Scavenging of U(VI) from Impregnated Water at Uranium Tailings

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Scavenging of U(VI) from Impregnated Water at Uranium Tailings Repository by Tripolyphosphate Intercalated LDH Hui Zhang, Zhongran Dai, Yang Sui, Nieying Wang, Haiying Fu, Dexin Ding, Nan Hu, Guangyue Li, Yongdong Wang, and Le Li Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.8b04636 • Publication Date (Web): 28 Nov 2018 Downloaded from http://pubs.acs.org on December 3, 2018

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Industrial & Engineering Chemistry Research

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Scavenging of U(VI) from Impregnated Water at Uranium Tailings

2

Repository by Tripolyphosphate Intercalated LDH

3

Hui Zhang a,b, Zhongran Dai a,b, Yang Sui c, Nieying Wanga,b, Haiying Fu a,b,c , Dexin

4

Ding a,b,*, Nan Hu a,b, Guangyue Li a,b, Yongdong Wang a,b, Le Li a,b

5

a

6

Mining and Hydrometallurgy, University of South China, Hengyang 421001, China

7

b

8

Low Grade Uranium Resources, Hengyang 421001, China

9

c

10

Key Discipline Laboratory for National Defense for Biotechnology in Uranium

Hunan Province Key Laboratory of Green Development Technology for Extremely

School of Nuclear and Technology, University of South China, Heng yang, Hunan,

421001,China

11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

* Corresponding author: Dexin Ding.

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E-mail: [email protected], [email protected]. 1 ACS Paragon Plus Environment

Industrial & Engineering Chemistry Research 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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ABSTRACT

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The impregnated water at uranium tailings repository has characteristics that its

3

uranium concentration is low, and it contains many other interfering ions. In order to

4

develop an efficient adsorbent for such wastewater, Mg-Al layered double hydroxide

5

(Mg-Al-NO3-LDH) and tripolyphosphate intercalated LDH (TPP-LDH-1 and

6

TPP-LDH-2 ) were synthesized by an anion exchange method and characterized by

7

using multiple analysis techniques, and their behavior and mechanism for U(VI)

8

removal from aqueous solutions were investigated. It is found that their adsorption

9

capacities for U(VI) follow the order Mg-Al-NO3-LDH < TPP-LDH-1 < TPP-LDH-2.

10

The maximum sorption capacities of Mg-Al-NO3-LDH, TPP-LDH-1 and TPP-LDH-2

11

for U(VI) at pH 5.0 and 298.15 K derived from Langmuir model are 201.27, 399.01

12

and 501.76 mg/g, respectively. In addition, tripolyphosphate intercalated LDH show a

13

higher sorption selectivity towards U(VI) over other metal cations and anions. X-ray

14

photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy

15

(FT-IR) characterizations suggest that the higher adsorption capacity and sorption

16

selectivity of TPP-LDH-2 are probably due to the inner-sphere surface complexes

17

resulted from the phosphate groups (P=O, -PO3) with U(VI). The applicability of

18

TPP-LDH-2 for scavenging of U(VI) from the impregnated water at a uranium

19

tailings repository in South China was further evaluated. It is found that TPP-LDH-2

20

show excellent removal efficiency for U(VI).

21

tripolyphosphate intercalated LDH is a promising adsorbent for scavenging of U(VI)

22

from the impregnated water at the uranium tailings repository.

The results indicate that

23 24 25

KEYWORDS Tripolyphosphate intercalated LDH, U(VI), scavenging mechanism, impregnated

26

water, uranium tailings repository.

27 28

1. INTRODUCTION

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Uranium mining and milling have resulted in the release of uranium into the

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environment.1-3 Bioavailable uranium in the environment poses serious threat to 2 ACS Paragon Plus Environment

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humans and other organisms because of its high toxicity and radioactivity.4-6 Thus,

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many researchers have paid much attention to the remediation of U(VI) contaminated

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water.

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In the last few decades, many technologies, such as chemical precipitation,7, 8 ion

5

exchange,9, 10 membrane separation11 and solvent extraction,12, 13 have been available

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for removing U(VI) from wastewater. As technology advances, electrochemical

7

method14, 15 and biomineralization16, 17 have emerged in recent years. However, some

8

shortcomings, such as high cost, secondary pollution and complex operation, were

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found in the application process, which limited the application of these methods in

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remediation of U(VI) contaminated wastewater18,

11

methods, adsorption, a cost-effective and environmental friendly technology, has

12

great potential in the removal of U(VI) from aqueous solutions.20-26 Researchers have

13

reported many adsorbents, such as clay minerals materials,4, 5, 19 carbon materials,3, 26

14

silicon materials,10,

15

polymer materials35, 36 and metal organic framework materials.37, 38 However, all these

16

adsorbents are used to treat the pure uranium solution instead of the actual uranium

17

wastewater and do not seem to be adequate for treating impregnated water at uranium

18

tailings repository since its uranium concentration is low and it contains many other

19

interfering ions.5, 26, 28, 30, 35, 38 Therefore, the development of novel and functional

20

adsorbents is of great significance to the remediation of the uranium wastewater.

