(562ax) Magnetic Graphene Oxide Modified with Chitosan and Cysteine Catalyst Was Synthesized for Removing (Pb 2+) Ions from Aqueous Solution

Synthesis and identification of modified magnetic Carbon
Nanoparticle and study of its application in removing Lead ions (pb ²⁺)
from aqueous solution

Ghazaleh. Ramezani ^a,, Bizhan. Honarvar ^a,b*,
Masoomeh. Emadi ^a , Sayyed Esmaeil. Moradi ^a

^a Department of Chemical Engineering, Marvdasht
Branch, Islamic Azad University,

Marvdasht, Iran

^b Department of Civil Engineering ,
University of Texas at Arlington, Arlington, Texas

Abstract                   

magnetic graphene oxide modified with Chitosan and Cysteine (GO/Fe3O4/chi/cys) was synthesized for removing (pb ²⁺) ions from
aqueous solution. The structural properties were analyzed by different
techniques such as FE-SEM, FTIR and VSM. Physicochemical analysis such as
effect of pH, contact time, adsorbent dosage and initial concentration of pb ²⁺
was also studied. The results showed that the maximum capacity of GO/Fe3O4/chi/cys in Lead ions adsorption (Equilibrium concentration of
120 ppm) occurred at

=5.75,

=30min and Adsorbent dosage=0.1 gr. Maximum empirical adsorption capacity

) was calculated 85.4

. The equilibrium data were analyzed using Langmuir and Freundlich
models. The experimental data could be well described by the Langmuir isotherm

. Also, the adsorption kinetics followed the mechanism of the
pseudo-second-order equation

; So Pb²⁺ions adsorption onto GO/Fe3O4/chi/cys may be monolayer and chemisorption.

Keywords:

 Water treatment; Removal of pb²⁺;
Nano composite; magnetic graphene oxide; Adsorption Isotherms; Kinetics

1.INTRODUCTION

Lead is one of the most toxic metal ions and it’s found in +2
oxidation state (pb ²⁺) in the inorganic form. Its
presence in drinking water resources, can damage to the brain, blood
composition, liver, kidney, nervous and reproductive system [1].So, removal of that,
from aquatic systems has attracted the

attention of researchers. The limit of lead concentration in
drinking water specified 0.05

 from the world Health Organization
[2]. Many processes were developed to treat water pollution with metal ions, such
as membrane separation process, chemical precipitation, ion exchange, reverse
osmosis and adsorption [3]. Among these commonly methods, adsorption processes
are more popular than the others due to their high removal efficiency and the
simplicity of the purification process [4].efficiency of adsorption processes
have directly depended on the kind of adsorbent. So In recent
decades, Nano materials
based on carbon allotropes specially graphene based materials, such as graphene
oxide (GO) and reduced graphene oxide(R-GO) have been used as efficient and
affordable adsorbents in adsorption processes [5]. Unique properties of
graphene like; mechanical strength, great flexibility, water solubility and particularly
large specific surface area are reasons that cause graphene
,as the famous material of the 21^st century, to be used in
synthesis various Nano composites[6,7].

In this paper, at first we synthesized  magnetic graphene oxide modified with Chitosan
and Cysteine (GO/Fe3O4/chi/Cys) as a novel adsorbent .The characterization of Nano
composite were analyzed carefully by Field Emission Scanning Electron Microscope (FE-SEM), Fourier Transform
Infrared Spectroscopy(FT-IR), and Vibrating Sample Magnetometer (VSM).then, we
used it to remove lead ions from synthetic wastewater in a batch system.in the
next step.

2. Experimental

2.1. Materials

Natural graphite powder, Pure ethanol

,

, Glacial acetic acid, ,

,

,sodium hydroxide

and

 were
purchased from merck,Germany.Acetic acid, glutaraldehyde,

,

,

,

, dapcco and  Ethanolic were obtained from sigma-Aldrich,
Germany. Ammonia (25% by weight) with a molecular weight of 17.03

 was bought
from Arvin Chem Co. Chitosan powder (CS, Mw 1.3 × 105 Da, 90% deacetylation) was
supplied by Sinopharm Chemical Reagent Ltd (Shanghai, china).metal solutions
were prepared by, Double distilled water from Aban Distillery Pasargad Co and Lead
nitrate salt (Pb (NO3) 2) from Company Products Merck.

