Fe3O4 Magnetic Hybrid Particles

Article pubs.acs.org/jced

Cite This: J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Flowerlike BSA/Zn3(PO4)2/Fe3O4 Magnetic Hybrid Particles: Preparation and Application to Adsorption of Copper Ions Baoliang Zhang,* Junjie Chen, Jiqi Wang, Yu Huyan, Hepeng Zhang, and Qiuyu Zhang*

J. Chem. Eng. Data Downloaded from pubs.acs.org by UNIV OF TEXAS SW MEDICAL CTR on 10/09/18. For personal use only.

MOE Key Laboratory of Material Physics and Chemistry Under Extraordinary Condition, Ministry of Education, Department of Applied Chemistry, School of Science, Northwestern Polytechnical University, Xi’an, 710072, China ABSTRACT: In this work, a novel flowerlike BSA/ Zn3(PO4)2/Fe3O4 magnetic hybrid particle is successfully synthesized through a simple and rapid one-step strategy. The kernel is to introduce Fe3O4 nanoparticles in the process of the precipitation and coordination reaction of Zn2+ ions with phosphate radical and BSA. The average diameter of the magnetic hybrid particle is 2.3 μm. The specific surface area is 51.61 m2/g, the average pore size is 15.30 nm. The saturation magnetization is 9.5 emu·g−1. The effects of the dosage of BSA and Fe3O4 nanoparticles on the properties of the magnetic hybrid particles are systematically investigated and optimized. The as-obtained BSA/Zn3(PO4)2/Fe3O4 magnetic hybrid particle is used for the removal of Cu2+ ions. The results reveal that the magnetic hybrid particles present excellent adsorption performance on Cu2+ ions with low concentration. The adsorption isotherms are fitted with the Langmuir equation. The maximum adsorption capacity is 12.56 mg·g−1 at 306 K estimated by the Langmuir model. It can maintain more than 90% of its initial capacity after 10 times of successive reuse. Meanwhile, the magnetic property brings great convenience to the reuse of the absorbent. mild reaction conditions. Yilmaz and co-workers18 have used BSA-Cu3(PO4)2 hybrid nanoflowers as solid-phase extraction reagents for Cd(II) and Pb(II) in water, foodstuffs, cigarettes, and hair samples. This material shows an excellent adsorption effect under different temperature and pH conditions. Pradyot Koley et al.19 have obtained silk fibroin-Cu3(PO4)2 hybrid nanoflowers using cheap and readily available silk protein and CuSO4 in a phosphate buffer solution. This material has good adsorption capacity on Pb(II), Cd(II), and Hg(II) ions; furthermore, needle-shaped multilayer structure nanoflowers have exhibited high adsorption capacity and better selectivity on Pb(II). In our work, a red-blood-cell-like BSA-Zn3(PO4)2 hybrid nanoflower was fabricated using Zn(II) particles as raw material.20 The results of copper ions adsorption research demonstrate that this material can achieve the rapid removal of Cu(II) in low concentration. All the above studies have confirmed that biomacromolecule-inorganic hybrid nanoflowers have tremendous potential application in the field of adsorptive separation. The effective separation of micro/nanoscale adsorbents has always been a nonnegligible section of its industrial applications. The separation and regeneration efficiency affect the heavy metal ions separation effect and production cost directly. Magnetic materials have prominent solid−liquid separation performance under the action of an external

1. INTRODUCTION In recent years, water pollution has become one of the most serious problems. As a significant part of environmental treatment, removing heavy metal ions from wastewater has attracted extensive attention. Therefore, exploring rapid and effective methods to eliminate heavy metal ions from wastewater has become a research hotspot.1−3 Copper ion is one of the most commonly contained heavy metal ions in wastewater. It has posed a serious threat to the ecosystem and human health due to its high toxicity. Consequently, the importance of removing copper ions from wastewater is selfevident. Currently, various methods have been developed for the removal of Cu2+ in wastewater, such as adsorptive separation materials,4−6 ion exchange,7 precipitation,8 membrane separation,9 reverse osmosis10 and so on. Among them, adsorptive separation materials are attractive because of their high separation efficiency, low cost, good separation effect, and reusability. The biomacromolecule-inorganic hybrid nanoflower is a new material found in recent years.11 It has received extensive attention in the fields of catalysis,12−14 detection,15,16 loading,17 and adsorption18−20 because of its high specific surface area and good stability. Because biological macromolecules are rich in functional groups which can chelate or coordinate with metal ions, biomacromolecule-inorganic hybrid nanoflowers should have obvious advantages in heavy metal ions removal. Meanwhile, many researchers have used it for the adsorption of heavy metal ions due to its simple preparation process, strong controllability of components, and © XXXX American Chemical Society

Received: June 28, 2018 Accepted: September 21, 2018

A

DOI: 10.1021/acs.jced.8b00544 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