27, 28

19

. Compared with the above

biomass materials,29-31 phosphate minerals materials,32-34

21

Layered double hydroxides (LDHs) are a class of typical 2D hydrotalcite-like

22

materials, which have aroused considerable interest from many researchers because of

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their special structures, excellent anion exchange capacities, effective active sites,

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moderate chemical stability and low cost.4, 19, 27, 39, 40 Xie et al.39 have reported the

25

preparation of Fe-Al LDHs by sono-assisted precipitation method and their

26

application in the removal of U(VI) from aqueous solutions. U(VI) (pH3), the

21

positively charged mononucleate uranyl species (UO2OH+) and polymeric uranyl

22

species ((UO2)2(OH)22+, (UO2)3(OH)5+ and (UO2) 4(OH)7+) are formed.6, 19 Meanwhile,

23

the hydroxide sites on the surface of Mg-Al-NO3-LDH become more deprotonated,

24

which promote the scavenging of U(VI). However, for TPP-LDH-1 and TPP-LDH-2,

25

within pH 5.0~7.0, the more deprotonated hydroxide/phosphate sites and the

26

negatively charged surfaces synergistically enhance the binding ability of

27

tripolyphosphate intercalated LDH with U(VI). Above pH 7.0, the negatively charged

28

species ((UO2)3(OH)7-, UO2(CO3)34- and UO2(CO3)22-) become dominated.3, 6 These

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species cannot interact with the negatively charged surfaces of TPP-LDH-1 and 8 ACS Paragon Plus Environment

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TPP-LDH-2 due to electrostatic repulsion, which decreases the U(VI) removal

2

percentage.

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3.3. Sorption kinetics

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The sorption kinetics data of U(VI) on Mg-Al-NO3-LDH and tripolyphosphate

5

intercalated LDH at pH 5.0 and 298.15 K were plotted in Fig.4. The adsorption

6

capacity of U(VI) on Mg-Al-NO3-LDH and tripolyphosphate intercalated LDH

7

increase sharply during the first 50 min, and then slow down until the sorption

8

equilibrium are achieved after ~100 min. The rapid sorption process may be attributed

9

to the rapid diffusion of U(VI) from the solution to the external surface of the

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adsorbents through the driving force of concentration gradient. As the functional sites

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are occupied, the loading U(VI) may tend to transport from the bulk phase to the

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functional sites of internal surface. In the later slow sorption process, the diffusion of

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U(VI) is slower than in the rapid sorption process, which decreases the sorption rate

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of U(VI). In a word, the sorption process is quite fast and 100 min reaction is enough

15

to reach equilibrium. To guarantee adsorption equilibrium, the following experiments

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were conducted with contact time of 120 min. As shown in Fig.4, the adsorption

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capacities of TPP-LDH-1 and TPP-LDH-2 for U(VI) are much higher than that of

18

Mg-Al-NO3-LDH. This phenomenon may be due to the reason that tripolyphosphate

19

intercalated LDH introduces negatively charged phosphate groups, which contributes

20

to the complexation of the positively charged U(VI) species.

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Adsorption kinetics can be used to study the speed of sorption, which is closely

22

related to contact time, and can provide valuable information for the mechanism of

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adsorption. In view of this, the experimental kinetics data were simulated by

24

pseudo-first-order

25

(Qt=Qet/(t+1/k2Qe)). Herein, Qe and Qt (mg g-1) are the amount of U(VI) adsorbed at

26

equilibrium time and time t (min), respectively; k1 (min-1) and k2 (g mg-1 min-1) are the

27

pseudo-first-order and pseudo-second-order rate constants, respectively. The obtained

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kinetic parameters from both models are listed in Table 1. As shown in Fig. 4, the

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adsorption kinetics data of U(VI) on Mg-Al-NO3-LDH and tripolyphosphate

model

(Qt=Qe(1-e-k1t))

and

pseudo-second-order

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model


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intercalated LDH are fitted very well by pseudo-second-order model as compared to

2

pseudo-first-order model, and the correlation coefficient (R2) of pseudo-second-order

3

model are higher than that of pseudo-first-order model, and besides, the calculated

4

sorption capacity Qe,cal are in good agreement with the experimental sorption capacity

5

Qe,exp. These results suggest that the rate controlling mechanism may be

6

chemisorption rather than physical sorption.

7

3.4. Sorption isotherms and thermodynamic

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Adsorption isotherm is fundamental in describing the distribution of the

9

adsorbate in liquid and adsorbent. In view of this, the sorption isotherms of U(VI) on

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Mg-Al-NO3-LDH, TPP-LDH-1 and TPP-LDH-2 were conducted at different initial

11

U(VI) concentrations. As shown in Fig. 5, the sorption isotherms exhibit a

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conventional L-type curve with a platform for U(VI) sorption capacity. Meanwhile, it

13

can be seen that the sorption isotherm curve of U(VI) on Mg-Al-NO3-LDH is lower

14

than those on TPP-LDH-1 and TPP-LDH-2. In order to better understand the possible

15

removal

16

(Qe=bQmaxCe/(1+bCe)) and Freundlich models (Qe=KFCen). Where Qe (mg g-1) and Ce

17

(mg L-1) are the sorption amount and U(VI) concentration at equilibrium, respectively.

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Qmax (mg g-1) refers to the maximum adsorption capacity and b represents the

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Langmuir constant related to the sorption heat. KF and n are the adsorption capacity

20

and the degree of dependence of sorption, respectively. The value of 1/n is an

21

indicator for adsorption intensity or surface heterogeneity. The isotherms parameters

22

and Qmax obtained from Langmuir and Freundlich models are summarized in Table 2.

23

The correlation coefficient (R2) values show that the Langmuir model is more suitable

24

to simulate the sorption isotherms than the Freundlich model. These results suggest

25

that the surface active sites are uniformly distributed on the surface of

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Mg-Al-NO3-LDH, TPP-LDH-1 and TPP-LDH-2 and interacted with U(VI) in a

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monolayer mode. As shown in Table 2, the Qmax value of U(VI) on TPP-LDH-1

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(399.01 mg/g) and TPP-LDH-2 (501.76 mg/g) are increased by 1.98 and 2.49 times

29

respectively as compared with that of Mg-Al-NO3-LDH (201.27 mg/g). The results

mechanism,

the

isotherms

data

were


subjected

to

Langmuir

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imply that the abundant negatively charged phosphate groups on tripolyphosphate

2

intercalated LDH play an important role in scavenging of U(VI).

