Development of Magnetic Silica Hybrid Material with P507 for Rare

Nov 10, 2016 - Tetraethoxysilane (TEOS) was supplied by Xiya Reagent Co., Ltd. Individual REE stock solution was prepared from its oxide (>99.99% puri...
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Development of Magnetic Silica Hybrid Material with P507 for Rare Earth Adsorption Sen Qiu,†,‡,§ Zeyuan Zhao,†,‡,§ and Xiaoqi Sun*,†,‡ †

Xiamen Institute of Rare Earth Materials, Haixi Institute, Chinese Academy of Sciences, Xiamen, 361021, P. R. China Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China § University of Chinese Academy of Sciences, Beijing, 100039, P. R. China ‡

ABSTRACT: A magnetic silica hybrid material (MSHM) containing 2ethylhexylphosphonic acid mono-(2-ethylhexyl) ester (P507) for rare earth adsorption was developed. Compared with a common grafting preparation method of magnetic silica hybrid material, the developed strategy of embedding the extractant using a sol−gel method revealed simple and efficient advantages. The prepared hybrid materials were analyzed by scanning electron microscopy, Fourier infrared spectroscopy, magnetization, energy dispersive spectrometry, and thermogravimetric analysis. As for the adsorption kinetics, the pseudo-second-order equation fitted well the experimental data. Adsorption of Y(III) using the MSHM fit well with the Langmuir isotherm model rather than the Freundlich isotherm model. The values of thermodynamic parameters at 303 K, 311 K, 318 K, and 333 K were calculated. Hydrochloric acid solution was used for the desorption of Y(III) loaded on MSHM. The effective separation of Y(III) and Eu(III) revealed its potential for phosphor recycling.

1. INTRODUCTION Rare earth elements (REEs) are used in the widest range of consumer products because of their unique physical and chemical properties.1 Those products include phosphors,2 catalysts,3 and magnets.4 Solvent extraction has been one of the most commonly used separation technologies for REEs. However, large inventories of diluents and modifiers were used in solvent extraction,5 thereby leading to severe environmental problems.6 Various techniques based on adsorption, such as polymeric composite bead,7 magnetic nanomaterial,8 hybrid material,9,10 modified carbon inverse opal,11 were developed to restrict the hazardous impacts of volatile organic compounds. The advantages of adsorption, that is, simplicity, flexibility, cost effectiveness, ease of operation, and lower consumption of hazardous reagent (no hazardous diluent is used), make it a competitive alternative to solvent extraction.12 Hybrid material is a kind of adsorption materials with large specific surface areas, long-range ordered pore channels, and highly tunable pore sizes.13 Some silica materials were investigated for REEs separation; that is, bifunctional ionic liquid doped in silica gel was used to extract yttrium,14 8hydroxyquinoline immobilized on silica gel was applied to preconcentrate and purify REEs from natural waters.15 However, centrifugation was necessary to collect those silica materials from the aqueous phase after adsorption. As revealed in Table 1, various magnetic composites were prepared to improve the collection efficiency. In the preparation of the above-mentioned silica adsorbent, a silanecoupling agent was necessary for the modification of an © 2016 American Chemical Society

Table 1. Application of Various Magnetic Composites material silica nanocomposite EDTA-functionalized composite CdS/C@Fe3O4 nanoreactor imprinted ICTX@Mfa functional ZnO/C/Fe3O4 imprinted TiO2 photocatalyst

application

ref

adsorption of La(III) separation of REEs

8 16

photodegradation of ciprofloxacin degradation of antibiotic ciprofloxacin photodegradation of danofloxacin mesylate have an excellent transparency

17 18 19 20

Fe3O4@SiO2 particle before the grafting of the extractant. As revealed in our recent investigation, the hydrolytic silanecoupling agent reacted not only with hydroxyl silicons but also with themselves, which resulted in lower yields of the adsorbents. Accordingly, developing a simple and efficient preparation strategy is essential to the hybrid magnetic adsorbent for potential industrial application. P507 is the most commonly used extractant in Chinese REEs separation industry. In this study, we first prepared magnetic silica hybrid material (MSHM) doped P507 by the sol−gel method. Compared with the common grafting method, the embedding strategy reveals the advantages of simple preparation and higher content of extractant. Received: August 29, 2016 Accepted: November 2, 2016 Published: November 10, 2016 469

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Figure 1. Chemical structures of silica and P507.

