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Frontiers of Environmental Science & Engineering

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ISSN 2095-221X(Online)

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Front. Environ. Sci. Eng.    2019, Vol. 13 Issue (5) : 71    https://doi.org/10.1007/s11783-019-1151-2
RESEARCH ARTICLE
Adsorption of phosphate on magnetite-enriched particles (MEP) separated from the mill scale
Muhammad Kashif Shahid1, Yunjung Kim2, Young-Gyun Choi1()
1. Department of Environmental Engineering, Chungnam National University, Daejeon 34134, Republic of Korea
2. Mechanical Process Research Group, Engineering Center, POSCO E&C, Incheon 220099, Republic of Korea
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Abstract

MEP were separated from mill scale at low magnetic intensity i.e., 300 to 500 gauss.

The phosphate adsorption capacity of MEP was determined 6.41 mg/g.

MEP packed-bed columns were successfully regenerated with alkaline solution.

Phosphate is a major pollutant in water, causing serious environmental and health consequences. In present study, the phosphate adsorption on novel magnetite-enriched particles (MEP) was comprehensively investigated. A new method and device were introduced for the separation of MEP from the mill scale at low magnetic intensity. Particles were characterized with different techniques such as XRD, XRF, SEM and EDS. The XRD and XRF analysis of MEP identified the dominant existence of crystalline magnetite. Furthermore, the morphological analysis of MEP confirmed the agglomerate porous morphology of magnetite. Oxygen and iron, the main constituents of magnetite were acknowledged during the elemental analysis using EDS. The phosphate adsorption on MEP is well explained using various isotherm and kinetic models, exhibiting the monolayer adsorption of phosphate on the surface of MEP. The maximum adsorption capacity was determined 6.41 mg/g. Based on particle size (45–75 and 75–150 µm) and empty bed contact time (1 and 2 h), four columns were operated for 54 days. MEP were appeared successful to remove all phosphate concentration from the column influent having 2 mg/L concentration. The operated column reactors were successfully regenerated with alkaline solution. The results indicated potential for practical application of the MEP for phosphate removal.
Keywords Adsorption      Magnetite      Mill-scale      Phosphate      Wastewater treatment     
Corresponding Author(s): Young-Gyun Choi   
Issue Date: 07 August 2019
 Cite this article:   
Muhammad Kashif Shahid,Yunjung Kim,Young-Gyun Choi. Adsorption of phosphate on magnetite-enriched particles (MEP) separated from the mill scale[J]. Front. Environ. Sci. Eng., 2019, 13(5): 71.
 URL:  
https://academic.hep.com.cn/fese/EN/10.1007/s11783-019-1151-2
https://academic.hep.com.cn/fese/EN/Y2019/V13/I5/71
Fig.1  Photo of the column operation with column design parameters at right side.
Period Column Particle size (µm) EBCT (h) Flow rate (L/h)
0–34 days C1 45–75 1 0.282±0.003
C2 75–150 1 0.285±0.003
C3 45–75 2 0.136±0.006
C4 75–150 2 0.142±0.007
34–50 days C1 45–75 1 0.283±0.001
C2 75–150 1 0.287±0.003
C3 45–75 2 0.147±0.003
C4 75–150 2 0.149±0.003
Tab.1  Description of column operation
Fig.2  XRD pattern of MEP.
Components Weight %
45–75 µm 75–150 µm 150–300 µm
Fe 98.05 98.50 98.32
Mn 0.80 0.77 0.78
Cr 0.37 0.13 0.14
Cl 0.28 0.22 0.04
Si 0.16 0.12 0.35
Ni 0.15 0.03 0.03
Ca 0.09 0.10 0.08
Cu 0.03 0.05 0.04
Mo 0.03 0.04 0.03
Nb 0.02 0.03 0.03
S – 0.02 –
Ti 0.02 – 0.03
Al – – 0.13
Tab.2  Composition (weight %) of different mesh sizes MEP as determined by XRF
Fig.3  SEM micrograph of MEP with wide range of size i.e., (a, b) 45–75 mm, (c, d) 75–150 mm and (e, f) 150–300 mm.
Fig.4  EDS spectra of MEP with wide range of size i.e., (a) 45–75 mm, (b) 75–150 mm and (c) 150–300 mm.
Range of size O Fe
45–75 μm 58.71 41.29
75–150 μm 61.77 38.23
150–300 μm 62.13 37.87
Tab.3  Elemental composition of MEP
Fig.5  Adsorption isotherm of phosphate by MEP. Error bars signify the standard deviation.
Model Parameters Value
Langmuir isotherm model qmax 6.414 mg/g
KL 0.021
R2 0.996
Freundlich isotherm model KF 0.329
n 1.711
R2 0.993
Pseudo-first-order kinetic model k1 3.1 × 10−3 min−1
R2 0.90
Pseudo-second-order kinetic model k2 4 × 10−4 (g·mg)/min
R2 0.94
Tab.4  Parameters obtained from Langmuir isotherm, Freundlich isotherm, pseudo-first-order and pseudo-second-order kinetic models for the phosphate adsorption on MEP
Fig.6  Adsorption kinetics of phosphate by MEP. Error bars signify the standard deviation.
Adsorbent Adsorption capacity (mg/g) Reference
MEP 6.41 This study
Magnetic iron oxide 5.03 Yoon et al. (2014)
Magnetite based nanoparticles 5.2 Daou et al. (2007)
Agro-waste rice husk ash 0.76 Mor et al. (2016)
Polypyrrole/BOF slag nanocomposite 5.18 Islam et al. (2014)
Magnetite mineral microparticles 0.83 Xiao et al. (2017)
Tab.5  Phosphate adsorption capacities for different adsorbents
Fig.7  Effect of pH and ionic strength on phosphate adsorption (a) and the effect of coexisting anions (b) on phosphate adsorption. Error bars signify the standard deviation
Fig.8  The schematic illustration of phosphate adsorption on MEP.
Fig.9  The operational behavior of columns.
Fig.10  The SEM image and EDS spectra of MEP after phosphate adsorption.
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