3

In order to further gain insight into the possible adsorption mechanism and the

4

inherent energetic changes during the sorption process, adsorption thermodynamic

5

experiments are conducted as a function of temperature ranging from 298.15 K to

6

318.15 K. The thermodynamic parameters including enthalpy (  H0), entropy (  S0),

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and Gibb’s free energy (  G0) are obtained from the following eqs:

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ln K d  

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G 0  H 0  TS 0

H 0 S 0  RT R

(1) (2)

10

Where R is the gas constant (8.314 J mol-1 K-1), T is the thermodynamic temperature

11

(K). The values of  H0 and  S0 are calculated from the linear plot of lnKd versus

12

1/T, and the thermodynamic parameters are listed in Table 3. The positive △H0 values

13

suggest the endothermic sorption of U(VI) on Mg-Al-NO3-LDH, TPP-LDH-1 and

14

TPP-LDH-2, and the positive △S0 values indicate an increase of structural disorder at

15

the solid/liquid interfaces during U(VI) sorption. The negative △G0 values suggest a

16

spontaneous process of U(VI) interaction with active sites on the above three sorbents

17

surfaces. Furthermore, the △G0 values shift to lower negative value with increasing

18

temperature, revealing that higher temperature is beneficial to U(VI) sorption.

19

Moreover, the △G0 values of TPP-LDH-2 are lower than that of Mg-Al-NO3-LDH

20

and TPP-LDH-1, implying that the sorption of U(VI) on TPP-LDH-2 are more

21

favorable than that on Mg-Al-NO3-LDH and TPP-LDH-1. This phenomenon can be

22

explained by the fact that higher temperature can accelerate the positively charged

23

U(VI) species diffusion and migration from solution to the surfaces of sorbents,48 and

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higher temperature can improve the deprotonation of phosphate groups, enhancing

25

binding ability of U(VI) with phosphate groups.48

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3.5. Desorption and recycle performance

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Desorption and recycle property of Mg-Al-NO3-LDH, TPP-LDH-1 and

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TPP-LDH-2 were investigated to further estimate their potential application. Various 11 ACS Paragon Plus Environment


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concentrations of NaHCO3 ranging from 0.01 to 1 M were used as eluting agent. The

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desorption efficiency of U(VI) by different concentrations of NaHCO3 is shown in

3

Table S2. For Mg-Al-NO3-LDH, the desorption percentage increase with increasing

4

NaHCO3 concentrations and reach a peak value of 97.8% at 0.2 M NaHCO3, and then

5

remain at this level with the increase of NaHCO3 concentrations. The desorption

6

percentages of U(VI) from TPP-LDH-1 and TPP-LDH-2 are coincided with that from

7

Mg-Al-NO3-LDH, and the maximum desorption percentages are 96.5% and 95.1%,

8

respectively. The results suggest that 0.2 M NaHCO3 solution is the best optimum

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eluting agent for Mg-Al-NO3-LDH and tripolyphosphate intercalated LDH.

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To assess the reusability of the adsorbents, the recycle performances were

11

investigated. After five cycles, the sorption capacity of Mg-Al-NO3-LDH decrease

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from 98.05 to 96.32 mg/g (by 1.8%), that of TPP-LDH-1 decrease from 205.49 to

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200.57 mg/g (by 2.4%), and that of TPP-LDH-2 decrease from 289.95 to 279.93 mg/g

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(by 3.5%). The reused adsorbents still exhibit high adsorption capacity for U(VI) even

15

after five cycles. The results show that Mg-Al-NO3-LDH and tripolyphosphate

16

intercalated LDH with excellent reusability property can be used as potential effective

17

adsorbents for U(VI).

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3.6. Comparison of Mg-Al-NO3-LDH and tripolyphosphate intercalated LDH

19

with other LDH sorbents

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To evaluate the practicability and superiority of using Mg-Al-NO3-LDH and

21

tripolyphosphate intercalated LDH as sorbents for the removal of U(VI) from

22

environmental water samples. The sorption capacities of U(VI) on different LDH

23

sorbents were compared and summarized in Table S3. As shown in Table S3, the

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maximum sorption capacity of tripolyphosphate intercalated LDH (TPP-LDH-1 and

25

TPP-LDH-2) is higher than those of NiFeAl LDH,49 Fe-Al LDHs,39 LDH/GO,4 Ni/Al

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LDH-Gl,19 MgFeAl LDH,49 Ca/Al LDH-Gl,19 rGO/LDH,40 SiO2@LDH27 and

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Ca/Al-LDH@CNTs50 except for Fe-NCNF-LDH.51 The results suggest that

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tripolyphosphate intercalated LDH could be the promising potential sorbents for the

29

efficient scavenging of U(VI) from aqueous solutions. 12 ACS Paragon Plus Environment

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3.7. Sorption selectivity of Mg-Al-NO3-LDH and tripolyphosphate intercalated

2

LDH

3

Some metal cations (Ca2+, Mg2+, Co2+, Ni2+, Al3+) and anions (CO32-, SO42-, NO3-)

4

always coexist with U(VI) in the actual environmental uranium wastewater and can

5

compete with U(VI) for binding sites on the surface of solid sorbents, leading to the

6

decrease of U(VI) removal efficiency. In view of this, the sorption selectivity of

7

Mg-Al-NO3-LDH and tripolyphosphate intercalated LDH towards U(VI) were

8

evaluated using solution at pH 5 containing 10 mg/L U(VI) and 50 mg/L another

9

competitive ion. As shown in Fig.6, Mg-Al-NO3-LDH has poor selectivity for

10

U(VI) over other competitor. However, for TPP-LDH-1 and TPP-LDH-2, the removal

11

percentage of U(VI) is nearly not influenced by the other interfering ions. The results

12

herein indicate that tripolyphosphate intercalated LDH exhibits a high sorption

13

affinity towards U(VI) even in the presence of other interfering ions. The high

14

sorption selectivity of tripolyphosphate intercalated LDH for U(VI) is due to the

15

stronger affinity of phosphate moieties to U(VI) than other metal ions.