2. EXPERIMENTAL SECTION 2.1. Reagents. 2-Ethylhexylphosphonic acid mono-(2ethylhexyl) ester (P507, HEHEHP) was purchased from J&K Scientific Ltd. (99% purity). Tetraethoxysilane (TEOS) was supplied by Xiya Reagent Co., Ltd. Individual REE stock solution was prepared from its oxide (>99.99% purity, Fujian Changting Golden Dragon Rare-Earth Co. Ltd.) via dissolution in concentrated hydrochloric acid and diluting with deionized water. Iron(III) oxide nanoparticle was obtained from Sinopharm Chemical Reagent Co. All other chemicals were reagent grade and used without further purification. The chemical structures of silica and P507 are shown in Figure 1. 2.2. Instrumentation. Elemental analysis of carbon element in P507 was performed on a Vario EL Cube elementary analysis instrument. TGA data analysis was obtained by Mettler-Toledo TGA/DSC-1, from 30 to 800 °C with the growth rate of temperature fixed at 10 °C/min. FT-IR spectra were obtained with KBr pellets, and the wavenumber ranged from 4000−500 cm −1 using a Nicolet IS 50 spectrometer. The scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) analysis were performed on HITACHI-SU1510 instrument (Japan). Magnetization curve of the composite material was recorded at room temperate with a vibrating sample magnetometer (VSM: USA model Lakeshore 7400) and applied magnetic field up to 18000G. The REE concentration in aqueous phase was determined by a Thermo scientific ICP 6500 series inductively coupled plasma-atomic emission spectroscope (ICP-OES). 2.3. Synthesis. The synthesis of MSHM was developed on the basis of a previous paper.17 Briefly, TEOS (8 mL) and a few drop of formic acid were mixed with deionized water (4.5 mL) under mild magnetic stirring at room temperature for 12 h. While the TEOS was entirely hydrolyzed, 2 mL of ethanol solution containing 2.5 mmol P507 was added and kept stirring for another 0.5 h. Then, Fe3O4 (0.2 g) was added to the mixture solution under sonication for 20 min. After that, the gel was generated quickly with the help of dilute ammonia at 70 °C. Finally, the MSHM was ground after rotary evaporation with RE-52AA rotary evaporator, washed with deionized water for several times, and dried at 90 °C in a vacuum for 6 h. 2.4. Adsorption Experiments. A series of adsorption experiments were conducted in a temperature-controlled mechanical shaker for 120 min at 298 K. The effect of solution pH on Y(III) ions adsorption was investigated using 0.3 mmol/ L of initial yttrium concentration in the pH range from 1 to 6. No buffer solution was used in this study. Adsorption experiments were carried out by shaking 8 mL of aqueous phase and 30 mg of adsorbent for 120 min in an equilibrium tube with the help of mechanical shaker. After equilibrium, the adsorbent was separated and collected by an external magnet.

The residual metal concentration in aqueous phase was determined by ICP-OES. The amount of adsorbed REE ion was calculated by mass balance between initial and raffinate concentration. The uptake percentage (%) and amount adsorbed per unit mass of adsorbent at equilibrium qe were defined as the following eq 1 and eq 2:8 %uptake =

qe =

C ini − Ce × 100 Cini

(C ini − Ce)V m

(1)

(2)

where Cini and Ce (mmol/L) represent the initial and equilibrium concentrations in aqueous phase, respectively. V (L) is the total volume of solution and m (g) is the mass of dry MSHM. 2.5. Thermodynamic Parameters of Adsorption. To study the effect of temperature on adsorption process, thermodynamic parameters such as Gibbs free energy change (ΔGθ), enthalpy change (ΔHθ), and entropy change (ΔSθ) were determined. The thermodynamic parameters were obtained from adsorption experiments at various temperatures (303 K, 311 K, 318 K, 333 K) and estimated using eqs 3−5:21 Kd =

Cad Ce

ΔG θ = −RT ln Kd ln Kd =

ΔS θ ΔH θ − R RT

(3) (4)

(5)

where Kd is the equilibrium constant, Cad (mol/L) is the adsorbed concentration of Y(III), C e (mol/L) is the equilibrium concentration of Y(III) in the solution, R (8.314 J/(mol K)) is the gas constant and T(K) is temperature. ΔHθ and ΔSθ are obtained from the slope and intercept of Van’t Hoff plot of lnKd versus 1/T.

