Guanidine and Amidoxime Cofunctionalized Polypropylene

Article pubs.acs.org/IECR

Cite This: Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

Guanidine and Amidoxime Cofunctionalized Polypropylene Nonwoven Fabric for Potential Uranium Seawater Extraction with Antifouling Property Huijun Zhang,†,⊥ Lixia Zhang,†,⊥ Xiaoli Han,† Liangju Kuang,‡ and Daoben Hua*,†,§ †

State Key Laboratory of Radiation Medicine and Protection, School for Radiological and Interdisciplinary Sciences (RAD−X), Soochow University, Suzhou 215123, China ‡ Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, Indiana 47907, United States § Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou 215123, China S Supporting Information *

ABSTRACT: Uranium seawater extraction is strategically important to the sustainable development of nuclear energy. Nevertheless, a challenge remains in uranium enrichment to overcome the microorganisms’ adhesion. In this article, we propose guanidine and amidoxime cofunctionalized polypropylene nonwoven fabric for potential uranium seawater extraction with an antifouling property. Specifically, glycidyl methacrylate was first grafted onto polypropylene nonwoven fabric under γ-ray irradiation, and then reacted with dicyandiamide, and followed by amidoximation to give the functionalized sorbents. The effect of sorbent dose, contact time, and coexisting ions on uranium adsorption and antibacterial assay were investigated. The sorption equilibrium could be reached with a capacity of 112 mg/g within 5 h at pH 8.0 and 298.15 K. The uranium sorption was not affected by other coexisting ions. The antibacterial assay indicated guanidine and amidoxime cofunctionalized fabric could efficiently inhibit the adhesion of Gram-negative E. coli and have bactericidal functions. In addition, it could be regenerated with high efficiency of uranium adsorption after five cycles. This work indicates that guanidine and amidoxime cofunctionalized polypropylene nonwoven fabric may be a promising material for uranium seawater extraction.

1. INTRODUCTION

sorption capacity could reach 5.22 g/kg after exposure in seawater for 49 days. However, it is still a challenge for the reported sorbents to overcome the biofouling in the process of uranium seawater extraction. Recently Hu et al.18 prepared amidoximated ultrahigh molecular weight polyethylene fiber for uranium sorption tests in seawater, and found that biofouling was an important factor influencing the amount of uranyl ions binding to the fibrous sorbent. Gill et al.19 evaluated the performance of amidoxime-based polymer sorbent in a uranium seawater test at Pacific Northwest National Laboratory, and a 30% decrease in uranium sorption capacity was noticed after exposure to raw seawater for 42 days in a flume because of biofouling. Biofouling usually occurs at the wetted surfaces where plants, algae, animals, or bacteria tend to accumulate. In the ocean environment, biofouling generally involves a four-step process.20−22 First, microorganism will rapidly coat the surfaces within 5−10 s once immersed. Single bacterial cells and diatoms then start to settle, adhere, and colonize on the surface.

Uranium seawater extraction has received more and more attention in the past decade, because the reserve of uranium in seawater is around 4.5 billion tons, which is approximately 1000 times larger than that in terrestrial ores.1−3 It will be enough to supply nuclear power production over the next few centuries if extracted economically. Currently, many methods for uranium seawater extraction have been developed, such as ionic exchange,4 membrane dialysis,5 bioconcentration,6 flotation,7 and sorption.8−10 Considering low cost, simple operation, and universality, sorption becomes a popular method for uranium enrichment from seawater.11,12 The sorbents for uranium must possess the following performances:2 large sorption capacity, excellent regenerability, good mechanical stability, and high selectivity for uranium among various competing ions. Among various sorbents, poly(acrylamidoxime)-functionalized fibrous sorbents are regarded as the best ones in a screening of 200 organic polymers in the field of uranium seawater extraction.13−15 For example, Liu et al.16 reported amidoxime-based polyethylene nonwoven fabric for the sorption of uranyl ions at pH 7.5; and Brown et al.17 developed amidoxime and tert-butyl acrylate modified poly(vinyl chloride)-co-chlorinated poly(vinyl chloride) fibers for uranium seawater extraction, and uranium © XXXX American Chemical Society

Received: November 12, 2017 Revised: January 12, 2018 Accepted: January 14, 2018

A

DOI: 10.1021/acs.iecr.7b04687 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

Article

Industrial & Engineering Chemistry Research At the third stage, microbial films generate, causing rough surfaces which will capture more particles and the larval forms. Finally, microorganisms such as barnacles, mussels, or algae outgrow on the fouled surface. Biofouling may have two adverse effects on uranium extraction:23 (1) hindering the accessibility of ligands to seawater during recovery, consequently reducing the sorption capacity; and (2) decreasing the reusability of sorbents on account of biocorrosion. Therefore, it is crucial to develop new sorbents with an antifouling property for uranium seawater extraction. Recently, various antifouling coatings, including zwitterionic materials,24 poly(ethylene glycol),25 poly(oxazoline),26 and glycopolymers,27 have been exploited. Nevertheless, bacterial cells deposited on the surface cannot be killed by such coatings.28 Thus, diverse bactericides are required, such as cationic polymers,29 antibiotics,30 antimicrobial peptides,31 antimicrobial enzymes,32 and guanidine polymers.33−35 Guanidine is recognized as one of the strongest organic bases (pKa = 13.6).36 The guanidine group remains protonated over a much wider range of pH in polar solvents,37,38 which can serve as an efficiently active group to interact with perssad in an organism, thereby destroying normal metabolism of substance and energy of the organism. Both Gram-negative and Gram-positive bacteria can be killed by guanidine polymers.39 Therefore, a guanidine-modified sorbent is promising to overcome bacterial fouling in the sorption process. However, there is no report about antifouling sorbents for uranium extraction from seawater until now. In this article, we propose a strategy for potential uranium seawater extraction with an antifouling property by guanidine and amidoxime cofunctionalized polypropylene nonwoven fabric (Scheme 1). Polypropylene (PP) nonwoven fabrics

Scheme 2. Resonance Forms of Guanidine in PP-g-AO

guanidine group can efficiently kill bacteria, and the introduction of hydrophilic function can inhibit bacterial adhesion. Therefore, it is expected that PP-g-AO could be utilized for potential uranium seawater extraction with an antifouling property.

