Selective reduction of Cu2+ with simultaneous degradation of tetracycline by the dual channels ion imprinted POPD-CoFe2O4 heterojunction photocatalyst

Accepted Manuscript Selective Reduction of Cu2+ with Simultaneous Degradation of Tetracycline by the Dual Channels Ion Imprinted POPD-CoFe2O4 Heterojunction Photocatalyst Fan He, Ziyang Lu, Minshan Song, Xinlin Liu, Hua Tang, Pengwei Huo, Weiqiang Fan, Hongjun Dong, Xiangyang Wu, Song Han PII: DOI: Reference:

S1385-8947(18)32507-5 https://doi.org/10.1016/j.cej.2018.12.034 CEJ 20574

To appear in:

Chemical Engineering Journal

Received Date: Revised Date: Accepted Date:

15 September 2018 4 December 2018 6 December 2018

Please cite this article as: F. He, Z. Lu, M. Song, X. Liu, H. Tang, P. Huo, W. Fan, H. Dong, X. Wu, S. Han, Selective Reduction of Cu2+ with Simultaneous Degradation of Tetracycline by the Dual Channels Ion Imprinted POPDCoFe2O4 Heterojunction Photocatalyst, Chemical Engineering Journal (2018), doi: https://doi.org/10.1016/j.cej. 2018.12.034

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Selective Reduction of Cu2+ with Simultaneous Degradation of Tetracycline by the Dual Channels Ion Imprinted POPD-CoFe2O4 Heterojunction Photocatalyst Fan He,a Ziyang Lu,a,* Minshan Song,b Xinlin Liu,c Hua Tang,d Pengwei Huo,e Weiqiang Fan,e Hongjun Dong,e Xiangyang Wu,a,* Song Hana

a

School of the Environment and Safety Engineering, Institute of Environmental Health and Ecological Security, Jiangsu University, Jiangsu, Zhenjiang 212013, China b

School of Science, Jiangsu University of Science and Technology, Jiangsu, Zhenjiang 212003, China

c

School of Energy and Power Engineering, Jiangsu University, Jiangsu, Zhenjiang 212013, China

d

School of Materials Science & Engineering, Jiangsu University, Jiangsu, Zhenjiang 212013, China e

School of Chemistry & Chemical Engineering, Jiangsu University, Jiangsu, Zhenjiang 212013, China

Abstract: The dual channels ion imprinted POPD-CoFe2O4 heterojunction photocatalyst (magnetic ion

imprinted

heterojunction

photocatalyst)

was

synthesized

by

utilizing

the

microwave-assisted ion imprinting technique. The as-prepared photocatalyst can selectively reduce Cu2+ owing to abundant Cu2+ imprinted cavities existed in the imprinted layer and Cu2+ was rapidly reduced by e- in POPD, the ions selectivity coefficient (kions) of Cu2+ to other ions over magnetic ion imprinted heterojunction photocatalyst was 11.495 (kions (Cu2+/Cd2+)), 4.716 (kions (Cu2+/Fe3+)) and 15.910 (kions (Cu2+/Zn2+)), respectively, and the materials selectivity

*

Corresponding authors. E-mail: [email protected] (Z. Y. Lu); [email protected] (X. Y. Wu). Tel.: +86-0511-88790955. 1

coefficient (kmaterials) of magnetic ion imprinted heterojunction photocatalyst relative to other materials was 4.998, 2.545, 10.474 and 4.918, respectively, both showed excellent selectivity. Furthermore, with the existence of mesoporous in the imprinted layer, tetracycline can easily contact with CoFe2O4 and further be degraded by h+ in CoFe2O4. Consequently, selective reduction of Cu2+ and simultaneous degradation of tetracycline can be realized via the dual channels of imprinted cavity and mesoporous. More importantly, the heterojunction structure formed between CoFe2O4 and POPD effectively separated e- and h+, which greatly promoted the photocatalytic activity of selective reduction of Cu 2+ and simultaneous degradation of tetracycline. With an enhanced stability for recyling, this work provided a high-efficient and economic technical approach for selective reduction of specific heavy metal ions and simultaneous degradation of organic contaminant in complex water environment.

Keywords: Ion imprinting technique, POPD-CoFe2O4 heterojunction photocatalyst, Dual channels, Selective Cu2+ reduction, Simultaneous tetracycline degradation

1. Introduction Nowadays, the topic of energy is closely concerned by researchers. Using an efficient and economical method to achieve the reuse of resources is the key to effectively saving resources. In addition, environmental pollution is also becoming more and more serious. As is well-known that the most severe pollutants present in water environment are residual antibiotic [1,2] and heavy metal ions [3,4], etc. Tetracycline is a common antibiotic that is extremely widely used in people’s daily life [5]. Nevertheless, abuse of tetracycline will not only cause vast residual pollutants discharged into the environment, leading to negative impact on the water atmosphere, but also suppress the progress of many water treatment [6,7]. Moreover, copper pollution in water is one of the heavy metal pollution, when the water body is subject to copper pollution [8,9], Cu2+ is uneasy to be removed, and then, it can be enriched 2

in the body through the food chain into the human body caused by acute poisoning. Taking into account the high value of Cu to the human life [10,11] and pollution of tetracycline to the environment, there is a very significant activity to selectively reduce Cu2+ and efficiently degrade tetracycline. Therefore, it is challenging and meaningful to design a material that can simultaneously selectively reduce Cu2+ and degrade tetracycline in wastewater. The removal of tetracycline by biological treatment and adsorption approach, are not reached anticipated efficiency [12,13] and other conventional water treatments are also suppressed by the deficient efficiency and high expense [14,15]. For removing tetracycline and reducing Cu2+ from water, the photocatalytic technology [16,17] is regarded as a high-efficient and economic solution due to its superiority like energy conservation [18], environmental friendliness [19] and low input [20]. Photodegradation methods oxidize the harmful antibiotics to substances which are less biotoxicity even nontoxic [21]. In addition, photocatalysts are capable of reducing Cu2+ to Cu [22,23], allowing heavy metals in sewage to be converted into useful resources. Abundant semiconductor, including TiO2 [24], CdS [25], CoFe2O4 [26] and others have been extensively researched for the degradation of contaminant under light. Especially, spinel ferrites have been regarded as potential candidates for good catalytic activity, stable crystalline structur and good magnetic response [27-29]. Especially, CoFe2O4 shows great visible-light-driven photocatalytic property in comparison with TiO2 for its narrow band gap energy [30]. And compared to CdS, CoFe2O4 is steady under light irradiation, therefore, it will not be light decomposed, resulting in secondary pollution [31]. Beyond that,

CoFe2O4 are very good magnetic material with good magnetic separation

characteristics [32-34] which helps ordinary composite materials to be separated and recovered. Consequently, it can also be used as a carrier to effectively separate and recover composite materials. However, the conduction band and valence band of CoFe2O4 cannot achieve oxidation of tetracycline and reduction of Cu2+, simultaneously. For this purpose, POPD as a functional monomer is introduced into the preparation of materials. 3

POPD as a common conductive polymer, widely used in the synthesis of nanomaterials [35-37]. On the one hand, the existence of POPD can form heterojuction structure with CoFe2O4 to achieve changing the position of VB and CB of as-prepared material [38], thereby attaining simultaneous selective reduction of Cu 2+ and degradation of tetracycline. On the other hand, POPD as a functional monomer in the synthesis of the ion imprinted layer, facilitates the preparation of the Cu2+ ion imprinted layer [39], so that Cu2+ can be selectively adsorbed then reduced to Cu. More than this, the good electrical conductivity of POPD enables the photo-induced e- and h+ to be effectively separated and the photocatalytic effect is improved [40]. At the same time, e- can be transferred to the imprinting layer, so that the adsorbed Cu2+ can be reduced and recycled. Ion imprinting is a technique to achieve selective adsorption of target ions [41-43]. Because plenty of imprinted cavities designed for the template ion are distributed, and such cavities are match with the template ion in many aspects such as size and group on the imprinted layer [44]. As a result, ion imprinted polymers could recognize and unit with template ion. In order to synthesize more stable material and uniform imprinted layer, microwave assisted synthesis method [45,46] has been considered as a promising method for the preparation of uniform photocatalyst. The simple and efficient method to synthesize expected material is main merit of microwave assisted approach [47,48]. Moreover, microwave assisted is promoting the uniformity of spherical samples [49,50]. Therefore, the microwave assisted synthesis method has created the possibility of realizing fast reactions and wide applications in the synthesis of spherical organic materials [51]. However, the coverage of the ion imprinted layer hinders the absorption of light by CoFe2O4 and also resists the tetracycline from contacting with CoFe2O4, they will lead to a great cut in the photocatalytic activity of material. So as to solve the above problems, P123 is used as porogen, because P123 can be used to prepare mesoporous [52,53] in the ion imprinted layer. These mesoporous provide access to make tetracycline reach the surface of 4

CoFe2O4 and be further degraded. Therefore, the introduction P123 well work out the problem of reducing the photocatalytic property of the composite material. In our work, magnetic ion imprinted heterojunction photocatalyst was synthesized by microwave-assisted ion imprinting technique which possessed dual channels of imprinted cavity and mesoporous. The structural characteristics of as-prepared material was further characterized by XRD, chemical composition was tested by XPS and FT-IR, SEM and TEM was used to obtain the morphology. N2 adsorption–desorption analysis with the BET method, UV-vis DRS and VSM. Finally, the photocatalytic reaction, degradation experiment, selectivity, reduction experiment, stability, and mechanism of magnetic ion imprinted heterojunction photocatalyst was also investigated.