3. RESULTS AND DISCUSSION 3.1. Characterization of MSHM. Here the embedded P507 was used as extractant and porogen. As shown in Figure 2, the SEM images of Fe3O4@SiO2 (a, b) and MSHM containing P507 (c, d) are quite different. Obviously, Figure 2 shows that there is no pore in the Fe3O4@SiO2 even below 10 μm and its surface is smooth (Figure 2a,b). On the contrary, the pores are quite dense in the prepared MSHM containing P507 (Figure 2c,d). The difference of SEM images confirms the porogen effect of doped P507 in the porous hybrid material. 470

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the characteristic peak of Si−O in the Fe3O4@SiO2, which coincides with the 1030 cm−1 (a) of P−OH stretching vibration from P507. Obviously, the spectra features of P507 can be observed on MSHM by the presence of peaks at 2960 cm−1, 2930 cm−1, and 2863 cm−1 (c), respectively. These spectral features confirm the presence of P507 in the MSHM. The band at 1637 cm−1 (c) of P(O)OH stretching vibrations in MSHM is replaced by the band at 1607 cm−1 (d) after Y(III) adsorption. The shift reveals there are obvious interactions between the P(O)OH and PO funcational groups and Y(III) in the adsorption processing. To determine the content of P507 in MSHM, elementary analysis instrument and TG-DTA Instruments were used, respectively. The presence of characteristic carbon element offered a labeling to measure the amount of P507 in MSHM. To confirm the reliability of elementary analysis, the determined value of carbon was compared with the calculated value of carbon in P507. As revealed in Table 3, the determined

Figure 2. SEMs of Fe3O4@SiO2 (a,b) and MSHM containing P507 (c,d).

Table 3. Amount of Carbon Determined by Elemental Analysis

IR spectrum is an effective method to investigate the adsorbent. As can be seen in Table 2, the characteristic stretching vibrations of Fe3O4@SiO2 and P507 are listed.

calculated values

Table 2. Characteristic Stretching Vibrations of Fe3O4@ SiO2, P507, MSHM, and MSHM Loaded with Y(III) no. Fe3O4@SiO2 P507

MSHM MSHM-Y(III)

v (cm−1) 1049 2958, 1465 2310, 1192 1030 2960, 1637 2968, 1607 1136

2927, 2862 1682

2930,2863 2933, 2971

no.

determined values of C (%)

C (%)

P507 Fe3O4@SiO2 MSHM

62.48 0.72 12.99

62.74 0

P507 (mmol/g)

0.676

assignments

value is 62.48%, and the calculated value is 62.74%. The minor difference reveals that the characteristic carbon element is effective to measure the amount of P507. As for Fe3O4@SiO2, there is only 0.72% carbon from the adsorbed carbon dioxide that can be determined. With the use of the above-mentioned elemental analysis method, the content of P507 in MSHM was calculated to be 0.676 mmol/g. As can be seen in Figure 4, the TGA of P507, Fe3O4@SiO2, and MSHM were studied. The Fe3O4@SiO2 reveals well

Si−O stretching vibration C−H stretching vibration of −CH3 more −CH3 group on a carbon atom P(O)OH vibrations PO stretching vibration P−OH stretching vibration C−H stretching vibration of −CH3 P(O)OH vibrations C−H stretching vibration of −CH3 P(O)OH vibrations PO stretching vibration

As shown in Figure 3, the IR spectra reveal the embedding of P507 in Fe3O4@SiO2 and the interactions between the MSHM and Y(III) clearly. The stretching vibration of 1049 cm−1 (b) is

Figure 4. TG-DTA plots of P507, Fe3O4@SiO2, and MSHM.

thermal stability from 200 to 800 °C; its weight loss before 100 °C can be attributed to the water. There are three obvious weight losses for P507 at temperature ranges from 200 to 220 °C, 220 to 280 °C, and 280 to 400 °C, respectively, which was due to the decomposition of the several organic groups in P507.8 As for the MSHM, the weight loss from 200 to 550 °C in TG curve matches well with the DTA peaks at 220−300 °C and 400−600 °C, which can also be attributed to the decomposition of the organic groups in P507.

Figure 3. IR spectra of (a) P507, (b) Fe3O4@SiO2, (c) MSHM, and (d) MSHM loaded with Y(III). 471

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Figure 5. Saturation of magnetization of Fe3O4 and MSHM.

Figure 6. EDS results of MSHM after Y(III) adsorption. (a) Image of SEM and (b) EDS results.