16

3.8. U(VI) scavenging mechanisms on TPP-LDH-2

17

In order to illustrate the U(VI) scavenging mechanisms by tripolyphosphate

18

intercalated LDH, FT-IR and XPS were used to characterize the changes of chemical

19

groups and elemental compositions of TPP-LDH-2 before and after U(VI) adsorption.

20

As shown in Fig.7A , the characteristic bands of P=O and –PO3 located at 1128

21

cm-1 and 979 cm-1 are shifted after U(VI) adsorption on TPP-LDH-2, respectively, and

22

the peaks intensities are decreased. Moreover, the stretching vibration band of P=O is

23

split into two peaks, which is attributed to phosphate forming protonated inner-sphere

24

surface complexes52, 53. The FT-IR results indicate that phosphate groups (P=O, -PO3)

25

may interact with U(VI), forming inner-sphere surface complexes.

26

The wide XPS survey spectra of TPP-LDH-2 before and after adsorption of U(VI)

27

are shown in Fig.7B. It can be seen that a doublet peak characteristic of U4f occurs

28

after U(VI) adsorption. The U4f 7/2 spectra (Fig.7C) have two components of 380.39

29

and 382.23 eV which originate from UO22+ and (UO2)n(OH)m(2n-m)+, and the 13 ACS Paragon Plus Environment


1

characteristic spectra are consistent with that found by Budnyak et al28, suggesting

2

that the adsorbed U(VI) may be UO22+ and (UO2)n(OH)m(2n-m)+. The P2p spectra of

3

TPP-LDH-2 (Fig.8A) are deconvoluted into two components: -PO3 and P-O-P at

4

133.09 and 133.97 eV, respectively. However, for TPP-LDH-2+U(VI), the bands of

5

–PO3 and P-O-P are shifted to 133.23 and 134.05 eV, respectively. Moreover, a new

6

peak at 134.89 eV appears, indicating the effective complexation of U(VI) with active

7

phosphate groups on the surface of TPP-LDH-2. The results are similar to those by

8

Shao et al54 and Drot et al55 for U(VI) adsorption by phosphate functionalized

9

polyethylene and SiO2, respectively. The O1s spectra of TPP-LDH-2 (Fig.8C) can be

10

deconvoluted into three components at 531.18 , 532.12 and 532.29 eV corresponding

11

to P=O, P-O and –OH, respectively, which coincide with the results by Yuan et al56.

12

After U(VI) adsorption, the P=O component significantly decreases, indicating P=O

13

participation in U(VI) complexation, and the increased content of P-O and –OH can

14

be ascribed to the complexed P-O-U(VI).

15

3.9. The applicability of TPP-LDH-2

16

Considering the excellent sorption capacity and sorption selectivity of TPP

17

-LDH-2 towards U(VI), the applicability of TPP-LDH-2 for removal of uranium from

18

impregnated water at uranium tailings repository was evaluated. The acid

19

impregnated water (pH=5.14) were collected from a uranium tailings repository in

20

South China, which contained 548.36 mg/L Ca2+, 46.98 mg/L Mg2+, 4.65 mg/L Al3+,

21

0.083 mg/L Co2+, 0.72 mg/L Ni2+, and 0.86 mg/L U(VI). 1 L uranium wastewater is

22

treated with 0.2 g TPP-LDH-2, the concentration of U(VI) in the wastewater decrease

23

to 0.045 mg/L by the TPP-LDH-2, and the removal efﬁciency of U(VI) reach 94.77%

24

after 2 h adsorption. The results suggest that the adsorbent is effective for U(VI)

25

scavenging from impregnated water at uranium tailings repository.

26 27

4. CONCLUSIONS AND OUTLOOKS

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In summary, polygonal sheet-shaped Mg-Al-NO3-LDH and tripolyphosphate

29

intercalated LDH were successfully prepared by an anion exchange method and 14 ACS Paragon Plus Environment

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characterized by advanced spectroscopy techniques, such as SEM-EDS, XRD, FT-IR,

2

Zeta potentiometer and XPS. The sorption isotherms and the corresponding

3

thermodynamic parameters suggest that U(VI) removal by Mg-Al-NO3-LDH and

4

tripolyphosphate intercalated LDH are an endothermic and spontaneous process. The

5

maximum sorption capacities of U(VI) on TPP-LDH-1 (399.01 mg/g) and

6

TPP-LDH-2 (501.76 mg/g) increase by 1.98 times and 2.49 times as compared with

7

that of Mg-Al-NO3-LDH (201.27 mg/g). In addition, tripolyphosphate intercalated

8

LDH exhibit higher sorption affinity for U(VI) than that for other metal cations and

9

anions. The higher adsorption capacity and sorption selectivity of TPP-LDH-2 are

10

probably due to the inner-sphere surface complexes resulted from phosphate groups

11

(P=O, -PO3) interaction with U(VI). The TPP-LDH-2 is further used for scavenging

12

of U(VI) from impregnated water at a uranium tailings repository in South China, and

13

it has excellent removal efficiency for U(VI). The results indicate that

14

tripolyphosphate intercalated Mg-Al layered double hydroxide is a promising

15

adsorbent for scavenging of U(VI) from impregnated water at uranium tailings

16

repository.

17 18

ACKNOWLEDGEMENTS

19

This work was supported by the National Natural Science Foundation of China

20

(U1401231 and 51704170), the Natural Science Foundation of Hunan Province

21

(2018JJ3428) and the Research Foundation of Education Bureau of Hunan Province

22

(16C1386).

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REFERENCES

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1. Zhang Z. B.; Liu J.; Cao X. H.; Luo X. P.; Hua R.; Liu Y.; Yu X. F.; He L. K.; Liu

26

Y. H. Comparison of U(VI) adsorption onto nanoscale zero-valent iron and red soil in

27

the presence of U(VI)-CO3/Ca-U(VI)-CO3 complexes. J. Hazard. Mater. 2015, 300,

28

633-642.

