Synthesis of Novel Magnetic Microspheres with Bi-metal Oxide Shell

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Synthesis of Novel Magnetic Microspheres with Bi-metal Oxide Shell for Excellent Adsorption of Oxytetracycline Lili Lian, Jinyi Lv, and Dawei Lou ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.7b02320 • Publication Date (Web): 13 Sep 2017 Downloaded from http://pubs.acs.org on September 14, 2017

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ACS Sustainable Chemistry & Engineering

Synthesis of Novel Magnetic Microspheres with Bimetal Oxide Shell for Excellent Adsorption of Oxytetracycline Lili Lian, Jinyi Lv and Dawei Lou* Department of Analytical Chemistry, Jilin Institute of Chemical Technology, No. 45 Chengde Street, Jilin 132022, P.R. China Corresponding Author * Dawei Lou. E-mail: [email protected]. Fax/Tel: 86-432-63083163.

KEYWORDS: magnetic, adsorption, antibiotic, oxytetracycline, core-shell

ABSTRACT: Multifunctional magnetic microspheres (Mag@ZnO-Co3O4) with bi-metal oxide shell were synthesized via a facile method. The Mag@ZnO-Co3O4 composite was characterized through vibrating sample magnetometer, N2 adsorption analysis, FTIR, powder Xray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy analyses. The structural analysis showed that the as-prepared microsphere possessed a mean diameter of 150 nm, a bi-metal oxide shell thickness of ~10.0 nm and a magnetic core, which endowed it with good dispersibility, strong magnetism, and excellent adsorption property for oxytetracycline (OTC). Several experimental conditions, such as solution pH, adsorption time, OTC concentration, and ionic strength were systematically investigated. The Mag@ZnO-Co3O4 composite exhibited a fast adsorption rate, that is, the equilibrium was

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reached within 90 min, when the concentration of OTC was between 10 and 30 mg/L. The composite showed favorable performance for the adsorption of OTC in the pH range of 5–9. According to the adsorption isotherms and kinetics, the removal of OTC was efficient and obeyed the pseudo-second-order rate equation and Langmuir adsorption model. INTRODUCTION The discovery of antibiotics is one of the greatest scientific achievements in the 20th century.1,2 However, antibiotics are regarded as environmental contaminants due to their potential long-term adverse effects and complex vicious cycle of transformation and bioaccumulation in the environment.3 Given that sewage treatment plants (STPs) are geared towards traditional pollutants, such as metal and organic pollutants, antibiotics are not efficiently removed in the environment.4-5 Hence, treatment of antibiotics-polluted environmental water has been a great challenge to the health care sector in the 21st century.6 Scholars must develop a highly efficient method for eliminating antibiotics in aquatic environment. Physical and chemical processes have been employed to remove antibiotics in environmental

waters

and

wastewaters;

these

processes

include

photo-catalytic,

flocculation/coagulation, oxidation, fungal treatment, adsorption, and membrane techniques.7-12 Adsorption is the most commonly used technique because of

its facile operation, high

efficiency, cost effectiveness, and low energy requirement; moreover, this process does not produce secondary pollutants. Many potential adsorbents have been applied in pollutant adsorption and degradation.13-15 In recent years, various adsorbents, such as activated carbon,16 zeolites17 and ion exchange resins18 have been used for adsorption of antibiotics from water. Specifically, Zhou19 et al. reported that tetracyclines in water can be rapidly removed using montmorillonite clay. Fu20 used powdered activated carbon to remove six frequently used


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quinolone (QN) antibiotics base on hydrophobic interaction, electrostatic interaction, and π–π dispersion force. Copper-based metal organic framework materials also exhibited an excellent adsorptive capacity for toxic sulfonamide antibiotics mainly through p–p stacking, hydrogen bonding and electrostatic interactions.2 Although some of these mentioned adsorbents show a good adsorption capacity for antibiotics, the difficulty in collecting them from the solution impedes their further application. Magnetic nanocomposites are a new generation of separation media designed to face this challenge. Previous researches indicated that incorporating magnetic nanoparticles into multifunctional shell facilitates convenient recovery of the adsorbent and the absorbed contaminants from the treated solution by magnetic separation.21-24 In the present work, we demonstrate a facile, mild and eco-friendly method for synthesis of magnetic microspheres with a magnetic core and a bi-metal oxide shell (ZnO-Co3O4). The asfabricated magnetic microspheres (Mag@ZnO-Co3O4 ) not only retain the functions of the magnetic nanoparticles but also provide additional unique physiological activities conferred by the bi-metal oxide shell. To investigate the growth mechanism for the unique core/shell Mag@ZnO-Co3O4 microspheres, we performed a series of experiments by using different dosages of Zn and Co as raw materials. Under the optimal Zn/Co molar ratio, the as-synthesized microspheres exhibited a fast adsorption rate for the removal of oxytetracycline (OTC), one of the most widely used tetracyclines antibiotic from aqueous solution. The effects of OTC concentration, coexisting ionic species and pH conditions were also evaluated to investigate and quantify the operational processes affecting the uptake capacity of the composite in the treated solution. EXPERIMENTAL SECTION


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Materials and Reagents. OTC (≥ 95% by HPLC) was purchased from Aladdin Chemistry Co., Ltd (Tianjin, China). A stock solution of OTC (1000 mg/L) was prepared by dissolving a required amount of OTC in methanol. The solution was diluted to the desired concentrations by adding water. Ferric chloride hexahydrate (FeCl3·6H2O), Cobalt nitrate hexahydrate (Co(NO)3 · 6H2O), and zinc nitrate hexahydrate (Zn(NO3)2 · 6H2O) were purchased from Damao chemical reagent factory (Tianjin, China). Pure water was obtained from a Milli-Q water purification system (Millipore Ltd., Bedford, MA, USA) and used for all dilutions. All other chemicals were of analytical grade and used as received. Preparation of Bi-metal Oxide Modified Magnetic Microspheres. Scheme 1 illustrates the strategy for preparing the core-shell Mag@ZnO-Co3O4 nanoadsorbents. The Fe3O4 nanoparticles were synthesized through a facile solvothermal process according to our previous report.25 In a beaker, 1.35 g of Fe(III) salts, 3.60 g of anhydrous sodium acetate, and 1.00 g o polyethylene glycol (Mr=2000) as a reductant were mixed in 40 mL of ethylene glycol. The mixture was continuously agitated by a magnetic stirrer for 30 min to form a homogeneous yellow solution. The resulting mixture was transferred into the hydrothermal synthesis reactor and heated at 190 °C for 8 h. The mixture was cool down to room temperature, and the black precipitate was magnetically separated and washed several times with ethanol and deionized water. The synthesized Fe3O4 nanoparticles were then dried at 60 °C under vacuum. ZnO-Co3O4 shell-coated microspheres were prepared via a facile hydrothermal process. Fe3O4 nanoparticles were used as seeds for subsequent ZnO-Co3O4 shell growth, by adding 0.1 g of Fe3O4 nanoparticles to a homogenous solution consisting of 30 mL of deionized water, 1 mmol Zn(NO3)2·6H2O, 1 mmol Co(NO3)2·6H2O, 4 mmol ammonium fluoride and 8 mmol urea. The mixture was transferred to a 50 mL hydrothermal synthesis reactor and heated at 120 oC for 6 h.


