Facile Fabrication of N-Doped Magnetic Porous Carbon for Highly

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Facile fabrication of N-doped magnetic porous carbon for highly efficient mercury removal Lijin Huang, Man He, Beibei Chen, and Bin Hu ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/acssuschemeng.8b01498 • Publication Date (Web): 12 Jul 2018 Downloaded from http://pubs.acs.org on July 14, 2018

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ACS Sustainable Chemistry & Engineering

Facile fabrication of N-doped magnetic porous carbon for highly efficient mercury removal Lijin Huang, Man He, Beibei Chen, Bin Hu* Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, No. 299, Bayi Road, Wuchang district, Wuhan 430072, P. R. China * E-mail: [email protected] Phone: 86-27-68752701. Fax: 86-27-68754067.

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ABSTRACT: N-doped magnetic porous carbon (N-MPC) is an emerging adsorbent for water pollution control. However, high cost and multi-steps procedure make the direct fabrication of N-MPCs difficult until now. Herein, highly dispersed N-MPCs were synthesized by a facial one-pot solid-state pyrolysis strategy. Heating the mixture of ZnO, Co(OH)2 and 2-methylimidazole (HmIm), Zn/Co bimetallic ZIFs formed at the initial stages, being the primary self-template to produce N-MPCs during subsequent high-temperature treatment. By altering the pyrolysis temperature and the molar ratio of ZnO/Co(OH)2 in the precursor, the magnetism, nitrogen content and surface areas of N-MPCs can be easily controlled. Due to its high special surface areas and the decoration of abundant nitrogen functional groups (pyrrole-N & pyridinic-N), the optimized N-MPC-700-7/3 exhibited a superior adsorption performance for Hg2+ uptake (489 mg g-1). Moreover, the N-MPCs exhibited fast dynamics in adsorption (K2 = 0.47 g mg-1 min-1) and good chemical stability. The simple, sustainable and impressive method provides an attractive way for manufacturing efficiency MPC sorbents and the prepared N-MPCs merit good application potential in environmental remediation. KEYWORDS: N-doped porous carbons, magnetic porous carbons, pyrolysis, magnetic separation, pollutant removal, mercury adsorption

INTRODUCTION Recently, mercury ion (Hg2+) with high toxicity and the ability to enrich in environment through food chains has attracted tremendous attention as one of the worldwide environmental issues.1-3 Among the treatment technologies for the removal of metal ions from water, adsorption has stimulated extensive studies because of its simple and easy operation, providing good promising applications in the field of environmental remediation. A number of materials, such as active carbon,4,5 magnetic mesoporous silica,6 graphene/graphene oxides (GN/GO),7 porous carbon (PC),8,9 metal-organic frameworks (MOFs),10-14 covalent-organic frameworks (COFs),15,16 and nanocomposites,17,18 have been adopted for the removal of Hg2+ by adsorption in 2


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recent years. Among them, PC, which has also been widely used in catalysis, energy storage and other fields19-21, merits great stability, robust porous structure, good adsorption performance and environmentally friendly. However, the sophisticated steps for separation of PC from aqueous solution are seriously throttling their application in the field of environmental regulation. To overcome this weakness, the preparation of magnetic PC (MPC) is a good alternative, which makes rapid separation possible with the aid of an external magnet field. Normally, magnetic hetero components can be introduced into carbon matrices via either post-treatment or direct-synthesis strategy, in which the magnetic nanoparticles (MNPs) are surrounded by a layer of carbon or located in the channel.22,23 Unfortunately, these methods are still greatly hindered by their imperfections, such as complex manufacturing process, surface active sites blocking as well as relatively poor stability in acidic solutions. Recently, MOFs with paramagnetic metallic notes (i.e. Fe, Co, or Ni) have served as self-template for preparing MPC materials by taking advantage of their various components as well as flexible structure.24-28 Utilizing porous materials (MOFs,29-31 COFs32 or LDHs33-34) as direct sacrificial template to prepare MPC simplifies the preparation greatly (i.e. only a single calcination step involved without any additional paramagnetic metal source),35,36 and provides an effective solution to meet the above issues. In our recent research work,37 a facial strategy was proposed for the synthesis of N-doped magnetic porous carbons (N-MPCs) by using the mixture of Fe3O4@SiO2 MNPs, ZnO and HmIm as precursor. However, MNPs should be prepared in advance and the serious aggregation of MNPs during pyrolysis would deteriorate the homogeneity of the obtained N-MPCs. In other words, simplifying the synthesis process of N-MPCs with high dispersion and lowing the preparation cost is expected urgently. ZIF-67, using Co as metallic nodes and HmIm as the organic linker, has been widely used as the template for the preparation of N-MPCs due to its high contents of C, N, Co as well as large surface areas.38-40 However, the N-MPCs obtained from ZIF-67 are highly graphitic and the porosity would be damaged greatly during the process of graphitization.41 As a result, N-MPCs obtained from ZIF-67 show 3



relatively low surface areas. Excitingly, recent research demonstrated that the pyrolysis of Zn/Co bimetallic ZIFs is helpful for preparing N-MPCs with both high surface area and good saturation magnetization, providing a new facile and controllable synthetic strategy for N-MPCs.42 On the other hand, due to their high N content, N-MPCs obtained from ZIFs showed rich N-component in the form of pyrrole and pyridine,43 both of which have shown good performance in capturing metal ions.44,

45

Nevertheless, the synthesis of N-MPCs from bimetallic ZIFs at

present requires the preparation of bimetallic ZIFs in advance, involving complex preparation process (i.e. wet-chemistry-based crystallization and separation), which are very time-consuming and costly. Therefore, development of low-cost and high efficiency method for N-MPCs is highly required.