The magnetization characteristics of Fe3O4 and MSHM were investigated. As shown in Figure 5, the saturation of magnetization of Fe3O4 and MSHM are 56.4 eum/g and 4.2eum/g, respectivly. There is an obvious decrease of saturation magnetization for MSHM, which may be due to the decrease of the content of Fe3O4 in unit weight sample.20 The separation of MSHM from the aqueous phase by a magnet can be observed clearly, indicating that the MSHM with magnetization characteristics has potential for industrial application. 3.2. EDS Result. EDS is an efficient technique used for the elemental analysis or chemical characterization of a sample. As shown in Figure 6, the EDS results of MSHM loaded with Y(III) were studied. The red rectangle area in Figure 6a is the test range of EDS to obtain the C, O, Si, P, Y elements from P507, silica matrix, and Y, respectively. As shown in Figure 6b, the EDS results of detected C, O, Si, P, Y elements further confirm the Y element was adsorbed from the aqueous phase to the MSHM containing P507. In both Figure 6a and Figure 6b, no Fe element was determined, the EDS results reveal that the iron(III) oxide nanoparticle was compactly embedded in the MSHM. 3.3. Adsorption Phenomena. The third phase is a common phenomenon in solvent extraction, which can be attributed to the lack of solubility of a metal−ligand complex in organic phase.22 The presence of a reverse micellar or a microemulsion was also proposed for the formation of the third phase.23 As mentioned above, the third phases in the solvent extraction are concerned with the organic diluent. As shown in Figure 7, the phenomena of solvent extraction (3) are quite different to that of adsorption (1 and 2) when the amounts of P507 in 1, 2, and 3 are the same 0.32 mmol. The difference may be attributed to the non-use of organic diluent in the

Figure 7. Solvent extraction vs adsorption using MSHM: (1) Adsorption with magnet; (2) Adsorption without magnet; (3) Solvent extraction.

adsorption. Also, it is easy to find that the MSHMs can be easy collected by their magnetic performances. 3.4. Adsorption Studies. To study the effect of acidity on the adsorption, the effects of pH on the Y(III) adsorption with MSHM and Fe3O4@SiO2 were studied. As shown in Figure 8, it is demonstrated that the adsorption processes are strongly affected by pH values. The adsorption of Y(III) by MSHM is the highest at pH 4 and then reaches a platform. The lower adsorption capacity of MSHM in stronger acidic solution can be attributed to the competitive adsorption between H+ and Y(III). Aqueous H+ ions with higher concentration and small ionic radii were indicated to be more easily adsorbed onto the MSHM than REE.24 When pH was increased, here the concentration of aqueous H+ decreased slowly and Y(III) was more easily coordinated with the adsorbent. As a consequence, 472

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Figure 8. Effect of pH on the Y(III) adsorption using MSHM and Fe3O4@SiO2. Cini = 0.3 mmol/L, temperature = 298 K, V = 8 mL, m = 0.03 g.

Figure 10. Uptake percentages of adsorption using MSHM and solvent extraction for mixed REEs: m = 40 mg, np507 = 0.013 mmol, pH = 1.

the adsorption of Y(III) increased at first, and then remained contant due to the saturation of binding sites. The adsorption of Y(III) by Fe3O4@SiO2 was performed under the same conditions, its adsorption capacity was far lower than that of MSHM at pH < 5.0, the sharp increase in adsorption of Y(III) from 5.0 to 6.0 can be attributed to a strong electrostatic interaction between Fe3O4@SiO2 and REE.8 The recycling of lamp phosphor is important; moreover, the recycling value of different phosphor components varies greatly. The phosphor with the highest economic value is the red Y2O3:Eu3+ (YOX) phosphor, which consists almost entirely of yttrium and europium. The yttrium and europium could be effectively leached from the YOX phosphor.25 To study the potential application of MSHM in waste red phosphor Y2O3:Eu3+ (YOX) recycling, the pH effect on the mixture solution contain Y3+ and Eu3+ was investigated. As shown in Figure 9, the uptakes of Y3+ and Eu3+ by MSHM reach a

of adsorption or solvent extraction in this experimental condition. As for heavy REEs, it is obvious that the uptake percentages of adsorption are much higher than those of solvent extraction. With the increase of atomic number, the uptake percentage of adsorption increased rapidly. One resonable explanation is lanthanide contraction; that is, the adsorption abilities of P507 in the MSHM increase as the radii of REEs decrease. 3.5. Adsorption Kinetics. The extraction time was varied from 5 to 120 min and the results are shown in Figure 11. The maximum uptake of Y(III) was achieved within 90 min; 120 min of contacting time was indicated to be enough for the adsorption experiments.

Figure 11. Effect of time on the adsorption. Cini = 0.32 mmol/L, T = 298 K, V = 8 mL, m = 0.03 g, pH = 4. Figure 9. Effect of pH on the adsorption of MSHM for Y3+ and Eu3+. Cini = 0.25 mmol/L, T = 298 K, V = 8 mL, m = 0.03 g.