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Figure 1. TEM image of Fe3O4 nanoparticles (A); SEM image of BSA/Zn3(PO4)2/Fe3O4 magnetic hybrid particles with different magnification (B, C, G); Surface scanning energy spectrum of BSA/Zn3(PO4)2/Fe3O4 magnetic hybrid particles (D); TEM image of BSA/Zn3(PO4)2/Fe3O4 magnetic hybrid particles with different magnification (E and F); particle size distribution curves of Fe3O4 nanoparticles and BSA/Zn3(PO4)2/ Fe3O4 magnetic hybrid particles (H)

magnetic field. They are particularly suitable for continuously automated operation, which can significantly improve the separation efficiency and reusability, and also reduce the production costs effectively. Thus, it has more obvious advantages compared with the traditional separation methods, such as filtration and centrifugation. At present, various kinds of magnetic nanomaterials have been synthesized. For instance, magnetic nanoparticles,21−23 magnetic nanofibers,24,25 and magnetic composite microspheres.26−31 The magnetic materials mentioned above have been used for the removal of heavy metal ions.30,32,33 However, the research on the preparation of magnetic hybrid nanoflowers by combining magnetic nanoparticles with biomacromolecule-inorganic hybrid nanoflowers has not been reported. To surmount the solid−liquid separation difficulties when the biomacromolecule-inorganic hybrid nanoflowers are used as adsorptive separation material, as well as to improve the reusability and stability, we have successfully prepared BSA/ Zn3(PO4)2/Fe3O4 magnetic hybrid particles (MHPs) with a simple one-step method under mild conditions. Magnetic nanoparticles participate in the formation of magnetic hybrid nanoflowers and endow them with external magnetic field responsiveness. In this paper, the structure and properties of BSA/Zn3(PO4)2/Fe3O4 MHPs were characterized systematically, and the effects of reaction conditions on their properties were investigated. In addition, the particles were used for the adsorption of Cu(II). The thermodynamics of the adsorption process was studied. The reusability and the stability of the magnetic particles were evaluated.

bought from American Amresco Co. Ltd. Water used in this work was ultrapure. 2.2. Preparation of Fe3O4 Nanoparticles. Fe3O4 nanoparticles were synthesized by a coprecipitation method, as described previously.26 Briefly, 8.20 g of FeCl3·6H2O and 5.80 g of FeSO4·7H2O were dissolved in 100 mL water in a flask. After dissolving completely, 5.40 g of NaOH dissolved in 50 mL of water was added under stirring for 40 min at 40 °C. The speed was 500 rpm. Then, the mixture was maintained at 80 °C for 30 min. The solid sample was separated and washed with water until pH = 7 using a magnetic field. The product was sealed and stored at room temperature. 2.3. Synthesis of BSA/Zn3(PO4)2/Fe3O4 MHPs. The appropriate amount of BSA was dissolved in 70 mL of PBS buffer containing a certain amount of Fe3O4 nanoparticles and introduced into the reactor with a mechanical stirrer. The stirring rate was controlled at 300 rpm; 5.6 mL of zinc acetate solution (0.05 g/mL) was added in the above mixture and the temperature was changed to 30 °C. After a 3 h reaction, the product was selected and washed with water three times. The products were dried by vacuum freeze-drying. The dosage of BSA and Fe3O4 was investigated. The additional amounts of BSA were 0.05, 0.03, 0.025, and 0.02 g. The dosage of Fe3O4 nanoparticles was 0.4, 0.3, 0.2, and 0.1 g. 2.4. Adsorption Study. According to our previous report,20,34 the adsorption properties of BSA/Zn3(PO4)2/ Fe3O4 MHPs were evaluated. Typically, the mixture with a total volume of 5 mL was prepared by ultrapure water and Cu2+ solution (15 mg/L). Subsequently, 2 mL of BSA/ Zn3(PO4)2/Fe3O4 MHPs (1 mg/mL) was added in the colorimetric tube. The adsorption process was implemented on a vertical mixing apparatus. The concentration of Cu2+ in the supernatant was determined at definite interval times. The adsorbents were separated from suspension via magnetic separation. The specific detection process was carried out as follows: First, 2 mL of Cu2+ solution was added into a colorimetric tube. After adding 5 mL of NH3−NH4Cl buffer and 0.3 wt % of SDDC aqueous solution in turn, the mixture was shaken up and left to stand for 5 min. Then, 5 mL of CCl4

2. EXPERIMENTAL SECTIONS 2.1. Chemicals. All the chemicals were analytically pure. Ferrous sulfate heptahydrate (FeSO4·7H2O), KCl, cupric sulfate (CuSO4·5H2O), ferric chloride hexahydrate (FeCl3· 6H2O), NaCl, hydrochloric acid, zinc acetate, KH2PO4, NH3· H2O, sodium diethyldithiocarbamate (SDDC), NH4Cl, carbon tetrachloride (CCl4), NaOH, Na2HPO4, edetate disodium (EDTA-2Na) were purchased from Sinopharm Chemical Reagent Co. Ltd. Bovine serum albumin (BSA, 60 KD) was B



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listed in Table. 1. From the obtained data, the nitrogen element only existed in BSA and BSA/Zn3(PO4)2/Fe3O4

was added and the mixture was shaken for 2 min. Moderate water was added to maintain a constant volume of 25 mL. Finally, the separated oil phase was tested via UV−vis at 440 nm. The computational formula of Cu2+ removal efficiency (η) was presented as ξ(%) =

(A 0 − A ) 100 A0

Table 1. Element Content Data of Raw Materials and Products sample

(I)