2. Experimental Section 2.1 Materials Analytical grade ferric trichloride (FeCl3, AR), cobalt chloride (CoCl2, AR), rthylene glycol (AR), ammonium acetate (NH4Ac, AR), citric acid (AR), o-phenylenediamine (CR), chloroform (CHCl3, AR), ammonium persulfate (AR), dimethyl sulfoxide (AR), ethyleneglycoldimethacrylate (EGDMA), ferric nitrate (Fe(NO3)3, AR), PEO-PPO-PEO (P123, 5800), copper nitrate (Cu(NO3)2, AR), azobisisobutyronitrile (AIBN, AR), acetone (AR), ethylene diamine tetraacetic acid (EDTA, AR), zinc nitrate (Zn(NO3)2, AR), cadmium nitrate (Cd(NO3)2, AR), Tetracyclne, DMPO (AR), potassium bromide (KBr, AR), barium sulfate (BaSO4, AR), sodium sulfate (Na2SO4, AR), potassium ferricyanide (K3Fe(CN)6, AR), potassium ferrocyanide (K4 Fe(CN)6, AR) and potassium chloride (KCl, AR) were obtained from Shanghai Chemical Reagents, China. Irgacure784 was acquired from Alibaba. Chemicals used in this experiment were all analytical grade. Deionized (DI) water from Milli-Q System (Millipore, Billerica, MA) was used in all our experiments. 2.2 Experimental methods 5

2.2.1 Synthesis of CoFe2O4 The synthesis of CoFe2O4 based on the literature [54,55] with slight modifications. 1.092 g FeCl3·6H2O and 0.476 g CoCl2 were simultaneously dissolved in 70 mL of ethylene glycol, then added 2.312 g NH4Ac into above-mentioned solution. The homogeneous solution was reacted at 180 °C for one day. Subsequently, washed and dried under vacuum at 35°C, CoFe2O4 was obtained. 2.2.2 Synthesis of Carboxylation CoFe2O4 The synthesis of Carboxylation CoFe2O4 based on the literature [56] with some modifications. Firstly, the powder of CoFe2O4 (3 g) was added into 100 mL DI under ultrasonic for 30 min at room temperature. After forming homogeneous solution, 1.5 mL citric acid added into the aforementioned solution under mechanical stirring for 1 h in 60 °C under the nitrogen atmosphere. Subsequently, washed for several times and dried under vacuum at 35 °C , carboxylation CoFe2O4 was formed. 2.2.3 Synthesis of POPD (polyo-phenylenediamine) The synthesis of POPD followed the literature [57]. Primarily, 2.16 g of o-phenylenediamine was distributed in chloroform (30 mL) to form an organic phase solution, meanwhile, 2.128 g of ammonium persulfate was distributed in 30 mL of DI to prepare an aqueous solution. Then, this organic phase was first transferred into a jar, and then the aqueous solution was added to the jar through the glass rod. The polyo-phenylenediamine was soon formed on the interface between the two phases and diffused to the aqueous phase. After standing at room temperature for a day, POPD was obtained after washing successively with methanol and ethanol vacuum dried at 50 °C. 2.2.4 Synthesis of magnetic ion imprinted heterojunction photocatalyst Firstly, 0.5 g of carboxylated CoFe2O4 was dispersed to 50 mL of dimethyl sulfoxide, followed by continuous stirring at 25 °C for half an hour, then added 0.1 g polyo-phenylenediamine into the solution and sonicated to uniformly dispersed. Then added 6

0.242 g of Cu(NO3)2·3H2O and ultrasonically stir for 15 min. During the polymerization, EGDMA (0.15 mL) and 0.0624 g AIBN were added. Finally added 3 g P123 for further microwave reaction. The resulting mixture was transferred to a 50 mL quartz glass vessel and placed in a microwave reactor. The operating parameters were as follows: 600 W, 70 °C, 90 min. After vigorously stirring at a speed of 2000 rpm for a while, until the vessel was cooled, the final product was seperated by magnet and centrifugation then flushed

for several times

and dried in a vacuum oven at 40 °C. The dry solid product was subjected to P123 removal in a Soxhlet extractor and extracted with acetone at 60 °C for 24 h. Then, the sample was rinsed with 100 mL of 0.5 g/L EDTA and transferred to the flask for elution of Cu2+ then mechanically stirred at 30 °C for 12 h. The solid samples were separated by magnet. At last, the solid sample was put in a vacuum oven at 40 °C (Fig. 1).

Fig. 1. Schematic illustration of preparation process of the magnetic ion imprinted heterojunction photocatalyst. 2.2.5 Synthesis of other samples The mesoporous non-imprinted photocatalyst was synthesized following the same instrument without adding Cu(NO3)2 and process of eluting Cu2+. The non-mesoporous imprinted photocatalyst was also synthesized following the instrument without adding P123 7

and process of removing P123. The non-mesoporous non-imprinted photocatalyst was also synthesized following the same instrument without adding Cu(NO3)2, P123 and process of eluting Cu2+ and removing P123. 2.3 Characterization The morphology of materials was studied by transmission electron microscopy (TEM, Hitachi H-7650, 100 kV) and scanning electron microscopy (SEM, JSM6700F, 5.0 kV) with energy dispersive spectrometer detector (EDS). High revolution transmission electron microscopy (HRTEM, JEM-2010, 200 kV) was used to obtain selected area electron diffraction (SAED) patterns and detailed morphology. X-ray diffraction (XRD) patterns were obtained with X-ray diffractometer (Rigaku, Japan) and X-ray photoelectron spectroscopy (XPS) was performed using a PHI5300 spectrometer. FT-IR (America thermo-electricity Company) in the range 400 cm-1 - 4000 cm-1. N2 adsorption-desorption isotherms was measured by Tristar II 3020 M. Brunauer-Emmett-Teller (BET) and Barret-Joyner-Halenda (BJH) methods were used to analyze surface area and pore size distribution. The magnetic properties of the samples were conducted by vibrating sample magnetometer (VSM). Multiplex pollutants concentration were analyzed and determined by Inductively coupled plasma optical emission spectrometry (ICP-OES, VISTA-MPX) and Ultraviolet-visible spectrophotometer (UV-2600, Shimadzu, Japan). UV-vis diffuse reflectance spectra (UV-2450,

Shimadzu,

Japan)

and

Spectrophotometer, VARIAN, USA)

fluorescence

spectrophotometer

(Cary

Eclipse

were also conducted to investigate UV-Vis DRs and

photoluminescence (PL) spectra. 2.4 Adsorption experiment The corresponding experiments were conducted to measure adsorption capability of different samples: adding 50 mg of sample into photocatalytic reactor, which contained 100 mL 100 mg/L Cu(NO3)2 solution or 100 mL 20 mg/L tetracycline solution, respectively, then took a certain amount of solution each 10 min after stirring for 1 h without light irradiation (stirring 8

speed: 600 rpm/min, aeration rate: 2 mL/min), the solutions were centrifuged or filtered. ICP and UV–vis spectroscopy were chosen to measure the concentration of Cu2+ and tetracycline. The adsorption of Cu2+ or tetracycline from corresponding aqueous solution over different samples was tested in a batch system. The adsorption capacity of Cu2+ or tetracycline could be calculated as following equation [58]: (1) Where Q stood for adsorption capacity (mg/g), C0 represented the initial concentration of Cu2+ or tetracycline, Ct represented the concentration of Cu2+ or tetracycline at time t, V was the metal ion solution (L) or tetracycline solution (L) volume, and m was the mass (g) of samples. 2.5 Photodegradation experiment Photodegradation of tetracycline was conducted by xenon lamp irradiating (PLS-SXE300, power 300 W, 1.8×105 lux), light wavelength was between 380 nm and 780 nm (ultraviolet wavelength was filtered), which performed in beaker containing 20 mg/L tetracycline aqueous solution (100 mL), 50 mg of photocatalyst under stirring at 300 rpm/min. when reached desired adsorption time without irradiation with magnetic stirring and aeration, the xenon lamp was turned on (rotate speed: 600 rpm/min, aeration rate: 2 mL/min). The degree of degradation could be calculated by Ct/C0 [59]: Where Ct was the concentration of tetracycline at time t, and C0 stood for the initial concentration of tetracycline after adsorbing. The concentration of tetracycline aqueous solution was analyzed by Ultraviolet-visible spectrophotometer. 2.6 Photoreduction experiment Photoreduction test of Cu2+ was performed under a xenon lamp (PLS-SXE300, power 300 W, 1.8×105 lux), light wavelength was between 380 nm and 780 nm (ultraviolet wavelength was filtered), which performed in beaker containing 100 mg/L Cu2+ aqueous solution (100 mL), 9