2. EXPERIMENTAL SECTION 2.1. Materials and Reagents. GMA (chemically pure), DC (analytical reagent), and hydroxylamine hydrochloride (analytical reagent) were obtained from Sinopharm Chemical Reagent Co., Ltd. The other common reagents were employed as received. PP nonwoven fabric (85 g/m2) was amicably supplied by Kingway Complex Material Co., Ltd. (Nantong, China). Characterization methods are shown in Supporting Information. 2.2. Synthesis of Guanidine and Amidoxime Cofunctionalized PP Nonwoven Fabric. PP-g-PGMA was first synthesized according to the method in Supporting Information.44 PP-g-PGMA with graft degree of 257% (Table S1) was chosen for the modification with DC. A typical procedure for the synthesis of PP-g-AO was described as follows: DC (5.32 g, 63.3 mmol) was first dissolved with N,N′-dimethylformamide (DMF, 300 mL) in a 500 mL of round bottomed flask, then PP-g-PGMA (6.0 g) was added. After refluxing for 24 h, the fabric was washed with 200 mL of DMF and 200 mL of ethanol three times, and then it was desiccated in a vacuum oven at 40 °C to get the guanidine-functionalized nonwoven fabric (PP-gDC). The PP-g-DC with a different composition was received by changing the recipes of the reactant (Table 1). The results show that the N content suffered almost no increase beyond the 1:4 molar ratio of PP-g-PGMA and DC, which may be attributed to the saturated graft on the surfaces. Thus, the material PP-g-DC3 from 1:4 molar ratio of PP-g-PGMA and DC was used in the following experiments.

Scheme 1. Schematic for Preparation of Guanidine and Amidoxime Cofunctionalized Polypropylene Nonwoven Fabric (PP-g-AO)

Table 1. Synthesis Recipes and Nitrogen Content of PP-gDC

were chosen because of thermal stability, excellent reusability, and large scale-production.40,41 Specifically, glycidyl methacrylate (GMA) was first grafted onto the PP nonwoven fabric through radiation-induced graft polymerization, and then reacted with dicyandiamide (DC) followed by amidoximation to give the functionalized sorbent (PP-g-AO). Particularly, the guanidine group can be protonated to generate positive charge, which may exist in three equivalent resonance forms (Scheme 2). The main speciation of uranium in seawater is [UO2(CO3)3]4−,42 and the amidoxime group can selectively coordinate with uranium via ligand exchange, while the positive guanidine groups accelerate the adsorption through improvement of adsorption rate and selectivity.11,43 On the other hand,

sample PP-gDC1 PP-gDC2 PP-gDC3 PP-gDC4 a

B

PP-gPGMA (g)

DC (g)

molar ratio

DMF (mL)

nitrogen content (wt%)a

6.0

2.66

1:1

300

10.12

6.0

5.32

1:2

300

11.50

6.0

10.64

1:4

300

15.08

6.0

15.96

1:6

300

15.10

Determined by energy dispersive X-ray spectroscopy (EDX). DOI: 10.1021/acs.iecr.7b04687 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

Article

Industrial & Engineering Chemistry Research

resolution inductively coupled plasma mass spectrometer (ICPMS) to ensure that all the uranium was removed. 2.5. Antibacterial Assay. The antibacterial test was conducted following a reported protocol.48 Bacterial attachment was assessed by Gram-negative E. coli on the modified PP fabric surface. First, E. coli cells were inoculated on an agar plate at 37 °C for 24 h. Then a single bacterial colony from the agar plate was utilized to inoculate 50 mL of Luria−Bertani liquid medium, and grew to the exponential growth phase at 37 °C for 24 h. The supernatant of a bacteria growth broth was removed by centrifuging at 3000 rpm for 10 min. The desired concentration was achieved by diluting the bacterial cells with a phosphate-buffered saline (PBS, pH 7.4). The bare PP and PP-g-AO3 fabrics were placed into the 24-well plates comprising 600 μL of bacterial suspension (∼ 1 × 106 cell) and reserved at 37 °C for 2 and 24 h, respectively. The PBS solution was then used to wash these fabrics three times, and then the fabrics were immobilized with paraformaldehyde (4 vol%) for 0.5 h. Finally, a suite of ethanol−water mixtures (10, 30, 50, 70, 100 vol% ethanol) was used to dehydrate these samples for 0.5 h every time, and then desiccated under reduced pressure at 40 °C to constant weight. The adhered bacterial cells were investigated through field-emitting scanning electron microscopy (FE-SEM). The spread plate method was employed to assess the capability of the materials to kill adhering bacteria. First, the bare PP and PP-g-AO3 fabrics were placed into the 24-well plates comprising 600 μL of bacterial suspension (∼ 1 × 106 cell) and reserved at 37 °C for 4 h. These fabrics were then washed with the PBS solution to get rid of the nonadherent bacteria three times. The fabrics were mixed with 2 mL PBS and ultrasonicated for 3 min to liberate the bacterial cells into the PBS. Then the bacterial suspension was diluted 100 times and spread on an agar plate. Finally, a colony count was used to determine the number of viable bacterial cells after culturing for 20 h. 2.6. Real Seawater Experiments. The experiments using real seawater (Bohai Sea, China) were conducted to test the adsorption and antifouling properties of PP-g-AO3. The adsorption study was conducted with an additional uranium(VI) of 1.26 × 10−7 mol/L using real seawater as background solution at 290.15K and 298.15K, respectively. The sorbent (125 mg) and real seawater (500 mL) were added into plastic bottles and shaken for 16 days until the equilibrium of sorption. The sorption efficiency (SE) was gained by analyzing the initial and final uranium concentration in seawater through ICP-MS. For the antifouling study, the PBS solution was then used to wash these fabrics three times, and then the fabrics were immobilized with paraformaldehyde (4 vol%) for 0.5 h. Finally, a suite of ethanol−water mixtures (10, 30, 50, 70, 100 vol% ethanol) was used to dehydrate these samples for 0.5 h every time, and then the samples were desiccated under reduced pressure at 40 °C to a constant weight. The adhered microorganisms were investigated through FE-SEM.