As shown from eq 6 to eq 8, three kinetic model equations including the pseudo-first-order,26 pseudo-second-order,27 and intraparticle diffusion28 models were used to analyze the adsorption data:

platform when the pH > 3. The Y(III) and Eu(III) can be well separated in the whole range of tested pH, which can be mainly attributed to the different ionic radii of Y(III) and Eu(III). The uptake percentages of adsorption and solvent extraction for mixed REEs have been compared. In this experiment, the amount of P507 in the organic phase of solvent extraction was consistent with that of P507 in MSHM, that is, 0.013 mmol, and all the REEs were equal at 0.04 mmol/L. As shown in Figure 10, there is almost no uptake for light REEs with the use

Pseudo-first-order model

473

ln(qe − qt ) = ln qe − k1t

(6)

Pseudo-second-order model t 1 1 = t+ qt qe k 2qe2

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adsorption capacity (qe) increases as the equilibrium concentration of Y(III) increases and reaches a plateau representing maximum adsorption capacity of MSHM for Y(III). From Figure 12, it also shows that the Y(III) adsorption capacity increases with increasing temperature for a certain initial concentration within the ranges of temperatures investigated. A reasonable explanation is that the adsorption of Y(III) is an endothermic process. The Langmuir and Freundlich models were used to analyze the relationships between Y(III) concentration and adsorption capacity of MSHM. Langmuir isotherm model29 represents monolayer adsorption occurring on an energetically uniform surface, where the adsorbed molecules are not interactive. Consequently, equilibrium is attained once the monolayer is completely saturated. The Langmuir adsorption isotherm can be simply presented as eq 9:

Intraparticle diffusion model qt = k pt 0.5 + L

(8)

where qe and qt are the amounts of Y(III) adsorbed on the MSHM at equilibrium and time t, respectively, k1 is the pseudofirst-order rare constant, k2 is the pseudo-second-order rare constant, kp is the intraparticle diffusion rare constant, and L represents the boundary layer diffusion effects. The correlation coefficient kinetic parameters are listed in Table 4. Higher correlation coefficient values (R2 > 0.98) than Table 4. Adsorption Kinetics Parameters of MSHM pseudo-firstorder

pseudo-second-order −1

MSHM

intraparticle diffusion

k1(min−1), R2

k2(g/mmol min ), R2

kp (mmol/g min0.5), R2

0.0446, 0.8435

0.39, 0.9816

72.1, 0.9676

qe = qmax bCe/(1 + bCe)

(9)

Below, qe is the amount of metal ion adsorbed at specified equilibrium (mmol/g), Ce is the equilibrium concentration (mmol/L), qmax and b are the Langmuir constants related to adsorption capacity and adsorption energy, respectively. The linear form of the Langmuir model can be described as eq 10:

those of pseudo-first-order and intraparticle diffusion indicate that the pseudo-second-order equation fits well the experimental data. 3.6. Adsorption Isotherms. The adsorption isotherm experiments were investigated in a temperature range of 303 K to 333 K. The results (Figure 12 and Table 5) indicate that the

1 1 1 1 = + qe qmax qmax b Ce

(10) 30

The Freundlich isotherm model, describes adsorption on an energetically heterogeneous material on which the adsorbed molecules are interactive. It can be presented as eq 11: qe = K f Ce1/ n

(11)

Kf and 1/n are Freundlich constants, representing adsorption capacity and adsorption intensity of the system, respectively. A linear form of the Freundlich model can be obtained by taking logarithms of eq 12. log qe = log K f +

Table 5. Parameters Fittings with Langmuir and Freundlich Models at Various Temperatures model parameters qm (10−3mmol/g)

isotherm model

T (K)

R

Langmuir

303 311 318 333

0.9974 0.987 0.992 0.9787

82.5 92.2 102.4 115.9 model parameters

b 4.39 5.74 29.23 28.2

isotherm model

T (K)

R2

Kf

n

Freundlich

303 311 318 333

0.9873 0.9608 0.9896 0.9676

0.69 1.00 0.98 1.11

10.96 11.62 34.84 21.45

(12)

As can be seen in Table 5, Langmuir parameters were calculated by the plot of 1/qe vs 1/Ce, Freundlich parameters were calculated by the plot of log qe vs log Ce. It is obvious that the adsorption is fitted well with to the Langmuir isotherm model than Freundlich isotherm model in the temperature range of 303 K−333 K as indicated by the numerical values of correlation coefficient (R2). A reasonable explanation is that Y(III) ions in the aqueous phase were monolayer adsorbed to the surface of MSHM through the coordination of Y(III) by P(O)OH groups and no interaction happened between Y(III) ions. 3.7. Comparison with Other Adsorbents. The adsorption performance of MSHM is compared with other adsorbents and the results are shown in Table 6. Among those materials, the silica-based TODGA/SiO2−P showed a high adsorption capacity; however, the equilibrium time was much longer. Although the equilibrium time of the composite membranes and silica hybrid material were the same as MSHM in this study, their adsorption capacities were lower than MSHM in this study. Because the adsorption performance was affected by various factors (such as adsorption capacity, equilibrium time, regeneration), it is hard to evaluate the different adsorption materials under the different conditions.