Scheme 1. The synthesis procedure for N-MPCs. In this study, a convenient and efficient strategy was developed to prepare N-MPCs with high surface areas and rich N-content just by pyrolysis of the mixture of ZnO, Co(OH)2 and HmIm (Scheme 1). During the pyrolysis process, ZnO and Co(OH)2 transformed into Zn/Co bimetallic ZIFs firstly. With the increase of temperature, the Zn/Co bimetallic ZIFs decomposed gradually and converted into N-MPCs finally. This simple and efficient method allows both high-content N atoms and uniform distribution of Co nanoparticles in the PC matrix. It is worth mentioning that both of the saturation magnetization and the compositions of the prepared N-MPCs can be controlled by varying the molar ratio of ZnO/Co(OH)2 or the pyrolysis temperature. 4


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The well dispersed and highly available N functional groups over the carbon matrix as well as high dispersion of N-MPCs make them good adsorbents for Hg2+ uptake, and the quick magnetic response makes its separation from aqueous solution more convenient. Compared with other preparation methods for N-MPCs (e.g. post functionalization or multi-step synthesis), the proposed method is simpler, more eco-friendly and cost-effective for industrial-scale preparation. EXPERIMENTAL Chemicals and Materials All chemicals used during experiment were analytical grade and used without further purification. ZnO NPs, Co(OH)2 and HmIm were purchased from Aladdin (Shanghai, China). Material Characterization The structure and components of the product were acquired using X-ray powder diffraction (XRD, Bruker D8, Germany) and X-ray photoelectron spectroscopy (XPS, ESCALAB 250 XPS, Al Kα). Thermodynamic analysis (TGA) was conducted on PE diamond TG/DTA 6300 (USA) under N2 flow (heating rate: 5 oC min-1). N2 adsorption/desorption isotherm of the product was measured on ASAP 2020 apparatus (Micromeritics, USA) at 77 K and the surface area of N-MPCs was evaluated through Brunauer-Emmet-Teller (BET) method. The morphology of N-MPCs was collected on JEM-2010 electron microscope (Tokyo, Japan). Fourier transform infrared spectrometer (FT-IR) spectra were recorded on NEXUS 870 spectroscopy (Thermo, Madison, USA). The saturation magnetization of N-MPCs were obtained through PPMS-9 vibrating sample magnetometer (VSM, QUANTOM, USA). The concentration of target metal ions was obtained using Intrepid XSP Radial inductively coupled plasma optical emission spectrometry (ICP-OES, Thermo, Waltham, MA, USA). Synthesis of N-MPCs N-MPCs were prepared via the modified pyrolysis method.37 In a typical synthesis process, a mixture of HmIm (11.0 mmol), Co(OH)2 (2.5 mmol) and ZnO NPs (2.5 mmol) were sealed in a quartz tube after uniform grinding. The mixture was calcined 5



at specified temperature (i.e. 600 °C, 700 °C and 800 °C) at a heating rate of 3 oC min-1 in N2 atmosphere, and then maintained at the required temperature for 1 h. The product was treated with HCl (1.0 M) under ultrasound for 2 h, followed by continuous stirring for 24 h to remove the unstable contents. Finally, the sample was collected, washed repeatedly with water to neutral and dried at 70 oC for 12 h. The obtained products are abbreviated as N-MPC-T-Y, where T represents the pyrolysis temperature (600 °C, 700 °C and 800 °C); and Y represents the molar ratio of ZnO/Co(OH)2 (i.e. 8/2, 7/3, 5/5, 2/8, 0/10). It should be noted that the molar ratio of (ZnO+Co(OH)2)/HmIm was kept constant at 1/2.2. Batch Adsorption Experiments The adsorption performance of Hg2+ by N-MPCs was carried out by batch experiments and the pH of the solution was adjusted by using 0.1 M HNO3 and 0.1 M NaOH. In a typical process, 10 mg of N-MPCs was added into 10 mL of Hg2+ solution, followed by continuously shaking for 60 min. Then the sorbent was separated from the solution with a magnet and the concentration of Hg2+ in the solution was measured by ICP-OES. In order to obtain the adsorption kinetic, N-MPC-700-7/3 was spiked into a solution containing Hg2+ and the mixture was fixed on a shaker. After shaking for a predetermined time, the supernatant was subjected to ICP-OES measurement.

RESULTS AND DISCUSSION Materials Characterization FT-IR Measurements

6


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Figure 1. XRD patterns (a) and FT-IR spectra (b). Note: Zn/Co-ZIFs represents the mixture that was heated up to 200 oC. Mixture: mixture of HmIm, Co(OH)2 and ZnO NPs. As illustrated in Scheme 1, ZnO, Co(OH)2 and HmIm were employed as precursors in this study to form Zn/Co bimetallic ZIFs directly under relative low temperature (~200 oC), and the subsequent pyrolysis at high temperature (>600 oC) led to the formation of N-MPCs. During the heating procedure, the color of the mixture changed from light wine to dark purple remarkably with the increase of the temperature from room temperature to 200 oC probably due to the conversion of the mixture into Zn/Co-ZIFs. With further increase of the pyrolysis temperature, the mixed sample changed to dark finally due to the decomposition of Zn/Co-ZIFs into N-MPCs. The process was demonstrated by the XRD characterization of the products obtained by using different pyrolysis temperature. The XRD patterns of Zn/Co-ZIFs (Figure 1a) was obtained by heating the mixture of ZnO, Co(OH)2 and HmIm to 200 o

C, and it showed a remarkable decreasing of the characteristic patterns of ZnO and

Co(OH)2, and occurrence of characteristic patterns for ZIFs, which matched well with that of phase-pure of ZIF-8, demonstrating no second secondary phases was formed during the heating. The XRD patterns of N-MPC-600-7/3, N-MPC-700-7/3 and N-MPC-800-7/3 (Figure 1a) showed that the characteristic patterns for ZIFs disappeared completely at high temperature (600 oC, 700 oC and 800 oC). Figure 1b presents the FT-IR spectra for the products obtained under different pyrolysis temperature, and the complete disappearance of absorption peaks attributed to ZIFs was observed under high temperature, probably due to its decomposition and the formation of N-MPCs. N2 Adsorption-Desorption Isotherms, EDX and magnetization Analysis To optimize the preparation conditions, N-MPCs obtained by using different molar ratio of ZnO/Co(OH)2 and pyrolysis temperature were further subjected to various characterization. The obtained results including surface area, pore volumes, saturation magnetization, adsorption capacity for Hg2+ and EDX data of the prepared N-MPCs are presented in Table 1. As can be seen, the adsorption capacity of N-MPCs for Hg2+ 7