PP-g-DC further reacted with hydroxylamine hydrochloride to convert grafted nitrile into amidoxime (AO) group.45 Typically, hydroxylamine hydrochloride (NH2OH·HCl, 1.2 g, 17.2 mmol) was dissolved in 40 mL of methanol/water (v/v %, 50/50; pH ∼ 8.0), and then PP-g-DC (1.0 g) was added into the mixture. After refluxing for 10 h, the amidoximated fabric was washed with 100 mL of ultrapure water and 100 mL of methanol three times, and then desiccated in a vacuum oven at 40 °C to obtain PP-g-AO. The functionalized fabrics related to PP-g-DC1, 2, and 3 were named as PP-g-AO1, 2, and 3, respectively. 2.3. Sorption Experiments. Alkaline treatment can increase the uranium sorption capacity because of two primary reasons:46 (i) increased hydrophilicity and (ii) conversion of open chain amidoxime to cyclic imidedioxime. Therefore, PP-gAO was first conditioned with 0.44 mol/L KOH for 1 h at room temperature prior to exposing them in a uranium solution. The samples were characterized by Fourier transform infrared spectroscopy (FT-IR), which indicated the ester groups in PP-g-AO could remain stable after the treatment (Figure S1). Sorption experiments were performed in wide-mouth plastic bottles. The sorbent (25 mg) and uranyl ion solution (2 × 10−5 mol/L, 100 mL) were added in plastic bottles and shaken for 15 h until the equilibrium of sorption. A nitric acid solution (2 mol/L) and sodium carbonate solution (2 mol/L) were used to adjust the pH of the solution to be 8.0 before sorption to ensure that [UO2(CO3)3]4− is the dominant species of uranium.47 The equilibrium sorption capacity (qe, mg/g) and sorption efficiency (SE) were measured according to eqs 1 and 2, respectively:

qe = (C0 − Ce) SE(%) =

V M

C0 − Ce × 100 C0

(1)

(2)

where C0 and Ce (mg/L) are the initial and final uranium concentrations, respectively. M (g) represents the desiccative sorbent weight, and V (L) is the volume of aqueous solution. The effect of contact time was investigated using uranyl solution (2 × 10−5 mol/L) at pH 8.0 and 298.15 K. The isotherm was carried out with different initial concentrations of uranium (10−100 ppm). Study for coexisting ions was based on binary system. The speciations of the tested metals were simulated by Medusa program as VO2(OH)2−, Co2+, Ni(CO3)22+, ZnOH+, Mg2+, Ca2+, and Fe3+, respectively. The effect of salt on uranium sorption was carried out with NaCl at 10−10000 times concentration of uranium. A simulated seawater test was conducted with 4.2 × 10−6 mol/L of uranium combined with 0.438 mol/L of NaCl and 2.297 mmol/L of NaHCO3. 2.4. Desorption and Regeneration Experiments. To evaluate the recyclability of PP-g-AO, uranium sorption and desorption were studied five times. In each loop, PP-g-AO3 (25 mg) and uranyl solution (2 × 10−5 mol/L, 100 mL) were shaken together. After saturated sorption, the PP-g-AOuranium complex was eluted by ethylenediaminetetraacetic acid disodium salt (EDTA) solution (0.1 mol/L) until the complete removal of uranium, and then rinsed with ultrapure water (200 mL) for reusing. The uranium concentration in the EDTA solution after elution was checked by thermo high

3. RESULTS AND DISCUSSION 3.1. Characterization of PP-g-AO. In order to prepare PP-g-AO, PGMA was first grafted onto polypropylene nonwoven fabric through radiation-induced graft polymerization. PP-g-PGMA with a graft degree of 257% was chosen for the modification with DC, and then amidoximated by NH2OH· HCl to yield the functionalized fabric PP-g-AO. The morphology of the resultant fabrics was characterized by FEC


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This point was further confirmed by the states of chemical bonds. Figure 2B represents the X-ray photoelectron spectroscopy (XPS) survey which shows elements present in PP nonwoven, PP-g-PGMA, PP-g-DC3, and PP-g-AO3, respectively. Compared with the bare nonwoven fabric (Figure 2B, trace a), PP-g-PGMA showed the new peak for O 1s which indicated the successful grafting of PGMA on the surface of nonwoven fabric (Figure 2B, trace b). It was observed that N 1s peak appeared on the XPS survey scan for PP-g-DC (Figure 2B, trace c) and PP-g-AO (Figure 2B, trace d), indicating the successful reaction between PP-g-PGMA, DC, and NH2OH· HCl. For PP-g-AO, XPS spectrum of C 1s could be curve-fitted with four peak components attributed to C−C, C−N, CN, and C−O species (Figure 2C), while N 1s to N−O, N−H, C N, and C−N species (Figure 2D), which further illustrated the sorbent PP-g-AO was successfully prepared. Water contact angles were performed to observe the hydrophilic behaviors of the fabrics, and the results are shown in Figure 3. Owing to the inherent hydrophobic

SEM. PP fabrics were not damaged during the reaction process (Figure 1). The average diameter of fabrics increased markedly

Figure 1. FE-SEM images of (A) PP nonwoven, (B) PP-g-PGMA, (C) PP-g-DC3, and (D) PP-g-AO3, respectively. Scale bar: 50.0 μm.

after modification (Figure 1B, C, and D) in comparison with the bare nonwoven fabric (Figure 1A), which was related to the increasing graft degree onto the fabric. FT-IR was employed to characterize the chemical structures of the resultant fabrics (Figure 2A). In comparison with the

Figure 3. Water contact angles of the samples: (a) PP nonwoven, (b) PP-g-PGMA, (c) PP-g-DC3, and (d) PP-g-AO3, respectively.

property, the bare PP nonwoven surface exhibited an initial water contact angle value of 126° (Figure 3A). After PGMA was introduced onto the PP nonwoven, a slight reduction of contact angle value was achieved (110°, Figure 3B). After PP-gPGMA was reacted with the DC and amidoximated reaction, the contact angle dropped to about 0° (Figure 3C and D), suggesting the excellent wettability and superhydrophilicity of the modified fabric, which may be beneficial for the sorption. 3.2. Sorption Kinetics and Isotherms. In this study, sorption kinetics of PP-g-AO was first conducted with the optimum adsorbent dose of 0.25 g/L (Figure S2) at pH 8.0 and 298.15 K. The relationship between sorption amount (qt) and contact time (t) is depicted in Figure 4A. We found the larger the graft degree, the shorter the equilibrium time and larger the sorption capacity for PP-g-AO. The fastest sorption equilibrium could be reached within 5 h. Pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models were utilized to simulate the sorption kinetics (Figures S3 and S4) and the related parameters are listed in Tables 2 and S2. It is found that the pseudo-secondorder model can be more appropriately used to describe kinetic

Figure 2. (A) FT-IR spectra of (a) PP nonwoven, (b) PP-g-PGMA, (c) PP-g-DC3, and (d) PP-g-AO3, respectively. (B) XPS spectra of (a) PP nonwoven, (b) PP-g-PGMA, (c) PP-g-DC3, and (d) PP-g-AO3, and XPS spectra of (C) C 1s and (D) N 1s of PP-g-AO3, respectively.