50 mg of the sample under stirring at 300 rpm/min at ambient temperature. When desired adsorption time was reached with magnetic stirring and aeration, the xenon lamp was turned on (rotate speed: 600 rpm/min, aeration rate: 2 mL/min). The reduction rate could be calculated by following formula: (2) Where C was the concentration of Cu2+ after light irradiation for 3 h, and C0 standed for the initial concentration of Cu2+ after adsorbing. The concentration of Cu2+ aqueous solution was analyzed by ICP. In order to further analyze the reduction products. The existence and concentration of Cu + was measured by ESR and Ultraviolet-visible spectrophotometer. 2.7 Selectivity Competitive reduction of Cd2+, Zn2+, Fe3+ with respect to Cu2+ was studied for different samples. Adding 50 mg of the sample into photocatalytic reactor containing Cu 2+, Zn2+, Fe3+ and Cd2+ single solution, respectively, the volume was 100 mL, the concentration was 100 mg/L. The multiple ion concentrations in the solution were analyzed by ICP. The selectivity was determined by reduction rate, the ions selectivity coefficient of Cu2+ relative to other heavy metal ions (kions) and the materials selectivity coefficient (kmaterials), the corresponding calculation formulas were as follows [60]: (3)

(4) Where Reduction rate(Cu2+) and Reduction rate(other ions) were the reduction rate of Cu2+ and other metal ions. kions (magnetic ion imprinted heterojunction photocatalyst) and kions (other materials) represented the ions selectivity coefficients of magnetic ion imprinted heterojunction photocatalyst and other materials, respectively. 10

2.8 Cycle experiment The regeneration of samples played an important role in practical application. On the one hand, each of magnetic ion imprinted heterojunction photocatalyst after photoreduction of Cu2+ was treated by ultrasound to remove Cu with magnetic separation, then eluted by 0.5 g/L EDTA solution with mechanical stirring at 30 °C, when no Cu2+ was detected, the regenerated magnetic ion imprinted heterojunction photocatalyst was reused for the next time. On the other hand, magnetic ion imprinted heterojunction photocatalyst was irradiated for 3 h to remove residual tetracycline, when no tetracycline was detected, the regenerated magnetic ion imprinted heterojunction photocatalyst was reused for the next cycle. Here, the regenerated magnetic ion imprinted heterojunction photocatalyst was reused for five cycles. 2.9 Photoelectrochemical measurements EIS were recorded on the electrochemical workstation (Zahner, Zennium). Pt wire and Ag/AgCl electrode was used as counter electrode and reference electrode, respectively. Sample was coated on a tidy FTO. Electrolyte was 0.5 M Na2SO4 solution. Photocurrent measurements were conducted with same workstation with irridiation by 300 W xenon lamp using same method as EIS, except the electrolyte was replaced by a mixed solution of 5mM K3 Fe(CN)6, 5 mM K4Fe(CN)6 and 0.1 M KCl. Mott–Schottky plots were conducted with same workstation at frequency of 1000 Hz and 2000 Hz in dark. 2.10 Electron spin resonance (ESR) spectroscopy ESR was conducted on a Brucker A300 ESR spectrometer. 5, 5-diamethyl-1-pyrroline N-oxide (DMPO) [61] was chosen to trap free radical species.

3. Discussion and Results 3.1 Characteristics 3.1.1 Structural characteristics

11

The structural characterizations of CoFe2O4 and magnetic ion imprinted heterojunction photocatalyst samples were shown in Fig. 2. According to the standard JCPDS card No. 03-0862, the diffraction peaks of CoFe2O4 at 2θ values of 30.16 °, 34.98 °, 43.06 °, 53.33 °, 57.13 ° and 62.58 ° were corresponded to the reflection (220), (311), (400), (422), (511) and (440), which implied that CoFe2O4 had the face-centered cubic structure. Compared with CoFe2O4, the XRD pattern of magnetic ion imprinted heterojunction photocatalyst was mainly same with that of CoFe2O4, indicating that the crystalline structure of CoFe2O4 was staying the same after coating the imprinted layer.

Fig. 2. XRD patterns of (a) CoFe2O4 and (b) magnetic ion imprinted heterojunction photocatalyst. 3.1.2 Chemical composition So as to investigate the chemical composition of the magnetic ion imprinted heterojunction photocatalyst, XPS analysis was conducted and the consequences was presented in Fig. 3. The XPS survey spectra displayed that the obvious binding energy peaks were attributed to C 1s, O 1s, N 1s, Fe 2p, Co 2p peaks, respectively. The binding energy peaks of 288.8 eV (C 1s) and 286.4 eV (C 1s) could be resulted from the C=O and C–O [59], respectively, indirectly proved the existence of EGDMA. Furthermore, the binding energy peaks of 400.0 eV (N 1s) could be attributed to the C–N from the POPD [62]. Moreover, Fe 2p, Co 2p and O 1s also indirectly indicated that CoFe2O4 was successfully synthesized. All of results convincingly 12

demonstrated that the magnetic ion imprinted heterojunction photocatalyst was synthesized as expected.

Fig. 3. XPS spectra of the magnetic ion imprinted heterojunction photocatalyst (a. C 1s, b. N 1s, c. O 1s, d. Fe 2p and e. Co 2p). The FT-IR spectra of CoFe2O4, Carboxylation CoFe2O4, magnetic ion imprinted heterojunction photocatalyst were shown in Fig. 4. It could be found that two metal-oxygen bands, standing for the vibration at tetrahedral and octahedral site of spinel ferrite, which existed at approximate 410 and 580 cm-1 [63,64], respectively, which certified the existence of Fe-O in every sample. Compared with CoFe2O4 many new peaks were appeared, the adsorption peaks at 1720 cm-1 were attributed to -COOH both in carboxylation CoFe2O4 and magnetic ion imprinted heterojunction photocatalyst, which demonstrated samples were successfully carboxylated. Furthermore, the adsorption peak at 1051 cm-1 and 1620 cm-1 were assigned to C-O and C=C in EGDMA [65],

the adsorption peak at 1422 cm-1 and 3452 cm-1

were assigned to C-N and N-H in POPD [66]. Above results further provided an evident that the magnetic ion imprinted heterojunction photocatalyst was successfully synthesized, which was also in accordance with the results in other characterization such as XRD and XPS.

13

Fig. 4. FT-IR spectra of (a) CoFe2O4, (b) Carboxylation CoFe2O4 and (c) magnetic ion imprinted heterojunction photocatalyst. 3.1.3 Morphology The morphology was characterized and exhibited in Fig. 5 and Fig. S1. It could be clearly seen that CoFe2O4 was monodispersed and the average diameter of it was 370 ± 40 nm. After forming the imprinted layer on the surface of CoFe2O4, the average diameter of magnetic ion imprinted heterojunction photocatalyst was 410 ± 53 nm bigger than that of CoFe2O4. The HRTEM images certified the close linkage between ion imprinted layer and CoFe2O4 [67]. The marked lattice spaces of 0.297 nm, 0.256 nm and 0.212 nm were in good agreement with the (220) plane, (311) plane and (400) planes of CoFe2O4, respectively. Furthermore, SAED pattern also comfirmd the existence of CoFe2O4. As shown in Fig. S2, The corresponding elemental mapping images of C, N, O, Fe and Co indirectly proved that the imprinted layer was successfully synthesized.

14

Fig. 5. TEM images of CoFe2O4 (a) and magnetic ion imprinted heterojunction photocatalyst (b), SAED pattern (c) and HRTEM image (d) of magnetic ion imprinted heterojunction photocatalyst. In order to investigate the presence of mesoporous and Cu2+ imprinted cavities, N2 adsorption-desorption experiments were conducted and displayed in Fig. 6 and Fig. S3. The BET specific surface area of CoFe2O4 was 19.53 m2/g, because abundant mesoporous and Cu2+ imprinted cavities were existed, it was much smaller than that of magnetic ion imprinted heterojunction photocatalyst (80.95 m2/g), and average pore diameter of CoFe2O4 and magnetic ion imprinted heterojunction photocatalyst were 6.13 nm and 3.52 nm, respectively. Moreover, the BET specific surface area of mesoporous non-imprinted photocatalyst, non-mesoporous imprinted photocatalyst and non-mesoporous non-imprinted photocatalyst were 46.72 m2/g, 37.66 m2/g and 3.07 m2/g, respectively, and the corresponding average pore diameter were 2.73 nm, 3.63 nm and 5.26 nm, respectively, the larger BET specific surface area and smaller average pore diameter were due to the existence of mesoporous in mesoporous non-imprinted photocatalyst and the existence of Cu2+ imprinted cavities in non-mesoporous imprinted photocatalyst, respectively. In addition, Fig. 6b showed that the magnetic ion imprinted heterojunction photocatalyst had typical type IV isotherms and 15

obvious H4 type hysteresis loops [68], indicating that the magnetic ion imprinted heterojunction photocatalyst possessed the mesoporous structure. Compared with other samples, because that the mesoporous and Cu2+ imprinted cavities were co-exsited in the magnetic ion imprinted heterojunction photocatalyst, magnetic ion imprinted heterojunction photocatalyst had the largest BET specific surface area (80.97 m2/g) and relatively smaller average pore diameter (3.52 nm). Therefore, above results further prove that the presence of mesoporous and Cu2+ imprinted cavities in the imprinted layer of the magnetic ion imprinted heterojunction photocatalyst which formed imprinted cavity and mesoporous dual channels.