BSA Zn3(PO4)2 Fe3O4 BSA/Zn3(PO4)2/ Fe3O4

where 3A0 and 3A are the absorbance of the initial and residual Cu2+ solution, separately. The initial concentration of copper ions and adsorption time were investigated systemically. The concentrations of copper ions range from 1 to 5 mg·L−1. The adsorption time detected ran from 2 to 30 min, separately. The reusability and reproducibility of BSA/Zn3(PO4)2/ Fe3O4 MHPs were deeply studied. For a typical repeated cycle, the MHPs were separated from the solution and washed with EDTA-2Na (3 mmol/L) for three times and deionized water for twice under ultrasound. The same dye analysis process was carried out for 10 repetitive cycles. 2.5. Characterization. The morphology of Fe3O4 nanoparticles and BSA/Zn3(PO4)2/Fe3O4 MHPs was observed in transmission electron microscope (TEM, FEI TALOS-F200X) and field emission scanning electron microscope (FESEM, JSM-6700F). The particle size distribution of the particles were measured with Delsa Nano Series zeta potential and particle size analyzer (Beckman Coulter). The test process was carried out in deionized water. Powder X-ray diffraction (XRD) patterns were recorded on a Shimadzu XRD-6000 diffractometer using Cu Ka radiation. Thermal properties were determined by thermogravimetric analysis (TGA, METTLER, TOLEDO). Specific surface areas and pore size distribution were calculated from the results of N2 physisorption (Tristar3020, Micromeritics) by using the BET (Brunauer− Emmet−Teller). The elemental composition of hybrid microspheres was analyzed on an elemental analyzer (Vario EL III, Elementar Analysensysteme GmbH) with CHN mode. Conversion was analyzed by gravimetric method. The concentrations of the solution samples were determined using a UV−vis spectrophotometer (BlueStar, LabTech).

C element content (%)

H element content (%)

N element content (%)

47.00 0.091 0.036 6.428

7.534 1.998 1.182 5.031

13.76 0.023 0.015 2.416

MHPs. Therefore, the BSA content of BSA/Zn3(PO4)2/ Fe3O4 MHPs was calculated to be 17.56% by nitrogen element content. The TEM images of the magnetic hybrid particle fragments were displayed in Figure 1E,F. The three components in the nanoplates, making up the hybrid particles, were clearly visible in the images. Zn3(PO4)2 and Fe3O4 both existed in the form of nanoparticles. BSA bonded these two kinds of nanoparticles together to form the laminated layers. Therefore, BSA played the role of adhesive, because BSA had amino and carboxyl groups, which could coordinate with metal ions (Zn2+ and Fe3+/Fe2+). This was also confirmed by the formation of BSA/Zn3(PO4)2 particles in our previous work.20,35,36 Figure 1H presented the particle size distribution curves of Fe3O4 nanoparticles and BSA/Zn3(PO4)2/Fe3O4 MHPs. The curves displayed that the Fe3O4 nanoparticles had a wide size distribution. The diameter range of Fe3O4 nanoparticles was from 4.6 to 21 nm, and the average particle size was 11.45 nm. The BSA/Zn3(PO4)2/Fe3O4 MHPs had narrow size distribution, and the average particle size was 2.2 μm, which was consistent with the results observed by SEM. The XRD spectrum of Fe3O4 nanoparticles and BSA/ Zn3(PO4)2/Fe3O4 MHPs were displayed in Figure 2A. The characteristic diffraction peaks marked in blue inverted triangle (▼) can be perfectly indexed to Zn3(PO4)2·4H2O (JCPDS, card 33-1474). The good crystallinity of MHPs could be confirmed by the sharp diffraction peaks with high intensity. The additional and relatively weak peaks marked in red star (★) belong to Fe3O4 nanoparticles with inverse spinel structure (JCPDS, card 19-0629). The visible difference of the peak intensity was caused by different content of these two substances. Figure 2B was the FTIR spectrum of BSA/Zn3(PO4)2/ Fe3O4 MHPs. It can be seen that the typical absorption peaks of hybrid particles occurred at 3540−3300, 1649, 1554, 1110, and 947 cm−1 belonged to BSA. The strong characteristic absorption peaks at around 585 cm−1 were attributed to Fe−O vibration. The peaks at 1018, 947, and 614 cm−1 were attributed to P−O vibrations. These results demonstrated that the hybrid particles were formed by BSA, Zn3(PO4)2, and Fe3O4. Figure 2C showed the magnetic hysteresis loops of obtained products. The saturation magnetization was found to be 53.1 emu·g−1 and 9.5 emu·g−1 for Fe3O4 nanoparticles and BSA/ Zn3(PO4)2/Fe3O4 MHPs, respectively. Furthermore, no distinct hysteresis loop could be found and the remanence of the MHPs was about zero, indicating that the as-prepared magnetic particles were superparamagnetic. Although the saturation magnetization value of the magnetic hybrid particles was lower than that of the Fe3O4 nanoparticles, it could be

3. RESULTS AND DISCUSSION 3.1. Characterization of BSA/Zn3(PO4)2/Fe3O4 MHPs. The morphology of as-prepared materials was systematically characterized, and the results were presented in Figure 1. The Fe3O4 nanoparticles prepared via the coprecipitation method have nearly a spherical shape with a mean diameter of about 10 nm, as shown in Figure 1A. Such a small scale should be conducive to the preparation of composite hybrid particles. Figure 1B, C, and G were the SEM images of BSA/Zn3(PO4)2/ Fe3O4 MHPs with different magnifications. The hybrid particles appeared as a flat globular shape with a distinct single hole in the middle, which looked the same as blooming flowers (Figure 1B). As observed in the partial enlargement, it can be clearly observed that BSA/Zn3(PO4)2/Fe3O4 were stacked by numerous nanoplates. Gaps existed between neighboring layers; meanwhile, cracks could be seen clearly on the surface (illustrated in Figure 1G). Surface scan energy spectrum analysis was carried on the selected area. The presence of C, Zn, and Fe elements exhibited a uniform distribution, indicating the successful hybridization of BSA, zinc phosphate, and Fe3O4 nanoparticles. Element data were C



