ArticlePDF Available

Attapulgite as an eco-friendly adsorbent in the treatment of real radioactive wastewater

Authors:

Abstract and Figures

Operators cannot ignore the radiation hazards arising from nuclear weapons. In this study, batch adsorption experiments were investigated to remove the radioactive isotope Cs-137 from the real radioactive wastewater. The attapulgite natural clay mineral was characterized and adopted as an adsorbent in a batch adsorption system. Equilibrium was reached after 2 h with a Cs-137 removal efficiency of 97% for attapulgite. The kinetics of Cs-137 adsorption on the attapulgite clay surface were evaluated. The pseudo-second-order kinetic model produced an excellent fit with the experimental kinetic data for attapulgite, indicating that attapulgite was the best adsorption medium.
Content may be subject to copyright.
Attapulgite as an eco-friendly adsorbent in the treatment of real radioactive
wastewater
Wasan Muslima, Salam Al-Nasrib, Talib M. Albayati c,*and Issam Salihd
a
Iraqi Geological Survey/Ministry of Industry and Minerals
b
Iraqi Atomic Energy Commission (IAEC)/Radiation and Nuclear Safety Directorate, Baghdad, Iraq
c
Department of Chemical Engineering, University of Technology Iraq, 52 Alsinaa St., P.O. Box 35010, Baghdad, Iraq
d
Department of Chemical Engineering and Petroleum Industries, Al-Mustaqbal University, Babylon 51001, Iraq
*Corresponding author. E-mail: Talib.M.Naieff@uotechnology.edu.iq
TMA, 0000-0001-5619-7760
ABSTRACT
Operators cannot ignore the radiation hazards arising from nuclear weapons. In this study, batch adsorption experiments were
investigated to remove the radioactive isotope Cs-137 from the real radioactive wastewater. The attapulgite natural clay mineral
was characterized and adopted as an adsorbent in a batch adsorption system. Equilibrium was reached after 2 h with a Cs-137
removal efciency of 97% for attapulgite. The kinetics of Cs-137 adsorption on the attapulgite clay surface were evaluated. The
pseudo-second-order kinetic model produced an excellent t with the experimental kinetic data for attapulgite, indicating that
attapulgite was the best adsorption medium.
Key words: attapulgite, cesium adsorption, clay minerals, Cs-137, wastewater remediation
HIGHLIGHTS
Very cheap attapulgite clay was used in a batch adsorption system.
Iraqi attapulgite natural clay proved as an efcient adsorbent for the removal of Cs-137.
Natural clay was modied and manufactured from a locally available material.
The real samples of radioactive wastewater containing 137Cs have been treated.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits copying,
adaptation and redistribution, provided the original work is properly cited (http://creativecommons.org/licenses/by/4.0/).
© 2023 The Authors Water Practice & Technology Vol 00 No 0, 1 doi: 10.2166/wpt.2023.131
Uncorrected Proof
Downloaded from http://iwaponline.com/wpt/article-pdf/doi/10.2166/wpt.2023.131/1285266/wpt2023131.pdf
by guest
on 01 September 2023
GRAPHICAL ABSTRACT
1. INTRODUCTION
Radioactive wastewater is one of the riskiest pollutants generated by energy stations, medical programs, and
diverse extractive industries worldwide (Paranhos Gazineu et al. 2005). Effective treatments need to be cost-effec-
tive and safely reduce the volume of aqueous waste (International Atomic Energy Agency 2002;Cherif et al.
2017) containing long-lived beta/gamma activity stored in large tanks under nuclear sites. Cs-137 has a radio-
active half-life of about 30 years and very high solubility in liquid systems, and incorporates into both the soil
environment and aquatic organisms (Al-Alawy & Mzher 2019;Ahmed 2022). Liquids contaminated with Cs-
137 are a potential environmental problem. High radioactivity aqueous wastes with long-lived radionuclides
may be treated using different treatment technologies, including ion exchange/sorption, chemical precipitation,
and/or evaporation, reverse osmosis, ltration, and solvent extraction (IAEA 1999). Many studies have found that
adsorption is a good technique for removing radioactive materials from wastewater, with high activity and low
operating cost (Alardhi et al. 2020;Kadhum et al. 2021;Ali et al. 2022a). The best media in the treatment of
industrial wastewater were clay minerals whose features make them optimal adsorbents due to their low pro-
duction cost, ready availability, non-toxic nature, high specic surfaces, excellent adsorption properties, and
great potential for ion exchange (Al-Ani & Sarapää; 2008). Clay minerals adsorb cesium to balance the negative
charge on the aluminosilicate structure caused by the counter-ions (e.g., Na, Ca, Mg, or K) as adsorption sites on
the clay sheet surface, interlayers between sheets, and broken bonds at the edges of clay crystals (Wilson 2007;
Yuan et al. 2013). Attapulgite is the rock name of palygorskite, a hydrated MgAl silicate material that has a 2:1
inverted structure, i.e., the apices of the silica tetrahedrons are regularly inverted along the a-axis. This results in
parallel channels throughout the particles, which give these minerals a high internal specic surface containing
exchangeable cations and water (Stewart & Mollins 1996). Large cation exchange capacities (CECs) and high
total uptake of cesium occur when the interlayer sites are available for adsorption, as has been recorded in
the cases of montmorillonite and palygorskite (Adebowale et al. 2006;Ohnuki & Kozai 2013;Okumura et al.
2013;Ali et al. 2022b). Several studies have inspected the mechanism of cesium adsorption by ion exchange
with different potential sites on mineral surfaces and studied the effect of the structural characteristics of these
clay minerals (Cornell 1993;Park et al. 2019;Zabulonov et al. 2021). Other research examined the parameters
that inuence adsorption, adsorption isotherms, thermodynamics, and kinetics for many clay minerals (Sheha &
Water Practice & Technology Vol 00 No 0, 2
Uncorrected Proof
Downloaded from http://iwaponline.com/wpt/article-pdf/doi/10.2166/wpt.2023.131/1285266/wpt2023131.pdf
by guest
on 01 September 2023
Metwally 2007;Hadadi et al. 2009;Akalin et al. 2018;Semenkova et al. 2018; Al-Alawy et al. 2020; Muslim et al.
2022).
In this work, natural attapulgite clay minerals from the Western Desert of Iraq were selected as potential low-
cost, readily available, environmentally friendly adsorbents adopted for use in a batch adsorption system. Attapul-
gite was implemented to treat real radioactive wastewater containing Cs-137 that has been accumulated since
1991 underneath the Al-Tuwaitha Nuclear Research Center near Baghdad, Iraq. The inuence of various vari-
ables on the adsorption process was investigated along with its isotherms and kinetics.