increases with the increment of the molar ratio of ZnO/Co(OH)2 from 0/10 to 8/2 with a pyrolysis temperature of 700 oC. The increased adsorption capacity is attributed to the increasing surface area and N content of the N-MPCs along with the increment of the molar ratio of ZnO/Co(OH)2. This phenomenon can be explained by the fact that the higher Co content would lead to highly graphitic and damage the porosity of N-MPCs during the process of pyrolysis.41 The saturation magnetization of the obtained N-MPCs is attributed to the content of Co, specifically, the size and number of the formed Co nanoparticles. The saturation magnetization intensity of N-MPCs increases from 4.47 to 24.7 emu g-1 with the increase of the molar ratio of ZnO/Co(OH)2 from 8/2 to 0/10. Thus, the ZnO/Co(OH)2 in 7/3 is the optimal ratio to simultaneously ensure high adsorption capacity and good saturation magnetization for separation. Moreover, the pyrolysis temperature was investigated by fixing the ZnO/Co(OH)2 ratio as 7/3. As shown in Table 1, the N-MPCs obtained under 600 oC displayed a very low surface area (46.3 m2 g-1) which was probably caused by the uncompleted conversion of the precursor into PC. With the further increase of temperature from 700 oC to 800 oC, the surface area of the as-obtained N-MPCs increased from 406 m2 g-1 to 528 m2 g-1. As illustrated in Figure S1, the carbon matrix shows a type IV isotherm with a H3 hysteresis loop, demonstrating that these carbons have mesoporous structure as evidenced by their narrow pore size distribution centered at ~3.8 nm (Figure S1 and Table 1), according to the IUPAC classification.46 In addition, to provide an overall picture of the final porosity of these materials, microporosity of N-MPC-700-7/3 and N-MPC-800-7/3 were determined using CO2 isotherms as examples to confirm that the pore structure of N-MPCs (Figure S2). The surface area values obtained via CO2 sorption at 300 K were about 24.5 and 39.4 m2 g-1 for N-MPC-700-7/3 and N-MPC-800-7/3, respectively. The results indicated that the porosity of N-MPCs prepared in this work were mesopore-dominant. Meanwhile, the results of EDX exhibit that the N content of N-MPC-800-7/3 obtained at 800 oC was less than that of N-MPC-600-7/3 and N-MPC-700-7/3, due to the poor stability of N species under high temperature. 8


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Table 1 Surface area, pore volumes, saturation magnetization, adsorption capacity for Hg2+ and EDX data of the prepared N-MPCs. BET

Por Pore

surfac

e

Adsorptio

N

Co

Saturation

size

n capacity

(wt%

(wt%

magnetizatio

(nm

(mg g-1)

)

)

n (emu g-1)

volum Samples

e areas (m2 g-1)

e (cm3 -1

g ) )

N-MPC-700-8/2

688

1.10

3.8

501

16.6

5.7

4.47

N-MPC-700-7/3

406

0.54

3.9

489

12.9

6.4

5.86

N-MPC-700-5/5

336

0.37

3.8

404

13.2

13.7

6.45

N-MPC-700-2/8

313

0.31

3.8

291

8.6

14.9

11.3

246

0.25

213

6.2

15.8

24.7

N-MPC-600-7/3

46

0.16

14.3

371

13.0

4.8

-

N-MPC-800-7/3

529

0.71

3.9

240

11.2

5.7

-

N-MPC-700-0/1

4.0

0

All these results confirmed that the surface areas, the composition and saturation magnetization of N-MPCs are controllable by altering the pyrolysis temperature or molar ratio of ZnO/Co(OH)2 for the precursors. On the other hand, for N-MPCs used as sorbent for metal ions uptake, the high surface area and N content would provide more active sites for adsorption, and the good saturation magnetization would ensure its rapid and efficient separation from solution. Figure S3 clearly showed the separation process of N-MPC-700-7/3 after starting the separation by a magnet for 60 s. In consideration of the suitable saturation magnetization (5.86 emu g-1) for separation, high N content (12.9 wt%) and high surface area (406 m2 g-1), N-MPC-700-7/3 was an attractive option to serve as sorbent and employed for the subsequent study. TEM/SEM, XPS and TG Analysis

9



Figure 2. SEM (a) and TEM (b) image of N-MPC-700-7/3. Further study was performed to assess the morphology of N-MPC-700-7/3 by SEM and TEM (Figure 2). SEM image revealed that N-MPC-700-7/3 had a uniform and bumpy surface. TEM images showed that magnetic Co NPs with uniform size (~9 nm) were wrapped by a shell of carbon and highly dispersed in carbon matrix. The existence of Co NPs was also confirmed by the XRD analysis. As shown in Figure S4, the wide peak around 25o is ascribed to the typical interlayer peak of graphitic carbon (002). The characteristic peaks around 44o and 51o is related to metallic Co (JCPDS No. 15-0806). It indicated that the Co(OH)2 in precursor had transformed into metallic Co during the pyrolysis process. In addition, the detailed morphological and structural features of N-MPC-700-0/10 and N-MPC-700-8/2 were further analyzed by TEM (Figure S5). The mean particles sizes were 11±3 nm, 9±3 nm and 7±3 nm for N-MPC-700-0/10, N-MPC-700-7/3 and N-MPC-700-8/2, respectively. Remarkably, with the increment of the molar ratio of ZnO/Co(OH)2 from 0/10 to 8/2, the amount of Co nanoparticles were decrease, which were in accordance with that of Co contents obtained by EDX detection. The result indicated that doping with Zn species not only reduces the Co nanoparticle size but also increases the nitrogen content of the products. Raman spectroscopy of the representative material, M-NPC-7/3, is provided for illustrating the degree of graphitization (Figure S6). The Raman spectra of M-NPC-7/3 clearly presented two peaks at about 1340 and 1597 cm-1, corresponding to the typical D and G bands of carbon, respectively. The ratio of ID/IG is calculated 10


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to be 1.48±0.06, implying the presence of amorphous carbon in M-NPC-7/3. The structure information of N-MPC-700-7/3 were determined by XPS measurement (Figure 3). As illustrated in Figure 3a, the content of N is calculated to be 4.65 at% while the Co metal peaks are almost undetectable in the XPS spectrum of N-MPC-700-7/3. This can be explained by the fact that XPS is only surface sensitive while most of metal species in N-MPC-700-7/3 are sheltered by carbon matrix.47 The spectra corresponding to N 1s (Figure 3b) is ascribed to pyridinic-N (397-399.5 eV) and pyrrolic-N (400.2-400.9 eV), which indicates that most of N in N-MPC-700-7/3 is bonded to the carbon skeleton.

