Amino Siloxane Oligomer Modified Graphene Oxide Composite for the

Oct 3, 2017 - Amino Siloxane Oligomer Modified Graphene Oxide Composite for the ... Abstract Image ... The modification by NH2 increased the sorption ...
0 downloads 0 Views 5MB Size
Download PDF
Research Article Cite This: ACS Sustainable Chem. Eng. 2017, 5, 10290-10297

pubs.acs.org/journal/ascecg

Amino Siloxane Oligomer Modified Graphene Oxide Composite for the Efficient Capture of U(VI) and Eu(III) from Aqueous Solution Donglin Zhao,† Lili Chen,†,‡ Mingwenchan Xu,‡ Shaojie Feng,† Yi Ding,*,† M. Wakeel,§ Njud S. Alharbi,∥ and Changlun Chen*,‡,∥ †

Key Laboratory of Functional Molecule Design and Interface Process, Anhui Jianzhu University, Hefei 230601, P. R. China CAS Key Laboratory of Photovoltaic and Energy Conservation Materials, Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031, P. R. China § Department of Environmental Sciences, Bahauddin Zakariya University, Multan 60800, Pakistan ∥ Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia

Downloaded via UNIV OF TOLEDO on June 29, 2018 at 20:40:13 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.

‡

S Supporting Information *

ABSTRACT: Poly 3-aminopropyltriethoxysilane is a highly reactive high-molecular polymer because of the existence of abundant amino groups, which presents a strong affinity toward different metal cations. In view of this, the novel poly amino siloxane oligomer modified graphene oxide composite (PAS−GO) was fabricated by a facile cross-linking reaction and applied to capture U(VI)/Eu(III) ions from aqueous solution. The interaction mechanisms between the PAS−GO and U(VI)/Eu(III) were elaborated. The modification by NH2 increased the sorption sites and improved the sorption capacities because of the synergistic effect of chelation with U(VI)/ Eu(III). X-ray photoelectron spectroscopy revealed that nitrogen groups are involved in the removal of U(VI)/Eu(III) since nitrogen atoms of amine groups provided the lone pair of electrons with U(VI)/Eu(III) species. The maximum sorption capacity of U(VI) and Eu(III) on the PAS−GO at 298 K calculated by the Langmuir isotherm model was 310.63 and 243.90 mg/g, respectively. The PAS−GO could be repeatedly used for more than five cycles with slight degradation of sorption. High sorption efficiency and excellent reusability make the PAS−GO composite an ideal candidate for the capture of U(VI)/Eu(III) from aqueous solution. KEYWORDS: Graphene oxide, Sorption, U(VI), Eu(III)

■

tion.24−27 However, the number of functional groups on GO surfaces is not enough to effectively eliminate radioactive elements from wastewater. According to the previous reports,28−31 the nitrogen-containing functional groups can form stable chelation with metal ions. Poly 3-aminopropyltriethoxysilane (PAS) is a highly reactive high-molecular polymer because of the existence of abundant amino groups, which presents a strong affinity toward different metal cations.32,33 With this as motivation, PAS−GO was synthesized by a simple cross-linking reaction between GO and oligomeric poly 3aminopropyltriethoxysilane and applied to capture U(VI)/ Eu(III) from aqueous solution. The sorption performance of PAS−GO was studied as a function of pH, contact time, initial concentration, and temperature. The Langmuir and Freundlich models were evaluated on the basis of the sorption equilibrium data, and the pseudo-first-order and pseudo-second-order

INTRODUCTION With the development of the nuclear industry, a large amount of radioactive elements are widely used, which results in a series of environmental problems. 1−4 Therefore, it is of urgent importance to find effective methods for radionuclide treatment. Sorption is considered an effective and economical method to capture trace-level concentrations of radionuclides from aqueous solution as compared with other conventional sewage treatment methods.5−7 In addition, many types of sorbents like porous carbonaceous materials have been applied in removing organic and inorganic contaminants from wastewater because of their high surface areas and high sorption capacity.8−15 Graphene oxide (GO), obtained via the oxidation of graphite,16,17 has attracted widespread interest because of its utility as a promising replacement for other conventional sorbents in waste treatment.18−23 The oxygen-containing functional groups play crucially important roles in removing organic compounds and heavy metal ions from wastewater, since they can provide strong coordination with metal ions by cation exchange, surface complexation, and electrostatic interac© 2017 American Chemical Society

Received: July 10, 2017 Revised: September 12, 2017 Published: October 3, 2017 10290

DOI: 10.1021/acssuschemeng.7b02316 ACS Sustainable Chem. Eng. 2017, 5, 10290−10297

Research Article

ACS Sustainable Chemistry & Engineering Scheme 1. Schematic Illustration of the Synthesis Procedure of PAS−GO

kinetics models were described by kinetics sorption data. The sorption mechanisms of U(VI)/Eu(III) onto PAS−GO were also elaborated by X-ray photoelectron spectroscopy (XPS) analysis.

■

sorption (%) = (C0 − Ce)/C0 × 100%

(1)

qe = (C0 − Ce) × V /m

(2)

where C0 and Ce represent the initial and equilibrium concentrations of the U(VI)/Eu(III) in the solution (mg/L), respectively. V is the volume of solution (L), and m is the quality of the sorbent (g).

