1. Magnetic nanoparticle (Fe3O4) impregnated onto NaOH-modified wheat straw for
Results and DiscussionAbstract
The magnetic separation technique has been shown to be a very
promising method for solid–liquid phase separation. Nano-Fe3O4,
which is super-paramagnetic, is used for purifying waste water
from the dying industry and the removal of heavy metals [1,2]. To
use this characteristic in the recovery of biosorbent, magnetic
wheat straw biomass (MWS) was made in our study. The new
material not only possesses the super-paramagnetic character of
nano-Fe3O4, but also has the good biosorption capability of wheat
straw which is advantageous for isolation and recovery.
Experimental
The Wheat Straw was washed, dried, crushed and sieved into a
range of a size range of 100-500 μm. The chemical precipitation
technique has been used to prepare magnetic particles. Then Wheat
Straw was added to prepared magnetic particles. The prepared
Fe3O4 –MWS adsorbent were tested with magnetic rod, and it was
observed that the adsorbent was attracted to the magnetic rod,
because of magnetic behavior of the iron (Fig1,2).
4. Optimal adsorbent dosage
Results and Discussion
Results and Discussion
8. Adsorption isotherms
6. Effect of contact time and initial dye concentration
Equilibrium data were fitted to the Langmuir, Freundlich, Temkin,
Sips and Redlich-Peterson models. The equations are shown in
Table 1. The fitness of these models was evaluated by the non-
linear coefficients of determination (R2).
6th National Seminar of Chemistry and Environment
University of Tehran
1.SEM analysis
Fig1. Raw wheat straw Fig2. Fe3O4 –MWS
As it clearly can be
understand from Fig7
and 8, for the this
particular condition,
0.6g of adsorbent is
the optimal dosage.
The optimal dosage
varies as the volume
and concentration of
solution differ.
5. Kinetic studies
Four kinetic models were studied, which are pseudo-first-order,
pseudo-second-order, Elovich and Intra-particle diffusion model
equations. The best kinetic model for MB adsorption, was pseudo-
second-order model while the worst was the Elovich equation
according to values of R2 listed in the table below.
As Fig 9 shows, as the contact time increases, the adsorption
increases until the equilibrium time. A two-stage kinetic
behavior was noticed: an initial quick stage where adsorption
was fast and a slower second stage whose contribution to the
total MB adsorption was relatively small.
7. Effect of pH
Effect of pH in the removal percent of MB
solution(100mL,100mgL−1) at constant temperature for 70 min was
investigated. Fig10 shows the pH effect on removal percent.
The optimal pH is 5 for the above condition. The removal
efficiency increased from 56.09 to 96.54% with the increase of pH
from 3 to 5.
Conclusion
Acknowledgements
References
The results revealed that nano-Fe3O4, with spherical and granular
morphology, were distributed on the surface of wheat straw
biomass. The functional groups such as carboxyl, hydroxyl and
amino groups found on the surface of Fe3O4-MWS may be
responsible for MB biosorption. The best kinetic model for MB
adsorption, was pseudo-second-order model. The Sips isotherm
found to be the best to describe sorption of MB on MWS. The
Langmuir and Freundlich were also satisfactory. Fe3O4-MWS
showed strong potential for MB adsorption.
8-9 October 2013
University of Tabriz
the removal of methylene blue from aqueous solution
In this work,. nano-Fe3O4 synthesized on NaOH-modified wheat
straw(MWS) and it’s biosorption potential was analyzed using
methylene blue (MB) as a model dye. The biosorption behavior of
MWS was examined by Five widely isotherms (The Langmuir,
Freundlich, Temkin, Redlish-Peterson and Sips) at different
temperatures, as well as the pseudo-first-order and the pseudo-
second-order kinetic models. The MWS characteristics and
biosorption mechanism were examined by SEM, XRD, FTIR and
zeta potential analysis.
Introduction
The Fe3O4-MWS befor and after MB adsorption were analyzed by
field emission scanning electron microscopy to examine their
surface structure(Fig3,4). The results show that the nano-Fe3O4
had good dispersivity on MWS and regular particle size.
Fig3. Fe3O4 –MWS Fig4. Fe3O4 –MWS + MB
2. XRD analysis
The diffraction peaks of Fe3O4 match well with the inverse cubic
spinel structure (JCPDS 19-0629). The XRD pattern of Fe3O4-
MWS confirms that the nano-Fe3O4 was loaded on wheat straw.
The peak intensity decreases and the full width of the peak
increases, which indicates the low crystallinity and small crystallite
size. It can be predominantly attributed to the existence of the
wheat straw which affects the crystal size and crystallinity.
3. FT-IR analysis and adsorption mechanism
NanoCore
C0 (mg/L) 25 50 100
Pseudo-first-order equation
k1(min-1) 0.0113 0.0161 0.0166
qe (mg g−1) 2.3554 3.4963 4.8939
R2 0.9692 0.8063 0.9648
Pseudo-second-order equation
k2(g mg-1 min-1) 0.0059 0.002710 0.001353
qe (mg g−1) 13.42 24.04 64.10
R2 0.9985 0.9943 0.9974
Elovich equation
A 3.2552 -15.685 12.592
B 1.8414 7.8325 9.6024
R2 0.9103 0.7896 0.8665
Intra-particle diffusion model
Kt1(mg g-1 min-1/2) 0.4243 4.8297 4.7767
C1(mg g-1) 7.2889 -17 17.488
R2 0.83 0.9315 0.9523
Kt2(mg g-1 min-1/2) - 0.0259 0.2059
C2(mg g-1) - 21.252 56.79
R2 - 0.9731 0.957
Temperature (K) 293 303 323
Langmuir
Qmax (mg/g) 500 476.191 625
kL (L/mg) 0.003294 0.00378 0.00268
R2 0.9961 0.9949 0.9866
Freundlich
1/n 0.96 0.9566 0.9671
kF (mg/g)(dm3/mg)1/n 1.7378 1.9024 1.7673
R2 0.9996 0.9998 0.9999
Temkin
bT (kj) 123.086 126.679 134.379
kT (L/mg) 0.26195 0.28412 0.2664
R2 0.9429 0.9436 0.9414
Sips
Qmax (mgg-1) 445.8 391.3 663
b ((mg-1)-1/n) 0.003657 0.00453 0.00254
1/n 1.007 1.011 0.9974
R2 1 1 1
Redlich-Peterson
a (LKg-1) 1.638 1.784 1.684
b (Kg mg-1) 0.001819 0.00154 0.00356
n 1.152 1.244 0.9294
R2 1 1 1
[1] Y.F. Shen, J. Tanga, Z.H. Nie, Y.D. Wang, Y. Ren, L. Zuo, Sep. Purif.Technol. 68
(2009) 312–319.
[2] Y.C. Chang, D.H. Chen, J. Colloid. Interface. Sci. 283 (2005) 446–451.
In the case of MWS after MB adsorption, there is remarkable shift
in positions of –OH, C =O and –C–C– group peaks which
indicates MB binding mostly at –OH and C= O groups.
Fig5. Before adsorption Fig6. After adsorption
Elham Saberikhah*1, Azadeh Ebrahimian Pirbazari1,2, Nima Gholami Ahmadgurabi1
1Faculty of Fouman, College of Engineering, University of Tehran
2 Faculty of Caspian, College of Engineering, University of Tehran
* E-Mail: Esaberikhah@ut.ac.ir
We gratefully acknowledge the Fouman Faculty of Engineering
supportment and financial support of Fouman Shimi Co.
0.6g
Fig7
Fig8
Fig 9
Fig10