bare nonwoven fabric (Figure 2A, trace a), the stretching vibrations of C−O (ring, 903 cm−1) and CO (1724 cm−1) (Figure 2A, trace b) suggested the successful graft of PGMA onto the nonwoven fabric.49 For PP-g-DC, the stretching vibrations of CN, CN, C−N, and −NH2 occurred at 2174, 1657, 1148, and 3395 cm−1, respectively39 (Figure 2A, trace c). The stretching vibrations of C−O−C (1255 cm−1) and CO (1724 cm−1) (Figure 2A, trace c and d) suggested ester groups in PP-g-AO3 could remain stable during the reaction process. The characteristic bands of the amidoximated fabric appeared at 971 cm−1 corresponding to N−O10 and the disappearance of CN stretching vibrations demonstrated the successful synthesis of PP-g-AO (Figure 2A, trace d). D


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Table 3. Comparison of Rate Constant from Pseudo-second Order Model and qmax from Langmuir Model between the Guanidine and Amidoxime Cofunctionalized Polypropylene Nonwoven Fabric and Other Fibrous Sorbents

Figure 4. (A) Effects of contact time on the uranium sorption by (a) PP-g-AO1, (b) PP-g-AO2, and (c) PP-g-AO3, respectively. (Experimental condition: 0.25 g/L sorbent dose, 100 mL solution, 2 × 10−5 mol/L uranium, pH 8.0, and 298.15 K.) (B) Sorption isotherm plots for uranium sorption by (a) PP-g-AO1, (b) PP-g-AO2, and (c) PP-gAO3, respectively. (Experimental condition: 0.25 g/L sorbent dose, 100 mL solution, pH 8.0, and 298.15 K.)

profiles because of the more accurate calculated qe and the relatively larger correlation coefficients (R2), implying that chemical adsorption was the rate-limiting step.10 The k2 for PPg-AO3 was larger than those for PP-g-AO1 and PP-g-AO2, implying the more rapid sorption. The results may be attributed to enhanced electrostatic attraction due to the larger guanidine content, which may be related to the more positive charge. Furthermore, there is an obviously larger rate constant k2 for the modified fabrics compared with the other fibrous sorbents (Table 3), which may be ascribed to the enhanced electrostatic attraction and superhydrophilic surface of the nonwoven fabric. To understand the sorbent capacity, sorption isotherm studies were performed with the uranium concentrations from 1.88 × 10−5 to 3.27 × 10−4 mol/L at pH 8.0 and 298.15 K. The relationship between qe and Ce is shown in Figure 4B. The sorption profiles were simulated with Langmuir, Freundlich, and Temkin models (Figures S5 and S6). The related parameters are listed in Table 4. It is found that the Langmuir model can be more appropriately used to describe the sorption process due to the relatively larger correlation coefficients (R2). The result might be attributed to active sites homogeneously distributed on the fabrics surface, which lead to monolayer sorption. Furthermore, the sorption capacity was increased with the graft degree, and qmax of 112 mg/g could be obtained for the modified fabric. Furthermore, there is a considerable sorption capacity qmax for the modified fabrics compared with the other fibrous sorbents (Table 3). 3.3. Effect of Coexisting Ions on Uranium Adsorption. The influence of coexisting ions on uranium adsorption was conducted to assess the selectivity of sorbents, such as V(V), Co(II), Fe(III), Cu(II), Ni(II), Zn(II), Ca(II), and Mg(II), which represent the common ions in seawater.54 As shown in Figure 5A, the sorption efficiency decreased less than ∼10% in the presence of any other ions, which indicates that these ions did not significantly affect the sorption of uranium. Vanadium has almost no influence on the adsorption efficiency due to enough binding sites of the material. The small effect of coexisting ions on sorption might be caused by a salt effect

matrix

pH

rate constant (g/mg/h)

PP-g-PVIm+Br−AO nonwoven fabric surface ion-imprinted polypropylene nonwoven fabric salophen anchored micro/meso porous activated carbon fibres amidoxime functionalized wool fibers PA66-g-PGMA-IDPAO fiber guanidine-modified polyamidoxime-functionalized fabric

8.0

5.7 × 10−4

119.76

10

8.0

0.015

133.30

50

6.0

0.042

142.86

51

5.0

0.144

59.35

52

5.0 8.0

0.05 0.405

41.98 112.00

53 this work

qmax (mg/g)

reference

and/or a precomplexation of the other metal ions with ligands. In any case, the maintenance of the high sorption efficiency indicates that PP-g-AO is a robust sorbent. The effect of salt (NaCl) on the sorption of uranium was also investigated to explore the practicability of imprinted fabrics since there were plenty of Na+/Cl− coexisting in seawater. The experiments were carried out with different concentrations of NaCl in a uranyl solution. The results showed that the efficiency can be retained at 70% when the concentration of NaCl was up to 0.1 mol/L (Figure 5B). Meanwhile, the sorption in simulated seawater with 0.438 mol/L of NaCl and 2.297 mmol/L of NaHCO3 at pH 8.0 was conducted. The result indicated that the sorption amount for uranium was up to 1.84 mg/g after 4 days exposure (Figure 5C), which is fairly lower than the sorption capacity in pH 8 aqueous solution (Figure 4B). The results may be attributed to the low uranium concentration (4.2 × 10−6 mol/L) and high salinity in the simulated seawater. Considering the fast rate to reach sorption equilibrium, the functional nonwoven fabric may be a promising sorbent for uranium seawater extraction. 3.4. Desorption and Regeneration Studies. Regenerability is vital for an economical and effective adsorbent. Five sorption/desorption cycles were performed to assess the reusability of the sorbent with an EDTA solution as the desorbing agent. The sorption efficiency almost remained constant after five cycles (Figure 6A). Furthermore, a typical FE-SEM image indicated that there was no obvious damage to the fabrics (Figure 6B), which may be attributed to that ligands were covalently combined on the fabric surface. Meanwhile, we took FE-SEM images of the fabric after extraction in simulated seawater, and the result showed that the morphology of fabric did not change in comparison with the original ones (Figure S7). Besides, we took FE-SEM images of the fabric before and after the material being washed and cleaned from the bacterial

Table 2. Kinetic Parameters for Uranium Sorption by PP-g-AO1, PP-g-AO2, and PP-g-AO3a pseudo-first order

a

−1

pseudo-second order 2

fabrics

qe,exp (mg/g)

k1 (h )

qe,cal (mg/g)

R

k2 (g/mg/h)

qe,cal (mg/g)

R2

PP-g-AO1 PP-g-AO2 PP-g-AO3

12.9 14.2 17.9

0.273 0.349 0.466

5.65 2.34 1.63

0.889 0.631 0.706

0.142 0.311 0.405

13.1 14.3 17.9

0.999 0.999 0.999

Experimental condition: 0.25 g/L sorbent dose, 100 mL solution, 2 × 10−5 mol/L uranium, pH 8.0, and 298.15 K. E


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Table 4. Parameters of Langmuir, Freundlich, and Temkin Models for Uranium Sorption by PP-g-AO1, PP-g-AO2, and PP-gAO3, Respectivelya Langmuir

a

Freundlich

Temkin

sorbent

qmax (mg/g)

b (L/mg)

R2

KF (mol1−nLn/g)

n

R2

At (L/g)

bT (kJ/mol)

R2

PP-g-AO1 PP-g-AO2 PP-g-AO3

47.8 92.2 112

0.0671 0.148 0.186

0.991 0.992 0.994

7.42 15.7 29.7

2.45 2.22 3.02

0.974 0.949 0.979

0.65 1.15 2.85

10.51 20.88 20.79

0.971 0.920 0.973

Experimental condition: 0.25 g/L sorbent dose, 100 mL solution, pH 8.0, and 298.15 K.