29

2. Sun Y. B.; Wang X. X.; Ai Y. J.; Yu Z. M.; Huang W.; Chen C. L.; Hayat T.; 15 ACS Paragon Plus Environment


1

Alsaedi A.; Wang X. K. Interaction of sulfonated graphene oxide with U(VI) studied

2

by spectroscopic analysis and theoretical calculations. Chem. Eng. J. 2017, 310,

3

292-299.

4

3. Sun Y. B.; Lu S. H.; Wang X. X.; Xu C.; Li J. X.; Chen C. L.; Chen J.; Hayat T.;

5

Alsaedi A.; Alharbi N. S.; Wang X. K. Plasma-Facilitated Synthesis of

6

Amidoxime/Carbon Nanofiber Hybrids for Effective Enrichment of (238)U(VI) and

7

(241)Am(III). Environ. Sci. Technol. 2017, 51, 12274-12282.

8

4. Linghu W. S.; Yang H.; Sun Y. X.; Sheng G. D.; Huang Y. Y. One-pot synthesis of

9

LDH/GO composites as highly effective adsorbents for decontamination of U(VI).

10

ACS Sustain. Chem. Eng. 2017, 5, 5608-5616.

11

5. Hu B. W.; Ye F.; Ren X. M.; Zhao D. L.; Sheng G. D.; Li H.; Ma J. Y.; Wang X.

12

K.; Huang Y. Y. X-ray absorption fine structure study of enhanced sequestration of

13

U(VI) and Se(IV) by montmorillonite decorated with zero-valent iron nanoparticles.

14

Environ, Sci: Nano 2016, 3, 1460-1472.

15

6. Zhu K. R.; Chen C. L.; Xu M. W. C.; Chen K.; Tan X. L.; Wakeel M.; Alharbi N.

16

S. In situ carbothermal reduction synthesis of Fe nanocrystals embedded into N-doped

17

carbon nanospheres for highly efficient U(VI) adsorption and reduction. Chem. Eng. J.

18

2018, 331, 395-405.

19

7. Mellah A.; Chegrouche S.; Barkat M. The precipitation of ammonium uranyl

20

carbonate (AUC): Thermodynamic and kinetic investigations. Hydrometallurgy 2007,

21

85, 163-171.

22

8. Smirnov A. L.; Rychkov V. N.; Titova S. M.; Poponin N. A.; Nalivayko K. A.

23

Precipitation of uranium from nitrate-sulfuric eluates by aqueous ammonia solution. J.

24

Radioanal. Nucl. Chem. 2018, 317, 863-869.

25

9. Amphlett J. T. M.; Ogden M. D.; Foster R. I.; Syna N.; Soldenhoff K. H.; Sharrad

26

C. A. The effect of contaminants on the application of polyamine functionalised ion

27

exchange resins for uranium extraction from sulfate based mining process waters.

28

Chem. Eng. J. 2018, 354, 633-640.

29

10. Chen Z.; Liang Y.; Jia D. S.; Chen W. Y.; Cui Z. M.; Wang X. K. Layered silicate 16 ACS Paragon Plus Environment

Page 16 of 35

Page 17 of 35 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


1

RUB-15 for efficient removal of UO22+ and heavy metal ions by ion-exchange.

2

Environ. Sci: Nano 2017, 4, 1851-1858.

3

11. Schulte-Herbruggen H. M.; Semiao A. J.; Chaurand P.; Graham M. C. Effect of

4

pH and Pressure on Uranium Removal from Drinking Water Using NF/RO

5

Membranes. Environ. Sci. Technol. 2016, 50, 5817-24.

6

12. Zarrougui R.; Mdimagh R.; Raouafi, N. Highly efficient extraction and selective

7

separation of uranium (VI) from transition metals using new class of undiluted ionic

8

liquids based on H-phosphonate anions. J. Hazard. Mater. 2018, 342, 464-476.

9

13. Beltrami D.; Cote G.; Mokhtari H.; Courtaud B.; Moyer B. A.; Chagnes A.

10

Recovery of uranium from wet phosphoric acid by solvent extraction processes. Chem.

11

Rev. 2014, 114, 12002-23.

12

14. Lu B. Q.; Li M.; Zhang X. W.; Huang C. M.; Wu X. Y.; Fang Q. Immobilization

13

of uranium into magnetite from aqueous solution by electrodepositing approach. J.

14

Hazard. Mater. 2018, 343, 255-265.

15

15. Li P.; Zhun B.; Wang X. G.; Liao P. P.; Wang G. H.; Wang L. Z.; Guo Y. D.;

16

Zhang W. M. Highly Efficient Interception and Precipitation of Uranium(VI) from

17

Aqueous Solution by Iron-Electrocoagulation Combined with Cooperative Chelation

18

by Organic Ligands. Environ. Sci. Technol. 2017, 51, 14368-14378.

19

16. Zhen X. Y.; Wang X. Y.; Shen Y. H.; Lu X.; Wang T. S. Biosorption and

20

biomineralization of uranium(VI) by Saccharomyces cerevisiae-Crystal formation of

21

chernikovite. Chemosphere 2017, 175, 161-169.

22

17. Zheng X. Y.; Shen Y. H.; Wang X. Y.; Wang T. S. Effect of pH on uranium(VI)

23

biosorption and biomineralization by Saccharomyces cerevisiae. Chemosphere 2018,

24

203, 109-116.

25

18. Zou Y. D.; Wang X. X.; Khan A.; Wang P. Y.; Liu Y. H.; Alsaedi A.; Hayat T.;

26

Wang X. K. Environmental remediation and application of nanoscale zero-valent iron

27

and its composites for the removal of heavy metal ions, Environ. Sci. Technol. 2016,

28

50, 7290-7304.