Fig. 6. N2 adsorption-desorption isotherms and the corresponding pore size distribution curves of CoFe2O4 (a and d), magnetic ion imprinted heterojunction photocatalyst (b and e) and non-mesoporous non-imprinted photocatalyst (c and f). 3.1.4 Optical property The optical property of photocatayst was researched by the UV–vis diffuse reflanctance spectroscopy. All of samples showed a broad light absorption range from 200 nm to 800 nm (Fig. 7) because that CoFe2O4 had great UV and visible light response and POPD had the full spectrum absorption characteristics. Compared with other samples, after coating the imprinted layer, magnetic ion imprinted heterojunction photocatalyst had the great adsorption ability in the UV and visible light as before owing to the POPD. In addition, for further discussing the 16

photocatalytic mechanism, the band gap was determined by UV–vis DRS spectra and calculated according to following formula [69]: (5) Where A stood for absorption coefficient, h stood for planck constant, ν stood for light frequenc, k stood for proportionality constant and Eg stood for band gap. n=1 or 4 depended on the type of semiconductor. Due to the fact that CoFe2O4 and POPD were belonged to the direct transition absorption, accordingly,

n=1, and the Eg of CoFe2O4 was approximately

1.75 eV. Similarly, the Eg of POPD was calculated as 1.61 eV.

Fig. 7. UV-Vis DRS spectra (A) of magnetic ion imprinted heterojunction photocatalyst (a), CoFe2O4 (b) and POPD (c), the (Ahν)2 versus hν curves of CoFe2O4 (B) and POPD (C). 3.1.5 Magnetic property Excellent magnetic properties made it easier to recycle materials and achieve material reuse. The magnetic property of magnetic ion imprinted heterojunction photocatalyst was measured by VSM. As presented in Fig. 8, the Ms value of CoFe2O4 was 66.53 emu/g which was little higher than magnetic ion imprinted heterojunction photocatalyst (58.21 emu/g). The Ms value of magnetic ion imprinted heterojunction photocatalyst was mildly decreased when imprinted layer coated, because the imprinted layer is not magnetic, after forming the imprinted layer on the surface of CoFe2O4, the content of CoFe2O4 would decrease in some extent in unit weight sample, which reduce the magnetic properties of the magnetic ion imprinted heterojunction photocatalyst [17,70], however, magnetic ion imprinted heterojunction photocatalyst could be

17

completely separated by placing a magnet. Above result indicated that the magnetic ion imprinted heterojunction photocatalyst possessed excellent magnetic separation ability.

Fig. 8. Magnetization patterns of CoFe2O4 (a) and magnetic ion imprinted heterojunction photocatalyst (b) at room temperature, and the photograph of magnetic ion imprinted heterojunction photocatalyst before and after separating from solution under a magnet (inset). 3.1.6 Photoelectrochemical property The transfer of photogenerated e- and h+ was characterized by Photocurrent, electrochemical impedance spectroscopy (EIS) and photoluminescence (PL), which were showed in Fig. 9 and Fig. S4. Compared with CoFe2O4, magnetic ion imprinted heterojunction photocatalyst and other photocatalyst, magnetic ion imprinted heterojunction photocatalyst exhibited the best photocurrent response, lowest impedance and smallest PL intensity, which were all similar to non-mesoporous non-imprinted photocatalyst, mesoporous non-imprinted photocatalyst and non-mesoporous imprinted photocatalyst, indicating that POPD could effectually separate the photogenerated e- produced by CoFe2O4 and the separation of the photogenerated electron was not affected for presence of imprinted layer.

18

Fig. 9. Transient photocurrent response (A), nyquist plots of EIS (B) and PL (C) of CoFe2O4 (a), magnetic ion imprinted heterojunction photocatalyst (b) and non-mesoporous non-imprinted photocatalyst (c). 3.2 Adsorption ability The adsorption ability of different samples were tested and showed in Fig. S5. As for Cu2+ adsorption, the adsorption capacity of magnetic ion imprinted heterojunction photocatalyst under the dark within 60 min was the highest (114.198 mg/g), which was 8.71, 3.80, 1.83 and 4.81 times to that of CoFe2O4, mesoporous non-imprinted photocatalyst, non-mesoporous imprinted photocatalyst and non-mesoporous non-imprinted photocatalyst, respectively, because sufficient Cu2+ imprinted cavities were existed in the magnetic ion imprinted heterojunction photocatalyst, and these Cu2+ imprinted cavities met the requirement to recognize Cu2+. The kinetics data were analyzed by pseudo-first-order kinetics equation and pseudo-second-order kinetics equation [71] and shown in Fig. S6 and Table S1 to further examine the mechanism of adsorption process of magnetic ion imprinted heterojunction photocatalyst. It could be clearly seen that the adsorption of Cu2+ followed the pseudo-second-order kinetics, indicating that the adsorption process was mainly controlled by chemical action, this result further proved that Cu2+ was adsorbed by the bonding groups of functional monomer which was existed in the imprinted layer. 19

Moreover, as shown in Fig. S5 (left) for adsorption of tetracycline, the adsorption capacity of magnetic ion imprinted heterojunction photocatalyst and mesoporous non-imprinted photocatalyst under the dark within 60 min was obviously higher than that of other samples due to the existence of mesoporous in the outer layer. Besides, when time exceeded 30 min, the adsorption capacity for tetracycline with all samples rose slowly, then achieved the desired adsorption stage. Hence, 30 min was chosen as the desired adsorption time before tetracycline degradation in corresponding experiments. Owing to imprinted cavity and mesoporous dual channels formed in magnetic ion imprinted heterojunction photocatalyst, Cu2+ imprinted cavities made great effect on adsorption of Cu2+ and mesoporous made great effect on adsorption of tetracycline, magnetic ion imprinted heterojunction photocatalyst possessed excellent adsorption ability for adsorption of tetracycline and Cu2+. 3.3 Photocatalytic degradation So as to investigate degradation ability of tetracycline with magnetic ion imprinted heterojunction photocatalyst, the experiment was conducted, and the degree of degradation (C/C0) was displayed in Fig. 10. Before photodegradation, adsorption process was performed for 30 minutes without light for achieving the desired adsorption capacity. For the purpose of highlighting the good photocatalytic activity of magnetic ion imprinted heterojunction photocatalyst, the comparative experiments were conducted. It could be clearly seen the C/C0 of magnetic ion imprinted heterojunction photocatalyst (0.398) was very close to CoFe2O4 (0.362), due to CoFe2O4 can transfer photo-induced h+ from POPD, more importantly, because the existence of mesoporous in the imprinted layer, tetracycline can easily contact with CoFe2O4. Moreover, the C/C0 of magnetic ion imprinted heterojunction photocatalyst was significantly higher than mesoporous non-imprinted photocatalyst (0.487), non-mesoporous imprinted photocatalyst (0.646) and non-mesoporous non-imprinted photocatalyst (0.699). The results demonstrated that the magnetic ion imprinted

20

heterojunction photocatalyst possessed high photocatalytic efficiency for degradation of tetracycline.

Fig. 10. The degree of degradation (C/C0) of tetracycline with different samples. 3.4 Selective photoreduction Selective photoreduction of target ions was the highlight of the material. Considering that some heavy metal ions in polluted water still had high recycling value, Cu 2+ was selected as target ions for selective reduction, thereby further recycling them. And competitive adsorption of Cu2+, Cd2+, Fe3+ and Zn2+ which was contained in mixed solutions to investigate the selectivity of the magnetic ion imprinted heterojunction photocatalyst, which was shown in Fig. 11. Due to abundant Cu2+ imprinted cavities were formed in magnetic ion imprinted heterojunction photocatalyst, and these Cu2+ imprinted cavities met the requirement to recognize Cu2+, compared with other samples, magnetic ion imprinted heterojunction photocatalyst showed the highest adsorption capacity (114.198 mg/g) for Cu2+ adsorption. As shown in Fig. S7, the EDS of magnetic ion imprinted heterojunction photocatalyst before and after adsorbing Cu2+ further demonstrated that as-prepared material can successfully adsorb Cu2+ [72]. Moreover, due to the difference between different heavy metal ions, the Cu2+ imprinted cavities exhibited efficient specific recognition ability of other ions, therefore, for adsorption of other ions, magnetic ion imprinted heterojunction photocatalyst exhibited a relatively poor adsorption capacity. 21

Fig. 11. Selectivity for adsorption of Cu2+ with CoFe2O4 (a), magnetic ion imprinted heterojunction photocatalyst (b), mesoporous non-imprinted photocatalyst (c), non-mesoporous imprinted photocatalyst (d) and non-mesoporous non-imprinted photocatalyst (e). Repeated reduction tests were conducted to further explore reduction availability. Compared with concentration of Cu2+ after light irradiation for 3 h (C), and the initial concentration of Cu2+ after adsorbing (C0), it could calculate the reduction rate of Cu2+ by Equation 2. Through the detection of ESR in Fig. S8, Cu+ was not be detected, so it could be inferred that the reduction products were all Cu. Since a large amount of Cu 2+ were adsorbed on the Cu2+ imprinted cavities, and the e- from CoFe2O4 was transferred to POPD owing to heterojunction strucure, the Cu2+ can be reduced to Cu by e- on the imprinted layer. Compared with different samples in Fig. 12, magnetic ion imprinted heterojunction photocatalyst exhibited highest reduction rate of Cu2+ (45.98 %) because there were abundant Cu2+ imprinted cavities in the imprinted layer and the e- generated in CoFe2O4 could transfer rapidly to POPD in the imprinted layer, causing the Cu 2+ directly reduced to Cu. The Cu2+ reduction rate of mesoporous non-imprinted photocatalsy was 9.20 %, non-mesoporous imprinted photocatalyst was 18.07 %, non-mesoporous non-imprinted photocatalyst was 4.39 % and CoFe2O4 was 9.35 %. Above results demonsrated that position of conduction band on CoFe2O4 determined whether Cu2+ could be reduced to Cu, and the reduction rate of Cu2+ 22

on different materials depended on its adsorption capacity of Cu 2+. Therefore, magnetic ion imprinted heterojunction photocatalyst exhibited better Cu2+ reduction performance. Furthermore, all samples possessed poor ability to reduce other ions (Cd2+, Fe3+, Zn2+), the reduction rate of these ions were overall under 10 %. On the one hand, because these samples had small adsorption capacity of Cd2+, Fe3+ and Zn2+ so only few ions can be reduced. On the other hand, on account of conduction position of CoFe2O4, it was difficult to reduce these ions to relative elementary substance.