Figure 5. (A) Effects of coexisting ions on the sorption of uranium by PP-g-AO3. (Experimental condition: 0.25 g/L sorbent dose, 100 mL solution, 2 × 10−5 mol/L uranyl and other ions, contact time = 5 h, pH 8.0, and 298.15 K.) (B) The effect of Na+/Cl− with different concentrations on the uranium sorption. (Experimental condition: 0.25 g/L sorbent dose, 100 mL solution, 10−5 mol/L uranium, pH 8.0, and 298.15 K.) (C) Uranium sorption by PP-g-AO3 in simulated seawater. (Experimental conditions: 0.25 g/L sorbent dose, 100 mL solution, 4.2 × 10−6 mol/L uranium, 0.438 mol/L NaCl, 2.297 mmol/L NaHCO3, pH 8.0, and 298.15 K.)

Figure 6. (A) Recycling of PP-g-AO3 for uranium sorption after five cycles, and (B) FE-SEM images of the PP-g-AO regenerated after five cycles. Scale bar: 50.0 μm. (Experimental condition: 0.25 g/L sorbent dose, 100 mL solution, 2 × 10−5 mol/L uranium, pH 8.0, and 298.15 K.)

matter. These fabric’s thickness did not change in comparison with the original ones (Figure S8). The results demonstrated the materials possessed a good regenerability for sorption. 3.5. Antibacterial Assay. Gram-negative E. coli was utilized to evaluate the bacterial attachment on the fabrics. The quantity and survivability of bacteria adhered on the fabrics could reflect the antibacterial effect after 2 and 24 h incubation. The quantity of adhered bacteria after incubation for 2 and 24 h was shown in Figure 7. Bacteria tended to adhere on the hydrophobic surface via hydrophobic interaction, so a great deal of bacteria appeared on the bare PP fabric (Figure 7A and C). In contrast, there was much less bacteria on the PP-g-AO surface (Figure 7B and D), and the quantitative value for bacterial reduction on the PP-g-AO compared to that of bare PP fabric is approximately 1.2 × 106 CPU/mL, which may be attributed that the bactericidal function of guanidine and the superhydrophilic property can prevent bacterial adhesion. The ability of fabrics to kill bacteria on contact was further assessed through the spread plate method. Plenty of bacteria recovered from the bare PP fabric grew into colonies on agar plates (Figure 7E) because of the nonbactericidal surface. A remarkable reduction in bacterial colonies appeared with respect to PP-g-AO (Figure 7F) on account of a potent bactericidal effect of the guanidine group.

Figure 7. FE-SEM images of E. coli on the (A) PP and (B) PP-g-AO3 for 2 h, and (C) PP and (D) PP-g-AO3 for 24 h, respectively (scale bar: 20.0 μm). Photographs of agar plates corresponding to the E. coli suspension recovered from (E) the bare PP and (F) PP-g-AO3 after 20 h culture.

3.6. Sorption and Antibacterial Assay in Real Seawater. One of the big challenges of uranium recovery from seawater is the fairly low concentration of uranium, leading to a quite slow adsorption process. Besides, relatively low hydrophilicity of current materials aggravates the slow sorption process. Hu et al.18 prepared an amidoximated ultrahigh F


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Figure 8. (A) Uranium adsorption by PP-g-AO3 in real seawater at (a) 298.15 K and (b) 290.15 K, respectively. (Experimental conditions: 0.25 g/L sorbent dose, 500 mL solution, 1.26 × 10−7 mol/L uranium, 290.15 K and 298.15 K.) FE-SEM images of microorganisms on (B) PP fabric and (C) PP-g-AO3 for 15 days after antifouling experiments in real seawater (scale bar: 100.0 μm).

molecular weight polyethylene fiber, which took 13 months to complete the uranium adsorption in simulated seawater. Brown et al.51 manufactured poly(vinyl chloride)-co-chlorinated poly(vinyl chloride) fiber and tested its adsorption performance in seawater, and the fiber possessed a high adsorption capacity of 5.22 mg/g after 49 days of exposure. In this study, the adsorption study was conducted with an additional uranium of 1.26 × 10−7 mol/L using real seawater as background solution at 290.15 K and 298.15 K, respectively. The result indicated that the adsorption capacity for uranium was 0.10 mg/g with 85.8% of adsorption efficiency after 10 days of exposure (Figure 8A), and the higher the temperature, the faster the adsorption. Considering the fast rate to reach sorption equilibrium, the functional nonwoven fabric may act as a promising sorbent for uranium seawater extraction. Antibacterial experiments in real seawater were carried out to further investigate the antibacterial property of the sorbents. Bacteria tended to adhere on the hydrophobic surface via hydrophobic interaction, so some microorganisms were observed on the bare PP fabric (Figure 8B). In contrast, much less microorganisms were observed on the PP-g-AO surface (Figure 8C), which may be attributed to antibiofouling function of guanidine and the superhydrophilic property of PPg-AO.

nonwoven fabrics are employed to achieve an easy and convenient adsorption of uranium from seawater. This study may unfold a new approach for efficient uranium enrichment from seawater.