Figure 12. Effect of temperature and initial concentration of Y(III) ions on the adsorption. pH = 3.2, m = 30 mg, V = 8 mL; contacting time, 120 min.

2

1 log Ce n

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Table 6. Comparison with Other Adsorbents adsorbent

metal ion

qe (mg/g)

equilibrium time (min)

ref.

composite membrane silica-based TODGA/SiO2−P silica hybrid material MSHM

Y(III) Y(III) Lu(III) Y(III)

2.31 13.35 5.83 7.34

60 300 60 90

31 32 33 this work

3.8. Thermodynamic Studies. The values of thermodynamic parameters are shown in Table 7. The negative values of Table 7. Estimation of Thermodynamic Parameters for the Adsorption of Y(III). Cini = 0.45 mmol/L T (K)

Kad

ΔG (kJ/mol)

ΔH (kJ/mol)

ΔS (J/mol K)

303 311 318 333

1.5468 2.2015 4.5006 17.8461

−1.098 −1.987 −3.976 −7.978

70.592

235.14

ΔG at all the experiment temperatures indicate that adsorption of Y(III) is a feasible and spontaneous process. Besides, the decrease of ΔG values with temperature suggests that the adsorption reaction is more spontaneous with higher temperature. The positive values of ΔS and ΔG match well. The positive value of ΔH indicates that the adsorption of Y(III) is endothermic which fits with the experiments. One reasonable explanation of endothermicity of heats of adsorption is that Y(III) ions are solvated. The Y(III) ions have to lose part of their hydration sheath in ordor to be adsorbed. This dehydration process of ions requires energy which offsets the exothemrmicity of the ions getting attach to the surface.34 3.9. Desorption and Recycling of MSHM. To investigate desorbed properities of MSHM for Y(III), 0.25 M EDTA, 0.02 M EDTA with pH = 3 and 0.67 mol/L HCl were chosen as reagents to desorb the Y(III) from adsorbents. As can be seen in Table 8, it is easy to find that hydrochloric acid solution is

Figure 13. Adsorption−desorption cycles of MSHM.

4. CONCLUSIONS For the development of a simple and efficient preparation strategy for MSHM, P507 was doped in magnetic silica nanocomposite by the sol−gel method. The doped P507 was indicated to be extractant and porogen in the hybrid material for REE adsorption. The characteristic carbon element offers a labeling to measure the amount of P507 in MSHM. The nonuse of organic diluent contributes to not only avoiding the hazardous impact but also eliminating the third phase. The adsorption of Y(III) by MSHM was fitted well with to the Langmuir isotherm model rather than the Freundlich isotherm model. The adsorption capacity of MSHM for Y(III) was strongly affected by pH value. The uptake percentages of adsorption using MSHM are bigger than those of solvent extraction for all the REEs. Y(III) and Eu(III) can be well separated using the prepared MSHM in the whole range of tested pH, which reveals potential of the developed MSHM for phosphor recycling.

Table 8. Desorption of Y(III) from MSHM by Various Eluents eluent

recovery%

0.25 mol/L EDTA 0.02 mol/L EDTA, pH = 3 0.67 mol/L HCl

39.9 49.5 95.7

■

AUTHOR INFORMATION

Corresponding Author

more fitted for the desorption of Y(III) loaded on MSHM. Therefore, 0.67 mol/L HCl was chosen as the eluent agent in this study. To examine reusability of the prepared MSHM, several consecutive adsorption−desorption cycles were performed. A 30 mg sample of MSHM was equilibrated with 8 mL of aqueous phase containing 0.2 mmol/L Y(III); the initial pH value of the aqueous phase was 3.0. HCl (0.67 mol/L) was chosen as eluent for the recovery of Y(III). Both adsorption and desorption experiments were conducted in a shake bath for 60 min. After each adsorption−desorption step, the MSHM was rinsed with deionized water for several times to remove the residue. As shown in Figure 13, there was no obvious loss in the initial binding affinity of MSHM for Y(III) in three cycles.

*E-mail: [email protected]. Tel.: +86 592 6376370. Fax: +86 592 6376370. Funding

This work was supported by “Hundreds Talents Program” from the Chinese Academy of Sciences, National Natural Science Foundation of China (21571179), Science and Technology Major Project of the Fujian Province, China (2015HZ0101), Xiamen Universities, and Research Institutions Jointing Enterprise Projects (3502Z20152009). Notes

The authors declare no competing financial interest.