Reduction rate of Cu2+ with CoFe2O4 (a), magnetic ion imprinted heterojunction

Fig. 12.

photocatalyst (b), mesoporous non-imprinted photocatalyst (c), non-mesoporous imprinted photocatalyst (d) and non-mesoporous non-imprinted photocatalyst (e). Moreover, the ions selectivity coefficient (kions) and materials selectivity coefficient (kmaterials) were presented in Table 1 and Table 2. The ions selectivity coefficient (kions) of Cu2+ to other ions (Cd2+, Fe3+ and Zn2+) over magnetic ion imprinted heterojunction photocatalyst (kions (Cu2+/Cd2+) =11.495, kions (Cu2+/Fe3+) =4.716, kions (Cu2+/Zn2+) =15.910) were all much higher than those over other materials. It was worth mentioning that non-meporous imprinted photocatalyst also showed great ions selectivity coefficient because there were abundant Cu2+ imprinted cavaties in the imprinted layer. More importantly, the materials selectivity coefficient (kmaterials) of magnetic ion imprinted heterojunction photocatalyst relative to mesoporous

non-imprinted

photocatalyst,

non-mesoporous 23

imprinted

photocatalyst,

non-mesoporous non-imprinted photocatalyst and CoFe2O4 was 4.998, 2.545, 10.474 and 4.918, respectively. All of results confirmed that the magnetic ion imprinted heterojunction photocatalyst possessed the specific recognition capacity for selective reduction of Cu2+. Table. 1 The ions selectivity coefficient (kions). Ions

Magnetic

Mesoporous

Non-mesop

Non-mesopor

CoFe2O4

selectivity

ion imprinted

non-imprinte

orous

ous

coefficient

heterojunction

d

imprinted

non-imprinted

(kions)

photocatalyst

photocatalyst

photocatalyst

photocatalyst

kions (Cu2+/Cd2+)

11.495

1.676

4.116

1.033

1.640

kions (Cu2+/Fe3+)

4.716

1.305

3.137

0.728

1.540

kions (Cu2+/Zn2+)

15.910

3.087

7.316

1.314

2.562

Table. 2 The materials selectivity coefficient (kmaterials). Materials selectivity coefficient (kmaterials) kmaterials (magnetic ion imprinted heterojunction photocatalyst /mesoporous non-imprinted photocatalyst)

4.998

kmaterials (magnetic ion imprinted heterojunction photocatalyst /non-mesoporous imprinted photocatalyst)

2.545

kmaterials (magnetic ion imprinted heterojunction photocatalyst /non-mesoporous non-imprinted 10.474 photocatalyst)

kmaterials (magnetic ion imprinted heterojunction photocatalyst /CoFe2O4)

4.918

3.5 Cycle experiment For proving the reusability of magnetic ion imprinted heterojunction photocatalyst, the regenerated magnetic ion imprinted heterojunction photocatalyst was reused for 5 cycles. The magnetic ion imprinted heterojunction photocatalyst still had a high photocatalytic activity after 5 cycles, similarly, after 5 cycles for reduction of Cu2+, the magnetic ion imprinted 24

heterojunction photocatalyst also had a high reduction ability (Fig. 13). It can be easily found that magnetic ion imprinted heterojunction photocatalyst could be recycled for several times with slight decline of photocatalytic activity, certifying that the magnetic ion imprinted heterojunction photocatalyst had promising stability and reusability.

Fig. 13. Degradation degree (C/C0) of tetracycline and reduction rate of Cu2+ over magnetic ion imprinted heterojunction photocatalyst with different cycles. 3.6 Photocatalytic and selective mechanism The photocatalytic mechanism of degradation of tetracycline and selective reduction of Cu2+ with magnetic ion imprinted heterojunction photocatalyst, many corresponding experiments were conducted solely. The band positions of CoFe2O4 and POPD was evaluated by Mott-Schottky experiment (Fig. S9). The flat band potential of CoFe2O4 and POPD was -1.32 V and 0.81 V vs. Ag/AgCl, respectively. Then, the flat band potential of CoFe2O4 and POPD could be calculated to -0.82 V and -0.16 V vs. NHE based on Nernst equation (Equation 6) [6]. Moreover, the flat potentials of n-type semiconductors are 0 eV - 0.1 eV lower than conduction bands [6]. Therefore, the estimated CB positions of CoFe2O4 and POPD was -0.82 eV and -0.16 eV vs. NHE, respectively. Combined with Eg of CoFe2O4 (1.75 eV) and Eg of POPD (1.61 eV), the VB of CoFe2O4 and POPD was 0.93 eV and 1.45 eV, respectively. ENHE = EAg/AgCl + 0.059 × pH + EθAg/AgCl

(6)

25

Where ENHE was potential vs. NHE, EAg/AgCl was potential vs. Ag/AgCl and the standard Ag/AgCl electrode potential at 25 °C (0.197 eV), respectively [6,74]. The electrolyte pH= 7.02. Furthermore, the migration path of e- and h+ was further determined. As shown in Fig. 14, generated e- in CoFe2O4 was transferred to POPD, meanwhile, all h+ from POPD was shifted to CoFe2O4, which formed dual channels of imprinted cavity and mesoporous , combined with ESR signals DMPO−·O2- of different samples in Fig. 15, it proved ·O2- was only generated in CoFe2O4 during the photodegradation and photocatalytic reduction reaction, and was not produced in POPD or magnetic ion imprinted heterojunction photocatalyst, which confirmed the as-prepared material was heterojunction strucure [73], because ·O2- would generate in magnetic ion imprinted heterojunction photocatalyst if e - was not transferred from CoFe2O4 to POPD, thus, it could exclude as-prepared material as other structure. As a result, according to the CB position and VB position of magnetic ion imprinted heterojunction photocatalyst, neither ·OH nor ·O2- was generated in magnetic ion imprinted heterojunction photocatalyst.

Fig. 14. Proposed selective reduction and photocatalytic degradation mechanism of the magnetic ion imprinted heterojunction photocatalyst.

26

Fig. 15. ESR signals DMPO−·O2- with the light irradiation of different samples. Based on aforementioned results, the inferred photocatalytic and selective mechanism was shown in Fig. 14. As for degradation of tetracycline, when magnetic ion imprinted heterojunction photocatalyst was dispersed in tetracycline solution (100 mL, 20 mg/L) under light, the e- and h+ were generated in CoFe2O4 and POPD, meanwhile, entire of h+ in POPD was transferred to CoFe2O4 and abundant tetracycline can reach the surface of CoFe2O4 through the mesoporous channel. Finally, tetracycline was degraded to CO2, H2O and other molecules by h+ in CoFe2O4. As for selective Cu2+ reduction, on the one hand, when magnetic ion imprinted heterojunction photocatalyst was dispersed in Cu2+ solution (100 mL, 100 mg/L), most of Cu2+ were selectively absorbed by Cu2+ imprinted cavities and other metal ions (Cd2+, Fe3+, Zn2+) was blocked outside. After turning on the light, absorbed Cu2+ can contact with e- in the imprinted layer due to POPD was transferred massive e - from CoFe2O4. Eventually, Cu2+ was reduced to Cu by e- in POPD. Therefore, due to the existence of imprinted cavity and mesoporous dual channels, photodegradation and photoreduction reactions were carried out at different positions of magnetic ion imprinted heterojunction photocatalyst, thereby enabling selective reduction of Cu2+ with simultaneous degradation of tetracycline. The specific reaction processes were displayed as follows: (7) 27

(8) (9) (10) (11)

4. Conclusion In summary, the magnetic ion imprinted heterojunction photocatalyst had been successfully synthesized via microwave-assisted ion imprinting technique. The as-prepared heterojunction photocatalyst possessed good electric conductivity, great magnetic separation capacity, fair stability and reusability. Moreover, the presence of Cu2+ imprinted cavities in the imprinted layer improved the ability of selective reduction of Cu2+. Meanwhile, tetracycline can easily contact with CoFe2O4 through the mesoporous in the imprinted layer and further be degraded. More importantly, the heterojunction structure formed between CoFe2O4 and POPD effectively separated e- and h+, which greatly promoted the photocatalytic activity of selective reduction of Cu2+ and simultaneous degradation of tetracycline. Therefore, the magnetic ion imprinted heterojunction photocatalyst achieved the goal for selectively reducing Cu2+ and simultaneously degrading tetracycline via the dual channels of imprinted cavity and mesoporous. The C/C0 of magnetic ion imprinted heterojunction photocatalyst for degradation of tetracycline was 0.398, which was almost same as that of CoFe2O4. The ions selectivity coefficient (kions) of Cu2+ to other ions (Fe3+, Cd2+ and Zn2+) over magnetic ion imprinted heterojunction photocatalyst (kions

(Cu

2+

2+ /Cd )

=11.495, kions

(Cu

2+

3+ /Fe )

=4.716, kions

(Cu

2+

2+ /Zn )

=15.910) were all much higher than those over other materials, and the materials selectivity coefficient (kmaterials) of magnetic ion imprinted heterojunction photocatalyst relative to mesoporous

non-imprinted

photocatalyst,

non-mesoporous

imprinted

photocatalyst,

non-mesoporous non-imprinted photocatalyst and CoFe2O4 was 4.998, 2.545, 10.474 and 4.918, respectively, which showed excellent selectivity. Compared with other photocatalysts, 28

magnetic ion imprinted heterojunction photocatalyst not only maintained the good photocatalytic ability to degrade organic pollutants, but also can selectively reduce target heavy metal ions. Our work provided a high-efficient and economic technical method for selective reduction of specific heavy metal ions and simultaneous degradation of organic pollutants in complex water environments. However, this work has not examined other alternative materials, therefore, the activity of different alternative materials would be investigated in future work.