2. EXPERIMENTAL WORK
2.1. Clay mineral preparation and characterization
Clays have characteristics that depend on their geological formation and mining location. Deposits of attapulgite
occur in Wadi Bashira in Iraqs Western Desert. The representative sample was crushed in a jaw crusher (Retsch
BB 1, Germany) and then milled in a rotating cylinder ball mill to pass a 75-μm sieve opening. Wet chemical analysis
to identify the attapulgites chemical composition was done in the Central Laboratories Department, Iraqi Geologi-
cal Survey. X-ray diffraction (XRD) mineralogical analyses were performed using the Ital structure model MPD
3000 (Spain, Al Razi Metallurgical Center, Tehran, Iran). Scanning electron microscopy (SEM) and energy-disper-
sive X-ray spectroscopy (EDX) were employed to investigate claysmorphologies with the MIRA3 TESCAN
instrument (Australia, Al Razi Metallurgical Center, Tehran, Iran). Particle size distribution analysis was done
using a Brookhaven Instruments (USA) 90Plus particle size analyzer (Nanotechnology Center, UOT, Iraq). The
mineralsspecic surfaces (SSA) and CECs were obtained from technical reports of the Iraqi Geological Survey
(Baghdad, Iraq). Fourier-transform infrared (FT-IR) spectroscopy analyses were run with a Bomem MB-Series
FT-IR Spectrometer (France) and operated according to ASTM E 1252-98(21) to specify the functional groups.
2.2. Radioactive wastewater sample preparation
The radioactive wastewater samples were taken from a reservoir underneath the destroyed Radiochemical Lab-
oratories (RCL) at the Al-Tuwaitha site (Iraq). The gamma spectroscopy analysis was conducted using a closed-
end, coaxial, p-type model (GEM65P4-95/ORTEC (USA, Al-Tuwaitha site, Iraq) high purity germanium detector
(HPGe), yielding high-level waste (HLW) containing radioactive cesium (Cs-137) with a specic activity of
4.5 GBq/L (Ibrahim et al. 2018). As per the appropriate safety procedure, the sample was diluted with distilled
water to a safe limit to be handled within the laboratory. The activity was reduced to about 6,372 Bq/L, which
is considered the initial activity concentration.
2.3. Batch adsorption experiments
Batch mode experiments were carried out to evaluate the use of the clay to adsorb Cs-137 from the radioactive
wastewater. In glass containers, 0.1 g of clay was added to 30 ml radioactive wastewater samples, with Cs-137
activity concentration of 6,372 Bq/L and pH 6. The sample containers were shaken at 200 rpm at room tempera-
ture (25 °C) for different mixing times (i.e., 0.5, 1, 1.5, 2, and 3 h). Solid particles were separated from the solution
by centrifugation rather than ltration, using lter paper, to avoid the adsorption of contaminants onto the lter
paper. Filtrate samples (20 ml) were put into a Marinelli beaker to measure the cesium radioactivity concen-
tration after treatment using gamma spectroscopy (HPGe detector). The Cs-137 (μg/L) concentrations in the
ltrates were estimated using Equations (1)(4) (Knoll & Wegst 1980).
Specific Activity(SA) ¼
l
Aav w
m(1)
w¼SA m
l
Aav (2)
where Aav is Avogadros number (6.02 10
23
nuclei/mol), λis the radioisotope decay constant (s
1
), mis the
atomic weight (g/mol), and wis the weight (g).
l
¼ln2
half life ¼0:693
t1=2(3)
Cs isotope concentration in filtrate (C)¼w
v(4)
Water Practice & Technology Vol 00 No 0, 3
Uncorrected Proof
Downloaded from http://iwaponline.com/wpt/article-pdf/doi/10.2166/wpt.2023.131/1285266/wpt2023131.pdf
by guest
on 01 September 2023
The clay was investigated by studying the removal efciency (R%), adsorption capacity, q
e
(mg/g), and adsorp-
tion coefcient, K
d
(L/g), respectively, of the Cs-137 isotope at equilibrium, using Equations (5)(7) (Abbood et al.
2022):
R%¼concentration of adsorbed cesium
initial concentration of cesium ¼C0Ce
C0
100 (5)
qe¼amount of cesium adsorbed
amount of adsorbent ¼(C0Ce)V
M(6)
Kd¼C0Ce
Ce
V
M¼qe
Ce
(7)
where C
0
and Care the initial and equilibrium concentrations of radioactive cesium (mg/L), Vis the solution
volume (L), and Mis the weight of the clay mineral (g).
2.4. Adsorption kinetics
The Cs-137 adsorption mechanism on the clay surfaces was investigated using the contact time data. Three lin-
earized adsorption kinetics models were used to evaluate the experimental results pseudo-rst-order (Lagergren
model), pseudo-second-order (Ho model), and intraparticle diffusion (WeberMorris model) which are rep-
resented by Equations (8)(10), respectively (Al-Jaaf et al. 2022;Jabbar et al. 2022).
ln(qeqt)¼lnqek1t(8)
t
qt
¼1
k2q2
e
þt
qe
(9)
qt¼KPt1=2þC(10)
where qand q
t
are the adsorption capacity (mg/g) at equilibrium and time t(min), respectively; K
1
and K
2
are
adsorption rate constants of the pseudo-rst-order (min
1
) and pseudo-second-order (g/mg·min), respectively; K
P
is the intraparticle diffusion rate (mg/g·min
0.5
) constant, and Cis the diffusion intraparticle constant (Khadim
et al. 2022).
3. RESULTS AND DISCUSSION
3.1. Clay mineral characterization
The results of the chemical and mineralogical analyses of the attapulgite are shown in Table 1 and Figure 1.
The attapulgite sample contains predominantly montmorillonite (smectite) associated with palygorskite as the
main minerals, in addition to impurities like silica, calcite, and gypsum, as shown in Table 1 (Al-Ajeel et al. 2008).
The montmorillonite is considered a Ca-montmorillonite on the basis of the ratio of (Na
2
OþK
2
O) to (CaO þ
MgO), which is approaching 0.136 (Abdou et al. 2013).
In Figure 1, the XRD analyses illuminate a convergence for attapulgite, in which the major peaks are palygors-
kite at 20° and diffraction angles (2θ), and the minor mineral is montmorillonite with 2θat 20.5° and 7°. In fact,
the sample is a montmorillonite-rich, palygorskite clay. The results show clearly that the clays have not been sub-
ject to any purication or modication processes (Al-Alawy et al. 2020).