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REFERENCES

(1) Castor, S. B.; Hedrick, J. B. Rare earth elements; Society for Mining, Metallurgy, and Exploration: Littleton, CO, 2006

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(2) Tan, Q.; Li, J.; Zeng, X. Rare earth elements recovery from waste fluorescent lamps: A review. Crit. Rev. Environ. Sci. Technol. 2015, 45, 749−776. (3) Zeng, S.; Du, D.; Bai, F.; Su, H. Bridging complexes of rare earth and cobalt cluster as catalyst precursors for Fischer−Tropsch synthesis. J. Rare Earths 2011, 29, 349−353. (4) Takeda, O.; Okabe, T. H.; Umetsu, Y. Recovery of neodymium from a mixture of magnet scrap and other scrap. J. Alloys Compd. 2006, 408−412, 387−390. (5) Keshav, A.; Chand, S.; Wasewar, K. L. Equilibrium studies for extraction of propionic acid using tri-n-butyl phosphate in different solvents. J. Chem. Eng. Data 2008, 53, 1424−1430. (6) Wellens, S.; Goovaerts, R.; Moller, C.; Luyten, J.; Thijs, B.; Binnemans, K. A continuous ionic liquid extraction process for the separation of cobalt from nickel. Green Chem. 2013, 15, 3160−3164. (7) Yadav, K. K.; Dasgupta, K.; Singh, D. K.; Anitha, M.; Varshney, L.; Singh, H. Solvent impregnated carbon nanotube embedded polymeric composite beads: An environment benign approach for the separation of rare earths. Sep. Purif. Technol. 2015, 143, 115−124. (8) Wu, D.; Sun, Y.; Wang, Q. Adsorption of lanthanum (III) from aqueous solution using 2-ethylhexyl phosphonic acid mono-2ethylhexyl ester-grafted magnetic silica nanocomposites. J. Hazard. Mater. 2013, 260, 409−19. (9) Zhang, Y. P.; Wang, X.; Liu, J. S.; Wu, L. L. Removal of copper (Cu2+) from water using novel hybrid adsorbents: kinetics and isotherms. J. Chem. Eng. Data 2013, 58, 1141−1150. (10) Florek, J.; Chalifour, F.; Bilodeau, F.; Lariviere, D.; Kleitz, F. Nanostructured hybrid materials for the selective recovery and enrichment of rare earth elements. Adv. Funct. Mater. 2014, 24, 2668−2676. (11) Turanov, A. N.; Karandashev, V. K.; Sukhinina, N. S.; Masalov, V. M.; Zhokhov, A. A.; Emelchenko, G. A. A novel sorbent for lanthanide adsorption based on tetraoctyldiglycolamide, modified carbon inverse opals. RSC Adv. 2015, 5, 529−535. (12) Rahmani-Sani, A.; Hosseini-Bandegharaei, A.; Hosseini, S. H.; Kharghani, K.; Zarei, H.; Rastegar, A. Kinetic, equilibrium and thermodynamic studies on sorption of uranium and thorium from aqueous solutions by a selective impregnated resin containing carminic acid. J. Hazard. Mater. 2015, 286, 152−163. (13) Wang, L.; Cheng, C.; Tapas, S.; Lei, J.; Matsuoka, M.; Zhang, J.; Zhang, F. Carbon dots modified mesoporous organosilica as an adsorbent for the removal of 2,4-dichlorophenol and heavy metal ions. J. Mater. Chem. A 2015, 3, 13357−13364. (14) Liu, Y. H.; Zhu, L. L.; Sun, X. Q.; Chen, J.; Luo, F. Silica materials doped with bifunctional ionic liquid extractant for yttrium extraction. Ind. Eng. Chem. Res. 2009, 48, 7308−7313. (15) Esser, B. K.; Volpe, A.; Kenneally, J. M.; Smith, D. K. Preconcentration and purification of rare-earth elements in naturalwaters using silica-immobilized 8-hydroxyquinoline and a supported organophosphorus extractant. Anal. Chem. 1994, 66, 1736−1742. (16) Dupont, D.; Brullot, W.; Bloemen, M.; Verbiest, T.; Binnemans, K. Selective uptake of rare earths from aqueous solutions by EDTAfunctionalized magnetic and nonmagnetic nanoparticles. ACS Appl. Mater. Interfaces 2014, 6, 4980−4988. (17) Lu, Z.; Zhao, X.; Zhu, Z.; Yan, Y.; Shi, W.; Dong, H.; Ma, Z.; Gao, N.; Wang, Y.; Huang, H. Enhanced recyclability, stability, and selectivity of CdS/C@Fe3O4 nanoreactors for orientation photodegradation of ciprofloxacin. Chem. - Eur. J. 2015, 21, 18528−18533. (18) Lu, Z.; Zhu, Z.; Wang, D.; Ma, Z.; Shi, W.; Yan, Y.; Zhao, X.; Dong, H.; Yang, L.; Hua, Z. Specific oriented recognition of a new stable ICTX@Mfa with retrievability for selective photocatalytic degrading of ciprofloxacin. Catal. Sci. Technol. 2016, 6, 1367−1377. (19) Lu, Z.; Zhao, X.; Zhu, Z.; Song, M.; Gao, N.; Wang, Y.; Ma, Z.; Shi, W.; Yan, Y.; Dong, H. A novel hollow capsule-like recyclable functional ZnO/C/Fe3O4 endowed with three-dimensional oriented recognition ability for selectively photodegrading danofloxacin mesylate. Catal. Sci. Technol. 2016, 6, 6513−6524. (20) Lu, Z.; Chen, F.; He, M.; Song, M.; Ma, Z.; Shi, W.; Yan, Y.; Lan, J.; Li, F.; Xiao, P. Microwave synthesis of a novel magnetic