EXPERIMENTAL SECTION

■

Materials. Graphite powder, potassium permanganate (KMnO4), sodium acetate (NaAc), sulfuric acid (H2SO4, 98%), hydrogen peroxide (H2O2, 30%), and ethylene glycol (EG) were purchased. U(VI) stock solution at 120 mg/L was prepared by dissolving UO2(NO3)2·6H2O. Eu(III) stock solution at 60 mg/L was prepared by diluting Eu(NO3)3. All other reagents were of analytical reagent grade and used without further purification. Milli-Q water was used in all experiments. Preparation of PAS−GO. GO was prepared from natural graphite powder according to the improved Hummers method:34 A 2.0 g portion of graphite powder was added to 50 mL of 98% H2SO4 in an ice bath under continuous stirring. With maintained vigorous stirring, 6.0 g of KMnO4 was slowly added, and the temperature was kept below 15 °C. The mixture was persistently stirred at 35 °C for 24 h. Subsequently, a 10 mL portion of 30% H2O2 solution was added dropwise until the color of the mixture became bright yellow. The mixture was centrifuged and washed with 0.2 M HCl, followed by washing with Milli-Q water and ethyl alcohol. Finally, the as-received solid was then dried at 50 °C for 48 h under vacuum. The PAS−GO composite was synthesized as follows. First, 250 mg of GO was mixed with 100 mL of deionized water under ultrasonication for 24 h. Then, 2 mL of 3-aminopropyltriethoxysilane (AS) and 100 mL of Milli-Q water were added into another beaker with constant stirring to obtain PAS oligomer at 318 K for 5 h. Subsequently, the above mixture was transferred into GO solution under vigorous stirring until the tawny solution became brown flock. Finally, the suspension was separated and washed several times with Milli-Q water, and the as-received solid was dried by vacuum freeze-drying equipment for 24 h. The synthesis of PAS−GO is presented in Scheme 1. The detailed characterization is shown in the Supporting Information. Sorption Experiments. Batch sorption experiments were carried out to study the sorption performances of U(VI)/Eu(III) on the PAS− GO. The sorption capacity of the PAS−GO toward U(VI)/Eu(III) was studied at a room temperature of 25 ± 2 °C. In addition, the pH values of U(VI)/Eu(III) solutions were adjusted to 5.5 ± 0.1 by adding 0.01 M HNO3 or NaOH. The effect of temperature was investigated at 298, 308, and 318 K to study the sorption thermodynamics of U(VI)/Eu(III). The mixture was shaken for 24 h to make sure that the sorption process reached full equilibrium, and sorbent was separated by centrifugation at 10 000 rpm for 10 min. The residual concentration of U(VI)/Eu(III) in liquid phase was measured by ICP−MS (Agilent 7900). The amounts of U(VI)/Eu(III) sorbed by the PAS−GO were calculated by the mass balance equation:

RESULTS AND DISCUSSION Characteristics. The SEM image (Figure 1a) shows that GO exhibits a slightl wrinkle because of its strong interactions between crystals.35 As shown in Figure 1b, the as-prepared PAS− GO presents lamellar wrinkled structures, which indicates that

Figure 1. SEM images of GO (a) and PAS−GO (b). TEM images of GO (c) and PAS−GO (d). TEM images of PAS−GO after sorption: U(VI) (e) and Eu(III) (f). 10291

DOI: 10.1021/acssuschemeng.7b02316 ACS Sustainable Chem. Eng. 2017, 5, 10290−10297

Research Article

ACS Sustainable Chemistry & Engineering

Figure 2. FTIR spectra (a), XRD patterns (b), Raman spectra (c), and TGA curves (d) of GO and PAS−GO. N2 adsorption−desorption isotherms of GO (e) and PAS−GO (f) [insets of parts e and f are the pore size distribution curves, correspondingly]. ζ potential (g) and XPS spectra (h) of PAS−GO.

of the NH stretching vibration frequency of the NH2 groups and the methylene stretching vibration bond.32,35−37 The XRD patterns of GO and the PAS−GO are shown in Figure 2b. The characteristic diffraction peaks of GO are observed at 2θ values of 11.2°, which corresponds to the (002) layer planes of GO sheets.19,25 Meanwhile, there is no obvious diffraction peak of the GO sheets observed in the PAS−GO, which indicates that the PAS−GO has been successfully prepared and further confirms that the as-prepared PAS−GO is effectively exfoliated. Figure 2c shows the Raman spectra of GO and the PAS−GO. Both samples show a D band at approximately 1352 cm−1 associated with the sp3 carbon atom vibration and a G band at 1595 cm−1 of the sp2 carbon atom vibration.38,39 However, a new peak is observed at 1150 cm−1 in the PAS−GO, which may be caused by the antisymmetric stretching vibration of Si−O−Si. The thermal stabilities of PAS, PAS−GO, and GO are shown in Figure 2d. In PAS−GO, the first stage can be seen between 30