Figure 2 displays the SEM images for the attapulgite clay. As can be seen, the original attapulgite structure con-
sisted of blocks, channels, and ribbon-likesheets, while after adsorption, the framework collapsed with the
disorder in the layered structure, and the particles were almost at (Muslim et al. 2022).
Table 1 |Chemical analyses of the clays
Chemical composition SiO
2
b (%) Al
2
O
3
(%) Fe
2
O
3
(%) CaO (%) MgO (%) SO
3
(%) LOI (%) Na
2
O (%) K
2
O (%) Cl (%)
Attapulgite 40.1 9.6 3.38 19.64 4.36 0.32 20.5 0.8 0.29
LOI, loss on ignition.
Water Practice & Technology Vol 00 No 0, 4
Uncorrected Proof
Downloaded from http://iwaponline.com/wpt/article-pdf/doi/10.2166/wpt.2023.131/1285266/wpt2023131.pdf
by guest
on 01 September 2023
EDX qualitative elemental composition analysis, by identifying the materials crystal structure, was achieved at
ain Figure 2, after adsorption on the attapulgite clay surface. The EDX results are shown in Figure 3.
The EDX spectrum detects the attapulgite clay surfaces after adsorption and the presence of Cs-137 of the
radioactive wastewater, as shown in Figure 3. The particle size test was based on dynamic light scattering
(DLS), and the clays mean particle size is presented in Figure 4.
According to the particle size analysis, attapulgite exhibited small particle size. The surface areas were
measured using the BET method. Attapulgites specic surface and cation exchange capacity are given in Table 2.
The infrared spectra for attapulgite are shown in Figure 5. The spectrum after adsorption (Ab) shows the
stretching vibration of AlOHAl, MgOH, and/or H
2
O at 3,427 cm
1
and the stretching vibration of SiOat
1,104 cm
1
, while the SiOH stretching vibration appeared at 1,029 cm
1
. Moreover, the spectrum showed
the stretching vibration bands of SiOSi and SiOAl at 767 and 778 cm
1
. The change in the spectra appeared
clearly when compared to the reading before the reaction, as shown in the spectrum before adsorption (Aa), with
a solid shift in the vibration of SiO, SiOH, and SiOSi, which appeared at 1,104, 1,026, and 870/772 cm
1
(Muslim et al. 2022).
Figure 2 |SEM images for attapulgite. arepresents a known point on the clay surface analyzed after adsorption.
Figure 1 |XRD patterns of attapulgite.
Water Practice & Technology Vol 00 No 0, 5
Uncorrected Proof
Downloaded from http://iwaponline.com/wpt/article-pdf/doi/10.2166/wpt.2023.131/1285266/wpt2023131.pdf
by guest
on 01 September 2023
3.2. Batch adsorption results
3.2.1. Activity concentration and removal (%)
The results of the batch adsorption experiments are shown in Figure 6(a). The maximum reduction in Cs-137
activity was achieved at 177 Bq/L during the 2 h required for cesium uptake to reach equilibrium for attapulgite.
The proportional removal (%) was determined using Equation (5) and is presented in Figure 6(b), which shows
that equilibrium was reached quickly, achieving 80% adsorption after 1 h. However, at an equilibrium time of 2 h,
attapulgite removal efciency reached 97%. The montmorillonite (smectite) content in attapulgite, as shown in
Figure 1, leads, rstly, to the reduction in attapulgite particle size. Also, attapulgite has high CEC, which rep-
resents the existence of active adsorption sites (Table 2). Secondly, montmorillonites existence in
attapulgite causes the absorption of a signicant amount of water (expandable clays), making the process
a combination of absorption and adsorption (called sorption), which boosted cesium uptake from the waste-
water (Park et al. 2019).
Figure 3 |EDX analysis of the attapulgite clay after adsorption.
Figure 4 |Particle size analysis for attapulgite.
Table 2 |Mean particle size and specic surface of attapulgite
Sample Mean particle diameter (nm) St. Deviation Density (g/cm
3
) CEC (meq/100 g) SSA (m
2
/g)
A41.2 1.42 2.4 14.08 60.7
Water Practice & Technology Vol 00 No 0, 6
Uncorrected Proof
Downloaded from http://iwaponline.com/wpt/article-pdf/doi/10.2166/wpt.2023.131/1285266/wpt2023131.pdf
by guest
on 01 September 2023
3.2.2. Mechanisms of Cs sorption
The extent of Cs adsorption on montmorillonite and attapulgite depends on the mineralsion exchange site types,
which is characterized by the function and availability of the interlayer site type (III) that offers high CECs and
cesium uptake. In attapulgite, the active sites are only in the planar (basal) surface (type I) and the edges of the
interlayers (type II), which both show low CECs compared to type III. In kaolinite, the ion exchange capability is
due to broken bonds at the edges of the clay plates and hydroxyl groups on the basal lamellar. The results indicate
Figure 5 |FT-IR spectra of attapulgite (Ab) before adsorption and (Aa) after adsorption.
Figure 6 |Effect of contact time on (a) activity concentration and (b) removal (%) of Cs-137 from radioactive wastewater for
attapulgite.
Water Practice & Technology Vol 00 No 0, 7
Uncorrected Proof
Downloaded from http://iwaponline.com/wpt/article-pdf/doi/10.2166/wpt.2023.131/1285266/wpt2023131.pdf
by guest
on 01 September 2023
that Cs is adsorbed not only at the frayed edgesites but also at other sites where the adsorption is reversible, as
reported by Erten et al. (1988),Comans et al. (1991),Comans & Hockley (1992), and Shahwan et al. (1999). One
is instantaneous and reversible on a timescale of a few days or less. The other is irreversible, occurs at longer
times, and is caused by Cs migration into the interlayers. Slow Cs migration into interlayers was also proposed
by Evans et al. (1983). These were in accord with the extent of cesium adsorption (desorption) by attapulgite
after 2 h in the results as claried in Figure 6(b), because some of the cesium sites are reversible on attapulgites
basal planes. The results of this study are agreement with the mechanism of adsorption (Ali et al. 2023;Khader
et al. 2023).
3.2.3. Adsorption capacity and distribution coefcient
The adsorption capacity (q
e
) and distribution coefcient (K
d
) for the attapulgite at different contact times were
calculated from Equations (6) and (7), respectively, and are shown in Figure 7(a) and 7(b), respectively. Clearly,
the prime K
d
and q
e
for attapulgite after 2 h of contact time were caused by the very low initial Cs-137 concen-
tration, because sorption increased sharply then (Missana et al. 2014;Baborová et al. 2018).