Figure 3. High-resolution spectra of Co (a) and N 1s (b) for N-MPC-700-7/3. The thermal stability of N-MPC-700-7/3 was also investigated by TGA, and the results are shown in Figure S7. The weight loss is observed at below 100 oC and above 800 oC, which is attributed to the removal of physically adsorbed water molecules and decomposition of N and C species, respectively. The result indicates that the N-MPC-700-7/3 is thermally stable. Adsorption Study for Hg2+ Effect of pH

11



Figure 4. The effect of pH on the removal efficiency of Hg2+ (10 mg L-1) by N-MPC-700-7/3. In this work, the influence of pH on the removal efficiency of Hg2+ was investigated by altering the solution pH within the range of 2-7. As shown in Figure 4, the removal efficiency increases gradually with the increase of solution pH from 2 to 4 and the complete removal of Hg2+ from the solution is achieved under pH>4. The good removal performance of N-MPC-700-7/3 is attributed to the strong affinity of pyrrolic-N and pyridinic-N toward Hg2+. The decrease in adsorption performance at pH 2 is due to the interference of proton. Considering the hydrolysis of mercury under high pH, as Hg(OH)2 at pH > 6, the removal efficiency at the basic pH range were not investigated.14 In subsequent experiments, pH 6 was adopted for a complete removal of Hg2+. This result suggests that the prepared N-MPC-700-7/3 can be used for the removal of Hg2+ from environmental water without pH adjustment. Coexisting ions In general, removal efficiency of interest ions would be affected by the coexisting ions, due to the competitive adsorption. In this work, the mixture of K+, Ca2+, Na+, Mg2+, Cd2+, Co2+, Cr3+, Cu2+, Mn2+, Ni2+ and Pb2+ was selected to evaluate the potential interferences on the adsorption behavior of Hg2+ by N-MPC-700-7/3 (Figure 5). The experimental results showed clearly that the effect of coexisting ions on the Hg2+ removal is negligible, indicating the prepared N-MPC-700-7/3 has a great potential utility for practical applications. The high selectivity is attributed to the affinity of the sorbent towards corresponding metal ions, which could be explained by 12


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the theory of Evert Nieboe.48 Compared with other metal ions, Hg2+ shows highest covalent index48 and could form the most stable covalent complexes with the pyridinic-N and pyrrolic-N groups on N-MPC-700-7/3. This result is similar to that obtained for other N-functionalized materials, including MNPC-T700-M337, Fe3O4/M-COFs49, and PPy-RGO50.

Figure 5 The influence of coexisting ions (mixture, each ion of 10 mg L-1 at pH6). Adsorption kinetics

Figure 6. Effect of incubation time on the removal of Hg2+ by N-MPC-700-7/3 (a), along with the pseudo-second-order kinetic plot for removal of Hg2+ (20 mg L-1 at pH6) (b). The removal efficiency of Hg2+ on N-MPC-700-7/3 was highly influenced by the exposure time, thus the adsorption kinetics was studied. As can be seen in Figure 6, the adsorption equilibrium as well as high removal efficiency is achieved within 10 min. To further understand the adsorption mechanism, pseudo second-order equation was employed to describe the removal process of Hg2+. Pseudo second-order equation was generally expressed as follows: 13



1 t t = + Qt Qe K 2Qe2

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Eq. (1)

Where Qe and Qt (mg g-1) are the amounts of Hg2+ at equilibrium and at time t (min), respectively, and K2 (g mg-1 min-1) are the adsorption rate constant of pseudo-second order. Plots of t vs. t/Qt are drawn in Figure 6(b) and they show a good linear relationship (R2>0.9999), indicating the adsorption of Hg2+ onto the N-MPC-700-7/3 follows the pseudo-second-order model. And, the K2 was calculated to be 0.47 g mg-1 min-1. Adsorption isotherms The adsorption isotherms of Hg2+ was investigated by exposing N-MPC-700-7/3 to Hg2+ solutions in the concentration range of 50-500 mg L-1. As can be seen from Figure 7, the saturated values were 489 mg g-1, remarkably higher than that of some magnetic carbon-based sorbents (Table 2). Meanwhile, data for Hg2+ adsorption was

Figure 7. Adsorption isotherms curve of Hg2+ (a) along with the linear regression by fitting the equilibrium adsorption data with Langmuir adsorption model (b). Table 2 Summarized adsorption capacities of Hg2+ for various magnetic adsorbents Adsorbents

Capacity (mg g-1)

Reference

Thiol-functionalized magnetite/GO

289.9

52

Magnetic GO composites

71.3

53

Ethylenediamine decorated Fe3O4/GO

127.2

54

Thiol-functionalized CNTs/Fe3O4

65.5

55

GO MNPs

16.6

56

14


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Amino functionalized magnetic GNs

168

57

Fe3O4/M-COFs

97.7

48

MNPC-T700-M3

429

37

N-MPC-700-8/2

501

N-MPC-700-7/3

489

N-MPC-700-5/5

404

N-MPC-700-2/8

291

N-MPC-700-0/10

213

N-MPC-600-7/3

371

N-MPC-800-7/3

240

This work

well depicted by Langmuir model (R2>0.9994), indicating that the Hg2+ adsorption mechanism on N-MPC-700-7/3 is a monolayer adsorption.51 The calculated maximum adsorption capacity (495 mg g-1) from Langmuir isotherm model is very close to the experimental value. Compared with MNPC-T700-M3 that reported in our previous work,37 the N-MPCs prepared here via one-pot pyrolysis exhibits better dispersion (e.g. without aggregation), lower cost as well as easier preparation process (MNPs was required to be prepared firstly for MNPC-T700-M3). What’s more, N-MPC-700-7/3 with lower surface area (406 versus 653 m2 g-1) and similar N content (12.8 versus 12.9 wt%) exhibited improved adsorption performance for Hg2+, which is probably due to the fact that their chemical forms of N are different. In addition to pyridinic-N and pyrrolic-N, graphitic N was also confirmed in MNPC-T700-M3, which causes a relatively low percentage of pyridinic-N and pyrrolic-N in MNPC-T700-M3. Adsorption mechanism

15



Figure 8. The high-resolution spectra of Hg 4f (a) and N 1s (b) of Hg2+ loaded N-MPC-700-7/3. In order to gain more insights into the adsorption mechanism, XPS analysis was performed for N-MPC-700-7/3 after Hg2+adsorption. For the spectra of Hg2+ loaded N-MPC-700-7/3, the intense signal of Hg 4f clearly confirmed that Hg2+ was adsorbed onto N-MPC-700-7/3 successfully. Compared with the binding energy of 4f7/2 for mercuric chloride (101.4 and 105.3 eV), the Hg 4f of Hg2+ loaded N-MPC-700-7/3 shifted toward high binding energy (~ 1.2 eV). This phenomenon demonstrated the formation of a covalent bond between the empty orbital of Hg2+ and π electrons of the N species on N-MPC-700-7/3. The high-resolution spectra of N 1s for Hg2+ loaded N-MPC-700-7/3 is shown in Figure 8 and the content of N is calculated to be 4.20 at%. Compared with un-loading sample (Figure 3), the peaks of N 1s shifted to a higher binding energy, which is probably due to the strong interaction between Hg2+ and N functional groups. In particular, the nitrogen content and the adsorption capacity that of N-MPCs obtained at 700 oC showed a very positive correlation, and the correlation value R2 was up to 0.949 (Figure S8). However, the materials obtained under 600 and 800 oC do not meet the linear well, which may be explained by the fact that the adsorption involves a variety of parameters, including materials’ surface area, N content and its species. As can be seen in Table 1, N-MPC-600-7/3 possesses the lowest surface areas (46 m g-1) and most of the N cannot be available for Hg2+ adsorption. Even though the surface area and N content of N-MPC-800-7/3 are relatively high, the adsorption capacity was 16


