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

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 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.

Full text

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 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.
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 efficient adsorbent for the removal of Cs-137.
•Natural clay was modified 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, filtration, 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 specific 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 Mg–Al 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 specific 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 influence 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 influence 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 Iraq’s 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 attapulgite’s 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 clays’morphologies 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
minerals’specific 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 specific 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 filtration, using filter paper, to avoid the adsorption of contaminants onto the filter
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
filtrates 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 Avogadro’s 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 efficiency (R%), adsorption capacity, q
e
(mg/g), and adsorp-
tion coefficient, 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 ¼C0Ce
C0
100 (5)
qe¼amount of cesium adsorbed
amount of adsorbent ¼(C0Ce)V
M(6)
Kd¼C0Ce
Ce
V
M¼qe
Ce
(7)
where C
0
and Cₑare 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-first-order (Lagergren
model), pseudo-second-order (Ho model), and intraparticle diffusion (Weber–Morris model) –which are rep-
resented by Equations (8)–(10), respectively (Al-Jaaf et al. 2022;Jabbar et al. 2022).
ln(qeqt)¼lnqek1t(8)
t
qt
¼1
k2q2
e
þt
qe
(9)
qt¼KPt1=2þC(10)
where qₑand 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-first-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 8° 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 purification or modification 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-like’sheets, while after adsorption, the framework collapsed with the
disorder in the layered structure, and the particles were almost flat (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 material’s crystal structure, was achieved at
‘a’in 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 clay’s 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. Attapulgite’s specific 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 Al–OH–Al, Mg–OH, and/or H
2
O at 3,427 cm
1
and the stretching vibration of Si–Oat
1,104 cm
1
, while the Si–OH stretching vibration appeared at 1,029 cm
1
. Moreover, the spectrum showed
the stretching vibration bands of Si–O–Si and Si–O–Al 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 Si–O, Si–OH, and Si–O–Si, which appeared at 1,104, 1,026, and 870/772 cm
1
(Muslim et al. 2022).
Figure 2 |SEM images for attapulgite. ‘a’represents 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 efficiency reached 97%. The montmorillonite (smectite) content in attapulgite, as shown in
Figure 1, leads, firstly, to the reduction in attapulgite particle size. Also, attapulgite has high CEC, which rep-
resents the existence of active adsorption sites (Table 2). Secondly, montmorillonite’s existence in
attapulgite causes the absorption of a significant 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 specific 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 minerals’ion 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 edge’sites 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 clarified in Figure 6(b), because some of the cesium sites are reversible on attapulgite’s
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 coefficient
The adsorption capacity (q
e
) and distribution coefficient (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-first-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 fit the pseudo-second-order kinetic model with a high
regression coefficient of 0.9971, which is higher than the pseudo-first-order model value of 0.9919.
The q
e
predicted for attapulgite by the pseudo-first-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 model’s correlation coefficient
(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 significant 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 coefficient (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 efficient 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-first-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-first-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 efficiency
(%)
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 efficiencies 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 specific surface, better cation exchangeability, and an effective func-
tional site. Excellent adsorption efficiencies of Cs-137 were achieved by attapulgite (97%) for a 2-h equilibrium
time. The high adsorption efficiencies 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 fit 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 scientific 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 conflict.
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 modified 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), 53–59. 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(1–3), 130–139. 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), 85–116. doi:10.18596/jotcsa.317771.
Al-Ajeel, A. A., Abdullah, N. S. & Mustafa, A. M. 2008 Beneficiation of attapulgite- montmorillonite claystone by dispersion
sedimentation. Iraqi Bulletin of Geology and Mining 4(1), 117–124.
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), 1–9. doi:10.1007/s12665-019-8122-6.
Al-Ani, T. & Sarapää, O. 2008 Clay and clay mineralogy. In: Geochemical Survey of Finland, pp. 1–94.
Alardhi, S. M., Alrubaye, J. M. & Albayati, T. M. 2020 Removal of methyl green dye from simulated waste water using hollow
fiber ultrafiltration membrane. In 2nd International Scientific 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.Scientific 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.Scientific 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 efficient bio-adsorbent for
treatment of oily domestic wastewater.Desalination and Water Treatment 245, 226–237. https://doi:.10.5004/dwt.2022.
27986.
Al-Rahmani, A. A., Al-Attafi, S. K., Al-Nasri, S. K. & Jasim, Z. W. 2020 Hierarchical structures incorporating carbon and zeolite
to remove radioactive contamination.Iraqi Journal of Science 1944–1951. 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, 2257–2262.
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), 22–37. 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, 1157–1164.
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 433–440.
Cornell, R. M. 1993 Adsorption of cesium on minerals: a review.Journal of Radioanalytical and Nuclear Chemistry Articles
171(2), 483–500. 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 44–45(1), 147–152. doi:10.1524/ract.1988.4445.1.147.
Evans, D. W., Alberts, J. J. & Clark, R. A. 1983 Reversible ion exchange fixation of cesium-137 leading to mobilization from
reservoir sediments.Geochimica et Cosmochimica Acta 47, 1041–1049.
Frost, R. L. 1998 Hydroxyl deformation in kaolins.Clays and Clay Minerals 46(3), 280–289. 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), 29–36.
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, 3852–3860.
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), 914–920. 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 refinery wastewater implementing different methods.Desalination and Water Treatment 231,44–53. 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 fixed-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), 397–398. 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 coefficients.Geochim
Cosmochim Acta 128, 266–277. 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 1–12. 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), 369–375. doi:10.1080/00223131.2013.773164.
Okumura, M., Nakamura, H. & Machida, M. 2013 Mechanism of strong affinity of clay minerals to radioactive cesium: first-
principles calculation study for adsorption of cesium at frayed edge sites in muscovite.Journal of the Physical Society of
Japan 82(3), 1–5. 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), 47–54. 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 340,49–54. 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, 888–895.
Semenkova, A. S. et al. 2018 Csþsorption onto Kutch clays: influence of competing ions.Applied Clay Science 166(September),
88–93. 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(2–3), 255–260.
Sheha, R. R. & Metwally, E. 2007 Equilibrium isotherm modeling of cesium adsorption onto magnetic materials.Journal of
Hazardous Materials 143(1–2), 354–361. 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), 243–252.
Sun, D., Cui, H. & Sun, W. 2009 Swelling of compacted sand-bentonite mixtures.Applied Clay Science 43(3–4), 485–492.
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, 142–149. 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, 326–332.
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, 387–393.
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), 41–48. 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