Acknowledgements This work was financially supported by the National Natural Science Foundation of China (No. 21607062), the Natural Science Foundation of Jiangsu Province (Nos. BK20160494 and BK20150536), the China Postdoctoral Science Foundation (Nos. 2016M600378 and 2017T100333), the Social Development Project of Key Research Program of Zhenjiang (No. SH2018021), the Youth Talent Development Program of Jiangsu University and the Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment.

References [1] F. Deng, L. N. Zhao, X. B. Luo, S. L. Luo, D. D. Dionysiou, Highly efficient visible-light photocatalytic performance of Ag/AgIn5S8 for degradation of tetracycline hydrochloride and treatment of real pharmaceutical industry wastewater, Chem. Eng. J. 333 (2018) 423-433. [2] L. B. Moreno, V. H. Sheridan, I. Goodhead, S. Armstrong, J. K. L. Wong, E. M. Waters, J. Sarsby, S. Panagiotou, J. Dunn, A. Chakraborty, Y. L. Fang, K. E. Griswold, C. Winstanley, J. L. Fothergill, A. Kadioglu, D. R. Neill, Evolutionary Trade-offs Associated with Loss of PmrB Function in Host-adapted Pseudomonas Aeruginosa, Nat. Commun. 9 (2018) 2635. [3] J. Z. Y. Tan, N. M. Nursam, F. Xia, M. A. Sani, W. Li, X. D. Wang, R. A. Caruso, High-Performance Coral Reef-like Carbon Nitrides: Synthesis and Application in 29

Photocatalysis and Heavy Metal Ion Adsorption, ACS Appl. Mater. Inter. 9 (2017) 4540-4547. [4] X. M. Zhang, D. Sarma, Y. Q. Wu, L. Wang, Z. X. Ning, F. Q. Zhang, M. G. Kanatzidis, Open-Framework Oxysulfide Based on the Supertetrahedral [In4Sn16O10S34](12-) Cluster and Efficient Sequestration of Heavy Metals, J. Am. Chem. Soc. 138 (2016) 5543-5546. [5] L. Zhang, L. G. Chen, Fluorescence Probe Based on Hybrid Mesoporous Silica/Quantum Dot/Molecularly Imprinted Polymer for Detection of Tetracycline, ACS Appl. Mater. Inter. 8 (2016) 16248-16256. [6] Z. Y. Lu, Z. H. Yu, J. B. Dong, M. S. Song, Y. Liu, X. L. Liu, Z. F. Ma, H. Su, Y. S. Yan, P. W. Huo, Facile Microwave Synthesis of a Z-scheme Imprinted ZnFe2O4/Ag/PEDOT with the Specific Recognition Ability Towards Improving Photocatalytic Activity and Selectivity for Tetracycline, Chem. Eng. J. 337 (2018) 228-241. [7] K. V. Bukhryakov, R. R. Schrock, A. H. Hoveyda, C. Tsay, P. Muller, Syntheses of Molybdenum Oxo Alkylidene Complexes through Addition of Water to an Alkylidyne Complex, J. Am. Chem. Soc. 140 (2018) 2797-2800. [8] W. Guan, B. F. Zhang, S. C. Tian, X. Zhao, The Synergism between Electro-Fenton and Electrocoagulation Process to Remove Cu-EDTA, Appl. Catal., B 227 (2018) 252-257. [9] S. J. Xia, X. F. Zhang, X. B. Zhou, Y. Meng, J. Xue, Z. M. Ni, The Influence of Different Cu Species onto Multi-copper-contained Hybrid Materials' Photocatalytic Property and Mechanism of Chlorophenol Degradation, Appl. Catal., B 214 (2017) 78-88. [10] L. J. Ma, Q. Wang, S. M. Islam, Y. C. Liu, S. L. Ma, M. G. Kanatzidis, Highly Selective and Efficient Removal of Heavy Metals by Layered Double Hydroxide Intercalated with the MoS42- Ion, J. Am. Chem. Soc. 138 (2016) 2858-2866. [11] L. Wang, D. Hu, X. K. Kong, J. G. Liu, X. H. Li, K. Zhou, H. G. Zhao, C. H. Zhou, Anionic

Polypeptide

Poly(gamma-glutamic

30

acid)-Functionalized

Magnetic

Fe3O4-GO-(o-MWCNTs) Hybrid Nanocomposite for High-efficiency Removal of Cd(II), Cu(II) and Ni(II) Heavy Metal Ions, Chem. Eng. J. 346 (2018) 38-49. [12] S. J. Li, S. W. Hu, W. Jiang, Y. P. Liu, Y. T. Zhou, Y. Liu, L. Y. Mo, Hierarchical architectures of bismuth molybdate nanosheets onto nickel titanate nanofibers: Facile synthesis and efficient photocatalytic removal of tetracycline hydrochloride, J. Colloid. Interf. Sci. 521 (2018) 42-49. [13] L. W. Hou, L. G. Wang, S. Royer, H. Zhang, Ultrasound-assisted heterogeneous Fenton-like degradation of tetracycline over a magnetite catalyst, J. Hazard. Mater. 302 (2016) 458-467. [14] X. L. Liu, P. Lv, G. X. Yao, C. C. Ma, P. W. Huo, Y. S. Yan, Microwave-assisted synthesis of selective degradation photocatalyst by surface molecular imprinting method for the degradation of tetracycline onto Cl-TiO2. Chem. Eng. J. 217 (2017) 398-406. [15] F. Chen, Q. Yang, X. M. Li, G. M. Zeng, D. B. Wang, C. G. Niu, J. W. Zhao, H. X. An, T. Xie, Y. C. Deng, Hierarchical assembly of graphene-bridged Ag3PO4/Ag/BiVO4 (040) Z-scheme photocatalyst: An efficient, sustainable and heterogeneous catalyst with enhanced visible-light photoactivity towards tetracycline degradation under visible light irradiation, Appl. Catal., B 200 (2017) 330-342. [16] Z. Y. Huang, X. Q. Zeng,

K. Li, S. M. Gao, Q. Y. Wang, J. Lu, Z-Scheme

NiTiO3/g-C3N4 Heterojunctions with Enhanced Photoelectrochemical and Photocatalytic Performances under Visible LED Light Irradiation, ACS Appl. Mater. Inter. 9 (2017) 41120-41125. [17] Z.Y. Lu, F. Chen, M. He, M.S. Song, Z.F. Ma, W.D. Shi, Y.S. Yan, J.Z. Lan, F. Li, P. Xiao, Microwave Synthesis of a Novel Magnetic Imprinted TiO2 Photocatalyst with Excellent Transparency for Selective Photodegradation of Enrofloxacin Hydrochloride Residues Solution, Chem. Eng. J. 249 (2014) 15-26.

31

[18] N. Razgoniaeva, P. Moroz, M. R. Yang, D. S. Budkina, H. Eckard, M. Augspurger, D. Khon, A. N. Tarnovsky, M. Zamkov, One-Dimensional Carrier Confinement in "Giant" CdS/CdSe Excitonic Nanoshells, J. Am. Chem. Soc. 139 (2017) 7815-7822. [19] J. L.Barrera, Ballesté, M. Liras,

V. L.Martín, T. Rigotti, F. Peccati, X. S. Monfort, M. Sodupe,

R. M.

J. Alemán, Visible-Light Photocatalytic Intramolecular Cyclopropane

Ring Expansion, Angew. Chem. Int. Edit.

56 (2017) 7826-7830.

[20] Y. Liu, J. J. Kong, J. L. Yuan, W. Zhao, X. Zhu, C. Sun, J. M. Xie, Enhanced photocatalytic activity over flower-like sphere Ag/Ag2CO3/BiVO4 plasmonic heterojunction photocatalyst for tetracycline degradation, Chem. Eng. J. 331 (2018) 242-254. [21] H. J. Snaith, P. Hacke, Enabling Reliability Assessments of Pre-commercial Perovskite Photovoltaics with Lessons Learned from Industrial Standards, Nat. Energy. 3 (2018) 459-465. [22] C. C. Dong, J. Lu, B. C. Qiu, B. Shen, M. Y. Xing, J. L. Zhang, Developing Stretchable and Graphene-oxide-based Hydrogel for the Removal of Organic Pollutants and Metal Ions, Appl. Catal., B 222 (2018) 146-156. [23] Z. Xu, C. Shan, B. H. Xie, Y. Liu, B. C. Pan, Decomplexation of Cu(II)-EDTA by UV/persulfate and UV/H2O2: Efficiency and Mechanism, Appl. Catal., B

200 (2017)

439-447. [24] Z. Y. Jiang, X. H. Zhang, Z. M. Yuan, J. C. Chen, B. B. Huang, D. D. Dionysiou, G. H. Yang, Enhanced photocatalytic CO2 reduction via the synergistic effect between Ag and activated carbon in TiO2/AC-Ag ternary composite, Chem. Eng. J. 348 (2018) 592-598. [25] Z. Y. Lu, X. X. Zhao, Z.