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The resulting magnetic microspheres were collected by a magnet, washed thoroughly with deionized water to remove the residues, and dried under vacuum at 60 °C for 6 h. After annealed at 350 oC in air for 2 h, Mag@ZnO-Co3O4 magnetic microspheres were successfully prepared. Magnetic composites were also prepared using the same technique with various Zn/Co molar ratios to determine the effect of the molar ratio on the adsorbent characteristics. Scheme 1. Schematic of the Synthesis and Application of Core-shell Mag@ZnO-Co3O4 Microspheres.

Characterizations. The surface area of Mag@ZnO-Co3O4 was measured using ASAP 2010 Micrometrics instrument (USA) by Brunauer-Emmett-Teller (BET) method. Magnetic property was assessed at 300 K on a superconducting quantum interference device magnetometer (MPMS XL-5, Quantum Design, USA). FTIR analysis was conducted through a Vertex 80V spectrometer (Bruker, Germany) within the range of 4000 cm−1–400 cm−1. Powder X-ray diffraction (XRD) analysis was conducted at room temperature by using a Bruker D8 Advanced X-ray diffractometer (Bruker Optik GmbH, Germany) with the Cu-Kα radiation in the range 2θ=10°–90°. X-ray photoelectron spectra (XPS, Thermo Fisher Scientific, K–Alpha, USA) were recorded to ascertain the chemical compositions and element chemical state in Mag@ZnOCo3O4. The morphology of the Mag@ZnO-Co3O4 was observed by a field-emission transmission


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electron microscope (TEM, JEOL, JEM-2100F, Japan) and scanning electron microscope (SEM, JEOL, JSM-7500F, Japan) equipped with an energy dispersive spectrometer (EDS, Oxford, XMax, UK). The surface charge of the product was measured on a zeta-potential analyzer (Malvern, Zetasizer Nano ZS90, UK). Oxytetracycline Analytical Method. The OTC residue remaining in the supernatant was analyzed at 280 nm through ultra-high-performance liquid chromatography (UPLC, Waters, U.S.A.) with a TUV detector using a BEH C18 column (Waters, 2.1 mm×50 mm, 1.7 µm particle size) at 30 oC. The mobile phase was consisted of 10% methanol, 20% acetonitrile and 70% oxalic acid buffer (0.02 mol/L). The flow rate was maintained at 0.2 mL/min and the injection volume was set as 10 µL. Pollutant Adsorption Experiments. Scheme 1 shows the application of the nanoadsorbent in the adsorption process. First, magnetic composites prepared using different dosages of Co and Zn raw materials were used as adsorbent to uptake OTC from the solution to validate the optimal Zn/Co molar ratio. The effect of coexisting ions on the adsorption was studied by shaking 0.0025 g of the nanoadsorbent with 10 mL of OTC at the initial dye concentration of 10 mg/L. The equilibrium time was 6 h. The effect of pH (2–11) on the adsorption was also evaluated under the same testing conditions. The pH of the sample solution was adjusted by adding 0.1 mol/L HCl and NaOH solutions. Adsorption isotherm experiments were conducted with a constant dosage of 0.0025 g of the adsorbent and initial OTC concentrations between 20 and 200 mg/L (V=10 mL) at 298 K under the same testing conditions. For the effect of concentration on the adsorption, 0.0025 g of Mag@ZnO-Co3O4 was suspended in 10 mL of the OTC solution (10–30 mg/L). In brief, 1 mL of the samples was taken at different intervals for each condition. The


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magnetic adsorbent was finally separated by a magnet, and the OTC residue remaining in the supernatant was determined by UPLC analysis. Adsorption capacity (qt mg/g) at time t was calculated using the following equation: qt =

(C0 − C t ) × V m

(1)

where C0 (mg/L) is the initial concentration; Ct (mg/L) and Ce (mg/L) are the remaining concentrations of OTC in solution at time t and equilibrium, respectively; m is the mass of adsorbent (g); and V is the volume of the solution (mL).

RESULTS AND DISSCUSSION Characterization of Mag-ZnO@Co3O4. As shown in Figure. 1, the magnetization curve indicates the ferromagnetic feature of the nanocomposite. The saturation magnetization (Ms) is 30.1emu/g; this high value allows the pollutants-adsorbed microspheres to aggregate together and then separate from the treated samples by using a magnet within 1 min. The N2 adsorptiondesorption isotherm of Mag@ZnO-Co3O4 is presented in Figure S1. The BET surface area of the prepared magnetic microspheres is measured to be 25.40 m2/g.

Figure 1. Magnetic hysteresis loop of Mag@ZnO-Co3O4.


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The XRD patterns of Fe3O4 and as-prepared Mag@ZnO-Co3O4 magnetic microspheres are presented in Figure 2. As shown in Figure 2, all peaks of Fe3O4 correspond to the standard diffraction patterns of the cubic inverse spinel lattice structure of Fe3O4 (JCPDS No. 19-629). 26 The new diffraction peaks indicated by diamonds can match well with the diffraction from the (100), (002), (101), (103), (110) and (202) planes of wurtzite ZnO (JCPDS No. 36-1451).27 The other peaks indicated by asterisks correspond to the diffractions of the face-centered-cubic spinel Co3O4 (JCPDS No. 42-1467); this finding suggests that the multifunctional shell was composed of both ZnO and Co3O4.28-29 However, distinguishing Fe2O3 from Fe3O4 in the XRD patterns was difficult due their very similar structures. Therefore, other characterization methods, namely, XPS and High-resolution TEM analyses were conducted to ascertain the element chemical state and crystallite size of Mag@ZnO-Co3O4.