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Figure 2. XRD pattern of BSA/Zn3(PO4)2/Fe3O4 magnetic hybrid particles (A); FTIR spectrum of BSA/Zn3(PO4)2/Fe3O4 magnetic hybrid particles (B); The magnetization curves of Fe3O4 nanoparticles and BSA/Zn3(PO4)2/Fe3O4 particles (C); BET curves of Fe3O4 nanoparticles and BSA/Zn3(PO4)2/Fe3O4 particles (D); Pore size distribution curves of Fe3O4 nanoparticles and BSA/Zn3(PO4)2/Fe3O4 particles (E).

magnetic hybrid particles was higher, illustrating richer pores in the structure and the specific surface area was mainly caused by hybrid structure. Two typical peaks could be observed in the pore size distribution curve of BSA/Zn3(PO4)2/Fe3O4. They were attributed to the gaps between neighboring layers and the cracks on the surface, which corresponded to the SEM image shown in Figure 1G. The average pore diameter of BSA/ Zn3(PO4)2/Fe3O4 MHPs was calculated to be 15.30 nm. 3.2. Effect of the Dosage of BSA. In our previous work, it had been found that the dosage of BSA had significant impact on the properties of BSA/Zn3(PO4)2 hybrid particles.20 Therefore, the effect of the dosage of BSA on the morphology of BSA/Zn3(PO4)2/Fe3O4 MHPs was investigated, and the SEM images of the products prepared with different dosage of

effectively separated from their water dispersions under an external magnetic field within several seconds. The nitrogen adsorption−desorption isotherm of the Fe3O4 nanoparticles and BSA/Zn3(PO4)2/Fe3O4 MHPs was presented in Figure 2D. The adsorption isotherm showed a typeIV curve with a type H3 hysteresis loop according to IUPAC classification, indicating that stack-type structure existed in the hybrid particles. The BET surface area of BSA/Zn3(PO4)2/ Fe3O4 was calculated to be 51.61 m2·g−1, which gave great potential of heavy metal ions adsorption. As shown in Figure 2E, the pore size distribution was plotted by using the results calculated via the Barrett−Joyner−Halenda (BJH) method from the desorption branch of the isotherm. Compared with Fe3O4 nanoparticles, the pore size distribution curve of the D



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Figure 3. SEM image of BSA/Zn3(PO4)2/Fe3O4 magnetic hybrid particles prepared with different dosage of BSA: 0.02 g (A); 0.025 g (B); 0.03 g (C); 0.05 g (D).

180 °C was attributed to the escape of crystal water of Zn3(PO4)2·4H2O. The weight loss higher than 180 °C was attributed to the complete decomposition of the BSA molecules of the magnetic hybrid particles. With the increase of the additional amount of BSA, the organic component in the MHPs increased. As the dosage of BSA was 0.03 g, the mass loss of the sample was 18.85%. After removing the weight loss of crystalline water, the BSA content was coincident to the result calculated by elemental analysis. Figure 5 panels A, C, E, and G displayed the BET curves of BSA/Zn3(PO4)2/Fe3O4 particles prepared with different dosages of BSA. All the adsorption isotherms showed typeIV curves with type H3 hysteresis loop, pointing out the presence of stack-type pores. Figure 5 panels B, D, F, and H plotted the corresponding pore size distribution curves resulting from the isotherms. As the dosage of BSA went up to 0.03 g, it could be seen that the pores below 20 nm increased significantly. The average pore size, porosity, and specific surface area of the samples were listed in Table 2. It could be seen from the obtained data that the porosity and specific surface area exhibited a tendency of decrease after the first increase with the increase of BSA dosage. The decrease might be caused by the irregular morphology and the big crack on the magnetic hybrid particles, which can be observed in Figure 3D. 3.3. Effect of the Dosage of Fe3O4. The magnetic properties of BSA/Zn3(PO4)2/Fe3O4 MHPs prepared with different dosages of Fe3O4 were measured by VSM at 25 °C, presented in Figure 6. It could be found that the saturation magnetization was 7.3, 9.5, 11.0, and 15.2 emu g−1 for the dosage of 0.1, 0.2, 0.3, and 0.4 g, respectively. Clearly, the magnetic saturation value of BSA/Zn3(PO4)2/Fe3O4 magnetic hybrid particles increased sharply, which was attributed to the increased dose of Fe3O4. Meanwhile, the products all showed superparamagnetism.

BSA were presented (Figure 3). When the BSA dosage was less than 0.025 g, a single layer structure could be observed clearly in individual particles and the overall appearance of each particle was quadrilateral (Figure 3A and B). With an increase of dosage of BSA, the particle size obviously decreased and the morphology tended to be regular. As the dosage went up to 0.03 g, the number of the lamella increased significantly and the flowerlike hybrid particles were obtained. With a further increase of BSA to 0.05 g, the morphology turned to the spherical shape with some cracks, shown in Figure 3D. The TGA of BSA/Zn3(PO4)2/Fe3O4 MHPs with different dosages of BSA were demonstrated in Figure 4. Two characteristic weight loss peaks were observed from the TG curves. It could be speculated that the weight loss lower than

Figure 4. TGA curves of BSA/Zn3(PO4)2/Fe3O4 magnetic hybrid particles prepared with different dosages of BSA. E



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Figure 5. BET and pore size distribution curves of BSA/Zn3(PO4)2/Fe3O4 particles prepared with different dosage of BSA: 0.02 g (A, B); 0.025 g (C, D); 0.03 g (E, F); 0.05 g (G, H).