3.3. Adsorption kinetics
The results from the kinetic models for attapulgite pseudo-rst-order (Equation (8)), pseudo-second-order
(Equation (9)), and intraparticle diffusion (Equation (10)) are displayed in Figure 8(a)8(c), respectively. The
Cs-137 adsorption mechanisms for attapulgite better t the pseudo-second-order kinetic model with a high
regression coefcient of 0.9971, which is higher than the pseudo-rst-order model value of 0.9919.
The q
e
predicted for attapulgite by the pseudo-rst-order model approached the experimental q
e
, as shown
in Table 3. The intraparticle diffusion adsorption kinetic model is based on the assumption that the rate-control-
ling step may involve valence forces through ion exchange, substitution, or complexation (Wei et al. 2019;
Al-Rahmani et al. 2020).
Since the plot of q
t
versus t
(0.5)
in the intraparticle model, as shown in Figure 8(c), did not pass the origin, intra-
particle diffusion did not wholly affect the adsorption process. Also, the diffusion models correlation coefcient
(R
2
) for attapulgite was lower than that of the pseudo-second-order (0.867), as shown in Table 3. The suitability of
the pseudo-second-order model with the experimental result means that adsorption is controlled by ion exchange,
in which electrostatic interactions play a signicant part ( Jiaojiao et al. 2009;Xiang et al. 2014).
3.4. Comparative study
The research focus is the exploration of novel and effective adsorbents for Cs removal. The widespread explora-
tion of advanced functional materials for nuclide pollution control is driven by increasingly severe environmental
problems. Researchers have extensively explored and designed adsorbents for Cs removal. A comparison
between the results of this study and previous studies is illustrated in Table 4 and suggests that attapulgite is a
Figure 7 |(a) Adsorption capacity (q
e
) and (b) adsorption distribution coefcient (K
d
) for attapulgite.
Water Practice & Technology Vol 00 No 0, 8
Uncorrected Proof
Downloaded from http://iwaponline.com/wpt/article-pdf/doi/10.2166/wpt.2023.131/1285266/wpt2023131.pdf
by guest
on 01 September 2023
strong, stable, and efcient sorbent for Cs-137 removal. Moreover, attapulgite is easily applied as an adsorbent
with a natural, low-cost, eco-friendly, and simple batch sorption process compared with synthesized adsorbents,
such as zeolites, composites, and bio-sorbents for Cs-137 radioactive decontamination. Excellent Cs-137
Figure 8 |Adsorption kinetic models of attapulgite: (a) pseudo-rst-order adsorption kinetic model, (b) pseudo-second-order
adsorption kinetic model, and (c) intraparticle diffusion model.
Table 3 |Kinetic model adsorption parameters for attapulgite
Experimental Pseudo-rst-order model
Pseudo-second-order
model
Intraparticle diffusion
model
q
e
(mg/g) q
e
(mg/g) R
2
q
e
(mg/g) R
2
C(mg/g) R
2
Attapulgite 0.58E-6 0.55E-6 0.991 0.45E-6 0.9971 0.3 0.867
Table 4 |Adsorption capacities of Cs-137 by various adsorbents
Adsorbents
Adsorption capacity Q
max
(mg/g)
Removal efciency
(%)
Equilibrium time
(h) References
Nanoclusters Microparticles 45.87 99.7 6 Yang et al. (2016)
Nanocomposites with graphene
oxide
55.56 90 12 Yang et al. (2014)
Nanoparticles 96.00 NA 24 Thammawong et al.
(2013)
Nanocomposites 280.82 NA 24 Jang & Lee (2016)
Nanoparticles with PEG 274.70 64.8 1 Qian et al. (2017)
Microparticles 16.30 97.0 10 min Wang et al. (2020)
Attapulgite NA 97 2 This study
Water Practice & Technology Vol 00 No 0, 9
Uncorrected Proof
Downloaded from http://iwaponline.com/wpt/article-pdf/doi/10.2166/wpt.2023.131/1285266/wpt2023131.pdf
by guest
on 01 September 2023
adsorption efciencies were achieved by attapulgite (97%) for a 2-h equilibrium time without functionalization or
treatment of its surface.
4. CONCLUSIONS
Attapulgite had a small particle size, a high specic surface, better cation exchangeability, and an effective func-
tional site. Excellent adsorption efciencies of Cs-137 were achieved by attapulgite (97%) for a 2-h equilibrium
time. The high adsorption efciencies achieved in this study resulted from using low Cs-137 radioactivity concen-
trations (6.372 KBq/L). The kinetics of Cs-137 adsorption on attapulgite were evaluated. The pseudo-second-
order kinetic model produces a good t with the experimental data. According to the results, the local raw atta-
pulgite was suitable clay and should be selected to manage the removal of the Cs-137 from wastewater. The
attapulgite adsorbents proved to be promising materials for removing Cs-137 because they are inexpensive, avail-
able, and effective.
ACKNOWLEDGEMENTS
We gratefully acknowledge the scientic support of the Department of Chemical Engineering, University of Tech-
nology-Iraq; Iraqi Atomic Energy Commission (IAEC)/Radiation and Nuclear Safety Directorate, Baghdad, Iraq,
and the Iraqi Geological Survey/Ministry of Industry and Minerals, and the Department of Chemical and Pet-
roleum Industries Engineering at Al-Mustaqbal University College in Babylon, Iraq.
DATA AVAILABILITY STATEMENT
All relevant data are included in the paper or its Supplementary Information.
CONFLICT OF INTEREST
The authors declare there is no conict.
REFERENCES
Abbood, N. S., Ali, N. S., Khader, E. H., Majdi, H. S., Albayati, T. M. & Cata Saady, N. M. 2022 Photocatalytic degradation of
cefotaxime pharmaceutical compounds onto a modied nanocatalyst.Research on Chemical Intermediates. https://doi.
org/10.1007/s11164-022-04879-3.
Abdou, M. I., Al-sabagh, A. M. & Dardir, M. M. 2013 Evaluation of Egyptian bentonite and nano-bentonite as drilling mud.
Egyptian Journal of Petroleum 22(1), 5359. doi:10.1016/j.ejpe.2012.07.002.
Adebowale, K. O., Unuabonah, I. E. & Olu-Owolabi, B. I. 2006 The effect of some operating variables on the adsorption of lead
and cadmium ions on kaolinite clay.Journal of Hazardous Materials 134(13), 130139. doi:10.1016/j.jhazmat.2005.
10.056.
Ahmed, B. A. 2022 Radiological Impact on Public Environment, and Risk Assessment Associated with Decommissioning of the
Iraq Destroyed IRT-5000 Research Reactor. https://doi.org/10.34726/hss.2022.27941.