Figure 2. XRD patterns of Fe3O4 (a), and Mag@ZnO-Co3O4 nanoadsorbent (b). The XPS survey spectrum in Figure 3a indicates the presence of Fe, Zn, Co, and O. Figure 3b shows the high-resolution spectrum of the Fe 2p region. The core-level binding energy peaks at 711 and 725 eV match well with Fe 2p3/2 and Fe 2p1/2. Moreover, the Fe 2p 3/2 and 2p 1/2 main peaks of the sample are accompanied by a shakeup satellite structure, which is the fingerprints of the electronic structures of Fe3+, at 719 eV (indicated by arrow), indicating the


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absence of Fe2+.30-31 Basing on these results, we conclude that Fe3O4 was transformed into γFe2O3 form during the annealing process. As shown in Figure 3c, the characteristic peaks of Co 2p3/2 and Co 2p1/2 at 780 and 795 eV, are in accordance with the presence of Co3O4, indicating that spinel Co3O4 successfully deposited on the magnetic nanoparticles surface.32 Additionally, the spinorbit splitting between the two peaks is 15 eV, consistent with the reported data of spinel Co3O4.33 Notably, after the incorporation of Co3O4 with ZnO, the lattice parameters did not change, and the crystal structure was maintained (Figure 3).

Figure 3. XPS spectra of Mag@ZnO-Co3O4 microspheres: (a) full spectrum, (b) Fe 2p, (c) Co 2p and (d) Zn 2p spectrum. EDS analysis were performed to determine the chemical compositions of the as-obtained Mag@ZnO-Co3O4. As shown in Figure 4a, the EDS spectrum peaks belonging to Zn and Co, with weight percentages of about 12% and 6% respectively, indicating the homogenous distribution of these elements in the magnetic microspheres. Consistent with the XRD and XPS


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results, the EDS data confirm the successful modification of a thin layer of ZnO-Co3O4. The morphologies of the Mag@ZnO-Co3O4 and its core-shell structure were characterized using SEM and TEM images. The SEM image shows that the as-synthesized microspheres mainly present a spherical structure with an average diameter of 150 nm (Figure 4b). The highmagnification SEM image (Inset of Figure 4b) reveals the rough surface feature of Mag@ZnOCo3O4. The morphology of the received adsorbent (Figure 4c) has an obscure interface between the magnetic core and ZnO-Co3O4 shell regions. The morphology differs from the reported coreshell magnetic microspheres, such as SiO2, dopamine and polyethyleneimine,34-37 possibly due to the similar crystal structure between the magnetic core and the bi-metal oxide shell. The highresolution TEM was used to reveal the detailed microstructures and crystallite size of the microspheres (Figure 4d and 4e). The bi-metal oxide layer is as thin as ~10 nm. The spaces 0.482 and 0.264 nm in the core regions correspond to the (111) and (310) planes of γ-Fe2O3, indicating that the Fe3O4 core changed into γ-Fe2O3 after calcination.38 The marked d-spacing of 0.467 nm in the shell region is in good agreement with the d-spacing of (111) plane of Co3O4.39-41 Moreover, the interplanar spacing of 0.248 nm corresponds well to the spacings of the (101) lattice planes of ZnO.30


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Figure 4. (a) EDX analysis, (b) SEM image; insets: the high magnification SEM image, (c) TEM, and (d, e) HRTEM images of Mag@ZnO-Co3O4.

Synthesis Mechanisms for Mag@ZnO-Co3O4 Microspheres. The core-shell microspheres with a magnetite core and a ZnO-Co3O4 shell were synthesized according to Scheme 1. In the first step, Fe3O4 nanoparticles were directly obtained by reduction of Fe3+ at 190 °C in the presence of polyethylene glycol and ethylene glycol under alkaline media. In the second step, the metal complexes were first obtained by reacting Zn2+ and Co2+ with F−. When the solution temperature was increased to 120 oC, the content of CO2 and OH− increased gradually because of urea decomposition (CO(NH2)2 + H2O → 2NH3 + CO2; H2O + NH3 → OH− + NH4+). With


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increasing of OH−, Zn(OH)2 was generated and agglomerated on the Fe3O4 nanoparticles surface due to the low solubility-product constant value (Ksp). The CO32− produced by CO2 hydrolyzation could react with Co2+, instead of F−, to form metal basic carbonate because of strong affinity (CoF+ + xOH− +0.5(2-x) CO32− + nH2O → Co(OH)x(CO3)0.5(2-x)·nH2O + F−).42 Finally, a thin layer of ZnO@Co3O4 shell was developed in the final annealing treatment (Zn(OH)2 → ZnO + H2O; Co(OH)x(CO3)0.5(2−x)·nH2O + O2→Co3O4 +CO2 + H2O).43,44 During synthesis, the presence of F− is necessary for the development of ZnO-Co3O4 layer shell. A system consisting of irregular separate Fe3O4@ZnO nanosheets and individual Co3O4 nanorods was obtained in the absence of F−. Scholars reported different methods for synthesis of pCo3O4/n-ZnO heterojunction. The well-dispersed core-shell nanoadsorbent evidently differs from the reported p-Co3O4/n-ZnO heterojunction45-47 and [email protected] The monodispersed magnetic Fe3O4 nanoparticles are believed to play a beneficial role in the functional behavior, and serve as substrates to facilitate subsequent metal oxide shell growth. Otherwise, hierarchical or clustered bi-metal oxide is easily received, thereby diminishing the magnetic response and reducing the recycle efficiency.

Determination of the Optimal Zn/Co Molar Ratio. A series of magnetic composites with different dosages of Co and Zn raw materials was tested as adsorbent for OTC adsorption. The final phases and adsorption amount of OTC for the obtained magnetic nanosorbent can be seriously affected by the amount of Zn and Co raw materials. As shown in Figure 5a, the adsorption capacity increased with increasing amount of Zn and Co raw materials from 0.5 mmol to 1 mmol. However, the adsorption amount decreased slightly with further increase in Zn and Co raw materials to 2 mmol; under this condition, the surplus Zn2+ and Co2+ generate other byproduct, thereby reducing the adsorption performance. In addition, the adsorption amount of


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OTC decreased as the dosage of the Zn2+ and Co2+ changed to 2:1 or 1:2. The differences in the adsorption capacity of the mentioned adsorbents can be attributed to their different structures. The SEM and TEM analyses show that the homogeneous core/shell microspheres were synthesized using 1 mmol Zn2+ and Co2+ as raw material (Figure 4). The well-defined bi-metal oxide shell and the small size of the microspheres are believed to play a beneficial role in improving the adsorption capacity. However, a portion of the separated ZnO nanosheet and Co3O4 nanorods would mix in the core-shell microspheres when the ratio of Zn2+ and Co2+ was changed to 2:1 and 1:2. As a consequence, the co-existence of ZnO and Co3O4 phases, with intimate contact between Mag@ZnO-Co3O4 magnetic microspheres, led to reduce the adsorption performances.