4. CONCLUSION In summary, we demonstrate a strategy for potential uranium seawater extraction with antifouling property by guanidine and amidoxime cofunctionalized polypropylene nonwoven fabric. Specifically, the functionalized fabric was prepared by the subsequent reactions of GMA graft polymerization, open-ring of epoxy group, and amidoximation. The characterization of FE-SEM, FT-IR, XPS, and water contact angles indicated the sorbent was successfully prepared. The pseudo-second-order model was more appropriate to simulate the sorption process. The sorption equilibrium of PP-g-AO could be reached with 112 mg/g capacity within 5 h at pH 8.0 and 298.15 K. The uranium sorption of PP-g-AO was not affected by the other coexisting ions and exhibited remarkable salt-resistant stability. In addition, the PP-g-AO could be regenerated effectively after five cycles. More importantly, the introduction of the guanidine group endowed the surface with superhydrophilic and antibacterial capability, which also means an antifouling property of PP-g-AO during the adsorption process. The results indicated that PP-g-AO may be a promising sorbent for uranium seawater sorption. To our best knowledge, this is the first report on a functionalized sorbent with an antifouling property for uranium extraction. Both selectivity and antibiofouling performance are improved via inclusion of guanidine groups, which can accelerate sorption for uranium. Besides, polypropylene

Author Contributions

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.iecr.7b04687. Characterization methods, synthesis of PP-g-PGMA, sorption kinetics and isotherms, the influences of radiation dose on graft degree, FT-IR spectra of PP-gAO3 before and after treated with 0.44 mol/L KOH, FESEM images after extraction and antibacterial experiments, and the effects of sorbent dose on uranium sorption (PDF)

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]; Tel and Fax: (+) 86−512−65883261 ORCID

Daoben Hua: 0000-0003-1813-6988 ⊥

H.Z. and L.Z. contributed equally to this work.

Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work is supported by Natural Science Foundation of China (U1532111, 91326202), a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), and Jiangsu Key Laboratory of Radiation Medicine and Protection.

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ABBREVIATIONS PP = polypropylene DC = dicyandiamide AO = amidoxime DMF = N,N′-dimethylformamide GMA = glycidyl methacrylate EDTA = ethylenediaminetetraacetic acid disodium salt PBS = phosphate buffered saline FE-SEM = field-emitting scanning electron microscopy EDX = energy-dispersive X-ray FT-IR = Fourier transform infrared ICP-MS = thermo high resolution inductively coupled plasma mass spectrometer XPS = X-ray photoelectron spectroscopy DOI: 10.1021/acs.iecr.7b04687 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

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(18) Hu, J.; Ma, H.; Xing, Z.; Liu, X.; Xu, L.; Li, R.; Lin, C.; Wang, M.; Li, J.; Wu, G. Preparation of Amidoximated Ultrahigh Molecular Weight Polyethylene Fiber by Radiation Grafting and Uranium Adsorption Test. Ind. Eng. Chem. Res. 2016, 55 (15), 4118−4124. (19) Gill, G. A.; Kuo, L. J.; Janke, C. J.; Park, J.; Jeters, R. T.; Bonheyo, G. T.; Pan, H.-B.; Wai, C.; Khangaonkar, T.; Bianucci, L.; Wood, J. R.; Warner, M. G.; Peterson, S.; Abrecht, D. G.; Mayes, R. T.; Tsouris, C.; Oyola, Y.; Strivens, J. E.; Schlafer, N. J.; Addleman, R. S.; Chouyyok, W.; Das, S.; Kim, J.; Buesseler, K.; Breier, C.; D’Alessandro, E. The Uranium from Seawater Program at the Pacific Northwest National Laboratory: Overview of Marine Testing, Adsorbent Characterization, Adsorbent Durability, Adsorbent Toxicity, and Deployment Studies. Ind. Eng. Chem. Res. 2016, 55 (15), 4264−4277. (20) Abarzua, S.; Jakubowski, S.; Eckert, S.; Fuchs, P. Biotechnological Investigation for the Prevention of Marine Biofouling II. BlueGreen Algae as Potential Producers of Biogenic Agents for the Growth Inhibition of Microfouling Organisms. Bot. Mar. 1999, 42 (5), 459− 465. (21) Lejars, M.; Margaillan, A.; Bressy, C. Fouling Release Coatings: A Nontoxic Alternative to Biocidal Antifouling Coatings. Chem. Rev. 2012, 112 (8), 4347−4390. (22) Callow, M. E.; Fletcher, R. L. The Influence of Low SurfaceEnergy Materials on Bioadhesion-A Review. Int. Biodeterior. Biodegrad. 1994, 34 (3−4), 333−348. (23) Park, J.; Gill, G. A.; Strivens, J. E.; Kuo, L.-J.; Jeters, R. T.; Avila, A.; Wood, J. R.; Schlafer, N. J.; Janke, C. J.; Miller, E. A.; Thomas, M.; Addleman, R. S.; Bonheyo, G. T. Effect of Biofouling on the Performance of Amidoxime-Based Polymeric Uranium Adsorbents. Ind. Eng. Chem. Res. 2016, 55 (15), 4328−4338. (24) Diaz Blanco, C.; Ortner, A.; Dimitrov, R.; Navarro, A.; Mendoza, E.; Tzanov, T. Building an Antifouling Zwitterionic Coating on Urinary Catheters Using an Enzymatically Triggered Bottom-Up Approach. ACS Appl. Mater. Interfaces 2014, 6 (14), 11385−93. (25) Hawkins, M. L.; Fay, F.; Rehel, K.; Linossier, I.; Grunlan, M. A. Bacteria and Diatom Resistance of Silicones Modified with PEO-Silane Amphiphiles. Biofouling 2014, 30 (2), 247−258. (26) Pidhatika, B.; Moller, J.; Benetti, E. M.; Konradi, R.; Rakhmatullina, E.; Muhlebach, A.; Zimmermann, R.; Werner, C.; Vogel, V.; Textor, M. The Role of the Interplay Between Polymer Architecture and Bacterial Surface Properties on the Microbial Adhesion to Polyoxazoline-Based Ultrathin Films. Biomaterials 2010, 31 (36), 9462−9472. (27) Li, M.; Neoh, K.-G.; Kang, E.-T.; Lau, T.; Chiong, E. Surface Modification of Silicone with Covalently Immobilized and Crosslinked Agarose for Potential Application in the Inhibition of Infection and Omental Wrapping. Adv. Funct. Mater. 2014, 24 (11), 1631−1643. (28) Liu, S. Q.; Yang, C.; Huang, Y.; Ding, X.; Li, Y.; Fan, W. M.; Hedrick, J. L.; Yang, Y. Y. Antimicrobial and Antifouling Hydrogels Formed In Situ from Polycarbonate and Poly(ethylene glycol) via Michael Addition. Adv. Mater. 2012, 24 (48), 6484−6489. (29) Krumm, C.; Harmuth, S.; Hijazi, M.; Neugebauer, B.; Kampmann, A. L.; Geltenpoth, H.; Sickmann, A.; Tiller, J. C. Antimicrobial Poly(2-methyloxazoline) s with Bioswitchable Activity through Satellite Group Modification. Angew. Chem., Int. Ed. 2014, 53 (15), 3830−3834. (30) Aumsuwan, N.; Danyus, R. C.; Heinhorst, S.; Urban, M. W. Attachment of Ampicillin to Expanded Poly(Tetrafluoroethylene): Surface Reactions Leading to Inhibition of Microbial Growth. Biomacromolecules 2008, 9 (7), 1712−1718. (31) Zasloff, M. Antimicrobial Peptides of Multicellular Organisms. Nature 2002, 415 (6870), 389−395. (32) Francesko, A.; Blandon, L.; Vazquez, M.; Petkova, P.; Morato, J.; Pfeifer, A.; Heinze, T.; Mendoza, E.; Tzanov, T. Enzymatic Functionalization of Cork Surface with Antimicrobial Hybrid Biopolymer/Silver Nanoparticles. ACS Appl. Mater. Interfaces 2015, 7 (18), 9792−9799. (33) Komarova, B. S.; Osterman, I. A.; Pletnev, P. I.; Ivanenkov, Y. A.; Majouga, A. G.; Bogdanov, A. A.; Sergiev, P. V. 2-Guanidino-

