figure 9. Removal and recovery percentage of metal ions at different amounts of adsorbent obtained with vice versa method in various
eluent.
Scheme captions
Scheme 1. Synthesis of modified magnetite nanoparticles with a normal method and a vice versa method
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Figure 1.
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Figure 2.
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Figure 3a.
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Figure 3b.
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Figure 4a.
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Figure 4b.
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Figure 5.
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Figure 6.
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Figure 7.
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Figure 8.
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Figure 9.
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Scheme 1.
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