Akalin, H. A., Hiçsönmez, U. & Yilmaz, H. 2018 Removal of cesium from aqueous solution by adsorption onto sivas-yildizeli
(Türkiye) vermiculite: equilibrium, kinetic and thermodynamic studies.Journal of the Turkish Chemical Society, Section A:
Chemistry 5(1), 85116. doi:10.18596/jotcsa.317771.
Al-Ajeel, A. A., Abdullah, N. S. & Mustafa, A. M. 2008 Beneciation of attapulgite- montmorillonite claystone by dispersion
sedimentation. Iraqi Bulletin of Geology and Mining 4(1), 117124.
Al-Alawy, I. T. & Mzher, O. A. 2019 Radiological characterization of the irt-5000(14-Tammuz) research nuclear reactor at Al-
Tuwaitha nuclear center in Iraq.Environmental Earth Sciences 78(6), 19. doi:10.1007/s12665-019-8122-6.
Al-Ani, T. & Sarapää, O. 2008 Clay and clay mineralogy. In: Geochemical Survey of Finland, pp. 194.
Alardhi, S. M., Alrubaye, J. M. & Albayati, T. M. 2020 Removal of methyl green dye from simulated waste water using hollow
ber ultraltration membrane. In 2nd International Scientic Conference of Al-Ayen University (ISCAU-2020), IOP Conf.
Series: Materials Science and Engineering, Vol. 928, p. 052020. doi:10.1088/1757-899X/928/5/052020.
Ali, N. S., Jabbar, N. M., Alardhi, S. M., Majdi, H. S. & Albayati, T. M. 2022a Adsorption of methyl violet dye onto a prepared
bio-adsorbent from date seeds: isotherm, kinetics, and thermodynamic studies.Heliyon 8, e10276. https://doi.org/10.
1016/j.heliyon.2022.e10276.
Ali, N. S., Kalash, K. R., Ahmed, A. N. & Albayati, T. M. 2022b Performance of a solar photocatalysis reactor as pretreatment for
wastewater via UV, UV/TiO
2
, and UV/H
2
O
2
to control membrane fouling.Scientic Reports 12, 16782. https://doi.org/10.
1038/s41598-022-20984-0.
Ali, N. S., Harharah, H. N., Salih, I. K., Cata Saady, N. M., Zendehboudi, S. & Albayati, T. M. 2023 Applying MCM-48
mesoporous material, equilibrium, isotherm, and mechanism for the effective adsorption of 4-nitroaniline from
wastewater.Scientic Reports 13, 9837. https://doi.org/10.1038/s41598-023-37090-4.
Water Practice & Technology Vol 00 No 0, 10
Uncorrected Proof
Downloaded from http://iwaponline.com/wpt/article-pdf/doi/10.2166/wpt.2023.131/1285266/wpt2023131.pdf
by guest
on 01 September 2023
Al-Jaaf, H. J., Ali, N. S., Alardhi, S. M. & Albayati, T. M. 2022 Implementing eggplant peels as an efcient bio-adsorbent for
treatment of oily domestic wastewater.Desalination and Water Treatment 245, 226237. https://doi:.10.5004/dwt.2022.
27986.
Al-Rahmani, A. A., Al-Atta, S. K., Al-Nasri, S. K. & Jasim, Z. W. 2020 Hierarchical structures incorporating carbon and zeolite
to remove radioactive contamination.Iraqi Journal of Science 19441951. Available form: https://ijs.uobaghdad.edu.iq/
index.php/eijs/article/view/1320.
Baborová, L., Vopálka, D. & C
ervinka, R. 2018 Sorption of Sr and Cs onto Czech natural bentonite: experiments and
modelling.Journal of Radioanalytical and Nuclear Chemistry 318, 22572262.
Cherif, M. A., Martin-Garin, A., Gérard, F. & Bildstein, O. 2017 A robust and parsimonious model for cesium sorption on clay
minerals and natural clay materials.Applied Geochemistry 87(October), 2237. doi:10.1016/j.apgeochem.2017.10.017.
Comans, R. N. J. & Hockley, D. E. 1992 Kinetics of Cs sorption on illite.Geochimica et Cosmochimica Acta 56, 11571164.
Comans, R. N. J., Hailer, M. & De Preter, P. 1991 Sorption of adsorption of Cs on kaolin & and illite 4073 Cs on illite:
nonequilibrium behavior and reversibility.Geochimica et Cosmochimica Acta 433440.
Cornell, R. M. 1993 Adsorption of cesium on minerals: a review.Journal of Radioanalytical and Nuclear Chemistry Articles
171(2), 483500. doi:10.1007/BF02219872.
Erten, H. N., Aksoyoglu, S., Hatipoglu, S. & Göktürk, H. 1988 Sorption of cesium and strontium on montmorillonite and
kaolinite.Radiochim Acta 4445(1), 147152. doi:10.1524/ract.1988.4445.1.147.
Evans, D. W., Alberts, J. J. & Clark, R. A. 1983 Reversible ion exchange xation of cesium-137 leading to mobilization from
reservoir sediments.Geochimica et Cosmochimica Acta 47, 10411049.
Frost, R. L. 1998 Hydroxyl deformation in kaolins.Clays and Clay Minerals 46(3), 280289. doi:10.1346/CCMN.1998.0460307.
Hadadi, N., Kananpanah, S. & Abolghasemi, H. 2009 Equilibrium and thermodynamic studies of cesium adsorption on natural
vermiculite and optimization of operation conditions. Iranian Journal of Chemistry & Chemical Engineering 28(4), 2936.
IAEA 1999 Review of the factors affecting the selection and implementation of waste management technologies. Atomic Energy
Agency. August.
IAEA 2002 Management of Low and Intermediate Level Radioactive Wastes with Regard to Their Chemical Toxicity.
International Atomic Energy Agency. Available from: https://www-pub.iaea.org/MTCD/publications/PDF/te_1325_web.pdf.
Ibrahim, Z. H., Mkhaiber, A. F. & Al-Nasri, S. K. 2018 Estimation and Reduction of the Total Activity for the Liquid Waste Pool
in Radiochemistry Laboratories in Al-Tuwaitha Site. University of Baghdad, Baghdad.
Jabbar, N. M., Alardhi, S. M., Mohammed, A. K., Salih, I. K. & Albayati, T. M. 2022 Challenges in the implementation of
bioremediation processes in petroleum-contaminated soils: a review.Environmental Nanotechnology, Monitoring &
Management 18, 100694. https://doi.org/10.1016/j.enmm.2022.100694.
Jang, J. & Lee, D. S. 2016 Magnetic Prussian blue nanocomposites for effective cesium removal from aqueous solution.
Industrial and Engineering Chemistry Research 55, 38523860.