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Figure 5. (a) Adsorption of OTC by magnetic composites with different Zn and Co raw materials; effect of (b) ion species, (c) pH, and (d) concentration on OTC adsorption.

Interferences and Complexation Mechanism. The coexisting ions could compete with OTC for adsorption by Mag@ZnO-Co3O4; as a result, these species can deteriorate the adsorption capacity for OTC. To study the influence of coexisting ionic species on the adsorption of OTC by the magnetic nanocomposite, we investigated several commonly encountered inorganic salts (NaCl, CaCl2, and KNO3) in tap water and environmental water samples (Figure 5b). Interestingly, the presence of Na+ and Cl− ions and the increase in the NaCl concentration have a neglectable influence on the OTC adsorption. By contrast, the presence of KNO3 and CaCl2 decreased the adsorption capacity for OTC. These results indicate that the OTC uptake by Mag@ZnO-Co3O4 was not influenced by the increase in ionic strength, but significantly influenced by the coexisting ionic species. The phenomenon can be associated with the surface properties of the nanoadsorbent and the molecular structure of OTC. OTC contains several electron donor groups such as diketone, dimethylammonium and tricarbonylmethane, which could complex with high polarizing transition metals by forming stable metal-OTC complexes. Consequently, the Mag@ZnO-Co3O4 microspheres, with a bi-metal oxide shell, can easily attract the OTC molecule, leading to the formation of Zn-OTC and Co-OTC complexes. Adsorption of OTC in water is affected by the coexisting metal ions, which can chelate. Consequently, binding of Ca2+ with the diketone, dimethylammonium and β-keto-enol groups decreased the availability of N-electrons of OTC, resulting in inhibition of OTC-adsorption.49 Not only the metal types, but some anions in the water environment also play an important role in the adsorption of OTC. For instance, NO3− could compete with the electron-rich functional groups of OTC for the binding of metal. Hence,


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a decline in the OTC uptake is observed when the concentration of KNO3 increased from 0 to 0.1 mol/L. All these phenomena certified that OTC adsorption by the magnetic composite was realized by the formation of surface complexes at the active sites on the surface of the adsorbent. The complexation between OTC and Mag@ZnO-Co3O4 was further certified by the FT-IR spectra. Figure S2 shows FTIR spectra of OTC, and the Mag@ZnO-Co3O4 microspheres before and after adsorption of OTC. As expected, the peaks at 661, 590, and 453cm−1 belonging to CoO, Fe-O, and ZnO-O stretching vibration of Mag@ZnO-Co3O4, indicating the successful coated of bi-metal oxide shell (Figure S2a and 2b). By comparison with OTC spectrum, it was found from the spectrum of OTC-adsorbed microspheres that the characteristic stretching absorption of phenolic-OH at 3317 cm−1 partially shifted to 3379 cm−1, and a new peak appeared at 1394 cm−1, implying cation–π interactions and the formation of surface complexation between OTC and the surface active sites of [email protected] Moreover, in order to study the interferences in real water, the uptake of OTC by the Mag@ZnO-Co3O4 composite was demonstrated for the treatment of tap water sample (Jilin, China). As illustrated in Figure S3, the OTC uptake capacity in tap water was found to be slightly lower compared with pure water. Although the presence of cation and anion in the tap water causes a slight decrease on the adsorption capacity, the favorable adsorption performance and magnetic recovery capability of the Mag@ZnO-Co3O4 composite are significant for its practical use in treating real water bodies.

Effect of pH and Electrostatic Interaction. The pH of the solution is one of the significant factors for the uptake of pollutants, which is essential to understand the effect of the electrostatic interactions on the adsorption process. The adsorption of OTC using Mag@ZnO-Co3O4 was investigated within the pH range of 2–11 with an initial concentration of 10 mg/L at 298 K.


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As shown in Figure 5c, the adsorption of OTC is more favorable at neutral pH over acidic and basic conditions; from pH 2 to pH 5, the adsorption capacity linearly increases, while above pH 5 and up to pH 9 the adsorption capacity is relatively stable with the highest value at pH 7; above pH 9, the adsorption tends to progressively decrease again. The results can be associated with the surface properties of the nanoadsorbent and the pH-dependent speciation of OTC. Zeta potential measurements results indicate that the surface of Mag@ZnO-Co3O4 is with negative charges over the pH range 5–11 (Figure S4). Moreover, OTC is one of the typical tetracyclines that form a series of species at different pH values. The charge of OTC molecule could be positive (pH < 3.53), zwitterion (3.53< pH < 9.58) or negative (pH > 9.58).52-53 At pH < 3, due to the electrostatic repulsion between OTC and positive charged surface of Mag@ZnO-Co3O4, the adsorption capacity was relative low. When the solution pH was between 5 and 9, the percentage of the positive and neutral form of OTC molecule increased, OTC are more easily attracted by the adsorbent with negative charges due to the electrostatic and complexation attractions, which increased the adsorption capacity. When the pH further increased, OTC becomes negative charged, which inhibits the adsorption due to the electrostatic repulsion. Consequently, electrostatic interaction is another important adsorption mechanism between OTC and Mag@ZnO-Co3O4.

Effect of Concentration. Concentration is one of the significant characteristics which control the residence time of adsorbate uptake at the solid-liquid interface. Figure 5d shows the effect of concentration on the adsorption process. Obviously, Mag@ZnO-Co3O4 shows a good OTC adsorption performance in the concentrations range of 10–30 mg/L. The magnetic adsorbent has a fast adsorption rate; the equilibrium is reached within 90 min. The fast uptake kinetics is derived from the small size of Mag@ZnO-Co3O4 microspheres and the particular bi-metal oxide


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layer on the adsorbent surface. On one hand, sub-micron-sized of the particles could not only accelerate the accessibility of the metal active binding sites, but also increase the intraparticle diffusion rate of OTC onto the adsorption sites. Moreover, the thin coating of bi-metal oxide shell on magnetic core is beneficial for the full exposure of active metal sites, and enables the easy adsorption of OTC onto bi-metal oxide surface by means of complexation between metal and OTC.