2.2.
Preparation of GO/ Fe3O4/Chi/CS Nano composite

In this study, Go was prepared via hummers method
[24].at first; 20 gr graphite powder and 40 gr NaNo₃ were added to
500 ml sulfuric acid solution at

. While the mixture was
stirred well, 120 gr KMno4 was added to the mixture gradually. Afterwards by using co-precipitation method GO was changed to GO/ Fe₃O₄
[25].For this purpose, 150 gr 

 and 60
gr

 were
dispersed in 100 ml Hcl solution (0.4 M). the
solution that contained iron ions (with molar ratios between Fe2+ and Fe3+ 2:1)
was added to 1100 ml the graphene oxide solution (0.01818 g/ml) Which was
synthesized in the previous step. The mixture was stirred for 2 hours and then added
immediately to 1.5 liters of ammonia solution (0.7 M). The ammonia solution was
degasified farther with Argon gas For 15 minutes. The reaction system was mixed at 60 ^oc for 2 Hours and then stirred at room
temperature for 12 hours. The black precipitate was collected and washed with
Double distilled water until its PH reached about

7.the Magnetic graphene oxide(GO/
Fe3O4) was kept wet  for the next step. For the last step of surface modification of Nano
composite with cysteine; at first,

 glutaraldehyde (25% wt.) and

 Glacial acetic acid were
suspended in

 pure ethanol and heated on the magnetic stirrer to

 ^0c. After that,

 added to

 pure ethanol and heated to 120 ° C. This solution
was added to the first solution. They were mixed well. The resultant mixture
was kept for 24 hours under reflux condition in an oil bath at

^0c.the green precipitate was filtered and washed with 50 ml hot
ethanol and then dried. The prepared Nano composite (GO/ Fe3O4/Chi/CS)
was used as adsorbent for removing of lead in a batch system.

3. Results and
discussion

3.1. Characterization
of GO/ Fe3O4/Chi/CS

3.1.1. Field
Emission Scanning
Electron Microscope (FE-SEM) Analysis

In order to study the morphology and structure of synthesized Nano
composite at different stages of surface modification, Field Emission Scanning Electron
Microscope (FE-SEM) Analysis Was investigated. For this purpose, FE-SEM
instrument (The SIGMA VP model) was used in 25 kv and the Results
was shown in Fig.1. As seen in Fig.1.a; Graphene oxides sheets had a completely porous and irregular
structure with Particle size smaller than 200 nm. according to Fig.1.b, Fe₃O₄
nanoparticles with the size of about 60 nm were take placed successfully on the
graphene oxides sheets.Fig.1.c represents a thin coating of chitosan at
the adsorbent surface which causes a fundamental change in the adsorbent
morphological structure. At this stage; the adsorbents surface seems relatively rough. According
to Fig.1.d the final structure of the Nano composite is Non-uniform and
heterogeneous.

4. Conclusion

In this paper, a novel adsorbent of GO/ Fe₃O₄/Chi/CS
composite was successfully prepared and investigated for the removal lead ions
from aqueous solutions. GO/ Fe₃O₄/Chi/CS is a Super-Paramagnetic
adsorbent and it can be separate by an external magnetic field so easily. The optimal conditions for adsorption of lead (II) ions were
achieved at

=5.75,

=30min and Adsorbent dosage=0.1 gr. Maximum empirical adsorption
capacity

) was 85.4

. The adsorption
isotherms could be explained by the Langmuir model and the adsorption kinetics
data were well fitted by the pseudo-second order model (R² = 0.9996)
Therefore the adsorption of lead (II) ions onto GO/Fe₃O₄/Chi/CS
Nano composite is a monolayer, favorable (0

 1). and chemical adsorption.

Acknowledgments

This research work was supported by the Islamic Azad University,
Marvdasht, Iran.

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