Jiaojiao, W., Bing, L., Jiali, L., Yue, F., Dong, Z., Jun, Z., Wei, W., Yuanyou, Y. & Ning, L. 2009 Behavior, and analysis of cesium
adsorption on montmorillonite mineral.Journal of Environmental Radioactivity 100(10), 914920. https://doi.org/10.
1016/j.jenvrad.2009.06.024.
Kadhum, S. T., Alkindi, G. Y. & Albayati, T. M. 2021 Determination of chemical oxygen demand for phenolic compounds from
oil renery wastewater implementing different methods.Desalination and Water Treatment 231,4453. doi:10.5004/dwt.
2021.27443.
Khader, E. H., Khudhur, R. H., Abbood, N. S. & Albayati, T. M. 2023 Decolourisation of anionic azo dye in industrial
wastewater using adsorption process: investigating operating parameters.Environmental Processes 10, 34. https://doi.org/
10.1007/s40710-023-00646-7.
Khadim, A. T., Albayati, T. M. & Cata Saady, N. M. 2022 Removal of sulfur compounds from real diesel fuel employing the
encapsulated mesoporous material adsorbent Co/MCM-41 in a xed-bed column.Microporous and Mesoporous Materials
341, 112020. https://doi.org/10.1016/j.micromeso.2022.112020.
Knoll, G. F. & Wegst, A. V. 1980 Radiation detection and measurement.Medical Physics 7(4), 397398. doi:10.1118/1.594739.
Missana, T., Benedicto, A., García-Gutiérrez, M. & Alonso, U. 2014 Modeling cesium retention onto Na-, K- and Ca-smectite:
effects of ionic strength, exchange and competing cations on the determination of selectivity coefcients.Geochim
Cosmochim Acta 128, 266277. doi:10.1016/j.gca.2013.10.007.
Muslim, W. A., Albayati, T. M. & Al-Nasri, S. K. 2022 Decontamination of actual radioactive wastewater containing Cs using
bentonite as a natural adsorbent: equilibrium, kinetics, and thermodynamic studies.Science Reports 112. doi:10.1038/
s41598-022-18202-y.
Ohnuki, T. & Kozai, N. 2013 Adsorption behavior of radioactive cesium by non-mica minerals.Journal of Nuclear Science and
Technology 50(4), 369375. doi:10.1080/00223131.2013.773164.
Okumura, M., Nakamura, H. & Machida, M. 2013 Mechanism of strong afnity of clay minerals to radioactive cesium: rst-
principles calculation study for adsorption of cesium at frayed edge sites in muscovite.Journal of the Physical Society of
Japan 82(3), 15. doi:10.7566/JPSJ.82.033802.
Paranhos Gazineu, M. H., de Araújo, A. A., Brandão, Y. B., Hazin, C. A. & de O Godoy, J. M. 2005 Radioactivity concentration
in liquid and solid phases of scale and sludge generated in the petroleum industry.Journal of Environmental Radioactivity
81(1), 4754. https://doi.org/10.1016/j.jenvrad.2004.11.003.
Water Practice & Technology Vol 00 No 0, 11
Uncorrected Proof
Downloaded from http://iwaponline.com/wpt/article-pdf/doi/10.2166/wpt.2023.131/1285266/wpt2023131.pdf
by guest
on 01 September 2023
Park, S. M., Lee, J., Jeon, E. K., Kang, S., Alam, M. S., Tsang, D. C. W., Daniel, S. A. & Kitae, B. 2019 , adsorption characteristics
of cesium on the clay minerals: structural change under wetting and drying condition.Geoderma 340,4954. https://doi.
org/10.1016/j.geoderma.2018.12.002.
Qian, J., Xu, J. Y., Kuang, L. J. & Hua, D. B. 2017 Cesium removal from human blood by poly(ethylene glycol)-decorated
Prussian blue magnetic nanoparticles.Chempluschem 82, 888895.
Semenkova, A. S. et al. 2018 Csþsorption onto Kutch clays: inuence of competing ions.Applied Clay Science 166(September),
8893. doi:10.1016/j.clay.2018.09.010.
Shahwan, T., Erten, H. N., Black, L. & Allen, G. C. 1999 TO-SIMS study of Csþsorption on natural 647 kaolinite.The Science
of the Total Environment 226(23), 255260.
Sheha, R. R. & Metwally, E. 2007 Equilibrium isotherm modeling of cesium adsorption onto magnetic materials.Journal of
Hazardous Materials 143(12), 354361. doi:10.1016/j.jhazmat.2006.09.041.
Stewart, D. I. & Mollins, L. H. 1996 Predicting the properties of bentonite-sand mixtures.Clay Minerals 31(2), 243252.
Sun, D., Cui, H. & Sun, W. 2009 Swelling of compacted sand-bentonite mixtures.Applied Clay Science 43(34), 485492.
doi:10.1016/j.clay.2008.12.006.
Thammawong, C., Opaprakasit, P., Tangboriboonrat, P. & Sreearunothai, P. 2013 Prussian blue-coated magnetic nanoparticles
for removal of cesium from contaminated environment.Journal of Nanoparticle Research 15, 10.
Wang, P. F., Zheng, J. L., Ma, X. L., Du, X., Gao, F. F. & Hao, X. G. et al. 2020 Electroactive magnetic microparticles for the
selective elimination of cesium ions in the wastewater. Environmental Research 2020(185), 9.
Wei, X., Sun, Y., Pan, D., Niu, Z., Xu, Z., Jiang, Y., Wu, W., Li, Z., Zhang, L. & Fan, Q. 2019 Adsorption properties of Na-
palygorskite for Cs sequestration: effect of pH, ionic strength, humic acid and temperature.Applied Clay Science
183(April). doi:10.1016/j.clay.2019.105363.
Wilson, I. 2007 Applied Clay Mineralogy. occurrences, processing, and application of kaolin palygorskite sepiolite, and
common clays.55, 6. doi:10.1007/bf03406033.
Xiang, L., Guan-Ru, C., Duu-Jong, L., Tohru, K., Hisashi, T., Man-Li, C. & Yu-Kuo, L. 2014 Adsorption removal of cesium from
drinking waters: a mini-review on use of bio sorbents and other adsorbents.Bioresource Technology 160, 142149. https://
doi.org/10.1016/j.biortech.2014.01.012.
Yang, H. J., Sun, L., Zhai, J. L., Li, H. Y., Zhao, Y. & Yu, H. W. 2014 In situ controllable synthesis of magnetic Prussian blue/
graphene oxide nanocomposites for removal of radioactive cesium in water.Journal of Materials Chemistry A 2, 326332.