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much lower, which can be ascribed to the fact that the higher pyrolysis temperature would lead to highly graphitic of N-MPCs. Pyrrolic-N and pyridinic-N in the NC material are mainly responsible for the excellent heavy-metal removal.37,58 In conclusion, the adsorption capacity was the result of a combination of N content, N species and the surface area of the materials. Reusability and application The reusability of the adsorbent is critical for practical application. Thus, a recycling experiment was conducted to evaluate the reusability of N-MPC-700-7/3. Before each adsorption test, the sorbent was regenerated by treating with 1 M HCl, and then washed with water and vacuum-dried at 50 oC. Figure 9 clearly showed that the adsorption capacity of N-MPC-700-7/3 exhibited no obvious loss after 5 adsorption/elution cycles. Furthermore, to evaluate the structure stability of N-MPC-700-7/3, TEM and N2 adsorption-desorption isotherms analysis were performed (Figure S9), and the results clearly demonstrated that both of the morphology and porous structure were well kept even after 5 adsorption-desorption cycles. All these results indicated that the as-prepared N-MPC-700-7/3 possessed good stability during the adsorption-desorption process.

Figure 9. Hg2+ removal by recycled N-MPC-700-7/3 (500 mg L-1 Hg2+ solution at pH6). Moreover, its application potential for practical water sample was investigated, with the cation concentration in the lake water and domestic sewage listed in Table S1. The fast kinetics (10 min) as well as high removal efficiency (>99%) of Hg2+ from 17



spiked lake water and domestic sewage (spiking at 50 µg L-1) indicated its wide application potential for water remediation. The concentration of Hg2+ in the treated water (0.6 µg L-1 and 1.1 µg L-1) was far below the EPA limit of 10 µg L-1 for the industrial wastewater discharge standard, even lower than the acceptable limit for national standard of drinking water (2 µg L-1). These results underscore the N-MPC-700-7/3 can be a superior candidate for metal ions removal from water. CONCLUSIONS In conclusion, a novel, stable, highly dispersed and low-cost N-MPCs was fabricated by one-pot pyrolysis strategy using the mixture of ZnO, Co(OH)2 and HmIm as precursors. The proposed strategy not only greatly reduces the preparation process and cost for N-MPCs, but also provides a robust way for preparing MPCs with different functional heteroatoms. The synthesis of N-MPCs was fully optimized for Hg2+ removal by varying the pyrolysis temperature and the molar ratios of ZnO/Co(OH)2. The as-prepared N-MPC-700-7/3 exhibited well adsorption capacity for Hg2+ (489 mg g-1) and could trap Hg2+ rapidly due to the high surface areas and abundant active adsorption sites. It can serve as an inexpensive and convenient material for the rapid sequestration of toxic ions from polluted water. Furthermore, due to the flexibility of MOFs, the proposed method is promising for preparation of other materials with enhanced performance in a wide range of applications.

ASSOCIATED CONTENT Supporting Information Materials characterization and other data. This material is available free of charge via the Internet at http://pubs.acs.org. Additional information, including the N2 adsorption-desorption isotherms and pore size distributions of different samples; XRD patterns and Raman spectra of N-MPC-700-7/3; TEM images of the prepared N-MPC-700-0/10 and N-MPC-700-8/2; TG curve of N-MPC-700-7/3; N contents of N-MPCs obtained at 700 oC versus their adsorption capacity for Hg2+; TEM image and N2 adsorption-desorption isotherms of N-MPC-700-7/3 after 5 cycles. 18


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AUTHOR INFORMATION Corresponding Author ∗

E-mail address: [email protected]. Phone: 86-27-68752701; Fax: 86-27-68754067.

ORCID Lijin Huang: 0000-0002-0555-7823 Man He: 0000-0002-2009-8098 Beibei Chen: 0000-0001-7772-5171 Bin Hu: 0000-0003-2171-2202 Notes The authors declare no competing financial interest. ACKNOWLEDGMENTS This work is financially supported by the National Natural Science Foundation of China (21575107, 217,75113, 21575108, 21675118), the Science Fund for Creative Research Groups of NSFC (20921062), and the Large-scale Instrument and Equipment Sharing Foundation of Wuhan University (LF20181063). REFERENCES (1) Bag, S.; Trikalitis, P. N.; Chupas, P. J.; Armatas, G. S.; Kanatzidis, M. G. Porous Semiconducting Gels and Aerogels from Chalcogenide Clusters. Science 2007, 317, 490-493, DOI: 10.1126/science.1142535. (2) Ai, K.; Ruan, C.; Shen, M.; Lu, L. MoS2 Nanosheets with Widened Interlayer Spacing for High-Efficiency Removal of Mercury in Aquatic Systems. Adv. Funct. Mater. 2016, 26, 5542-5549, DOI: 10.1002/adfm.201601338. (3) Crockett, M. P.; Evans, A. M.; Worthington, M. J.; Albuquerque, I. S.; Slattery, A. D.; Gibson, C. T.; Campbell, J. A.; Lewis, D. A.; Bernardes, G. J.; Chalker, J. M. Sulfur-Limonene Polysulfide: A Material Synthesized Entirely from Industrial by-Products and Its Use in Removing Toxic Metals from Water and Soil. Angew. Chem. Int. Ed. 2016, 55, 1714-1718, DOI: 10.1002/anie.201508708. (4) Zhu, J.; Yang, J.; Deng, B. Enhanced Mercury Ion Adsorption by Amine-Modified Activated Carbon. J. Hazard. Mater. 2009, 166, 866-872, DOI: 10.1016/j.jhazmat.2008.11.095. 19