Figure 7 was the SEM images of BSA/Zn3(PO4)2/Fe3O4 MHPs prepared with different dosages of Fe3O4. As shown in Figure 7A,B, the morphology distinction was not obvious between the samples prepared with 0.1 and 0.2 g of Fe3O4, respectively. However, small Fe3O4 nanoparticles were attached to the surface of the hybrid particles at the dosage

of 0.3 g, and independent Fe3O4 nanoparticles were also observed in the visual field (Figure 7C). This phenomenon indicated that the dosage of Fe3O4 had reached its limitation. Furthermore, as the dosage of Fe3O4 went up to 0.4 g, Fe3O4 aggregates could be seen obviously around the hybrid particles in the view. The excess Fe3O4 could not be combined into F



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3.4. Adsorption Properties of BSA/Zn3(PO4)2/Fe3O4 on Cu2+ Ions. To confirm the influence of time on Cu2+ ions adsorption performance, kinetics experiments were actualized at 301 K. As shown in Figure 8A, the BSA/ Zn3(PO4)2/Fe3O4 MHPs exhibited an excellent performance in adsorption during the first 20 min, and the adsorbing capacity had no obvious augment with increasing time. It confirmed that the BSA/Zn3(PO4)2/Fe3O4 MHPs were able to reach adsorption equilibrium quickly. Therefore, the contact time of 30 min was sufficient to reach the equilibrium for BSA/ Zn3(PO4)2/Fe3O4 MHPs in the adsorption of Cu2+ ions, which was selected in the subsequent experiments. Figure 8B showed the adsorption isotherms of Cu2+ ions on BSA/Zn3(PO4)2/Fe3O4 MHPs at different temperatures. The adsorption curves indicated that the absorbency of Cu2+ ions increased as the temperature increased. Each single line illustrated the effect of the initial concentrations of Cu2+ ions on the adsorption at corresponding temperature. As observed, the adsorption capacity of the as-prepared magnetic hybrid particles increased initially and then gradually became constant with the increasing concentration of Cu2+ ions. Thus, the magnetic hybrid particles could be completely saturated with Cu2+ ions at enough high initial concentrations. The Langmuir and Freundlich models were applied to simulate the adsorption isotherms, illustrated in Figure 8C,D. The linear form of the Langmuir isotherm is described through the following equation:

Table 2. Nitrogen Adsorption Data of BSA/Zn3(PO4)2/ Fe3O4 Hybrid Particles Prepared with Different Dosages of BSA dosage of BSA (g)

BET (m2/g)

average pore size (nm)

pore volume (cm3/g)

0.02 0.025 0.03 0.05

14.14 25.40 51.61 40.81

29.10 15.92 15.30 14.94

0.0614 0.0960 0.2353 0.1760

Figure 6. Magnetization curves of BSA/Zn3(PO4)2/Fe3O4 magnetic hybrid particles prepared with different dosages of Fe3O4.

Ce C 1 = + e qe KLqm qm

BSA/Zn3(PO4)2/Fe3O4 MHPs and even had great impact on the morphology, as seen in Figure 7D. Thus, 0.2 g was the most suitable dosage of Fe3O4 for the preparation of BSA/ Zn3(PO4)2/Fe3O4 MHPs.

(II)

where Ce is the equilibrium concentration (mg·L−1), qe is the amount of adsorbate adsorbed per unit weight of adsorbent at the equilibrium state (mg·g−1), KL is Langmuir constant

Figure 7. SEM images of BSA/Zn3(PO4)2/Fe3O4 magnetic hybrid particles prepared with different dosages of Fe3O4: 0.1 g (A); 0.2 g (B); 0.3 g (C); 0.4 g (D). G



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Figure 8. Time dependence of adsorption quantity (A); plot of adsorption isotherm (B), Langmuir isotherms (C), Freundlich isotherms (D) for the adsorption of Cu2+ onto BSA/Zn3(PO4)2/Fe3O4 magnetic hybrid particles (error bars represent standard deviations, n = 3).

related to the affinity of binding sites (L·mg−1), qm is the maximum capacity (mg·g−1). The linear equation of Freundlich isotherm is presented by the following equation: 1 log qe = log KF + log Ce (III) n

The thermodynamic parameters were calculated according to a previous work.37,42 The results were shown in Table 4. Table 4. Thermodynamic Parameters for the Adsorption of Cu(II) onto the BSA/Zn3(PO4)2/Fe3O4 Magnetic Hybrid Particle

where KF is Freundlich constant (mg1‑n·Ln·g−1) related to adsorption capacity, and n is the heterogeneity factor related to adsorption intensity. The fitting parameters of the two models were given in Table 3. It could be seen from the R2 values that the

Langmuir

296 301 306

qm KL (mg·g−1) (L·mg−1) 9.56 11.15 12.56

0.25 0.24 0.26

Freundlich R2

KF (mg1−n· Ln·g−1)

1/n

R2

0.9932 0.9948 0.9866

1.7187 1.9574 2.2902

0.7054 0.7266 0.7466

0.9821 0.9852 0.9852

Gibbs free energy change ΔG° (J/mol)

enthalpy change ΔH° (kJ/mol)

entropy change ΔS° (J/mol K)