PAS is decorated onto the surface of GO sheets. The TEM image was used to further characterize the crystal structure and morphology of the PAS−GO. Figure 1d shows the PAS−GO stacks of few-layered carbon sheets compared to the TEM image of GO (Figure 1c), indicating that the PAS−GO is successfully synthesized and that multiarm PAS prevents GO sheets from aggregation. Compared to its morphology before sorption (Figure 1d), the PAS−GO layered features are still maintained after sorption (Figure 1e,f), which implies that PAS−GO has excellent structural stability. The FTIR spectra of GO and the PAS−GO were used to study the type of oxygen-containing groups and NH2 groups. The FTIR results are shown in Figure 2a. In GO, a strong and broad absorption peak at ∼3420 cm−1 is observed because of the OH stretching vibration. The FTIR spectrum of the PAS−GO shows the presence of CC (1630 cm−1), CO (1218 cm−1), and CO (1035 cm−1). The peaks at 3420 and 2927 cm−1 in PAS−GO are ascribed to the presence 10292

DOI: 10.1021/acssuschemeng.7b02316 ACS Sustainable Chem. Eng. 2017, 5, 10290−10297

Research Article

ACS Sustainable Chemistry & Engineering

Figure 3. Effect of pH on sorption of U(VI) (a) and Eu(III) (b); T = 298 K, m/V = 0.1 g/L, and C0 = 16 and 6 mg/L, respectively.

and 152 °C in which there is 10.2% weight loss, owing to the removal of adsorbed water and the decomposition of labile oxygen functional groups. Then, an abrupt weight loss (17.4%) occurs from 152 to 225 °C, which can be attributed to the decomposition of the oxygen- or nitrogen-containing functional groups. The weight loss at higher temperature should be due to the pyrolysis of the carbon skeleton of GO.32,40 As shown in Figure 2d, the thermal stability of PAS−GO is obviously better than that of GO. In addition, according to the thermogravimetric test results, we can observe that the amount of PAS grafted on the surface of GO is calculated to be 2.6%. The N2 adsorption−desorption isotherms of GO and the PAS−GO are shown in Figure 2e,f. The BET surface areas of the GO and PAS−GO are calculated to be 20.66 and 36.24 m2/g, respectively. The pore volume for PAS−GO is calculated to be 0.18 cm3/g, and the average pore size of 3.5 nm is obtained, indicating the mesoporous structure of the prepared PAS−GO.41 From Figure S1, it can be seen that the sizes of PAS−GO in solution have no obvious effect on the sorption capacity. The ζ potential of the PAS−GO was investigated at room temperature and shown in Figure 2g. The pHzpc of the PAS−GO is 5.3. The PAS−GO was negatively charged when pH > 5.3. The ζ potential of the PAS−GO becomes more negative as the pH value increases, which means that the PAS−GO is negatively charged in a natural water system, which promotes the sorption capacities of cation pollutants. Therefore, positively charged metal ions were attracted to the surface of PAS−GO by the surface complexation.42 For a study of the chemical states of elements on the sorbent surface, the XPS analysis of the PAS−GO was performed. The survey spectrum of the PAS−GO is shown in Figure 2h; there are C (284.77 eV), N (399.71 eV), and O (531.99 eV) elements. In addition, the presence of the N 1s peak of PAS−GO at around 400.1 eV further indicates the formation of amino groups in the composites.43 Effect of pH. Figure 3 presents the effect of initial pH values ranging from 2 to 10 on the removal of U(VI)/Eu(III) by the PAS−GO. Figure 3 shows that the sorption of U(VI)/Eu(III) on PAS−GO increases as pH values vary from 2.5 to 6.5. The high concentration of H+ has a competitive sorption with U(VI) and Eu(III) and makes the amino groups of PAS−GO protonated under the low pH condition, and only a few of the NH2 species present a strong affinity toward U(VI) and Eu(III). R−NH 2 + H+ ↔ R−NH3+ (amino protonate)

under alkaline conditions because of the surface deprotonation process. In addition, the PAS−GO is negatively charged at solution pH > 5.3 (the pHzpc of PAS−GO is close to 5.3) and the electrostatic forces of attraction between cation pollutants occur, which promotes the sorption at a relatively high pH value. As pH increases, the majority of OH is released into the solution, which prevents NH2 from translating into NH3+ and results in the surface of PAS−GO having more NH2 to establish the combination of U(VI)/Eu(III). The main U(VI) species in aqueous solution as a function of pH are predominated by (UO2)3(OH)7− and UO2(CO3)22− species at pH > 6.5 according to the thermodynamic data.44 The distribution of aqueous U(VI) species in water solution is given in Figure S2. The removal of U(VI) on the PAS−GO decreases because of the electrostatic repulsion between negatively charged species [(UO2)3(OH)7− or UO2(CO3)22−] and the negatively charged PAS−GO. However, the amounts of Eu(III) sorbed on the PAS−GO basically remain constant, which contributes to electrostatic attractions between Eu2(OH)24+ species and the negatively charged PAS−GO in aqueous solution at pH > 6.5.45 Typically, the initial pH values for the sorption of U(VI) range from 5.0 to 6.0.46 Therefore, the sorption of U(VI) was performed at pH 5.5 ± 0.1 in the following experiments. Similarly, the sorption of Eu(III) on the PAS−GO was studied at pH 5.5 ± 0.1. Sorption Kinetics. Generally, sorption is a time-consuming process that draws considerable interest in economical wastewater treatment plants.47 Figure S3 shows the kinetics of U(VI)/ Eu(III) sorption onto the PAS−GO. As shown in Figure S3a, the sorption increases with contact time, and U(VI) is removed by the PAS−GO within approximately 30 min at 298 K. Figure S3b shows that the sorption of Eu(III) on the PAS−GO attains equilibrium rapidly in the first 50 min at 298 K. Two kinetics models have been explored for the sorption mechanisms of PAS−GO. The pseudo-first-order model is widely used for the sorption process, and its linearized-integral form is expressed by the following equation:48 ln(qe − qt ) = ln qe − k1t