Uptake Kinetics. To further understand the adsorption behaviors of Mag@ZnO-Co3O4, the batch experimental data (20, 30 mg/L) were analyzed in terms of kinetic models via pseudo-firstorder and pseudo-second order,54 which can be expressed as follows:

log ( qe − qt ) = log qe −

k1 t 2.303

（2）

t 1 t = + 2 qt K 2 qe qe

（3）

where qe and qt are the amount of OTC adsorbed on adsorbent (mg/g) at equilibrium and at time t, respectively. k1 and k2 are the adsorption rate constants of pseudo-first-order (min-1) and pseudo-second-order (g/mg/min) equations. Figure S5 depicts the model fitting results of pseudo-second-order adsorption for OTC by Mag@ZnO-Co3O4, and the corresponding kinetic parameters of pseudo-first-order and pseudosecond-order adsorption from the linear plots and correlation coefficients (R2) are presented in Table 1. The pseudo-second-order model shows better correlation with high correlation coefficients (R2 > 0.997). In addition, the calculated qe obtained are also very close to the experimental values of qe,exp. These facts indicate that the adsorption process obeyed the pseudosecond-order model. Therefore, adsorption of OTC onto the Mag@ZnO-Co3O4 nanoparticles


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could be a chemisorption process involving electron sharing or electron transfer between adsorbent and adsorbate.55

Table 1. Kinetic Models and Other Statistical Parameters of Mag@ZnO-Co3O4 nanoadsorbent at 298 °C. Pseudo-first-order model C0 (mg/L) qe (mg/g)

Pseudo-second-order model

k1 (1/min)

R2

qe (mg/g)

k2 (g min/mg)

R2

qe,exp (mg/g)

20

13.6

1.47×10-2

0.8543

49.3

7.35×10-3

0.9977

50.8

30

14.6

1.43×10-2

0.6435

68.0

4.58×10-3

0.9993

66.8

Adsorption Isotherms. Langmuir and Freundlich isotherms models were employed to fit the adsorption equilibrium data. Figure 6 shows the uptake of OTC versus concentrations for the typical Mag@ZnO-Co3O4 microspheres. While the dosage of the magnetic microspheres remains constant (0.0025 g), the uptake amount of OTC shows a very rapid increase with the initial OTC concentration increasing from 20 to 80 mg/L for the synthesized Mag@ZnO-Co3O4 microspheres; subsequently, the adsorption rate decreases gradually and the uptake reaches saturation when the OTC concentration reached 160 mg/L.


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Figure 6. OTC adsorption isotherm curve on the Mag@ZnO-Co3O4 microspheres. As shown in Table S1, by comparing the correlation coefficients (R2), the Langmuir model could describe the experimental data better than the Freundlich model, indicating a monolayer adsorption onto the Mag@ZnO-Co3O4 surface.56-57 The n value calculated from the Freundlich isotherm model is larger than unity, which indicating the strong interaction force between OTC and Mag@ZnO-Co3O4 adsorbent. The maximum adsorption capacity (qmax) of MagZnO@Co3O4 is found to be 128 mg/g for OTC, calculated by the Langmuir model, which indicate that the experimental values of qmax are in good agreement with the theoretical results. Additionally, we compared the uptake of OTC on various adsorbents in Table 2. Obviously, some carbon materials showed the highest adsorption capacity. However, it always need so much time to obtained adsorption equilibrium or too expensive to use in the adsorption. Obviously, the Mag@ZnO-Co3O4 magnetic composite possesses a relatively large adsorption capacity and a fast adsorption rate as compared to previously reported adsorbents. Moreover, the high saturation magnetization enables the pollutants-adsorbed microspheres conveniently recovered from the treated samples using a magnet compare with the other metal oxides, including Co3O4 and ZnO.

Table 2. Uptake Parameters of OTC on Various Adsorbents Recently Reported. Adsorbents

qmax (mg/g)

Equipment time

Ref.

Goethite/ Hematie

2

72 h

58

Activated sludge

91

48 h

51

Rsin MN-100/150

60/120

72 h

59

Grapheme oxide

212

90 min

60

MFe2O4

0.1

10 min

61

GO-MPS

45

10 min

62

Zerovalent iron

34

480 min

63


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Mag@ZnO-Co3O4

128

90 min

Page 20 of 30

This work

Recycling the Nanoadsorbent. The regeneration performance of adsorbents is one of the vital factors in practical water treatment applications. Consequently, the UPLC mobile phase (consisting of 10% methanol, 20% acetonitrile and 70% 0.02 mol/L oxalic acid buffer) was used as eluent for the desorption and reusability of Mag@ZnO-Co3O4. The results (Figure. S6) show that the mobile phase could efficiently cause the adsorbed OTC to undergo desorption. The uptake capacity decreased slightly at the first five cycles (uptake loss < 20 %), indicating that Mag@ZnO-Co3O4 possesses good reusability

CONCLUSION In conclusion, the magnetic microspheres with bi-metal oxide shell were successfully prepared by a simple method. The as-synthesized Mag@ZnO-Co3O4 magnetic microspheres showed two advantageous structural features: the small microsphere structure and a thin well-defined bimetal oxide layer on the surface, resulting in an excellent adsorption performance for OTC. Such super adsorption performance of the Mag@ZnO-Co3O4 can be attributed to its unique structures, high isoelectric point, and strong surface complexation. The ratio of Zn and Co raw materials played a crucial factor in controlling the core-shell structure formation, and the presented of F− during the modification of Zn and Co should be responsible for the formation of the bi-metal oxide shell. Moreover, this bi-metal oxide modified magnetic adsorbent had preferential adsorption of OTC in their aqueous mixtures at neutral and weak basic conditions. This work provides a novel method to prepare bi-metal oxide modified magnetic microsphere with welldefined core-shell morphologies. Furthermore, the novel magnetic microspheres can be also expected to have potential applications in catalysis, photodegradation, and other fields due to the multifunction transition metal oxide shell.


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ASSOCIATED CONTENT Supporting Information. Isotherm and the statistical parameters (Table S1), N2 adsorptiondesorption isotherms (Figure S1), FT-IR spectra (Figure S2), time-course uptake of OTC by Mag-ZnO@Co3O4 in pure water and tap water (Figure S3), zeta potentials (Figure S4), pseudosecond-order kinetics plots (Figure S5), and potential regeneration of Mag-ZnO@Co3O4 magnetic microspheres (Figure S6). This material is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION Notes The authors declare no competing financial interest.

ACKNOWLEDGMENT The present work is supported by the projects of National Natural Science Foundation of China (Nos. 21605056 and 21375046), Science and Technology Development of Jilin Province (No. 20140203013GX), and the Science Foundation for Distinguished Young Scholars of Jilin City (No. 20166028). Financial support from the Key Laboratory of Fine Chemicals of Jilin Province is also acknowledged.

REFERENCES (1)

Ahmed, S.; Ning, J.; Cheng, G. Y.; Ahmad, I.; Li, J.; Liu, M. Y.; Qu, W.; Iqbal, M.;

Shabbir, M. A. B.; Yuan, Z. H., Receptor-based Screening Assays for the Detection of Antibiotics Residues - A Review. Talanta 2017, 166, 176-186.