296 301 306

−545.59 −443.85 −315.83

−13.56

−42.27

ΔH°, ΔG°, and ΔS° were obtained through an empirical equation. Three temperatures were chosen for the data. The results showed that the ΔG° for the adsorption reaction was less than zero, which indicated that the reaction was spontaneous. ΔH° and ΔS° being less than zero indicated the reaction was exothermic and the entropy of the adsorption system was relatively low. To investigate the reusability of BSA/Zn3(PO4)2/Fe3O4 MHPs, the adsorption−desorption cycle was repeated 10 times; results shown in Figure 9A. It could maintain more than 90% of its initial capacity after 10 times of successive reuse. Figure 9B showed the SEM image of BSA/Zn3(PO4)2/Fe3O4 particles, which had been used for 10 times. The particles exhibited morphological stability, which can be confirmed by the image of BSA/Zn3(PO4)2/Fe3O4 particles with no change (Figure 1C). In view of the above results, it was clear to see that the particles exhibited excellent stability. Therefore, it can be concluded that the as-obtained magnetic hybrid particles can be used repeatedly as efficient adsorbents for the removal of Cu2+ ions with low concentration. Comparison of the performance of different adsorbents for Cu2+ was given in

Table 3. Langmuir, Freundlich Isotherm Constants and Correlation Coefficients for the Adsorption of Copper Ions onto BSA/Zn3(PO4)2/Fe3O4 Hybrid Particles temp (K)

temp (K)

adsorption process was better fitted to the Langmuir model, which indicated mainly monolayer adsorption in the procedure. Moreover, the maximum adsorption capacity of Cu2+ ions estimated from the Langmuir model was calculated to be 12.56 mg·g−1 at 306 K. The adsorption mechanism of Cu2+ on BSA/Zn3(PO4)2/Fe3O4 may not only be physical interaction. And the amino and carboxyl groups on BSA may play a more important role. These functional groups can interact with copper ions. H



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concluded that the obtained functional material exhibited excellent reusability, adsorption ability, and stability.

4. CONCLUSION In summary, we have realized the hybridization of BSA, zinc phosphate, and Fe3O4 nanoparticles, and a novel kind of flowerlike magnetic hybrid particles was synthesized. The asprepared BSA/Zn3(PO4)2/Fe3O4 MHPs are rich in the pores stacked by lamella and the surface functional groups from the natural macromolecule, which endows them with excellent adsorption performance of Cu2+ ions at low concentration. In addition, the magnetic hybrid particles exhibit outstanding magnetic properties, reusability, and stability. Therefore, the as-prepared BSA/Zn3(PO4)2/Fe3O4 MHPs are promising for broad application in the adsorption of Cu2+ ions from wastewater.

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AUTHOR INFORMATION

Corresponding Authors

*Tel.: +86-029-88431675. Fax: +86-029-88431653. E-mail: [email protected]. *E-mail: [email protected]. ORCID

Baoliang Zhang: 0000-0002-0290-4949 Qiuyu Zhang: 0000-0002-4823-5031 Funding

The authors are grateful for the financial support provided by the State Key Program of National Natural Science of China (Grant No. 51433008), the National Natural Science Foundation of China (Grant No. 21704084, 51711530233), and the Fundamental Research Funds for the Central Universities (Grant No. 3102017jc01001). Notes

Figure 9. Reusability of BSA/Zn3(PO4)2/Fe3O4 magnetic hybrid particles (A); SEM image of BSA/Zn3(PO4)2/Fe3O4 magnetic hybrid particles after using for 10 times (B) (error bars represent standard deviations, n = 3).

The authors declare no competing financial interest.

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Table 5. Compared with as-prepared BSA/Zn3(PO4)2/Fe3O4 MHPs with previously reported adsorbents, it could be Table 5. Performance of Adsorption Properties of Various Materials reuse stability

adsorbents for Cu2+ BSA/Zn3(PO4)2/ Fe3O4 magnetic chitosancitrate gel beads BSA/Zn3(PO4)2 hybrid particles magnetic iron oxide@graphene composites porous chitosan gel beads chemically crosslinked metalcomplexed chitosan

adsorption capacity (mg/g)

equilibrium time of adsorption (min)

residual activity

cycle numbers

refs

12.56

25

92.26%

10

294.11

3000

97.4%

1

this work 37

6.85

30

93.9

6

38

50.4

150

85%

8

39

130

720

33

240

40 60%

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REFERENCES

(1) Zou, Y.; Wang, X.; Khan, A.; Wang, P.; Liu, Y.; Alsaedi, A.; Hayat, T.; Wang, X. Environmental Remediation and Application of Nanoscale Zero-Valent Iron and Its Composites for the Removal of Heavy Metal Ions: A Review. Environ. Sci. Technol. 2016, 50, 7290− 7304. (2) Ahmed, M. J. K.; Ahmaruzzaman, M. A review on potential usage of industrial waste materials for binding heavy metal ions from aqueous solutions. J. Water Process Eng. 2016, 10, 39−47. (3) Mosayebi, E.; Azizian, S. Study of copper ion adsorption from aqueous solution with different nanostructured and microstructured zinc oxides and zinc hydroxide loaded on activated carbon cloth. J. Mol. Liq. 2016, 214, 384−389. (4) Sani, H. A.; Ahmad, M. B.; Hussein, M. Z.; Ibrahim, N. A.; Musa, A.; Saleh, T. A. Nanocomposite of ZnO with montmorillonite for removal of lead and copper ions from aqueous solutions. Process Saf. Environ. Prot. 2017, 109, 97−105. (5) Benzaoui, T.; Selatnia, A.; Djabali, D. Adsorption of copper (II) ions from aqueous solution using bottom ash of expired drugs incineration. Adsorpt. Sci. Technol. 2018, 36, 114−129. (6) Aflaki Jalali, M.; Dadvand Koohi, A.; Sheykhan, M. Experimental study of the removal of copper ions using hydrogels of xanthan, 2acrylamido-2-methyl-1-propane sulfonic acid, montmorillonite: Kinetic and equilibrium study. Carbohydr. Polym. 2016, 142, 124−132. (7) Siu, P. C. C.; Koong, L. F.; Saleem, J.; Barford, J.; McKay, G. Equilibrium and kinetics of copper ions removal from wastewater by ion exchange. Chin. J. Chem. Eng. 2016, 24, 94−100. (8) Figueroa, G. V.; Parga, J. R.; Valenzuela, J. L.; Vázquez, V.; Valenzuela, A.; Rodriguez, M. An Improved Process for Precipitating