(5) Zhang, J.; Duan, Y.; Zhou, Q.; Zhu, C.; She, M.; Ding, W. Adsorptive Removal of Gas-Phase Mercury by Oxygen Non-Thermal Plasma Modified Activated Carbon. Chem. Eng. J. 2016, 294, 281-289, DOI: 10.1016/j.cej.2016.02.002. (6) Wang, Y.; Li, B.; Zhang, L.; Li, P.; Wang, L.; Zhang, J. Multifunctional Magnetic Mesoporous Silica Nanocomposites with Improved Sensing Performance and Effective Removal Ability toward Hg(II). Langmuir 2012, 28, 1657-1662, DOI: 10.1021/la204494v. (7) Thakur, S.; Das, G.; Raul, P. K.; Karak, N. Green One-Step Approach to Prepare Sulfur/Reduced Graphene Oxide Nanohybrid for Effective Mercury Ions Removal. J Phys. Chem. C 2013, 117, 7636-7642, DOI: 10.1021/jp400221k. (8) Anbia, M.; Dehghan, R. Functionalized CMK-3 Mesoporous Carbon with 2-Amino-5-Mercapto-1,3,4-Thiadiazole for Hg(II) Removal from Aqueous Media. J Environ. Sci. 2014, 26, 1541-1548, DOI: 10.1016/j.jes.2014.05.021. (9) Shin, Y.; Fryxell, G. E.; Um, W.; Parker, K.; Mattigod, S. V.; Skaggs, R. Sulfur-Functionalized Mesoporous Carbon. Adv. Funct. Mater. 2007, 17, 2897-2901, DOI: 10.1002/adfm.200601230. (10) He, J.; Yee, K.K.; Xu, Z.; Zeller, M.; Hunter, A. D.; Chui, S. S.Y.; Che, C.M. Thioether Side Chains Improve the Stability, Fluorescence, and Metal Uptake of a Metal-Organic Framework. Chem. Mater. 2011, 23, 2940-2947, DOI: 10.1021/cm200557e. (11) Yee, K. K.; Reimer, N.; Liu, J.; Cheng, S. Y.; Yiu, S. M.; Weber, J.; Stock, N.; Xu, Z. T. Effective Mercury Sorption by Thiol-Laced Metal-Organic Frameworks: In Strong Acid and the Vapor Phase. J. Am. Chem. Soc. 2013, 135, 7795-7798, DOI: 10.1021/ja400212k. (12) Ke, F.; Qiu, L. G.; Yuan, Y. P.; Peng, F. M.; Jiang, X.; Xie, A. J.; Shen, Y. H.; Zhu, J. F. Thiol-Functionalization of Metal-Organic Framework by a Facile Coordination-Based Post-synthetic Strategy and Enhanced Removal of Hg2+ from Water. J. Hazard. Mater. 2011, 196, 36-43, DOI: 10.1016/j.jhazmat.2011.08.069. (13) Huang, L. J.; He, M.; Chen, B. B.; Hu, B. A Mercapto Functionalized Magnetic Zr-MOF by Solvent-Assisted Ligand Exchange for Hg2+ Removal from Water. J 20


Page 20 of 27

Page 21 of 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


Mater. Chem. A 2016, 4, 5159-5166, DOI: 10.1039/c6ta00343e. (14) Huang, L.; He, M.; Chen, B.; Hu, B. A Designable Magnetic MOF Composite and Facile Coordination-Based Post-Synthetic Strategy for the Enhanced Removal of Hg2+ from Water. J Mater. Chem. A 2015, 3, 11587-11595, DOI: 10.1039/c5ta01484k. (15)Ding, S. Y.; Dong, M.; Wang, Y. W.; Chen, Y. T.; Wang, H. Z.; Su, C. Y.; Wang, W. Thioether-Based Fluorescent Covalent Organic Framework for Selective Detection and Facile Removal of Mercury(II). J. Am. Chem. Soc. 2016, 138, 3031-3037, DOI: 10.1021/jacs.5b10754. (16) Li, B.; Zhang, Y.; Ma, D.; Shi, Z.; Ma, S. Mercury Nano-Trap for Effective and Efficient Removal of Mercury(II) from Aqueous Solution. Nat. Commun. 2014, 5, 5537, DOI: 10.1038/ncomms6537. (17) Ma, Y.; Lv, L.; Guo, Y.; Fu, Y.; Shao, Q.; Wu, T.; Guo, S.; Sun, K.; Guo, X.; Wujcik,

E.

K.;

Guo,

Z.

Porous

Lignin

Based

Poly

(Acrylic

Acid)/Organo-Montmorillonite Nanocomposites: Swelling Behaviors and Rapid Removal

of

Pb(II)

Ions.

Polymer

2017,

128,

12-23,

DOI:

10.1016/j.polymer.2017.09.009. (18) Wang, Y. P.; Zhou, P.; Luo, S. Z.; Guo, S.; Lin, J.; Shao, Q.; Guo, X.; Liu, Z.; Shen, J.; Wang, B.; Guo, Z. In Situ Polymerized Poly(Acrylic Acid)/Alumina Nanocomposites for Pb2+ Adsorption. Adv. Polym. Technol. 2018, DOI: 10.1002/adv.21969. (19) Su, T.; Shao, Q.; Qin, Z.; Guo, Z.; Wu, Z. Role of Interfaces in Two-Dimensional Photocatalyst for Water Splitting. ACS Catal. 2018, 8 (3), 2253-2276, DOI: 10.1021/acscatal.7b03437. (20) Luo, Q.; Ma, H.; Hou, Q. Z.; Li, Y. X.; Ren, J.; Dai, X. Z.; Yao, Z. B.; Zhou, Y.; Xiang, L. C.; Du, H. Y.; He, H. C.; Wang, N.; Jiang, K. L.; Lin, H.; Zhang, H. W.; Guo, Z. H. All-Carbon-Electrode-Based Endurable Flexible Perovskite Solar Cells.

Adv.

Funct.

Mater.