REFERENCES

(1) Davies, R. V.; Kennedy, J.; Hill, K. M.; McIlroy, R. W.; Spence, R. Extraction of Uranium from Seawater. Nature 1964, 203 (495), 1110. (2) Kim, J.; Tsouris, C.; Mayes, R. T.; Oyola, Y.; Saito, T.; Janke, C. J.; Dai, S.; Schneider, E.; Sachde, D. Recovery of Uranium from Seawater: A Review of Current Status and Future Research Needs. Sep. Sci. Technol. 2013, 48 (3), 367−387. (3) Singhal, P.; Jha, S. K.; Vats, B. G.; Ghosh, H. N. ElectronTransfer-Mediated Uranium Detection Using Quasi-Type II CoreShell Quantum Dots: Insight into Mechanistic Pathways. Langmuir 2017, 33 (33), 8114−8122. (4) Ma, S.; Huang, L.; Ma, L.; Shim, Y.; Islam, S. M.; Wang, P.; Zhao, L.-D.; Wang, S.; Sun, G.; Yang, X.; Kanatzidis, M. G. Efficient Uranium Capture by Polysulfide/Layered Double Hydroxide Composites. J. Am. Chem. Soc. 2015, 137 (10), 3670−3677. (5) Das, S.; Pandey, A. K.; Athawale, A. A.; Natarajan, V.; Manchanda, V. K. Uranium Preconcentration from Seawater Using Phosphate Functionalized Poly(propylene) Fibrous Membrane. Desalin. Water Treat. 2012, 38 (1−3), 114−120. (6) Ren, X.; Yang, S.; Tan, X.; Chen, C.; Sheng, G.; Wang, X. Mutual Effects of Copper and Phosphate on Their Interaction With GammaAl2O3: Combined Batch Macroscopic Experiments with DFT Calculations. J. Hazard. Mater. 2012, 237, 199−208. (7) Caballero, M.; Cela, R.; Perezbustamante, J. A. Analytical Applications of Some Flotation Techniques-A Review. Talanta 1990, 37 (3), 275−300. (8) Camp, C.; Antunes, M. A.; Garcia, G.; Ciofini, I.; Santos, I. C.; Pecaut, J.; Almeida, M.; Marcalo, J.; Mazzanti, M. Two-electron Versus One-Electron Reduction of Chalcogens by Uranium(III): Synthesis of a Terminal U(V) Persulfide Complex. Chem. Sci. 2014, 5 (2), 841− 846. (9) Qian, J.; Zhang, S.; Zhou, Y.; Dong, P.; Hua, D. Synthesis of Surface Ion-Imprinted Magnetic Microspheres by Locating Polymerization for Rapid and Selective Separation of Uranium(VI). RSC Adv. 2015, 5 (6), 4153−4161. (10) Zeng, Z.; Wei, Y.; Shen, L.; Hua, D. Cationically Charged Poly(amidoxime)-Grafted Polypropylene Nonwoven Fabric for Potential Uranium Extraction from Seawater. Ind. Eng. Chem. Res. 2015, 54 (35), 8699−8705. (11) Singhal, P.; Jha, S. K.; Pandey, S. P.; Neogy, S. Rapid extraction of uranium from sea water using Fe3O4 and humic acid coated Fe3O4 nanoparticles. J. Hazard. Mater. 2017, 335, 152−161. (12) Leggett, C. J.; Rao, L. Complexation of Calcium and Magnesium with Glutarimidedioxime: Implications for the Extraction of Uranium from Seawater. Polyhedron 2015, 95, 54−59. (13) Das, S.; Brown, S.; Mayes, R. T.; Janke, C. J.; Tsouris, C.; Kuo, L. J.; Gill, G.; Dai, S. Novel Poly(imide dioxime) Sorbents: Development and Testing for Enhanced Extraction of Uranium from Natural Seawater. Chem. Eng. J. 2016, 298, 125−135. (14) Gao, Q.; Hu, J.; Li, R.; Xing, Z.; Xu, L.; Wang, M.; Guo, X.; Wu, G. Radiation Synthesis of a New Amidoximated UHMWPE Fibrous Adsorbent with High Adsorption Selectivity for Uranium over Vanadium in Simulated Seawater. Radiat. Phys. Chem. 2016, 122, 1−8. (15) Ling, C.; Liu, X.; Yang, X.; Hu, J.; Li, R.; Pang, L.; Ma, H.; Li, J.; Wu, G.; Lu, S.; Wang, D. Uranium Adsorption Tests of AmidoximeBased Ultrahigh Molecular Weight Polyethylene Fibers in Simulated Seawater and Natural Coastal Marine Seawater from Different Locations. Ind. Eng. Chem. Res. 2017, 56 (4), 1103−1111. (16) Liu, X.; Liu, H.; Ma, H.; Cao, C.; Yu, M.; Wang, Z.; Deng, B.; Wang, M.; Li, J. Adsorption of the Uranyl Ions on an AmidoximeBased Polyethylene Nonwoven Fabric Prepared by PreirradiationInduced Emulsion Graft Polymerization. Ind. Eng. Chem. Res. 2012, 51 (46), 15089−15095. (17) Brown, S.; Yue, Y.; Kuo, L.-J.; Mehio, N.; Li, M.; Gill, G.; Tsouris, C.; Mayes, R. T.; Saito, T.; Dai, S. Uranium Adsorbent Fibers Prepared by Atom-Transfer Radical Polymerization (ATRP) from Poly(vinyl chloride)-co-Chlorinated Poly(vinyl chloride) (PVC-coCPVC). Ind. Eng. Chem. Res. 2016, 55 (15), 4139−4148. H