21


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

(2)

Page 22 of 30

Azhar, M. R.; Abid, H. R.; Sun, H.; Periasamy, V.; Tadé, M. O.; Wang, S., Excellent

Performance of Copper Based Metal Organic Framework in Adsorptive Removal of Toxic Sulfonamide Antibiotics from Wastewater. J. Colloid Interf. Sci 2016, 478, 344-352. (3)

Watkinson, A. J.; Murby, E. J.; Costanzo, S. D., Removal of Antibiotics in Conventional

and Advanced Wastewater Treatment: Implications for Environmental Discharge and Wastewater Recycling. Water Res. 2007, 41 (18), 4164-4176. (4)

Liu, P.; Zhang, H.; Feng, Y.; Yang, F.; Zhang, J., Removal of Trace Antibiotics from

Wastewater: A Systematic Study of Nanofiltration Combined with Ozone-based Advanced Oxidation Processes. Chem. Eng. J. 2014, 240, 211-220. (5)

Homem, V.; Santos, L., Degradation and Removal Methods of Antibiotics from Aqueous

Aatrices – A Review. J. Environ. Manage. 2011, 92 (10), 2304-2347. (6)

Ahmed, S.; Ning, J.; Cheng, G.; Ahmad, I.; Li, J.; Mingyue, L.; Qu, W.; Iqbal, M.;

Shabbir, M. A. B.; Yuan, Z., Receptor-based Screening Assays for the Detection of Antibiotics Residues – A Review. Talanta 2017, 166, 176-186. (7)

Li, Q.; Guan, Z.; Wu, D.; Zhao, X.; Bao, S.; Tian, B.; Zhang, J., Z-scheme BiOCl-Au-

CdS Heterostructure with Enhanced Sunlight-Driven Photocatalytic Activity in Degrading Water Dyes and Antibiotics. ACS Sustainable Chem. Eng. 2017. (8)

Chen, J.; Sun, P.; Zhang, Y.; Huang, C. H., Multiple Roles of Cu(II) in Catalyzing

Hydrolysis and Oxidation of β-Lactam Antibiotics. Environ. Sci.Techol. 2016, 50 (22), 12156. (9)

Lucas, D.; Badiafabregat, M.; Vicent, T.; Caminal, G.; Rodríguezmozaz, S.; Balcázar, J.

L.; Barceló, D., Fungal Treatment for the Removal of Antibiotics and Antibiotic Resistance Genes in Veterinary Hospital Wastewater. Chemosphere 2016, 152, 301-308.


22

Page 23 of 30

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


(10)

Attallah, O. A.; Al-Ghobashy, M. A.; Nebsen, M.; Salem, M. Y., Adsorptive Removal of

Fluoroquinolones from Water by Pectin-Functionalized Magnetic Nanoparticles: Process Optimization Using a Spectrofluorimetric Assay. ACS Sustainable Chem. Eng. 2017, 5 (1), 133145. (11)

Mi, L.; Licina, G. A.; Jiang, S., Nonantibiotic-Based Pseudomonas Aeruginosa Biofilm

Inhibition with Osmoprotectant Analogues. ACS Sustainable Chem. Eng. 2014, 2 (10), 24482453. (12)

Nakata, K.; Harada, N.; Sumitomo, K.; Yoneda, K., Enhancement of Plant Stem Growth

by Flocculation of the Antibiotic-producing Bacterium, Pseudomonas Fluorescens S272, on the Roots. Biosci. Biotech. Bioch. 2000, 64 (3), 459-465. (13)

Kumar, K. Y.; Muralidhara, H. B.; Nayaka, Y. A.; Balasubramanyam, J.;

Hanumanthappa, H., Low-cost Synthesis of Metal Oxide Nanoparticles and Their Application in Adsorption of Commercial Dye and Heavy Metal Ion in Aqueous Solution. Powder Technol.

2013, 246 (6), 125-136. (14)

Muralidhara, H. B., Hydrothermal Synthesis of Hierarchical Copper Oxide Nanoparticles

and its Potential Application as Adsorbent for Pb(II) with High Removal Capacity. Sep. Sci. Technol. 2014, 49 (15), 2389-2399. (15)

Saravanakumar, K.; Senthil Kumar, P.; Vinoth Kumar, J.; Karuthapandian, S.; Philip, R.;

Muthuraj, V., Controlled Synthesis of Plate Like Structured MoO3 and Visible Light Induced Degradation of Rhodamine B Dye Solution. Energy Environ. Focus 2016, 5 (1), 1-8. (16)

Ji, L.; Wan, Y.; Zheng, S.; Zhu, D., Adsorption of Tetracycline and Sulfamethoxazole on

Crop Residue-derived Ashes: Implication for the Relative Importance of Black Carbon to Soil Sorption. Environ. Sci. Technol. 2011, 45 (13), 5580-5586.


23


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

(17)

Page 24 of 30

Braschi, I.; Blasioli, S.; Buscaroli, E.; Montecchio, D.; Martucci, A., Physicochemical

Regeneration of High Silica Zeolite Y Used to Clean-up Water Polluted with Sulfonamide Antibiotics. J. Environ. Sci. 2016, 43, 302-312. (18)

Zheng, S.; Li, X.; Zhang, X.; Wang, W.; Yuan, S., Effect of Inorganic Regenerant

Properties on Pharmaceutical Adsorption and Desorption Performance on Polymer Anion Exchange Resin. Chemosphere 2017, 182, 325-331. (19)

Saitoh, T.; Shibayama, T., Removal and Degradation of β-lactam Antibiotics in Water

using Didodecyldimethylammonium Bromide-Modified Montmorillonite Organoclay. J. Hazard. Mater. 2016, 317, 677-685. (20)

Fu, H.; Li, X.; Wang, J.; Lin, P.; Chen, C.; Zhang, X.; Suffet, I. H., Activated Carbon

Adsorption of Quinolone Antibiotics in Water: Performance, Mechanism, and Modeling. J. Environ. Sci. 2017, 56, 145-152. (21)

Shao, M. F.; Ning, F. Y.; Zhao, J. W.; Wei, M.; Evans, D. G.; Duan, X., Preparation of

Fe3O4@SiO2@Layered Double Hydroxide Core-Shell Microspheres for Magnetic Separation of Proteins. J. Am. Chem. Soc. 2012, 134 (2), 1071-1077. (22)

Wang, C. X.; Yin, L. W.; Zhang, L. Y.; Kang, L.; Wang, X. F.; Gao, R., Magnetic

(gamma-Fe2O3@SiO2)(n)@TiO2 Functional Hybrid Nanoparticles with Actived Photocatalytic Ability. . J. Phys. Chem. C 2009, 113 (10), 4008-4011. (23)

Shen, J.; Zhu, Y.; Yang, X.; Zong, J.; Li, C., Multifunctional Fe3O4@Ag/SiO2/Au Core-

shell Microspheres as a Novel SERS-Activity Label via Long-Range Plasmon Coupling. Langmuir. 2013, 29 (2), 690-695.