Zhu, Y. S. Yan, W. D. Shi, H. J. Dong, Z. F. Ma, N. L. Gao,

Y. S. Wang, H. Huang, Enhanced Recyclability, Stability, and Selectivity of CdS/C@Fe3O4 Nanoreactors for Orientation Photodegradation of Ciprofloxacin, Chem. Eur. J. 21 (2015) 18528–18533.

32

[26] K. Chakrapani, G. Bendt, H. Hajiyani, T. Lunkenbein, M. T. Greiner, L. Masliuk, S. Salamon, J. Landers, R. Schlögl, H. Wende, R. Pentcheva, S. Schulz, M. Behrens, The Role of Composition of Uniform and Highly Dispersed Cobalt Vanadium Iron Spinel Nanocrystals for Oxygen Electrocatalysis, ACS Catal. 8 (2018) 1259-1267. [27] Q. Zhou, Y. X. Lin, K. Y. Zhang, M. J. Li, D. P. Tang, Reduced graphene oxide/BiFeO3 nanohybrids-based signal-on photoelectrochemical sensing system for prostate-specific antigen detection coupling with magnetic microfluidic device, Biosens. Bioelectron. 101 (2018) 146-152. [28] J. Li, Y. Ren, F. Z. Ji, B. Lai, Heterogeneous catalytic oxidation for the degradation of p-nitrophenol in aqueous solution by persulfate activated with CuFe2O4 magnetic nano-particles, Chem. Eng. J. 324 (2017) 63-73. [29] Y. C. Du, W. J. Ma, P. X. Liu, B. H. Zou, J. Ma, Magnetic CoFe2O4 nanoparticles supported on titanate nanotubes (CoFe2O4/TNTs) as a novel heterogeneous catalyst for peroxymonosulfate activation and degradation of organic pollutants, J. Hazard. Mater. 308 (2016) 58-66. [30] L. Q. Jing, Y. G. Xu, S. Q. Huang, M. Xie, M. Q. He, H. Xu, H. M. Li, Q. Zhang, Novel Magnetic CoFe2O4/Ag/Ag3VO4 Composites: Highly Efficient Visible Light Photocatalytic and Antibacterial Activity, Appl. Catal., B 199 (2016) 11-22. [31] B. C. Qiu, Q. H. Zhu, M. M. Du, L. G. Fan, M. Y. Xing, J. H. Zhang, Efficient Solar Light Harvesting CdS/Co 9S8 Hollow Cubes for Z-Scheme Photocatalytic Water Splitting, Angew. Chem. Int. Edit. 56 (2017) 2684-2688. [32]

D. Erdem, N. S. Bingham, F. J. Heiligtag, N. Pilet, P. Warnicke, L. J. Heyderman, M.

Niederberger, CoFe2O4 and CoFe2O4-SiO2 Nanoparticle Thin Films with Perpendicular Magnetic Anisotropy for Magnetic and Magneto-Optical Applications, Adv. Funct. Mater. 26 (2016) 1954-1963.

33

[33] X. F. Lu, L. F. Gu, J. W. Wang, J. X. Wu, P. Q.

Liao, G. R. Li, Bimetal-Organic

Framework Derived CoFe2O4/C Porous Hybrid Nanorod Arrays as High-Performance Electrocatalysts for Oxygen Evolution Reaction, Adv. Mater. 29 (2017) 1604437. [34] A. H. E. Foulani, A. Aamouche, F. Mohseni, J. S. Amaral, D. M. Tobaldi, R. C. Pullar, Effect of surfactants on the optical and magnetic properties of cobalt zinc ferrite Co0.5Zn0.5Fe2O4, J. Alloy. Compd. 774 (2019) 1250-1259. [35] M. N. Timofeeva, V. N. Panchenko, S.A.Prikhod'ko, A. B. Ayupov, Y. V. Larichev, N. A. Khan, S. H. Jhung, Metal-organic Frameworks as Efficient Catalytic Systems for the Synthesis of 1,5-Benzodiazepines from 1,2-Phenylenediamine and Ketones, J. Catal. 354 (2017) 128-137. [36] U. Riaz, S. Jadoun, P. Kumar, M. Arish, M. Rub, S. M. Ashraf, Influence of Luminol Doping of Poly(o-phenylenediamine) on the Spectral, Morphological, and Fluorescent Properties: A Potential Fluorescent Marker for Early Detection and Diagnosis of Leishmania Donovani, ACS Appl. Mater. Inter. 9 (2017) 33159-33168. [37] Z. Y. Lu, Z. H. Yu, J. B. Dong, M. S. Song, Y. Liu, X. L. Liu, D. Fan, Z. F. Ma, Y. S. Yan, P. W. Huo, Construction of Stable Core-shell Imprinted Ag-(poly-o-phenylenediamine) /CoFe2O4 Photocatalyst Endowed with the Specific Recognition Capability for Selective Photodegradation of Ciprofloxacin, RSC Adv. 7 (2017) 48894–48903. [38] Z. F. Jiang,

W. M. Wan, H. M. Li,

S. Q. Yuan, H. J. Zhao, P. K. Wong, A

Hierarchical Z-Scheme alpha-Fe2O3/g-C3N4 Hybrid for Enhanced Photocatalytic CO2 Reduction, Adv. Mater. 224 (2018) 579-585. [39] M. E. Mahmoud, G. M. Nabil, A. H. Abdel, N. A. Fekry, M. M. Osman, Imprinting "Nano-SiO2-Crosslinked Chitosan-Nano-TiO2" Polymeric Nanocomposite for Selective and Instantaneous Microwave-Assisted Sorption of Hg(II) and Cu(II), ACS Sustain. Chem. Eng. 6 (2018) 4564-4573.

34

[40] L. Wang, S. H. Ma, B. Yang, W. W. Cao, X. J. Han, Morphology-controlled Synthesis of Ag Nanoparticle Decorated Poly(o-phenylenediamine) Using Microfluidics and Its Application for Hydrogen Peroxide Detection, Chem. Eng. J. 268 (2015) 102-108. [41] X. B. Luo, B. Guo, J. M. Luo, F. Deng, S. Y. Zhang, S. L. Luo, J. Crittenden, Recovery of Lithium from Wastewater Using Development of Li Ion-Imprinted Polymers, ACS Sustainable. Chem. Eng. 3 (2015) 460–467. [42] Y. J. Yang,

Z. J. Yan, L. L. Wang,

Q. H. Meng, Y. Yuan, G. S. Zhu, Constructing

Synergistic Groups in Porous Aromatic Frameworks for the Selective Removal and Recovery of Lead(II) Ions, J. Mater. Chem. A. 6 (2018) 5202-5207. [43] Y. Liu, X. G. Meng, M. Luo, M. J. Meng, L. Ni, J. Qiu, Z. Y. Hu, F. F. Liu, G. X. Zhong, Z. C. Liu, Y. S. Yan, Synthesis of Hydrophilic Surface Ion-imprinted Polymer Based on Graphene Oxide for Removal of Strontium from Aqueous Solution, J. Mater. Chem. A. 3 (2015) 1287-1297. [44] Z. Q. Ren, D. L. Kong, K. Y. Wang, W. D. Zhang, Preparation and Adsorption Characteristics of an Imprinted Polymer for Selective Removal of Cr(VI) Ions from Aqueous Solutions, J. Mater. Chem. A. 2 (2014)

17952-17961.

[45] A. M. Schwenke, S. Hoeppener, U. S. Schubert, Synthesis and Modification of Carbon Nanomaterials Utilizing Microwave Heating, Adv. Mater. 27 (2015) 4113-4141. [46] J. Wan, L. Huang, J. B. Wu, L. K. Xiong, Z. M. Hu, H. M. Yu, T. Q.

Li, J. Zhou,

Microwave Combustion for Rapidly Synthesizing Pore-Size-Controllable Porous Graphene, Adv. Funct. Mater. 28 (2018) 1800382. [47] F. Zhu, L. W. Li, J. D. Xing, Selective adsorption behavior of Cd(II) ion imprinted polymers synthesized by microwave-assisted inverse emulsion polymerization: Adsorption performance and mechanism, J. Hazard. Mater. 321 (2017) 103-110.