29

19. Zou Y. D.; Liu Y.; Wang X. X.; Sheng G. D.; Wang S. H.; Ai Y. J.; Ji Y. F.; Liu Y. 17 ACS Paragon Plus Environment


1

H.; Hayat T.; Wang X. K. Glycerol-Modified Binary Layered Double Hydroxide

2

Nanocomposites for Uranium Immobilization via Extended X-ray Absorption Fine

3

Structure Technique and Density Functional Theory Calculation. ACS Sustain. Chem.

4

Eng. 2017, 5, 3583-3595.

5

20. Li Z. J.; Wang L.; Yuan L. Y.; Xiao C. L.; Mei L.; Zheng L. R.; Zhang J.; Yang J.

6

H.; Zhao Y. L.; Zhu Z. T.; Chai Z. F.; Shi W. Q. Efficient removal of uranium from

7

aqueous solution by zero-valent iron nanoparticle and its graphene composite. J.

8

hazard. Mater. 2015, 290, 26-33.

9

21. Wang L.; Tao W. Q.; Yuan L.Y; Liu Z. R.; Huang Q.; Chai Z. F.; Gibson J. K.; Shi

10

W. Q. Rational control of the interlayer space inside two-dimensional titanium

11

carbides for highly efficient uranium removal and imprisonment. Chem. Commun.

12

2017, 53, 12084-12087.

13

22. Lan J. H.; Chai Z. F.; Shi W. Q. A combined DFT and molecular dynamics study

14

of U (VI)/calcite interaction in aqueous solution. Sci. Bull. 2017, 62, 1064-1073.

15

23. Li Z. J.; Huang Z. W.; Guo W. L.; Wang L.; Zheng L. R.; Chai Z. F.; Shi W. Q.

16

Enhanced photocatalytic removal of uranium (VI) from aqueous solution by magnetic

17

TiO2/Fe3O4 and its graphene composite. Environ. Sci. Technol. 2017, 51, 5666-5674.

18

24. Wang L.; Song H.; Yuan L. Y.; Li Z. J.; Zhang Y. J.; Gibson J. K.; Zheng L. R.;

19

Chai Z. F.; Shi W. Q. Efficient U (VI) Reduction and Sequestration by Ti2CTx MXene.

20

Environ. Sci. Technol. 2018, 52(18): 10748-10756.

21

25. Huang Z. W.; Li Z. J.; Wu Q. Y.; Zheng L. R.; Zhou L. M.; Chai Z. F.; Wang X. L.;

22

Shi W. Q. Simultaneous elimination of cationic uranium (VI) and anionic rhenium

23

(VII) by graphene oxide–poly (ethyleneimine) macrostructures: a batch, XPS, EXAFS,

24

and DFT combined study. Environ. Sci: Nano. 2018, 5, 2077-2087.

25

26. Wang H.; Ma L. J.; Cao K. C.; Geng J. X.; Liu J.; Song Q.; Yang X. D.; Li S. J.

26

Selective solid-phase extraction of uranium by salicylideneimine-functionalized

27

hydrothermal carbon. J. Hazard. Mater. 2012, 229-230, 321-30.

28

27. Yang D. X.; Song S.; Zou Y. D.; Wang X. X.; Yu S. J.; Wen T.; Wang H. Q.;

29

Hayat T.; Alsaedi A.; Wang X. K. Rational design and synthesis of monodispersed 18 ACS Paragon Plus Environment

Page 18 of 35

Page 19 of 35 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


1

hierarchical SiO2 @layered double hydroxide nanocomposites for efficient removal of

2

pollutants from aqueous solution. Chem. Eng. J. 2017, 323, 143-152.

3

28. Budnyak T. M.; Strizhak A. V.; Gladysz-Plaska A.; Sternik D.; Komarov I. V.;

4

Kolodynska D.; Majdan M.; Tertykh Vcapital A, C. Silica with immobilized

5

phosphinic acid-derivative for uranium extraction. J. Hazard. Mater. 2016, 314,

6

326-340.

7

29. Bayramoglu G.; Akbulut A.; Arica M. Y. Study of polyethyleneimine and

8

amidoxime-functionalized hybrid biomass of Spirulina (Arthrospira) platensis for

9

adsorption of uranium (VI) ion. Environ. Sci. Pollut. Res. Int. 2015, 22, 17998-8010.

10

30. Wang F. H.; Tan L. C.; Liu Q.; Li R. M.; Li Z. S.; Zhang H. S.; Hu S. X.; Liu L.

11

H.; Wang J. Biosorption characteristics of Uranium (VI) from aqueous solution by

12

pollen pini. J. Environ. Radioact. 2015, 150, 93-8.

13

31. Li L.; Hu N.; Ding D. D.; Xin X.; Wang Y. D.; Xue J. H.; Zhang H.; Tan Y.

14

Adsorption and recovery of U(VI) from low concentration uranium solution by

15

amidoxime modified Aspergillus niger. RSC Adv. 2015, 5, 65827-65839.

16

32. Simon F. G.; Biermann V.; Peplinski B. Uranium removal from groundwater using

17

hydroxyapatite. Appl. Geochem. 2008, 23, 2137-2145.

18

33. Krestou A.; Xenidis A.; Panias D. Mechanism of aqueous uranium(VI) uptake by

19

hydroxyapatite. Miner. Eng. 2004, 17, 373-381

20

34. Fuller C. C.;

21

Interactions with Hydroxyapatite: Implications for Groundwater Remediation.

22

Environ. Sci. Technol. 2002, 36, 158-165.

23

35. Alexandratos S. D.; Zhu X. P.; Florent M.; Sellin R. Polymer-Supported

24

Bifunctional Amidoximes for the Sorption of Uranium from Seawater. Ind. Eng.

25

Chem. Res. 2016, 55, 4208-4216.