24

Page 25 of 30

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


(24)

Hun, P. H.; Kyoungja, W.; Jae-Pyoung, A., Core–Shell Bimetallic Nanoparticles

Robustly Fixed on the Outermost Surface of Magnetic Silica Microspheres. Scientific Reports

2013, 3 (3), 1497. (25)

Lian, L.; Cao, X.; Wu, Y.; Lou, D.; Han, D., Synthesis of Organo-functionalized

Magnetic Microspheres and Application for Anionic Dye Removal. J. Taiwan Inst. Chem. E.

2013, 44 (1), 67-73. (26)

Karunakaran, C.; Vinayagamoorthy, P.; Jayabharathi, J., Nonquenching of Charge

Carriers by Fe3O4 Core in Fe3O4/ZnO Nanosheet Photocatalyst. Langmuir. 2014, 30 (49), 1503115039. (27)

Li, G. R.; Wang, Z. L.; Zheng, F. L.; Ou, Y. N.; Tong, Y. X., ZnO@MoO3 Core/shell

Nanocables: Facile Electrochemical Synthesis and Enhanced Supercapacitor Performances. J. Mater. Chem. 2011, 21 (12), 4217-4221. (28)

Fan, H. Q.; Zhong, Y.; Chang, L.; Zhu, S. S.; Wang, K.; Shao, H. B.; Wang, J. M.;

Zhang, J. Q.; Cao, C. N., Facile Morphology Controlled Synthesis of Nanostructured Co3O4 Films on Nickel Foam and Their Pseudo Capacitive Performance. Rsc Advances 2016, 6 (58), 52957-52965. (29)

Mu, J.; Zhang, L.; Zhao, M.; Wang, Y., Catalase mimic property of Co3O4 nanomaterials

with different morphology and its application as a calcium sensor. ACS Appl. Mater.Inte. 2014, 6 (10), 7090-7098. (30)

Chen, Y. J.; Zhang, F.; Zhao, G.; Fang, X.; Jin, H. B.; Gao, P.; Zhu, C. L.; Cao, M. S.;

Xiao, G., Synthesis, Multi-Nonlinear Dielectric Resonance, and Excellent Electromagnetic Absorption Characteristics of Fe3O4/ZnO Core/Shell Nanorods. J. Phys. Chem. C 2010, 114 (20), 9239-9244.


25


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

(31)

Page 26 of 30

Sun, G.; Dong, B.; Cao, M.; Wei, B.; Hu, C., Hierarchical Dendrite-Like Magnetic

Materials of Fe3O4, γ-Fe2O3, and Fe with High Performance of Microwave Absorption. Chem. Mater. 2011, 23 (6). (32)

Zhu, J. J.; Kailasam, K.; Fischer, A.; Thomas, A., Supported Cobalt Oxide Nanoparticles

as Catalyst for Aerobic Oxidation of Alcohols in Liquid Phase. Acs Catal. 2011, 1 (4), 342-347. (33)

Nie, R. F.; Shi, J. J.; Du, W. C.; Ning, W. S.; Hou, Z. Y.; Xiao, F. S., A sandwich N-

doped Graphene/Co3O4 Hybrid: an Efficient Catalyst for Selective Oxidation of Olefins and Alcohols. J. Mater. Chem. A 2013, 1 (32), 9037-9045. (34)

Sun, X.; Liu, X.; Feng, J.; Li, Y.; Deng, C.; Duan, G., Hydrophilic Nb5+-immobilized

Magnetic Core–shell Microsphere – A Novel Immobilized Metal Ion Affinity Chromatography Material for Highly Selective Enrichment of Phosphopeptides. Anal. Chim. Acta 2015, 880, 6776. (35)

Xue, C.; Wang, J.; Tu, B.; Zhao, D., Hierarchically Porous Silica with Ordered

Mesostructure from Confinement Self-assembly in Skeleton Scaffolds. Chem. Mater. 2010, 22 (2), 494-503. (36)

Liu, Z.; Li, M.; Yang, X.; Yin, M.; Ren, J.; Qu, X., The Use of Multifunctional Magnetic

Mesoporous Core/shell Heteronanostructures in a Biomolecule Separation System. Biomaterials.

2011, 32 (21), 4683-4690. (37)

Wang, X. L.; Zhou, L. Z.; Ma, Y. J.; Li, X.; Gu, H. C., Control of Aggregate Size of

Polyethyleneimine-coated Magnetic Nanoparticles for Magnetofection. Nano Res. 2009, 2 (5), 365-372.


26

Page 27 of 30

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


(38)

Li, N.; Zhang, J.; Tian, Y.; Zhao, J.; Zhang, J.; Zuo, W., Precisely Controlled Fabrication

of Magnetic 3D Gamma-Fe2O3@ZnO Core-shell Photocatalyst with Enhanced Activity: Ciprofloxacin Degradation and Mechanism Insight. Chem. Eng. J. 2017, 308, 377-385. (39)

Cai, D. P.; Huang, H.; Wang, D. D.; Liu, B.; Wang, L. L.; Liu, Y.; Li, Q. H.; Wang, T.

H., High-Performance Supercapacitor Electrode Based on the Unique ZnO@Co3O4 Core/Shell Heterostructures on Nickel Foam. Acs Applied Materials & Interfaces 2014, 6 (18), 1590515912. (40)

Zhu, T.; Chen, J. S.; Lou, X. W., Shape-controlled Synthesis of Porous Co3O4

Nanostructures for Application in Supercapacitors. J. Mater. Chem. 2010, 20 (33), 7015-7020. (41)

Xia, X. H.; Tu, J. P.; Zhang, Y. Q.; Mai, Y. J.; Wang, X. L.; Gu, C. D.; Zhao, X. B.,

Freestanding Co3O4 Nanowire Array for High Performance Supercapacitors. Rsc Adv. 2012, 2 (5), 1835-1841. (42)

Zhu, L. P.; Wen, Z.; Mei, W. M.; Li, Y. G.; Ye, Z. Z., Porous CoO Nanostructure Arrays

Converted from Rhombic Co(OH)F and Needle-like Co(CO3)(0.5)(OH) Center Dot 0.11H(2)O and Their Electrochemical Properties. J. Phys. Chem. C 2013, 117 (40), 20465-20473. (43)

Xu, F.; Sun, L. T.; Dai, M.; Lu, Y. N., Fluorine-ion-mediated Electrodeposition of

Rhombus-like

ZnFOH

Nanorod

Arrays:

An

Intermediate

Route

to

Novel

ZnO

Nanoarchitectures. J. Phys. Chem. C 2010, 114 (36), 15377-15382. (44)

Wang, B.; Zhu, T.; Wu, H. B.; Xu, R.; Chen, J. S.; Lou, X. W., Porous Co3O4 Nanowires

Derived from Long Co(CO3)(0.5)(OH)center dot 0.11H(2)O Nanowires with Improved Supercapacitive Poperties. Nanoscale 2012, 4 (6), 2145-2149. (45)

Park, S.; Kim, S.; Kheel, H.; Lee, C., Oxidizing Gas Sensing Properties of the n-ZnO/p-

Co3O4 Composite Nanoparticle Network Sensor. Sensor. Actuat. B-Che 2016, 222, 1193-1200.