Article

Industrial & Engineering Chemistry Research Quinazolines as a Novel Class of Translation Inhibitors. Biochimie 2017, 133, 45−55. (34) Nizalapur, S.; Kimyon, O.; Yee, E.; Ho, K.; Berry, T.; Manefield, M.; Cranfield, C. G.; Willcox, M.; Black, D. S.; Kumar, N. Amphipathic Guanidine-Embedded Glyoxamide-Based Peptidomimetics as Novel Antibacterial Agents and Biofilm Disruptors. Org. Biomol. Chem. 2017, 15 (9), 2033−2051. (35) Nikkola, J.; Liu, X.; Li, Y.; Raulio, M.; Alakomi, H. L.; Wei, J.; Tang, C. Y. Surface modification of thin film composite RO membrane for enhanced anti-biofouling performance. J. Membr. Sci. 2013, 444, 192−200. (36) Gobbi, A.; Frenking, G. Y-Conjugated Compounds the Equilibrium Geometries and Electronic-Structures of Guanidine, Guanidine Cation, Urea, and 1,1-Diaminoethylene. J. Am. Chem. Soc. 1993, 115 (6), 2362−2372. (37) Riordan, J. F. Arginyl Residues and Anion Binding-Sites in Proteins. Mol. Cell. Biochem. 1979, 26 (2), 71−92. (38) Echavarren, A.; Galan, A.; Lehn, J. M.; Demendoza, J. Chiral Recognition of Recognition of Aromatic Carboxylate Anions by an Optically-Active Abiotic Receptor Containing a Rigid Guanidinium Binding Subunit. J. Am. Chem. Soc. 1989, 111 (13), 4994−4995. (39) Xin, Z.; Du, S.; Zhao, C.; Chen, H.; Sun, M.; Yan, S.; Luan, S.; Yin, J. Antibacterial Performance of Polypropylene Nonwoven Fabric Wound Dressing Surfaces Containing Passive and Active Components. Appl. Surf. Sci. 2016, 365, 99−107. (40) Vandenbossche, M.; Jimenez, M.; Casetta, M.; Traisnel, M. Remediation of Heavy Metals by Biomolecules: A Review. Crit. Rev. Environ. Sci. Technol. 2015, 45 (15), 1644−1704. (41) Guo, M.; Zhang, C.; Xu, J.; Luo, Z.; Wei, W. An Efficient, Simple and Facile Strategy to Synthesize Polypropylene-g-(acrylic acidco-acrylamide) Nonwovens by Suspension Grafting Polymerization and Melt-Blown Technique. Fibers Polym. 2016, 17 (8), 1123−1130. (42) Hirotsu, T.; Katoh, S.; Sugasaka, K.; Seno, M.; Itagaki, T. Adsorption Equilibrium of Uranium from Aqueous UO2(CO3) Solutions on a Polymer Bearing Amidoxime Groups. J. Chem. Soc., Dalton Trans. 1986, No. 9, 1983−1986. (43) Wei, Y.; Qian, J.; Huang, L.; Hua, D. Bifunctional Polymeric Microspheres for Efficient Uranium Sorption from Aqueous Solution: Synergistic Interaction of Positive Charge and Amidoxime Group. RSC Adv. 2015, 5 (79), 64286−64292. (44) Kavakli, P. A.; Seko, N.; Tamada, M.; Guven, G. RadiationInduced Graft Polymerization of Glycidyl Methacrylate onto Pe/Pp Nonwoven Fabric and Its Modification Toward Enhanced Amidoximation. J. Appl. Polym. Sci. 2007, 105 (3), 1551−1558. (45) Ting, C. F.; Jie, X.; Wei, H. J.; Mei, G.; Sheng, H.; Lin, W. X. Improvement in Uranium Adsorption Properties of Amidoxime-Based Adsorbent Through Cografting of Amine Group. J. Dispersion Sci. Technol. 2013, 34 (4), 604−610. (46) Das, S.; Tsouris, C.; Zhang, C.; Kim, J.; Brown, S.; Oyola, Y.; Janke, C. J.; Mayes, R. T.; Kuo, L. J.; Wood, J. R.; Gill, G. A.; Dai, S. Enhancing Uranium Uptake by Amidoxime Adsorbent in Seawater: An Investigation for Optimum Alkaline Conditioning Parameters. Ind. Eng. Chem. Res. 2016, 55 (15), 4294−4302. (47) Cao, Q.; Huang, F.; Zhuang, Z.; Lin, Z. A Study of the Potential Application of Nano-Mg(OH)2 in Adsorbing Low Concentrations of Uranyl Tricarbonate from Water. Nanoscale 2012, 4 (7), 2423−30. (48) Li, P.; Poon, Y. F.; Li, W.; Zhu, H.-Y.; Yeap, S. H.; Cao, Y.; Qi, X.; Zhou, C.; Lamrani, M.; Beuerman, R. W.; Kang, E.-T.; Mu, Y.; Li, C. M.; Chang, M. W.; Leong, S. S. J.; Chan-Park, M. B. A polycationic antimicrobial and biocompatible hydrogel with microbe membrane suctioning ability. Nat. Mater. 2011, 10 (2), 149−156. (49) Tian, B.; Wang, X.-Y.; Zhang, L.-N.; Shi, F.-N.; Zhang, Y.; Li, S.X. Preparation of PVDF Anionic Exchange Membrane by Chemical Grafting of GMA onto PVDF Macromolecule. Solid State Ionics 2016, 293, 56−63. (50) Zhang, L.; Yang, S.; Qian, J.; Hua, D. Surface ion-imprinted polypropylene nonwoven fabric for potential uranium seawater extraction with high selectivity over vanadium. Ind. Eng. Chem. Res. 2017, 56, 1860−1867.

(51) Mishra, S.; Dwivedi, J.; Kumar, A.; Sankararamakrishnan, N. Studies on salophen anchored micro/meso porous activated carbon fibres for the removal and recovery of uranium. RSC Adv. 2015, 5, 33023−33036. (52) Yin, Z.; Xiong, J.; Chen, M.; Hu, S.; Cheng, H. Recovery of uranium (VI) from aqueous solution by amidoxime functionalized wool fibers. J. Radioanal. Nucl. Chem. 2016, 307, 1471−1479. (53) Zhang, M.; Gao, Q.; Yang, C.; Pang, L.; Wang, H.; Li, H.; Li, R.; Xu, L.; Xing, Z.; Hu, J.; Wu, G. Preparation of amidoxime-based nylon66 fibers for removing uranium from low-concentration aqueous solutions and simulated nuclear industry effluents. Ind. Eng. Chem. Res. 2016, 55, 10523−10532. (54) Lu, Y. Uranium Extraction: Coordination Chemistry in the Ocean. Nat. Chem. 2014, 6 (3), 175−177.

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Guanidine and Amidoxime Cofunctionalized Polypropylene

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