26

36. Yuan D. Z.; Chen L.; Xiong X.; Yuan L. G.; Liao S. J.; Wang Y. Removal of

27

uranium (VI) from aqueous solution by amidoxime functionalized superparamagnetic

28

polymer microspheres prepared by a controlled radical polymerization in the presence

29

of DPE. Chem. Eng. J. 2016, 285, 358-367.

Bargar J. R.; Davis J. A.; Piana M. J. Mechanisms of Uranium



1

37. Bai Z. Q.; Yuan L.Y.; Zhu L.; Liu Z. R.; Chu S. Q.; Zheng L. R.; Zhang J.; Chai Z.

2

F.; Shi W. Q. Introduction of amino groups into acid-resistant MOFs for enhanced

3

U(VI) sorption. J. Mater. Chem. A 2015, 3, 525-534.

4

38. De Decker J.; Folens K.; De Clercq J.; Meledina M.; Van Tendeloo G.; Du Laing

5

G.; Van Der Voort P. Ship-in-a-bottle CMPO in MIL-101(Cr) for selective uranium

6

recovery from aqueous streams through adsorption. J. Hazard. Mater. 2017, 335, 1-9.

7

39. Xie L. X.; Zhong Y.; Xiang R. J.; Fu G. Y.; Xu Y. Z.; Cheng Y. X.; Liu Z.; Wen T.;

8

Zhao Y. Y.; Liu X. Q. Sono-assisted preparation of Fe(II)-Al(III) layered double

9

hydroxides and their application for removing uranium (VI). Chem. Eng. J. 2017, 328,

10

574-584.

11

40. Tan L. C.; Wang Y. L.; Liu Q.; Wang J.; Jing X. Y.; Liu L. H.; Liu J. Y.; Song D. L.

12

Enhanced adsorption of uranium (VI) using a three-dimensional layered double

13

hydroxide/graphene hybrid material. Chem. Eng. J. 2015, 259, 752-760.

14

41. Jin C.; Liu H. M.; Kong X. G.; Yan H.; Lei X. D. Enrichment of rare earth metal

15

ions by the highly selective adsorption of phytate intercalated layered double

16

hydroxide. Dalton Trans. 2018, 47, 3093-3101.

17

42. Deng L.; Shi Z.; Wang L.; Zhou S. Q. Fabrication of a novel NiFe2O4 /Zn-Al

18

layered double hydroxide intercalated with EDTA composite and its adsorption

19

behavior for Cr(VI) from aqueous solution. J. Phys. Chem. Solids 2017, 104, 79-90.

20

43. Tran H. N.; Lin C. C.; Chao H. P. Amino acids-intercalated Mg/Al layered double

21

hydroxides as dual-electronic adsorbent for effective removal of cationic and

22

oxyanionic metal ions. Sep. Purif. Technol. 2018, 192, 36-45.

23

44. Sureshkumar M. K.; Das D.; Mallia M. B.; Gupta P. C. Adsorption of uranium

24

from aqueous solution using chitosan-tripolyphosphate (CTPP) beads. J. Hazard.

25

Mater. 2010, 184, 65-72.

26

45. Ay A. N.; Zümreoglu-Karan B.; Temel A. Boron removal by hydrotalcite-like,

27

carbonate-free Mg–Al–NO3-LDH and a rationale on the mechanism. Micropor.

28

Mesopor. Mater. 2007, 98, 1-5.

29

46. Ma L. J.; Wang Q.; Islam S. M.; Liu Y. C.; Ma S. L.; Kanatzidis M. G. Highly 20 ACS Paragon Plus Environment

Page 20 of 35

Page 21 of 35 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


1

Selective and Efficient Removal of Heavy Metals by Layered Double Hydroxide

2

Intercalated with the MoS42- Ion. J. Am. Chem. Soc. 2016, 138, 2858-66.

3

47. Zhao D. L.; Wang X. B.; Yang S. T.; Guo Z. Q.; Sheng G. D. Impact of water

4

quality parameters on the sorption of U(VI) onto hematite. J. Environ. Radioact. 2012,

5

103, 20-9.

6

48. Cai, Y. W.; Yuan, F.; Wang, X. M.; Sun, Z.; Chen, Y.; Liu, Z. Y.; Wang, X. K.;

7

Yang, S. T; Wang, S. A. Synthesis of core–shell structured Fe3O4@carboxymethyl

8

cellulose magnetic composite for highly efficient removal of Eu(III). Cellulose 2016,

9

24 (1), 175-190.

10

49. Song S.; Yin L.; Wang X. X.; Liu L.; Huang S. Y.; Zhang R.; Wen T.; Yu S. J.; Fu

11

D.; Hayat T.; Wang X. K. Interaction of U(VI) with ternary layered double hydroxides

12

by combined batch experiments and spectroscopy study. Chem. Eng. J. 2018, 338,

13

579-590.

14

50. Chen H. J.; Chen Z.; Zhao G. X.; Zhang Z. B.; Xu C.; Liu Y. H.; Chen J.; Zhuang

15

L.; Haya T.; Wang X. K. Enhanced adsorption of U(VI) and (241)Am(III) from

16

wastewater using Ca/Al layered double hydroxide@carbon nanotube composites. J.

17

Hazard. Mater. 2018, 347, 67-77.

18

51. Zhu J. H.; Liu Q.; Liu J. Y.; Chen R. R.; Zhang H. S.; Li R. M.; Wang J. Ni–Mn

19

LDH-decorated 3D Fe-inserted and N-doped carbon framework composites for

20

efficient uranium(VI) removal. Environ. Sci: Nano 2018, 5, 467-475.

21

52. Yuan F.; Wu C. F.; Cai Y. W.; Zhang L. J.; Wang J. Q.; Chen L. H.; Wang X. K.;

22

Yang S. T.; Wang S. A. Synthesis of phytic acid-decorated titanate nanotubes for high

23

efficient and high selective removal of U(VI). Chem. Eng. J. 2017, 322, 353-365.