2018,

28

(11),

1706777,

DOI:

10.1002/adfm.201706777. (21) He, Y.; Yang, S.; Liu, H.; Shao, Q.; Chen, Q.; Lu, C.; Jiang, Y.; Liu, C.; Guo, Z. 21



Page 22 of 27

Reinforced Carbon Fiber Laminates with Oriented Carbon Nanotube Epoxy Nanocomposites: Magnetic Field Assisted Alignment and Cryogenic Temperature Mechanical Properties. J. Colloid Interface Sci. 2018, 517, 40-51, DOI: 10.1016/j.jcis.2018.01.087. (22) Kharissova, O. V.; Dias, H. V. R.; Kharisov, B. I. Magnetic Adsorbents Based on Micro- and Nano-Structured Materials. RSC Adv. 2015, 5, 6695-6719, DOI: 10.1039/c4ra11423j. (23) Zhu, M.; Diao, G. Review on the Progress in Synthesis and Application of Magnetic Carbon Nanocomposites. Nanoscale 2011, 3, 2748-2767, DOI: 10.1039/c1nr10165j. (24) Liu, B.; Shioyama, H.; Akita, T.; Xu, Q. Metal-Organic Framework as a Template for Porous Carbon Synthesis. J. Am. Chem. Soc. 2008, 130, 5390-5391, DOI: 10.1021/ja7106146. (25) Chen, D.; Shen, W.; Wu, S.; Chen, C.; Luo, X.; Guo, L. Ion Exchange Induced Removal of Pb(II) by MOF-Derived Magnetic Inorganic Sorbents. Nanoscale 2016, 8 (13), 7172-7179, DOI: 10.1039/c6nr00695g. (26) Banerjee, A.; Gokhale, R.; Bhatnagar, S.; Jog, J.; Bhardwaj, M.; Lefez, B.; Hannoyer, B.; Ogale, S. MOF Derived Porous Carbon-Fe3O4 Nanocomposite as A High Performance, Recyclable Environmental Superadsorbent. J. Mater. Chem. 2012, 22, 19694-19699, DOI: 10.1039/c2jm33798c. (27) Lux, L.; Williams, K.; Ma, S. Heat-Treatment of Metal-Organic Frameworks for Green

Energy

Applications.

CrystEngComm

2015,

17,

10-22,

DOI:

10.1039/c4ce01499e. (28) Tang, J.; Yamauchi, Y. Carbon Materials: MOF Morphologies in Control. Nat. Chem. 2016, 8, 638-639, DOI: 10.1038/nchem.2548. (29) Kaneti, Y. V.; Tang, J.; Salunkhe, R. R.; Jiang, X.; Yu, A.; Wu, K. C.; Yamauchi, Y. Nanoarchitectured Design of Porous Materials and Nanocomposites from Metal-Organic Frameworks. Adv. Mater. 2017, 29 (12), 1604898, DOI: 10.1002/adma.201604898. (30) Hu, M.; Reboul, J.; Furukawa, S.; Torad, N. L.; Ji, Q.; Srinivasu, P.; Ariga, K.; 22


Page 23 of 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


Kitagawa, S.; Yamauchi, Y. Direct Carbonization of Al-based Porous Coordination Polymer for Synthesis of Nanoporous Carbon. J. Am. Chem. Soc. 2012, 134 (6), 2864-2867, DOI: 10.1021/ja208940u. (31) Carrasco, J. A.; Romero, J.; Abellan, G.; Hernandez-Saz, J.; Molina, S. I.; Marti-Gastaldo, C.; Coronado, E. Small-Pore Driven High Capacitance in A Hierarchical Carbon via Carbonization of Ni-MOF-74 at Low Temperatures. Chem. Commun. 2016, 52 (58), 9141-9144, DOI: 10.1039/c6cc02252a. (32) Romero, J.; Rodriguez-San-Miguel, D.; Ribera, A.; Mas-Ballesté, R.; Otero, T. F.; Manet, I.; Licio, F.; Abellán, G.; Zamora, F.; Coronado, E. Metal-Functionalized Covalent Organic Frameworks as Precursors of Supercapacitive Porous N-Doped Graphene. J Mater. Chem. A 2017, 5 (9), 4343-4351, DOI: 10.1039/c6ta09296a. (33) Abellan, G.; Coronado, E.; Marti-Gastaldo, C.; Ribera, A.; Sanchez-Royo, J. F. Layered Double Hydroxide (LDH)-Organic Hybrids as Precursors for Low-Temperature Chemical Synthesis of Carbon Nanoforms. Chem. Sci. 2012, 3 (5), 1481-1485, DOI: 10.1039/c2sc01064j. (34) Abellán, G.; Coronado, E.; Martí‐Gastaldo, C.; Ribera, A.; Otero, T. F. Magnetic Nanocomposites Formed by FeNi3 Nanoparticles Embedded in Graphene. Application as Supercapacitors. Part. Part. Syst. Char. 2013, 30 (10), 853-863, DOI: 10.1002/ppsc.201300186. (35)Kaneti, Y. V.; Tang, J.; Salunkhe, R. R.; Jiang, X.; Yu, A.; Wu, K. C.; Yamauchi, Y. Nanoarchitectured Design of Porous Materials and Nanocomposites from Metal-Organic

Frameworks.

Adv.

Mater.

2017,

29,

1604898,

DOI:

10.1002/adma.201604898. (36) Hu, M.; Reboul, J.; Furukawa, S.; Torad, N. L.; Ji, Q.; Srinivasu, P.; Ariga, K.; Kitagawa, S.; Yamauchi, Y. Direct Carbonization of Al-Based Porous Coordination Polymer for Synthesis of Nanoporous Carbon. J. Am. Chem. Soc. 2012, 134, 2864-2867, DOI: 10.1021/ja208940u. (37) Huang, L.; He, M.; Chen, B. B.; Cheng, Q.; Hu, B. Highly Efficient Magnetic Nitrogen-Doped Porous Carbon Prepared by One-Step Carbonization Strategy for Hg2+ Removal from Water. ACS Appl. Mater. Interfaces 2017, 9, 2550-2559, DOI: 23