(4)

where k1 is the pseudo-second-order constant. The pseudo-second-order kinetics model is described as49 t 1 t = + 2 qt qe k 2qe

(5)

(3)

where k2 is the sorption rate constant of the pseudo-first-order. A series of parameters (qe values, kinetic constants, and correlation coefficients) about pseudo-first-order and pseudosecond-order kinetics models are shown in Table S2. According to the correlation coefficient (R2) values of the linear plots, the

The variation of pH in solution during the sorption process is shown in Table S1. The solution pH after sorption increases a little under acidic conditions because of the protonation reaction on the surfaces of PAS−GO. However, the solution pH decreases 10293

DOI: 10.1021/acssuschemeng.7b02316 ACS Sustainable Chem. Eng. 2017, 5, 10290−10297

Research Article

ACS Sustainable Chemistry & Engineering pseudo-second-order model fits well with the experimental values of the removal of U(VI)/Eu(III) by the PAS−GO.50 Sorption Isotherm. The removal of U(VI) and Eu(III) by the PAS−GO was carried out at the temperature of 298, 308, and 318 K with a constant pH of 5.5 ± 0.1 (Figure S4a,b). The Langmuir theory assumes that monolayer sorption onto a surface contains a certain number of identical and energetically equivalent sorption sites. The Freundlich isotherm model is an empirical theory that represents the sorption sites with different sorption energies on heterogeneous surfaces, which suggests that the capacity of sorption is related to the equilibrium concentration of sorbates. The Langmuir model is represented as follows:51 Ce C K = e + L qe qmax qmax

The Freundlich model is described as follows: 1 ln qe = ln KF + ln Ce n

mL of 0.05 M NaOH was used as sorbing agent solution to disperse the sorbent after sorption. After being shaken for 12 h, the U(VI)/Eu(III)-sorbent was separated and washed by 0.05 M HNO3 and deionized water. Finally, the PAS−GO was dried by freeze-drying and reused. From Figure S5, the sorption efficiency of U(VI) on PAS−GO decreases slightly from 87.39% to 82.70% after five consecutive processes of sorption−desorption cycles while the sorption efficiency of Eu(III) declines from 84.79% to 70.36%. Therefore, the PAS−GO shows a good reusability after 5 cycles. Sorption Mechanisms. The FTIR spectra of the PAS−GO before and after sorption shown in Figure 4 were used to identify

(6)

(7)

where Ce (mg/L) is the equilibrium concentration of U(VI)/ Eu(III) in solution, qe (mg/g) is the amount of U(VI)/Eu(III) sorbed at equilibrium, qmax (mg/g) is the maximum sorption capacity of the PAS−GO, KL (mg/L) is a constant that relates to the heat of sorption, KF (mg1−n Ln g−1) is the constant related to the sorption capacity, and n is the Freundlich constant depended on the sorption at equilibrium concentration. The results of the isotherm constants based on the experimental data as well as the correlation coefficients are shown in Table S3. The values of correlation coefficients of the Langmuir model are higher than those of the Freundlich model at 298, 308, and 318 K. The Langmuir model describes the sorption equilibrium better than the Freundlich model within the studied temperature range. The maximum sorption capacity of U(VI) and Eu(III) on the PAS−GO at 298 K calculated by the Langmuir isotherm model was 310.63 and 243.90 mg/g, respectively. A comparison of maximum sorption capacities with other sorbents is shown in Table S4. The PAS−GO presents a much higher sorption capacity. Sorption Thermodynamics. The changes in Gibbs free energy (ΔG), entropy (ΔS), and enthalpy (ΔH) are used to investigate sorption thermodynamics at 298, 308, and 318 K, which can be determined from the following equations: ΔG = −RT ln Kd

Figure 4. FTIR spectra of PAS−GO samples before and after Eu(III) and U(VI) sorption.