27


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

(46)

Page 28 of 30

Bai, S.; Guo, J.; Shu, X.; Xiang, X.; Luo, R.; Li, D.; Chen, A.; Liu, C. C., Surface

Functionalization of Co3O4 Hollow Spheres with ZnO Nanoparticles for Modulating Sensing Properties of Formaldehyde. Sensor. Actuat. B-Che 2017, 245, 359-368. (47)

Jana, T. K.; Pal, A.; Chatterjee, K., Magnetic and Photocatalytic Study of Co3O4–ZnO

Nanocomposite. J. Alloy. Compd. 2015, 653, 338-344. (48)

Ge, S. J.; Agbakpe, M.; Zhang, W.; Kuang, L. Y.; Wu, Z. Y.; Wang, X. Q., Recovering

Magnetic Fe3O4-ZnO Nanocomposites from Algal Biomass Based on Hydrophobicity Shift under UV Irradiation. ACS Appl. Mater. Inter. 2015, 7 (21), 11677-11682. (49)

Pulicharla, R.; Hegde, K.; Brar, S. K.; Surampalli, R. Y., Tetracyclines Metal

Complexation: Significance and Fate of Mutual Existence in the Environment. Environ. Pollut.

2017, 221, 1-14. (50)

Wang, W.; Tian, G.; Li, Z.; Qin, W.; Zhou, Y.; Wang, A., Mesoporous Hybrid Zn-silicate

Derived from Red Palygorskite Clay as a High-efficient Adsorbent for Antibiotics. Microporous & Mesoporous Materials 2016, 234, 317-325. (51)

Song, X.; Liu, D.; Zhang, G.; Frigon, M.; Meng, X.; Li, K., Adsorption Mechanisms and

the Effect of Oxytetracycline on Activated Sludge. Bioresource. Technol. 2014, 151 (1), 428431. (52)

Yang, X.; Yang, C.; Yan, X., Zeolite Imidazolate Framework-8 as Sorbent for on-line

Solid-phase Extraction Coupled with High-performance Liquid Chromatography for the Determination of Tetracyclines in Water and Milk Samples. J. Chromatogr. A 2013, 1304, 2833.


28

Page 29 of 30

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


(53)

Şanli, S.; Şanli, N.; Alsancak, G., Determination of Protonation Constants of Some

Tetracycline Antibiotics by Potentiometry and lc Methods in Water and Acetonitrile-water Binary Mixtures. J.braz.chem.soc 2009, 20 (5), 939-946. (54)

Srivastava, V.; Sharma, Y. C.; Sillanpää, M., Application of Nano-magnesso Ferrite (n-

MgFe2O4) for the Removal of Co2+ Ions from Synthetic Wastewater: Kinetic, Equilibrium and Thermodynamic Studies. Appl. Surf. Sci. 2015, 338, 42-54. (55)

Zhang, F.; Yin, X.; Zhang, W., Development of Magnetic Sr5(PO4)3(OH)/Fe3O4 Nanorod

for Adsorption of Congo red from Solution. J. Alloy. Compd. 2016, 657, 809-817. (56)

Fu, Z.; He, C.; Li, H.; Yan, C.; Chen, L.; Huang, J.; Liu, Y., A Novel Hydrophilic–

hydrophobic Magnetic Interpenetrating Polymer Networks (IPNs) and Its Adsorption Towards Salicylic Acid from Aqueous Solution. Chem. Eng. J. 2015, 279, 250-257. (57)

Li, M.; Liu, Y.; Liu, S.; Shu, D.; Zeng, G.; Hu, X.; Tan, X.; Jiang, L.; Yan, Z.; Cai, X.,

Cu(II)-influenced Adsorption of Ciprofloxacin from Aqueous Solutions by Magnetic Graphene Oxide/nitrilotriacetic Acid Nanocomposite: Competition and Enhancement Mechanisms. Chem. Eng. J. 2017, 319, 219-228. (58)

Figueroa, R. A.; Mackay, A. A., Sorption of Oxytetracycline to Iron Oxides and Iron

Oxide-rich Soils. Environ. Sci. Technol. 2005, 39 (17), 6664-71. (59)

Yang, W.; Zheng, F.; Lu, Y.; Xue, X.; Li, N., Adsorption Interaction of Tetracyclines

with Porous Synthetic Resins. Ind. Eng. Chem. Res. 2016, 50 (24), 13892-13898. (60)

Gao, Y.; Li, Y.; Zhang, L.; Huang, H.; Hu, J.; Shah, S. M.; Su, X., Adsorption and

Removal of Tetracycline Antibiotics from Aqueous Solution by Graphene Oxide. J. Colloid. Interf. Sci. 2012, 368 (1), 540.


29


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

(61)

Page 30 of 30

Bao, X.; Qiang, Z.; Ling, W.; Chang, J. H., Sonohydrothermal Synthesis of MFe2O4

Magnetic Nanoparticles for Adsorptive Removal of Tetracyclines from Water. Sep. Purif. Technol. 2013, 117 (1), 104-110. (62)

Lin, Y.; Xu, S.; Li, J., Fast and Highly Efficient Tetracyclines Removal from

Environmental Waters by Graphene Oxide Functionalized Magnetic Particles. Chem. Eng. J.

2013, 225 (6), 679-685. (63)

Hanay, O.; Yıldız, B.; Aslan, S.; Hasar, H., Removal of Tetracycline and Oxytetracycline

by Microscale Zerovalent Iron and Formation of Transformation Products. Environ Sci. Pollut. R. 2014, 21 (5), 3774-3782.

TOC Graphic

Synopsis: The magnetic microspheres with bi-metal oxide shell exhibit strong magnetism and excellent adsorption property for oxytetracycline.


30

Synthesis of Novel Magnetic Microspheres with Bi-metal Oxide Shell

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