41

I



Article

Cyanide Ions from the Barren Solution at Different pHs. JOM 2016, 68, 540−547. (9) Gao, F.; Du, X.; Hao, X.; Li, S.; An, X.; Liu, M.; Han, N.; Wang, T.; Guan, G. An electrochemically-switched BPEI-CQD/PPy/PSS membrane for selective separation of dilute copper ions from wastewater. Chem. Eng. J. 2017, 328, 293−303. (10) Ben-Sasson, M.; Lu, X.; Nejati, S.; Jaramillo, H.; Elimelech, M. In situ surface functionalization of reverse osmosis membranes with biocidal copper nanoparticles. Desalination 2016, 388, 1−8. (11) Altinkaynak, C.; Tavlasoglu, S.; Ozdemir, N.; Ocsoy, I. A new generation approach in enzyme immobilization: Organic-inorganic hybrid nanoflowers with enhanced catalytic activity and stability. Enzyme Microb. Technol. 2016, 93−94, 105−112. (12) Ge, J.; Lei, J.; Zare, R. N. Protein-inorganic hybrid nanoflowers. Nat. Nanotechnol. 2012, 7, 428−432. (13) Wang, L. B.; Wang, Y. C.; He, R.; Zhuang, A.; Wang, X.; Zeng, J.; Hou, J. G. A new nanobiocatalytic system based on allosteric effect with dramatically enhanced enzymatic performance. J. Am. Chem. Soc. 2013, 135, 1272−1275. (14) Yin, Y.; Xiao, Y.; Lin, G.; Xiao, Q.; Lin, Z.; Cai, Z. An enzymeinorganic hybrid nanoflower based immobilized enzyme reactor with enhanced enzymatic activity. J. Mater. Chem. B 2015, 3, 2295−2300. (15) Lin, Z.; Xiao, Y.; Yin, Y.; Hu, W.; Liu, W.; Yang, H. Facile synthesis of enzyme-inorganic hybrid nanoflowers and its application as a colorimetric platform for visual detection of hydrogen peroxide and phenol. ACS Appl. Mater. Interfaces 2014, 6, 10775−10782. (16) Ariza-Avidad, M.; Salinas-Castillo, A.; Capitan-Vallvey, L. F. A 3D microPAD based on a multi-enzyme organic-inorganic hybrid nanoflower reactor. Biosens. Bioelectron. 2016, 77, 51−55. (17) Zhang, Z.; Zhang, Y.; He, L.; Yang, Y.; Liu, S.; Wang, M.; Fang, S.; Fu, G. A feasible synthesis of Mn3(PO4)2@BSA nanoflowers and its application as the support nanomaterial for Pt catalyst. J. Power Sources 2015, 284, 170−177. (18) Yilmaz, E.; Ocsoy, I.; Ozdemir, N.; Soylak, M. Bovine serum albumin-Cu(II) hybrid nanoflowers: An effective adsorbent for solid phase extraction and slurry sampling flame atomic absorption spectrometric analysis of cadmium and lead in water, hair, food and cigarette samples. Anal. Chim. Acta 2016, 906, 110−117. (19) Koley, P.; Sakurai, M.; Aono, M. Controlled Fabrication of Silk Protein Sericin Mediated Hierarchical Hybrid Flowers and Their Excellent Adsorption Capability of Heavy Metal Ions of Pb(II), Cd(II) and Hg(II). ACS Appl. Mater. Interfaces 2016, 8, 2380−2392. (20) Zhang, B.; Li, P.; Zhang, H.; Li, X.; Tian, L.; Wang, H.; Chen, X.; Ali, N.; Ali, Z.; Zhang, Q. Red-blood-cell-like BSA/Zn3(PO4)2 hybrid particles: Preparation and application to adsorption of heavy metal ions. Appl. Surf. Sci. 2016, 366, 328−338. (21) Hedayatnasab, Z.; Abnisa, F.; Daud, W. M. A. W. Review on magnetic nanoparticles for magnetic nanofluid hyperthermia application. Mater. Des. 2017, 123, 174−196. (22) Zhu, X.; Chen, W.; Wu, K.; Li, H.; Fu, M.; Liu, Q.; Zhang, X. A colorimetric sensor of H2O2 based on Co3O4-montmorillonite nanocomposites with peroxidase activity. New J. Chem. 2018, 42, 1501−1509. (23) Wu, K.; Zhao, X.; Chen, M.; Zhang, H.; Liu, Z.; Zhang, X.; Zhu, X.; Liu, Q. Synthesis of well-dispersed Fe3O4 nanoparticles loaded on montmorillonite and sensitive colorimetric detection of H2O2 based on its peroxidase-like activity. New J. Chem. 2018, 42, 9578−9587. (24) Xu, G.; Zhang, S.; Zhang, Q.; Gong, L.; Dai, H.; Lin, Y. Magnetic functionalized electrospun nanofibers for magnetically controlled ultrasensitive label-free electrochemiluminescent immune detection of aflatoxin B1. Sens. Actuators, B 2016, 222, 707−713. (25) Lee, B.; Kim, B. C.; Chang, M. S.; Kim, H. S.; Na, H. B.; Park, Y. I.; Lee, J.; Hyeon, T.; Lee, H.; Lee, S. W.; et al. Efficient protein digestion using highly-stable and reproducible trypsin coatings on magnetic nanofibers. Chem. Eng. J. 2016, 288, 770−777. (26) Zhang, B.; Zhang, H.; Fan, X.; Li, X.; Yin, D.; Zhang, Q. Preparation of thermoresponsive Fe3O4/P(acrylic acid-methyl methacrylate-N-isopropylacrylamide) magnetic composite microspheres