the interaction mechanisms between PAS−GO, and U(VI) and Eu(III). It can be seen that the peaks at 696 and 472 cm−1 disappear, and a new band is observed at 1385 cm−1 after sorption, suggesting the bond formation between oxygencontaining groups and U(VI)/Eu(III).52 The elemental mapping analyses of the PAS−GO after sorbing U(VI)/Eu(III) are shown in Figure S6. The elemental mapping images indicate that the N element uniformly disperses on the surface of GO and indicate the successful synthesis of PAS−GO. In addition, in agreement with the FTIR results, the existence of elemental U and Eu mapping for PAS−GO further confirms that the lost U and Eu in solution are sorbed by the PAS−GO. For a better understanding of the removal mechanisms of U(VI)/Eu(III) on the PAS−GO, the XPS spectra of samples were measured to identify surface complexation, and XPS spectra of the PAS−GO after sorption are given in Figure 5. The occurrence of U 4f and Eu 3d in wide scan spectra (Figure 5a) and the high-resolution XPS spectra of U (Figure 5b) and Eu (Figure 5c) clearly confirms the presence of U(VI)/Eu(III) on the PAS−GO. The high-resolution XPS spectra of N 1s are shown in Figure 5d. The shifts of binding energy for both peaks are observed after the sorption of U(VI)/Eu(III). In the case of the PAS−GO−Eu systems, the binding energy of the N 1s peak is shifted from 399.71 to 400.08 eV (Figure 5d), and the peak width (W) increased from 3.08 to 3.95 eV compared with the corresponding binding energy of PAS−GO, which demonstrates that nitrogen groups are involved in the Eu(III) sorption since nitrogen atoms of amine groups provide the lone pair of electrons with Eu(III) species.53 In addition, the one peak (C NOH) shifted from 401.06 to 401.49 eV, and another shift (N CCH) increased from 399.14 to 399.46 eV after sorbing Eu(III), further indicating the formation of the coordination bond of NEu(III). On the basis of the XPS measurement, the

(8)

ΔS ΔH − (9) R RT where R [8.314 J/(mol K)] is the universal gas constant, T is the temperature in K, Kd is the thermodynamic equilibrium constants, which can be obtained by the linear plot of qe/Ce under different temperatures. Plotting ln Kd versus Ce (Figure S4c,d) gives an intercept equal to ln K0 when Ce is about zero. Values of ΔH/R and ΔS/R are obtained from the slope and intercept by potting ln Kd against 1/T. The results of ΔG, ΔS, and ΔH are listed in Table S5, and the values of ΔG are negative for U(VI)/Eu(III) at different temperatures, which demonstrated that the sorption process is spontaneous. In addition, the U(VI) and Eu(III) sorption increases with the increase of temperature. The positive value of ΔH confirms that the sorption process of U(VI)/Eu(III) is endothermic. Regeneration Study. The recycling of the PAS−GO in removing U(VI)/Eu(III) ions was also investigated. In brief, 150 ln Kd =

10294

DOI: 10.1021/acssuschemeng.7b02316 ACS Sustainable Chem. Eng. 2017, 5, 10290−10297

Research Article

ACS Sustainable Chemistry & Engineering

Figure 5. Spectra of PAS−GO with Eu(III) and U(VI) sorbed. (a) Survey scans of Eu(III) and U(VI) sorbed on PAS−GO. High-resolution spectra of U 4f (b) and Eu 3d (c). (d) N 1s spectra of U(VI) and Eu(III) sorbed on PAS−GO.

final pH in the sorption system of U(VI)/Eu(III) onto PAS−GO, kinetic parameters and isotherm parameters, thermodynamic parameters, and comparison of the maximum U(VI)/Eu(III) sorption capacity (PDF)

same analysis of the sorption mechanism of U(VI) on the PAS− GO is similar to that of Eu(III).

■

CONCLUSIONS In the study, the PAS−GO was successfully prepared in sitepolymerizing PAS onto GO and was studied as a highly efficient sorbent in removing U(VI)/Eu(III). Sorption isotherms and kinetics studies suggested that the sorption of U(VI)/Eu(III) followed the Langmuir isotherm and pseudo-second-order kinetics models. The maximum sorption capacities of U(VI) and Eu(III) on the PAS−GO at 298 K calculated by the Langmuir model were 310.63 and 243.90 mg/g, respectively. The modification by NH2 increased the sorption sites, caused chelation with U(VI)/Eu(III), and thus improved the sorption capacities. XPS analysis revealed that nitrogen groups are involved in the U(VI)/Eu(III) sorption since nitrogen atoms of amine groups provided the lone pair of electrons with U(VI) and Eu(III) species. The PAS−GO has a good stability and reusability. The results revealed that the PAS−GO represented a potentially suitable material in removing U(VI)/Eu(III) ions from radioactive polluted water. However, the practical application of PAS−GO as a sorbent is limited because of the difficulty in traditional centrifugation and filtration from aqueous solutions. Further research is needed to evaluate some iron oxide nanomaterials composited with PAS−GO as magnetic sorbents.

■

■

AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. Phone: +86-551-65592788. Fax: 86-551-65591310. (Y.D.) *E-mail: [email protected]. (C.L.C.) ORCID

Changlun Chen: 0000-0002-7986-8077 Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS Financial support from the National Natural Science Foundation of China (21377005 and 21477133), and Natural Science Fund of Education Department of Anhui province (KJ2015ZD15) is acknowledged.