Yang, H. M., Jang, S. C., Hong, S. B., Lee, K. W., Roh, C. & Huh, Y. S. et al. 2016 Prussian blue functionalized magnetic
nanoclusters for the removal of radioactive cesium from water.Journal of Alloys and Compounds 657, 387393.
Yuan, G. D., Theng, B. K. G., Churchman, G. J. & Gates, W. P. 2013 Clays and Clay Minerals for Pollution Control, 2nd ed., Vol.
5, no. C. Elsevier Ltd. doi:10.1016/B978-0-08-098259-5.00021-4.
Zabulonov, Y., Kadoshnikov, V., Zadvernyuk, H., Melnychenko, T. & Molochko, V. 2021 Effect of the surface hydration of clay
minerals on the adsorption of cesium and strontium from dilute solutions.Adsorption 27(1), 4148. doi:10.1007/s10450-
020-00263-y.
First received 4 April 2023; accepted in revised form 2 August 2023. Available online 31 August 2023
Water Practice & Technology Vol 00 No 0, 12
Uncorrected Proof
Downloaded from http://iwaponline.com/wpt/article-pdf/doi/10.2166/wpt.2023.131/1285266/wpt2023131.pdf
by guest
on 01 September 2023
ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
In this work, the MCM-48 mesoporous material was prepared and characterized to apply it as an active adsorbent for the adsorption of 4-nitroaniline (4-Nitrobenzenamine) from wastewater. The MCM-48 characterizations were specified by implementing various techniques such as; scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area, pore size distribution (PSD), and Fourier transform infrared (FTIR). The batch adsorption results showed that the MCM-48 was very active for the 4-nitroaniline adsorption from wastewater. The adsorption equilibrium results were analyzed by applying isotherms like Langmuir, Freundlich, and Temkin. The maximum experimental uptake according to type I Langmuir adsorption was found to be 90 mg g⁻¹ approximately. The Langmuir model with determination coefficient R² = 0.9965 is superior than the Freundlich model R² = 0.99628 and Temkin model R² = 0.9834. The kinetic adsorption was investigated according to pseudo 1st order, pseudo 2nd order, and Intraparticle diffusion model. The kinetic results demonstrated that the regression coefficients are so high R² = 0.9949, that mean the pseudo 2nd order hypothesis for the adsorption mechanism process appears to be well-supported. The findings of adsorption isotherms and kinetics studies indicate the adsorption mechanism is a chemisorption and physical adsorption process.
Article
Full-text available
In this study, the anionic azo dye was taken out of an aqueous solution using the batch adsorption approach. Zeolite NaX and Fe3O4 magnetic nanoparticle adsorbents were employed. The effects of the variables such as initial azo dye concentration (5–45 mg/L), shaking rotary speed (100–200 rpm), pH (2–10) and contact time (10–140 min) were examined with both doses of adsorbents (0.1–0.5 g) Zeolite NaX and Fe3O4 magnetic nanoparticles. The outcomes showed that good removal efficiencies were attained for both adsorbents Zeolite NaX and Fe3O4 magnetic nanoparticles, with values of 72.34% and 99.99%, respectively. The ideal values for both adsorbents were achieved, including pH of 2, initial azo dye concentration of 5 mg/L, shaking speed of 180 rpm, contact period of 120 min and adsorbent dose of 0.3 g of Zeolite NaX and Fe3O4 magnetic nanoparticles. The results demonstrated that when the Langmuir, Freundlich and Temkin isotherm adsorption models were compared, the Langmuir isotherm adsorption model showed a higher correlation coefficient R² for Zeolite NaX and Fe3O4 magnetic nanoparticles of 0.9958 and 0.9767, respectively. Zeolite NaX and Fe3O4 magnetic nanoparticle adsorption rates were found to support pseudo-first-order kinetics with strong correlation R² values of 0.9894 and 0.9728, respectively. The findings indicate that Zeolite NaX has a lower dye removal efficiency than Fe3O4 magnetic nanoparticles under the same working conditions.
Article
Full-text available
The photocatalytic advanced oxidation process as treatment for the removal of cefotaxime pharmaceutical compounds was conducted onto a modified nanocatalyst. Using photocatalysis with hydrogen peroxide (H2O2) in advanced oxidation processes (AOPs) is a suitable and alternative method. Therefore, this study targeted acquiring insights into using ultraviolet (UV) light radiation sources with two types of nanocatalysts (i.e., TiO2 and TiO2/kaolin) to reduce cefotaxime contaminants. The characterization properties of both catalysts were determined using X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), and Fourier-transform infrared spectroscopy (FT-IR). The study investigated the effects of the irradiation time (10–120 min), cefotaxime concentration (10–40 mg/L), TiO2 dose (0.05–0.2 g), and pH (4–8) on the decomposition cefotaxime. The highest degradation with pure TiO2 was obtained at a contact time of 90 min, cefotaxime concentration of 10 mg/L, TiO2 dose of 0.2 g, and a pH of 4, with a removal efficiency of almost 68%. The results indicated that cefotaxime can easily be oxidized with a TiO2/kaolin catalyst with a removal efficiency of approximately 99.8% when using a UV/H2O2 treatment. The UV/H2O2 oxidation was more effective and sustainable as well as being a promising technique for the treatment of cefotaxime in wastewater.
Article
Full-text available
The performance of a solar photocatalysis reactor as pretreatment for the removal of total organic carbon (TOC) and turbidity from municipal wastewater was achieved by implementing an integrated system as tertiary treatment. The process consisted of ultraviolet (UV) sunlight, UV sunlight/H 2 O 2 , and UV sunlight/TiO 2 nanocatalysts as pretreatment steps to prevent ultrafiltration (UF) membrane fouling. The characterization of TiO 2 was conducted with X-ray diffraction spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy , and Brunauer–Emmett–Teller surface area analysis. This study investigated the effect of time and solar radiation using UV, UV/H 2 O 2 , and UV/TiO 2 to remove TOC and turbidity. The transmembrane pressure improvement was studied using a UF membrane system to pretreat wastewater with different UV doses of sunlight for 5 h and UV/H 2 O 2 and UV/TiO 2 . The results showed that the highest removal efficiency of the turbidity and TOC reached 95% and 31%, respectively. The highest removal efficiency of the turbidity reached 40, 75, and 95% using UV, UV/H 2 O 2 , and UV/TiO 2 , respectively, while the optimal removal efficiency of TOC reached 20%, 30%, and 50%, respectively.