imprinted TiO2 photocatalyst with excellent transparency for selective photodegradation of enrofloxacin hydrochloride residues solution. Chem. Eng. J. 2014, 249, 15−26. (21) Chen, Y.; Zhu, B.; Wu, D.; Wang, Q.; Yang, Y.; Ye, W.; Guo, J. Eu(III) adsorption using di(2-thylhexly) phosphoric acid-immobilized magnetic GMZ bentonite. Chem. Eng. J. 2012, 181−182, 387−396. (22) Marcus, Y.; Kertes, A. S. Ion exchange and solvent extraction of metal complexes; Wiley Interscience: New York. 1969. (23) Chiarizia, R.; Jensen, M. P.; Borkowski, M.; Ferraro, J. R.; Thiyagarajan, P.; Littrell, K. C. Third phase formation revisited: The U(VI), HNO3-TBP, n-dodecane system. Solvent Extr. Ion Exch. 2003, 21, 1−27. (24) Zhu, B.; Wu, D.; Yang, Y.; Chen, Y.; Li, W.; Guo, J.; Wang, Q. Selective removal of La(III) ions using super-paramagnetic nanosorbent coated by saponifiedsec-octylphenoxy acetic acid. J. Chem. Eng. Data 2012, 57, 553−560. (25) Dupont, D.; Binnemans, K. Rare-earth recycling using a functionalized ionic liquid for the selective dissolution and revalorization of Y2O3:Eu3+ from lamp phosphor waste. Green Chem. 2015, 17, 856−868. (26) Lagergren, S. Zur theorie der sogenannten adsorption geloster stoffe (On the theory of the so-called adsorption of dissolved substances). K. Sven. Vetenskapsakad. Handl. 1989, 24, 1−39. (27) Ho, Y. S.; McKay, G. Pseudo-second order model for sorption processes. Process Biochem. 1999, 34, 451−465. (28) Torrado, A.; Valiente, M. Kinetics characterization of ions release under dynamic and batch conditions. Strong acid and strong base type ion exchange resins. Solvent Extr. Ion Exch. 2008, 26, 240− 260. (29) Langmuir, I. The constitution and fundamental properties of solids and liquids, part I, solids. J. Am. Chem. Soc. 1916, 38, 2221− 2295. (30) Freundlich, H. Concerning adsorption in solutions. J. Phys. Chem. 1906, 57, 385−470. (31) Jin-Woo, L.; Sher, B. K.; Hadi, M. M.; Kalsoom, A.; Abdullah, M. A.; Muhammad, T. S. C.; Jongchul, S.; Haksoo, H. Development of Composite Membranes as Selective Adsorbent for Yttrium Ion. Int. J. Electrochem. Sci. 2013, 8, 12028−12036. (32) Xu, Y.; Kim, S. Y.; Ito, T.; Nakazawa, K.; Funaki, Y.; Tada, T.; Hitomi, K.; Ishii, K. Adsorption and separation behavior of yttrium and strontium in nitric acid solution by extraction chromatography using a macroporous silica-based adsorbent. J. Chromatogr. A 2012, 1263, 28− 33. (33) Zhao, Z. Y.; Sun, X. Q.; Dong, Y. M. Synergistic effect of doped functionalized ionic liquids in silica hybrid material for rare earth adsorption. Ind. Eng. Chem. Res. 2016, 55, 2221−2229. (34) Naseem, R.; Tahir, S. S. Removal of Pb(II) from aqueous/acidic solutions by using bentonite as an adsorbent. Water Res. 2001, 35, 3982−3986.

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DOI: 10.1021/acs.jced.6b00764 J. Chem. Eng. Data 2017, 62, 469−476