■

REFERENCES

(1) Xie, Y.; Helvenston, E. M.; Shuller-Nickles, L. C.; Powell, B. A. Surface complexation modeling of Eu(III) and U(VI) interactions with graphene oxide. Environ. Sci. Technol. 2016, 50, 1821−1827. (2) Sun, Y. B.; Shao, D. D.; Chen, C. L.; Yang, S. B.; Wang, X. K. Highly efficient enrichment of radionuclides on graphene oxide-supported polyaniline. Environ. Sci. Technol. 2013, 47, 9904−9910. (3) Zhu, K. R.; Lu, S. H.; Gao, Y.; Zhang, R.; Tan, X. L.; Chen, C. L. Fabrication of hierarchical core-shell polydopamine@MgAl-LDHs composites for the efficient enrichment of radionuclides. Appl. Surf. Sci. 2017, 396, 1726−1735. (4) Gao, Y.; Chen, K.; Tan, X. L.; Wang, X. L.; Alsaedi, A.; Hayat, T.; Chen, C. L. Interaction mechanism of Re(VII) with zirconium dioxide nanoparticles archored onto reduced graphene oxides. ACS Sustainable Chem. Eng. 2017, 5, 2163−2171.

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acssuschemeng.7b02316. Characterization, effect of particle size on sorption of U(VI)/Eu(III), distribution of aqueous U(VI) species in water solution, sorption kinetics, sorption isotherms, recycling of the PAS−GO for the removal of U(VI)/ Eu(III) ions, elemental mapping images, the initial and 10295

DOI: 10.1021/acssuschemeng.7b02316 ACS Sustainable Chem. Eng. 2017, 5, 10290−10297

Research Article

ACS Sustainable Chemistry & Engineering (5) Manos, M. J.; Kanatzidis, M. G. Layered metal sulfides capture uranium from seawater. J. Am. Chem. Soc. 2012, 134, 16441−16446. (6) Yang, S. B.; Hu, J.; Chen, C. L.; Shao, D. D.; Wang, X. K. Mutual effect of Pb(II) and humic acid adsorption onto multiwalled carbon nanotubes/poly(acrylamide) composites from aqueous solution. Environ. Sci. Technol. 2011, 45, 3621−3627. (7) Li, J.; Chen, C. L.; Zhang, R.; Wang, X. K. Reductive immobilization of Re(VII) by graphene modified nanoscale zero-valent iron particles using a plasma technique. Sci. China: Chem. 2016, 59, 150−158. (8) Wang, Y. Q.; Zhang, Z. B.; Liu, Y. H.; Cao, X. H.; Liu, Y. T.; Li, Q. Adsorption of U(VI) from aqueous solution by the carboxylmesoporous carbon. Chem. Eng. J. 2012, 198−199, 246−253. (9) Chen, L. L.; Zhao, D. L.; Chen, S. H.; Wang, X. X.; Chen, C. L. One-step fabrication of amino functionalized magnetic graphene oxide composite for uranium (VI) removal. J. Colloid Interface Sci. 2016, 472, 99−107. (10) Zhang, R.; Chen, C. L.; Li, J.; Wang, X. K. Preparation of montmorillonite@carbon composite and its application for U(VI) removal from aqueous solution. Appl. Surf. Sci. 2015, 349, 129−137. (11) Li, Z. J.; Wang, L.; Yuan, L. Y.; Xiao, C. L.; Mei, L.; Zheng, L. R.; Zhang, J.; Yang, J. H.; Zhao, Y. L.; Zhu, Z. T.; Chai, Z. F.; Shi, W. Q. Efficient removal of uranium from aqueous solution by zero-valent iron nanoparticle and its graphene composite. J. Hazard. Mater. 2015, 290, 26−33. (12) Zare-Dorabei, R.; Jalalat, V.; Tadjarodi, A. Central composite design optimization of Ce(III) ion removal from aqueous solution using modified SBA-15 mesoporous silica. New J. Chem. 2016, 40, 5128− 5134. (13) Dashtian, K.; Zare-Dorabei, R. Synthesis and characterization of functionalized mesoprous SBA-15 decorated with Fe3O4 nanoparticles for removal of Ce(III) ions from aqueous solution: ICP−OES detection and central composite design optimization. J. Colloid Interface Sci. 2017, 494, 114−123. (14) Dashtian, K.; Zare-Dorabei, R. An easily organic−inorganic hybrid optical sensor based on dithizone impregnation on mesoporous SBA-15 for simultaneous detection and removal of Pb(II) ions from water samples: Response-surface methodology. Appl. Organomet. Chem. 2017, 3842, e3842−e3842-14. (15) Dashtian, K.; Zare-Dorabei, R. Preparation and characterization of a novel optical chemical sensor for determination of trace amounts of Praseodymium ion by UV/Vis spectrophotometry. Sens. Actuators, B 2017, 242, 586−594. (16) Hummers, W. S., Jr.; Offeman, R. E. Preparation of graphitic oxide. J. Am. Chem. Soc. 1958, 80, 1339. (17) Zhu, Y.; Murali, S.; Cai, W.; Li, X.; Suk, J. W.; Potts, J. R.; Ruoff, R. S. Graphene and graphene oxide: synthesis, properties, and applications. Adv. Mater. 2010, 22, 3906−3924. (18) Wang, S. B.; Sun, H. Q.; Ang, H. M.; Tade, M. O. Adsorptive remediation of environmental pollutants using novel graphene-based nanomaterials. Chem. Eng. J. 2013, 226, 336−347. (19) Zhao, G. X.; Jiang, L.; He, Y. D.; Li, J. X.; Dong, H. L.; Wang, X. K.; Hu, W. P. Sulfonated graphene for persistent aromatic pollutant management. Adv. Mater. 2011, 23, 3959−3963. (20) He, Y. Q.; Liu, Y.; Wu, T.; Ma, J. K.; Wang, X. R.; Gong, Q. J.; Kong, W. N.; Xing, F. B.; Liu, Y.; Gao, J. P. An environmentally friendly method for the fabrication of reduced graphene oxide foam with a super oil absorption capacity. J. Hazard. Mater. 2013, 260, 796−805. (21) Zare-Dorabei, R.; Ferdowsi, S. M.; Barzin, A.; Tadjarodi, A. Highly efficient simultaneous ultrasonic-assisted adsorption of Pb(II), Cd(II), Ni(II) and Cu(II) ions from aqueous solutions by graphene oxide modified with 2,20-dipyridylamine: Central composite design optimization. Ultrason. Sonochem. 2016, 32, 265−276. (22) Tadjarodi, A.; Ferdowsi, S. M.; Zare-Dorabei, R.; Barzin, A. Highly efficient ultrasonic-assisted removal of Hg(II) ions on graphene oxide modified with 2-pyridinecarboxaldehyde thiosemicarbazone: Adsorption isotherms and kinetics studies. Ultrason. Sonochem. 2016, 33, 118−128.