Article
Full-text available
Batch adsorption treatment using Iraqi bentonite as a natural adsorbent was adopted in this study to decontaminate actual ¹³⁷ Cs radioactive wastewater from the Al-Tuwaitha Nuclear Research Center, located south of Baghdad. The bentonite characterization was applied before and after treatment, using chemical compositions analyses, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) surface area analysis and Fourier-transform infrared spectroscopy (FT-IR). The batch adsorption mode was applied with the initial radioactivity concentration (1440.5 Bq/L), solid/liquid ratio (1 g/L), pH (6–8), contact time (1.5 h), and temperature (298°K). The adsorption experiments showed a decontamination removal efficiency of about 95.66% of ¹³⁷ Cs. A Freundlich adsorption isotherm model was approved for the adsorption of ¹³⁷ Cs, with a coefficient of determination R ² = 0.998. A pseudo-second-order model fitted well with the adsorption of ¹³⁷ Cs, with R ² = 0.983. The positive value of ΔH° in the thermodynamic results indicated that the adsorption process was endothermic physisorption (ΔH° = 15.01 kJ mol ⁻¹ ), spontaneous and favorable (ΔG° = −7.66 kJ mol ⁻¹ K ⁻¹ ), with a very low degree of disorder (ΔS° = 0.076 kJ mol ⁻¹ K ⁻¹ ).
Article
Full-text available
Raw date seeds, as prospective natural, broadly obtainable and low-price agricultural waste for adsorbing cationic dyes from aqueous solutions, have been studied. In this work, Iraqi date seeds were prepared and characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and Brunauer–Emmett–Teller (BET) surface area analysis before being used as an efficient bio-adsorbent for methyl violet (MV) dye removal. Adsorption tests were conducted with three investigated parameters, namely, time of contact, first adsorbate concentration and adsorbent dose. Compared with the pseudo first-order model (coefficient of determination = 0.9001), the pseudo second-order model was determined to be the best-fitting model with a coefficient of determination (R²) of 0.9917. The equilibrium isotherms for MV were obtained, and their ultimate capacity of adsorption was (59.5 mg g¹). Two isotherm models, Langmuir and Freundlich, were studied to fit the equilibrium data. Compared with the Freundlich isotherm model (R² = 0.8154), the Langmuir model functioned better as an adsorption isotherm with R² of 0.9837. In addition, the adsorption process was endothermic and spontaneous. The date seeds acted as active adsorbents to remove MV from the aqueous solutions in the model experiments.
Article
Full-text available
The removal of oil from domestic wastewater was achieved by implementing eggplant peels (EPP) powder as an efficient bio-adsorbent material. The batch adsorption process was adopted to reach the acceptable range that allowed in Iraqi standardizations, which should not exceed (10 mg L-1). The characterization of EPP was conducted with X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared (FT-IF) spectroscopy, and Brunauer-Emmett-Teller (BET). Two variables were taken into consideration, including time and temperature. It was noticed that these two variables had an essential impact in decreasing oil concentration in domestic wastewater. The temperature has an excellent effect comparing with time in decreasing the oil concentration from domestic wastewater; as both time and temperature increased, the oil concentration decreased. Results manifested that the adsorption method was effective in decreasing the oil concentration. Also, the results elucidated that the adsorption isotherms can be reasonably befitting via the Langmuir model due to the chemisorption that occurs on the surface between bio-adsorbent and pollutant with a determination coefficient of (0.8376). The adsorption kinetics of the oily west water upon the adsorbate was vigorously denoted via a pseudo-first-order kinetic model. The thermodynamic variables were assessed for determining free energy change (ΔG°), enthalpy change (ΔH°), and entropy change (ΔS°).
Article
Full-text available
In this study, the reduction of the chemical oxygen demand (COD) for the wastewater contaminated by phenolic compounds was investigated using three techniques: batch adsorption, electro-chemical processing, and adding a granular third electrode (GTE) to an electrochemical process. The COD removal rate of the simulated phenolic wastewater with a phenol concentration range from 500 to 1,500 mg/L was measured. The actual samples from the Al-Daura Refinery (Iraq) oil refinery wastewater (ORW) were examined as a case study. Adsorption was conducted with either nanoparticle zero-valent iron (nFe 0) or silty clay-supported for nFe0 (SC-nFe 0) as an efficient adsor-bent. The electrochemical process and electrochemical process with nFe 0 or SC-nFe 0 as a GTE were also investigated. The influences of various parameters (e.g., time, pH, nFe 0 and SC-nFe 0 dose, phenol concentration, temperature, current density, and electrode distance) were examined to determine the optimal operating conditions of each process. The maximum removal rate of the COD in adsorption with nFe 0 and SC-nFe 0 was 89.5% and 84.2%, respectively. When using the electrochemical process and GTE in an electrochemical process with nFe 0 or SC-nFe 0 , the maximum removal rates were 79.8%, 93% and 94%, respectively. All of the proposed processes achieved an excellent COD removal rate when applied to actual petroleum refinery wastewater and rates higher than those attained in the refinery wastewater treatment plant.
Article
In this study, sulfur compounds were removed from real diesel fuel in a continuous system employing the encapsulated mesoporous material with cobalt. The Co/MCM-41 was characterized with the help of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) techniques, Fourier transform-infrared spectroscopy (FT-IR), and BET surface area. The effects of two variables, namely the height (2–6 cm) of the bed and the rate of flow (0.8–2 mL min⁻¹) were investigated. The maximum capacity (1310.63 mg. g⁻¹) of the bed was achieved with the following ideal values: column height of 6 cm, the rate of flow of 0.8 mL min⁻¹, and a preliminary concentration of 12,000 mg. L⁻¹ of sulfur. The bed depth influenced the time of breakthrough and exhaustion in a column apparatus operating at a low flow rate. The Thomas and Yoon-Nelson models were used to anticipate the breakthrough curves (BTC) and compute the usual laboratory continuous adsorption characteristics required for the best design of this process. According to the regression coefficient studies, the Yoon model outperformed the Thomas model. The BTC effectiveness demonstrated that Co/MCM-41 can be employed for application in fixed-bed adsorption systems for sulfur concentration removal.
Article
Environmental pollution is regarded as a major problem, and traditional strategies such as chemical or physical remediation are not sufficient to overcome the problems of pollution. Petroleum-contaminated soil results in ecological problems, representing a danger to human health. Bioremediation has received remarkable attention, and it is a procedure that uses a biological agent to remove toxic waste from contaminated soil. This approach is easy to handle, inexpensive, and environmentally friendly; its results are highly satisfactory. Bioremediation is a biodegradation process in which the organic contaminants are completely mineralized to inorganic compounds, carbon dioxide, and water. This review discusses the bioremediation of petroleum-contaminated soil and the limiting factors that affect it. Furthermore, the advantages and disadvantages of the bioremediation process are reported.