with controlled shell thickness and its releasing property for phenolphthalein. J. Colloid Interface Sci. 2013, 398, 51−58. (27) Zhang, B.; Zhang, H.; Tian, L.; Li, X.; Li, W.; Fan, X.; Ali, N.; Zhang, Q. Magnetic microcapsules with inner asymmetric structure: Controlled preparation, mechanism, and application to drug release. Chem. Eng. J. 2015, 275, 235−244. (28) Zhang, B.; Wang, J.; Chen, J.; Li, H.; Wang, H.; Zhang, H. Fe3O4@P(DVB/MAA)/Pd composite microspheres: preparation and catalytic degradation performance. RSC Adv. 2016, 6, 100598− 100604. (29) Zhang, B.; Zhang, H.; Li, X.; Lei, X.; Li, C.; Yin, D.; Fan, X.; Zhang, Q. Synthesis of BSA/Fe3O4 magnetic composite microspheres for adsorption of antibiotics. Mater. Sci. Eng., C 2013, 33, 4401−4408. (30) Abd Ali, L. I.; Ibrahim, W. A.; Sulaiman, A.; Kamboh, M. A.; Sanagi, M. M. New chrysin-functionalized silica-core shell magnetic nanoparticles for the magnetic solid phase extraction of copper ions from water samples. Talanta 2016, 148, 191−199. (31) Zhang, B.; Huyan, Y.; Wang, J.; Chen, X.; Zhang, H.; Zhang, Q. Fe3O4@SiO2@CCS porous magnetic microspheres as adsorbent for removal of organic dyes in aqueous phase. J. Alloys Compd. 2018, 735, 1986−1996. (32) Mohammed, L.; Gomaa, H. G.; Ragab, D.; Zhu, J. Magnetic nanoparticles for environmental and biomedical applications: A review. Particuology 2017, 30, 1−14. (33) Mutneja, R.; Singh, R.; Kaur, V.; Wagler, J.; Fels, S.; Kroke, E. Schiff base tailed silatranes for the fabrication of functionalized silica based magnetic nano-cores possessing active sites for the adsorption of copper ions. New J. Chem. 2016, 40, 1640−1648. (34) Liu, Y.; Chen, L.; Yang, Y.; Li, M.; Li, Y.; Dong, Y. The efficient removal of Cu(II) from aqueous solutions by Fe3O4@hexadecyl trimethoxysilane@chitosan composites. J. Mol. Liq. 2016, 219, 341− 349. (35) Zhang, B.; Li, P.; Zhang, H.; Wang, H.; Li, X.; Tian, L.; Ali, N.; Ali, Z.; Zhang, Q. Preparation of lipase/Zn3(PO4)2 hybrid nanoflower and its catalytic performance as an immobilized enzyme. Chem. Eng. J. 2016, 291, 287−297. (36) Zhang, B.; Li, P.; Zhang, H.; Fan, L.; Wang, H.; Li, X.; Tian, L.; Ali, N.; Ali, Z.; Zhang, Q. Papain/Zn3(PO4)2 hybrid nanoflower: preparation, characterization and its enhanced catalytic activity as an immobilized enzyme. RSC Adv. 2016, 6, 46702−46710. (37) Mi, F. L.; Wu, S. J.; Chen, Y. C. Combination of carboxymethyl chitosan-coated magnetic nanoparticles and chitosan-citrate complex gel beads as a novel magnetic adsorbent. Carbohydr. Polym. 2015, 131, 255−263. (38) Zhang, B.; Li, P.; Zhang, H.; Li, X.; Tian, L.; Wang, H.; Chen, X.; Ali, N.; Ali, Z.; Zhang, Q. Red-blood-cell-like BSA/Zn3(PO4)2 hybrid particles: Preparation and application to adsorption of heavy metal ions. Appl. Surf. Sci. 2016, 366, 328−338. (39) Yang, Z. F.; Li, L. Y.; Hsieh, C. T.; Juang, R. S.; Gandomi, Y. A. Fabrication of magnetic iron Oxide@Graphene composites for adsorption of copper ions from aqueous solutions. Mater. Chem. Phys. 2018, 219, 30−39. (40) Zhao, F.; Yu, B.; Yue, Z.; Wang, T.; Wen, X.; Liu, Z.; Zhao, C. Preparation of porous chitosan gel beads for copper(II) ion adsorption. J. Hazard. Mater. 2007, 147, 67−73. (41) Chen, A. H.; Yang, C. Y.; Chen, C. Y.; Chen, C. Y.; Chen, C. W. The chemically crosslinked metal-complexed chitosans for comparative adsorptions of Cu(II), Zn(II), Ni(II) and Pb(II) ions in aqueous medium. J. Hazard. Mater. 2009, 163, 1068−1075. (42) Mi, F. L.; Wu, S. J.; Lin, F. M. Adsorption of copper(II) ions by a chitosan-oxalate complex biosorbent. Int. J. Biol. Macromol. 2015, 72, 136−144.

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