35

[48] A. H. Mady, M. L. Baynosa, D. Tuma, J. J. Shim, Facile microwave-assisted green synthesis of Ag-ZnFe2O4@rGO nanocomposites for efficient removal of organic dyes under UV- andvisible-light irradiation, Appl. Catal., B 203 (2017) 416-427. [49] . . Mi a, E. Csefalvay,

. R. Nemeth, Catalytic Conversion of Carbohydrates to Initial

Platform Chemicals: Chemistry and Sustainability, Chem. Rev. 118 (2018) 505-613. [50] M. R. Martinez, C. A. Camur, A. W. Thornton, I. Imaz, D. Maspoch, M. R. Hill, New synthetic routes towards MOF production at scale, Chem. Soc. Rev. 46 (2017) 3453. [51] Y. Yang, G. Z. Wang, Q. Deng, D. H. L. Ng,

H. J. Zhao, Microwave-Assisted

Fabrication of Nanoparticulate TiO2 Microspheres for Synergistic Photocatalytic Removal of Cr(VI) and Methyl Orange, ACS Appl. Mater. Inter. 6 (2014) 3008-3015. [52] B. Y. Guan, S. L.

Zhang, X. W. Lou, Realization of Walnut-Shaped Particles with

Macro-/Mesoporous Open Channels through Pore Architecture Manipulation and Their Use in Electrocatalytic Oxygen Reduction, Angew. Chem. Int. Edit. 57 (2018) 6176-6180. [53] L. Yu, J. F. Yang, B. Y.

Guan, Y. Lu, X. W. Lou, Hierarchical Hollow Nanoprisms

Based on Ultrathin Ni-Fe Layered Double Hydroxide Nanosheets with Enhanced Electrocatalytic Activity towards Oxygen Evolution, Angew. Chem. Int. Edit. 57 (2018) 172-176. [54] Y. Zhang, L. K. Shen, M. Liu, X. Li, X. L. Lu, L. Lu, C. R. Ma, C. Y. You, A. P. Chen, C. W. Huang, L. Chen, M. Alexe, C. L. Jia, Flexible Quasi-Two-Dimensional CoFe2O4 Epitaxial Thin Films for Continuous Strain Tuning of Magnetic Properties, ACS. Nano. 11 (2017) 8002-8009. [55] A. A. Anazi, W. H. Abdelraheem, C. Han, M. N. Nadagouda, L. Sygellou, M. K. Arfanis, P. Falaras, V. K. Sharma, D. D. Dionysiou, Cobalt ferrite nanoparticles with controlled composition-peroxymonosulfate mediated degradation of 2-phenylbenzimidazole-5-sulfonic acid,

Chem. Eng. J. 221 (2018) 266-279.

36

[56] K. Shimomaki, K. Murata, R. Martin, N. Iwasawa, Visible-Light-Driven Carboxylation of Aryl Halides by the Combined Use of Palladium and Photoredox Catalysts, J. Am. Chem. Soc. 139 (2017) 9407-9470. [57] M. N. Jackson, S. Oh, C. J. Kaminsky, S. B. Chu, G. H. Zhang, J. T. Miller, Y. Surendranath, Strong Electronic Coupling of Molecular Sites to Graphitic Electrodes via Pyrazine Conjugation, J. Am. Chem. Soc. 140 (2018) 1004-1010. [58] X. N.

Liu, P. H. Du, W. Y. Pan, C. Y. Dang, T. W. Qian, H. F. Liu, W. Liu, D. Y. Zhao,

Immobilization of Uranium(VI) by Niobate/titanate Nanoflakes Heterojunction through Combined Adsorption and Solar-light-driven Photocatalytic Reduction, Appl. Catal., B 231 (2018) 11-12. [59] X. X. Zhao, Z. Y. Lu, M. B. W, M. H. Zhang, H. J. Dong, C. W. Yi, R. Ji, Y. S. Yan, Synergetic Effect of Carbon Sphere Derived from Yeast with Magnetism and Cobalt Oxide Nanochains towards Improving Photodegradation Activity for Various Pollutants, Appl. Catal., B 220 (2018) 137-147. [60] Z. Y. Lu, Z. Zhu, D. D. Wang, Z. F. Ma, W. D. Shi, Y. S. Yan, X. X. Zhao, H. J. Dong, L. Yang, Z. F. Hua, Specific Oriented Recognition of a New Stable ICTX@Mfa with Retrievability for Selective Photocatalytic Degrading of Ciprofloxacin, Catal. Sci. Technol. 6 (2016) 1367–1377. [61] F. Chen, Q. Yang, Y. L. Wang, F. B. Yao, Y. H. Ma, X. D. Huang, X. M. Li, D. B. Wang, G. M. Zeng, H. Q. Yu, Efficient Construction of Bismuth Vanadate-based Z-scheme Photocatalyst for Simultaneous Cr(VI) Reduction and Ciprofloxacin Oxidation under Visible Light: Kinetics, Degradation Pathways and Mechanism, Chem. Eng. J. 348 (2018) 157-170. [62] S.Komatsudaa, Y. Asakuraa, J. J. M. Vequizob, A. Yamakatab, S. Yin, Enhanced Photocatalytic NOx Decomposition of Visible-light Responsive F-TiO2/(N,C)-TiO2 by Charge Transfer between F-TiO2 and (N,C)-TiO2 through Their Doping Levels, Appl. Catal., B 238 (2018) 358-364. 37

[63] M. Naushad, T. Ahamad, B. M. A. Maswari, A. A. Alqadami, S. M. Alshehri, Nickel ferrite bearing nitrogen-doped mesoporous carbon as efficient adsorbent for the removal of highly toxic metal ion from aqueous medium, Chem. Eng. J. 330 (2017) 1351-1360. [64] W. Shen, B. Y. Ren, K. Cai, Y. F. Song, W. Wang, Synthesis of nonstoichiometric Co0.8Fe2.2O4/reduced

graphene

oxide

(rGO)

nanocomposites

and

their

excellent

electromagnetic wave absorption property, J. Alloy. Compd. 774 (2019) 997-1008. [65] X. Lu, Y. W. Yang, Y. B. Zeng, L. Li, X. H. Wu, Rapid and Reliable Determination of p-nitroaniline in Wastewater by Molecularly Imprinted Fluorescent Polymeric Ionic Liquid Microspheres, Biosens. Bioelectron. 99 (2018) 47-55. [66] Y. B. Yan, J. Chen, N. Li, J. Q. Tian, K. X. Li, J. Z. Jiang, J. Y. Liu, Q. H. Tian, P. Chen, Systematic Bandgap Engineering of Graphene Quantum Dots and Applications for Photocatalytic Water Splitting and CO2 Reduction, ACS Nano. 12 (2018) 3523-3532. [67] R. R. Xing, S. S. Wang, Z. J. Bie, H. He, Z. Liu, Preparation of Molecularly Imprinted Polymers Specific to Glycoproteins, Glycans and Monosaccharides via Boronate Affinity Controllable-oriented Surface Imprinting, Nat. Protoc. 12 (2017) 964-987. [68] A. K. Ilunga, I. R. Legodi, S. Gumbi, R. Meijboom, Isothermic adsorption of morin onto the reducible mesoporous manganese oxide materials surface, Appl. Catal., B 224 (2018) 928-939. [69] X. F. Hu, F. Deng, W. Y. Huang, G. S. Zeng, X. B. Luo, D. D. Dionysiou, The band structure control of visible-light-driven rGO/ZnS-MoS2 for excellent photocatalytic degradation performance and long-term stability, Chem. Eng. J. 350 (2018) 248-256. [70] Z. Y. Lu, X. X. Zhao, Z. Zhu, M. S. Song, N. L. Gao, Y. S. Wang, Z. F. Ma, W. D. Shi, Y. S. Yan, H. J. Dong. 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. 6 (2016) 6513.

38

[71] S. Matsui, T. Kureha, S. Hiroshige, M. Shibata, T. Uchihashi, D. Suzuki, Fast Adsorption of Soft Hydrogel Microspheres on Solid Surfaces in Aqueous Solution, Angew. Chem. Int. Edit. 56 (2017) 12146-12149. [72] J. Liu, D. H. Su, J. R. Yao, Y. F. Huang, Z. Z. Shao, X. Chen, Soy protein-based polyethylenimine hydrogel and its high selectivity for copper ion removal in wastewater treatment, J. Mater. Chem.A. 5 (2017) 4163-4171. [73] Z. Y. Lu, J. Y. Peng, M. S. Song, Y. Liu, X. L. Liu, P. W. Huo, H. J. Dong, S. Q. Yuan, Z. F. Ma, S. Han, Improved recyclability and selectivity of environment-friendly MFA-based heterojunction imprinted photocatalyst for secondary pollution free tetracycline orientation degradation, Chem. Eng. J. 2018, DOI: 10.1016/j.cej.2018.10.200. [74] Z. Zhu, X. Tang, C. C. Ma, M. S. Song, N. L. Gao, Y. S. Wang, P. W. Huo, Z. Y. Lu, Y. S. Yan, Fabrication of conductive and high-dispersed Ppy@Ag/g-C3N4 composite photocatalysts for removing various pollutants in water, Appl. Surf. Sci. 387 (2016) 366–374.

39

Graphical Abstract

Magnetic ion imprinted heterojunction photocatalyst realize selective reduction of Cu2+ and simultaneous degradation of tetracycline based on the imprinted cavity and mesoporous dual channels.

40

Highlights

► The as-prepared photocatalyst is obtained by microwave-assisted ion imprinting technique. ► The existence of the Cu2+ imprinted cavities in the imprinted layer improves the selectivity. ► Tetracycline contact with CoFe2O4 via mesoporous in the imprinted layer and further be degraded. ► Heterojunction formed between CoFe2O4 and POPD greatly improves the photocatalytic activity. ► Dual channels realize selective reduction of Cu2+ and simultaneous degradation of tetracycline.

41