10.1021/acsami.6b15106. (38) Torad, N. L.; Hu, M.; Ishihara, S.; Sukegawa, H.; Belik, A. A.; Imura, M.; Ariga, K.; Sakka, Y.; Yamauchi, Y. Direct Synthesis of MOF-Derived Nanoporous Carbon with Magnetic Co Nanoparticles toward Efficient Water Treatment. Small 2014, 10, 2096-2107, DOI: 10.1002/smll.201302910. (39) Hong, S.; Yoo, J.; Park, N.; Lee, S. M.; Park, J. G.; Park, J. H.; Son, S. U. Hollow Co@C Prepared from a Co-ZIF@Microporous Organic Network: Magnetic Adsorbents for Aromatic Pollutants in Water. Chem. Commun. 2015, 51, 17724-17727, DOI: 10.1039/c5cc06873h. (40) Sun, N.; Zhang, X.; Deng, C. Designed Synthesis of MOF-Derived Magnetic Nanoporous Carbon Materials for Selective Enrichment of Glycans for Glycomics Analysis. Nanoscale 2015, 7, 6487-6491, DOI: 10.1039/c5nr00244c. (41) Tang, J.; Salunkhe, R. R.; Liu, J.; Torad, N. L.; Imura, M.; Furukawa, S.; Yamauchi, Y. Thermal Conversion of Core-Shell Metal-Organic Frameworks: A New Method for Selectively Functionalized Nanoporous Hybrid Carbon. J. Am. Chem. Soc. 2015, 137, 1572-1580, DOI: 10.1021/ja511539a. (42) Sun, N. R.; Yao, J. Z.; Wang, J. W.; Zhang, X. M.; Li, Y.; Deng, C. H. Magnetic Nanoporous Hybrid Carbon from Core-Shell Metal-Organic Frameworks for Glycan Extraction. RSC Adv. 2016, 6, 34434-34438, DOI: 10.1039/c6ra01434h. (43) Bai, F.; Xia, Y.; Chen, B.; Su, H.; Zhu, Y. Preparation and Carbon Dioxide Uptake Capacity of N-Doped Porous Carbon Materials Derived from Direct Carbonization of Zeolitic Imidazolate Framework. Carbon 2014, 79, 213-226, DOI: 10.1016/j.carbon.2014.07.062. (44) Shin, K.Y.; Hong, J.Y.; Jang, J. Heavy Metal Ion Adsorption Behavior in Nitrogen-Doped Magnetic Carbon Nanoparticles: Isotherms and Kinetic Study. J. Hazard. Mater. 2011, 190, 36-44, DOI: 10.1016/j.jhazmat.2010.12.102. (45) Li, R.; Liu, L.; Yang, F. Preparation of Polyaniline/Reduced Graphene Oxide Nanocomposite and Its Application in Adsorption of Aqueous Hg(II). Chem. Eng. J. 2013, 229, 460-468, DOI: 10.1016/j.cej.2013.05.089. (46) Rouquerol, J.; Rouquerol, F.; Llewellyn, P.; Maurin, G.; Sing, K. S. Adsorption 24


Page 24 of 27

Page 25 of 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


by Powders and Porous Solids: Principles, Methodology and Applications, Academic Press: 2013. (47) Wang, X.; Zou, L.; Fu, H.; Xiong, Y.; Tao, Z.; Zheng, J.; Li, X. Noble Metal-Free Oxygen Reduction Reaction Catalysts Derived from Prussian Blue Nanocrystals Dispersed in Polyaniline. ACS Appl. Mater. Interfaces 2016, 8, 8436-8444, DOI: 10.1021/acsami.5b12102. (48) Nieboer, E.; Richardson, D. H. S. The Replacement of the Nondescript Term ‘Heavy Metals’ by A Biologically and Chemically Significant Classification of Metal

Ions.

Environ.

Pollut.,

Ser.

B

1980,

1,

3-26,

DOI:

10.1016/0143-148x(80)90017-8. (49) Ge, J. L.; Xiao, J. D.; Liu, L. L.; Qiu, L. G.; Jiang, X. Facile Microwave-Assisted Production of Fe3O4 Decorated Porous Melamine-Based Covalent Organic Framework for Highly Selective Removal of Hg2+. J. Porous Mater. 2016, 23, 791-800, DOI: 10.1007/s10934-016-0134-y. (50) Chandra, V.; Kim, K. S., Highly Selective Adsorption of Hg2+ by a Polypyrrole Reduced Graphene Oxide Composite. Chem. Commun. 2011, 47, 3942-3944, DOI: 10.1039/c1cc00005e. (51) Langmuir, I. The Constitution and Fundamental Properties of Solids and Liquids. Part

I.

Solids.

J.

Am.

Chem.

Soc.

1916,

38,

2221-2295,

DOI:

10.1021/ja02268a002. (52) Bao, J.; Fu, Y.; Bao, Z. H. Thiol-Functionalized Magnetite/Graphene Oxide Hybrid as a Reusable Adsorbent for Hg2+ Removal. Nanoscale Res. Lett. 2013, 8, 486, DOI: 10.1186/1556-276x-8-486. (53) Guo, Y.; Deng, J.; Zhu, J.; Zhou, X.; Bai, R. Removal of Mercury(II) and Methylene Blue from a Wastewater Environment with Magnetic Graphene Oxide: Adsorption Kinetics, Isotherms and Mechanism. RSC Adv. 2016, 6, 82523-82536, DOI: 10.1039/c6ra14651a. (54) Liu, M.; Tao, Z.; Wang, H.; Zhao, F.; Sun, Q. Study on the Adsorption of Hg(Ii) by One-Pot Synthesis of Amino-Functionalized Graphene Oxide Decorated with a Fe3O4 microsphere Nanocomposite. RSC Adv. 2016, 6, 84573-84586, DOI: 25



10.1039/c6ra16904j. (55) Zhang, C.; Sui, J.; Li, J.; Tang, Y.; Cai, W. Efficient Removal of Heavy Metal Ions by Thiol-Functionalized Superparamagnetic Carbon Nanotubes. Chem. Eng. J. 2012, 210, 45-52, DOI: 10.1016/j.cej.2012.08.062. (56) Diagboya, P. N.; Olu-Owolabi, B. I.; Adebowale, K. O. Synthesis of Covalently Bonded Graphene Oxide-Iron Magnetic Nanoparticles and the Kinetics of Mercury Removal. RSC Adv. 2015, 5, 2536-2542, DOI: 10.1039/C4RA13126F. (57) Guo, X.; Du, B.; Wei, Q.; Yang, J.; Hu, L.; Yan, L.; Xu, W. Synthesis of Amino Functionalized Magnetic Graphenes Composite Material and Its Application to Remove Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II) from Contaminated Water. J. Hazard. Mater. 2014, 278, 211-20, DOI: 10.1016/j.jhazmat.2014.05.075. (58) Gao Y.; Chen X.; Zhang J.; Yan N. Chitin-Derived Mesoporous, Nitrogen-Containing Carbon for Heavy-Metal Removal and Styrene Epoxidation. ChemPlusChem 2015, 80 (10), 1556-1564, DOI: 10.1002/cplu.201500293.

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TOC GRAPHIC

Synopsis: N-doped magnetic porous carbon prepared via facile one-pot pyrolysis strategy possesses good performance for removal of Hg2+ from aqueous solutions.

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Facile Fabrication of N-Doped Magnetic Porous Carbon for Highly

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