(23) Keramat, A.; Zare-Dorabei, R. Ultrasound-assisted dispersive magnetic solid phase extraction for preconcentration and determination of trace amount of Hg (II) ions from food samples and aqueous solution by magnetic graphene oxide (Fe3O4@GO/2-PTSC): central composite design optimization. Ultrason. Sonochem. 2017, 38, 421−429. (24) Li, J.; Chen, C. L.; Zhang, S. W.; Ren, X. M.; Tan, X. L.; Wang, X. K. Critical evaluation of adsorption−desorption hysteresis of heavy metal ions from carbon nanotubes: Influence of wall number and surface functionalization. Chem. - Asian J. 2014, 9, 1144−1151. (25) Zhao, G. X.; Li, J. X.; Ren, X. M.; Chen, C. L.; Wang, X. K. Fewlayered graphene oxide nanosheets as superior sorbents for heavy metal ion pollution management. Environ. Sci. Technol. 2011, 45, 10454− 10462. (26) Yang, S. B.; Chen, C. L.; Chen, Y.; Li, J. X.; Wang, D. Q.; Wang, X. K.; Hu, W. P. Competitive adsorption of Pb(II), Ni(II) and Sr(II) ions on graphene oxides: A combined experimental and theoretical study. ChemPlusChem 2015, 80, 480−484. (27) Li, J.; Chen, C. L.; Zhang, S. W.; Wang, X. K. Surface functional groups and defects on carbon nanotubes affects adsorption-desorption hysteresis of metal cations and oxoanions in water. Environ. Sci.: Nano 2014, 1, 488−495. (28) Zhu, K. R.; Gao, Y.; Tan, X. L.; Chen, C. L. Polyaniline modified Mg/Al layered double hydroxide composites and their application in efficient removal of Cr(VI). ACS Sustainable Chem. Eng. 2016, 4, 4361− 4369. (29) Gao, Y.; Chen, C. L.; Chen, H.; Zhang, R.; Wang, X. K. Synthesis of a novel organic-inorganic hybrid of polyaniline/titanium phosphate for Re(VII) removal. Dalton Trans. 2015, 44, 8917−8925. (30) Gao, Y.; Chen, C. L.; Tan, X. L.; Xu, H.; Zhu, K. R. Polyaniline modified 3D-flowerlike molybdenum disulfide composite for Cr(VI) removal. J. Colloid Interface Sci. 2016, 476, 62−70. (31) Hu, R.; Shao, D. D.; Wang, X. K. Graphene oxide/polypyrrole composites for highly selective enrichment of U(VI) from aqueous solutions. Polym. Chem. 2014, 5, 6207−6215. (32) Luo, S. L.; Xu, X. L.; Zhou, G. Y.; Liu, C. B.; Tang, Y. H.; Liu, Y. T. Amino siloxane oligomer-linked graphene oxide as an efficient adsorbent for removal of Pb(II) from wastewater. J. Hazard. Mater. 2014, 274, 145−155. (33) Shao, D. D.; Hu, J.; Sheng, G. D.; Ren, X. M.; Chen, C. L.; Wang, X. K. Polyaniline multiwalled carbon nanotube magnetic composite prepared by plasma induced graft technique and its application for removal of aniline and phenol. J. Phys. Chem. C 2010, 114, 21524− 21530. (34) Gao, Y.; Wu, J. C.; Ren, X. M.; Tan, X. L.; Hayat, T.; Alsaedi, A.; Cheng, C.; Chen, C. L. Impact of graphene oxide on antibacterial activity of antibiotics against bacteria. Environ. Sci.: Nano 2017, 4, 1016−1024. (35) Wang, H.; Zhang, Q.; Chu, X.; Chen, T.; Ge, J.; Yu, R. Graphene oxide-peptide conjugate as an intracellular protease sensor for caspase-3 activation imaging in live cells. Angew. Chem., Int. Ed. 2011, 50, 7065− 7069. (36) Zhao, D. L.; Gao, X.; Wu, C. N.; Xie, R.; Feng, S. J.; Chen, C. L. Facile preparation of amino functionalized graphene oxide decorated with Fe3O4 nanoparticles for the adsorption of Cr(VI). Appl. Surf. Sci. 2016, 384, 1−9. (37) Hu, Y. Z.; Shen, J. F.; Li, N.; Shi, M.; Ma, H. W.; Yan, B.; Wang, W. B.; Huang, W. S.; Ye, M. X. Amino-functionalization of graphene sheets and the fabrication of their nanocomposites. Polym. Compos. 2010, 31, 1987−1994. (38) Chen, C. L.; Liang, B.; Lu, D.; Ogino, A.; Wang, X. K.; Nagatsu, M. Amino group introduction onto multiwall carbon nanotubes by NH3/Ar plasma treatment. Carbon 2010, 48, 939−948. (39) Sablok, K.; Bhalla, V.; Sharma, P.; Kaushal, R.; Chaudhary, S.; Suri, C. Amine functionalized graphene oxide/CNT nanocomposite for ultrasensitive electrochemical detection of trinitrotoluene. J. Hazard. Mater. 2013, 248−249, 322−328. (40) Fang, F.; Kong, L. T.; Huang, J. R.; Wu, S. B.; Zhang, K. S.; Wang, X. L.; Sun, B.; Jin, Z.; Wang, J.; Huang, X. J.; Liu, J. H. Removal of cobalt ions from aqueous solution by an amination graphene oxide nanocomposite. J. Hazard. Mater. 2014, 270, 1−10. 10296