24

53. Elzinga E. J.; Sparks D. L. Phosphate adsorption onto hematite: an in situ

25

ATR-FTIR investigation of the effects of pH and loading level on the mode of

26

phosphate surface complexation. J. Colloid Interface Sci. 2007, 308, 53-70.

27

54. Shao D. D.; Li Y. Y.; Wang X. L.; Hu S.; Wen J.; Xiong J.; Asiri A. M.; Marwani

28

H. M., Phosphate-Functionalized Polyethylene with High Adsorption of Uranium(VI).

29

ACS Omega 2017, 2, 3267-3275. 21 ACS Paragon Plus Environment


1

55. Kowal-Fouchard A.; Drot R.; Simoni E.; Ehrhardt J. J. Use of spectroscopic

2

techniques for uranium (VI) montmorillonite interaction modeling, Environ. Sci.

3

Technol. 2004, 38, 1399-1407.

4

56. Yuan D. Z.; Wang Y.; Qian Y.; Liu Y.; Feng G.; Huang B.; Zhao X. H. Highly

5

selective adsorption of uranium in strong HNO3 media achieved on a phosphonic acid

6

functionalized nanoporous polymer. J. Mater. Chem. A 2017, 5, 22735-22742.

7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 22 ACS Paragon Plus Environment

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1

FIGURE CAPTIONS

2

Fig.1. SEM-EDS images of Mg-Al-NO3-LDH (A), TPP-LDH-1 (B) and TPP-LDH-2

3

(C).

4

Fig.2. XRD patterns (A) and FT-IR spectras (B) of Mg-Al-NO3-LDH, TPP-LDH-1

5

and TPP-LDH-2.

6

Fig.3. Effect of pH on U(VI) sorption. CU(VI)initial=50 mg/L, m/V=0.2g/L, T=298.15K.

7

Fig.4. Pseudo first order and second order kinetic profiles for U(VI) adsorption by

8

Mg-Al-NO3-LDH, TPP-LDH-1 and TPP-LDH-2. CU(VI), initial=50 mg/L, m/V=0.2g/L,

9

pH=5.0, T=298.15K.

10

Fig.5. Adsorption isotherm models for U(VI) sorption by Mg-Al-NO3-LDH,

11

TPP-LDH-1 and TPP-LDH-2. m/V=0.2g/L, pH=5.0, T=298.15K.

12

Fig.6. Influence of other coexisting cations and anions on the sorption of U(VI) on

13

Mg-Al-NO3-LDH, TPP-LDH-1 and TPP-LDH-2. CU(VI),

14

=50 mg/L, m/V=0.2g/L, pH=5.0, T=298.15K.

15

Fig.7. FT-IR spectra (A) and the wide scan XPS spectrum (B) of TPP-LDH-2 before

16

and after U(VI) sorption; U4f XPS spectrum of TPP-LDH-2 after U(VI) sorption

17

(C).

18

Fig.8. High resolved P2p XPS spectrum (D, E) and O1s XPS spectrum (F, G) of

19

TPP-LDH-2 before and after U(VI) sorption.

20 21 22 23 24 25 26 27 28 29 23 ACS Paragon Plus Environment

initial=10,

Ccoexisting

ions, initial


Page 24 of 35

Table 1 Kinetic parameters for U(VI) sorption by Mg-Al-NO3-LDH, TPP-LDH-1 and TPP-LDH-2. Adsorbents

Qe,exp (mg/g)

Mg-Al-NO3-LDH TPP-LDH-1 TPP-LDH-2

98.05 205.50 244.04

Pseudo-first -order

Pseudo-second-order

Q1,cal (mg/g)

k1 (min-1)

R2

Q2,cal (mg/g)

k2 (min-1)

R2

94.17 199.64 240.90

0.0677 0.0948 0.399

0.917 0.889 0.742

103.75 214.63 245.76

0.000946 0.000728 0.00491

0.987 0.983 0.985

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 24 ACS Paragon Plus Environment

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1

Table 2 Isotherm parameters of U(VI) sorption by Mg-Al-NO3-LDH, TPP-LDH-1

2

and TPP-LDH-2.

pH Mg-Al-NO3-LDH TPP-LDH-1 TPP-LDH-2

Langmuir isotherm model Qmax (mg/g) 201.27 399.01 501.76

b (L/mg) 0.032 0.13 0.71

Freundlich isotherm model R2

KF (Ln/ mgn-1/ g)

n

R2

13.46 66.74 196.78

0.57 0.48 0.41

0.973 0.932 0.895

0.998 0.997 0.993

3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 25 ACS Paragon Plus Environment


Page 26 of 35

1

Table 3 Thermodynamic parameters of U(VI) sorption by Mg-Al-NO3-LDH,

2

TPP-LDH-1 and TPP-LDH-2. Adsorbents

△H0 (KJ/mol)

△S0 (J/mol·K)

Mg-Al-NO3-LDH TPP-LDH-1 TPP-LDH-2

34.85 23.32 38.40

132.08 109.75 178.57

298.15 K -4.53 -9.41 -14.84

3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 26 ACS Paragon Plus Environment

△G0 (KJ/mol) 308.15 K -5.85 -10.50 -16.63

318.15 K -7.17 -11.60 -18.41

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Fig.1

2 3 4 5 6 7 8 9 10 11 12 13 27 ACS Paragon Plus Environment


1

Fig.2

2 3 4 5 6 7 8 9 10 11 12 13 14 28 ACS Paragon Plus Environment

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1

Fig.3



1

Fig.4


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1

Fig.5



1

Fig.6


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1

Fig.7



1

Fig.8


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1

GRAPHICAL ABSTRACT

2


Scavenging of U(VI) from Impregnated Water at Uranium Tailings

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