DOI: 10.1021/acssuschemeng.7b02316 ACS Sustainable Chem. Eng. 2017, 5, 10290−10297

Research Article

ACS Sustainable Chemistry & Engineering (41) Wu, Z. B.; Zhong, H.; Yuan, X. Z.; Wang, H.; Wang, L. L.; Chen, X. H.; Zeng, G. M.; Wu, Y. Adsorptive removal of methylene blue by rhamnolipid-functionalized graphene oxide from wastewater. Water Res. 2014, 67, 330−334. (42) Li, J.; Zhang, S. W.; Chen, C. L.; Zhao, G. X.; Yang, X.; Li, J. X.; Wang, X. K. Removal of Cu(II) and fulvic acid by graphene oxide nanosheets decorated with Fe3O4 nanoparticles. ACS Appl. Mater. Interfaces 2012, 4, 4991−5000. (43) Huang, J.; Ye, M.; Qu, Y.; Chu, L.; Chen, R.; He, Q.; Xu, D. Pb(II) removal from aqueous media by EDTA-modified mesoporous silica SBA-15. J. Colloid Interface Sci. 2012, 385, 137−146. (44) Gorman-Lewis, D.; Burns, P. C.; Fein, J. B. Review of uranyl mineral solubility measurements. J. Chem. Thermodyn. 2008, 40, 335− 352. (45) Sun, Y. B.; Wang, Q.; Chen, C. L.; Tan, X. L.; Wang, X. K. Interaction between Eu(III) and graphene oxide nanosheets investigated by batch and extended X-ray absorption fine structure spectroscopy and by modeling techniques. Environ. Sci. Technol. 2012, 46, 6020−6027. (46) Zhang, R.; Chen, C. L.; Li, J.; Wang, X. K. Investigation of interaction between U(VI) and carbonaceous nanofibers by batch experiments and modeling study. J. Colloid Interface Sci. 2015, 460, 237− 246. (47) Chen, C. L.; Wang, X. K. Adsorption of Ni(II) from aqueous solution using oxidized multiwall carbon nanotubes. Ind. Eng. Chem. Res. 2006, 45, 9144−9149. (48) Chen, C. L.; Hu, J.; Shao, D. D.; Li, J. X.; Wang, X. K. Adsorption behavior of multiwall carbon nanotube/iron oxide magnetic composites for Ni(II) and Sr(II). J. Hazard. Mater. 2008, 164, 923−928. (49) Ho, Y. S.; Mckay, G. Pseudo-second order model sorption processes. Process Biochem. 1999, 34, 451−465. (50) Chen, C. L.; Wang, X. K.; Nagatsu, M. Europium adsorption on multiwall carbon nanotube/ iron oxide magnetic composite in the presence of polyacrylic acid. Environ. Sci. Technol. 2009, 43, 2362−2367. (51) Li, J.; Chen, C. L.; Zhao, Y.; Hu, J.; Shao, D. D.; Wang, X. K. Synthesis of water-dispersible Fe3O4@ beta-cyclodextrin by plasmainduced grafting technique for pollutant treatment. Chem. Eng. J. 2013, 229, 296−303. (52) Li, F. Z.; Li, D. M.; Li, X. L.; Liao, J. L.; Li, S. J.; Yang, J. J.; Yang, Y. Y.; Liu, J. N. Microorganism-derived carbon microspheres for uranium removal from aqueous solution. Chem. Eng. J. 2016, 284, 630−639. (53) Liu, M. C.; Chen, C. L.; Wen, T.; Wang, X. K. Synthesis of magnetic ion-imprinted composites and selective separation and preconcentration of U(VI). Dalton Trans. 2014, 43, 7050−7056.

10297

DOI: 10.1021/acssuschemeng.7b02316 ACS Sustainable Chem. Eng. 2017, 5, 10290−10297