Magnetic copper-ferrosilicon composites as regenerable sorbents for Hg0 removal

Colloids and Surfaces A 590 (2020) 124447

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Magnetic copper-ferrosilicon composites as regenerable sorbents for Hg0 removal

T

Fashan Zhou, Yongfa Diao* School of Environmental Science and Engineering, Donghua University, 2999 North Renmin Road, Shanghai 201620, PR China

G R A P H I C A L A B S T R A C T

Figure S1. Illustration of fabrication process of MagFeSi-Cu0 and its use as regenerable sorbents for Hg0 removal. a)The components of MagFeSi-Cu0, b) FeSi loaded with Cu and Fe3O4@SiO2 nanoparticles by powder metallurgy, c) its use for Hg0 removal by amalgamation and regeneration from (c) to (b) by thermal treatment.

A R T I C LE I N FO

A B S T R A C T

Keywords: Copper-Ferrosilicon adsorbent Elemental mercury removal Cu-Hg0 amalgam Regeneration

As a dangerous environmental pollutant, mercury is widely existed in coal-fired power plant gases. In this manuscript, a novel and reliable high-capacity adsorbent (MagFeSi-Cu°) was synthesized by powder metallurgy method to remove Hg° from flue gases. The FeSi, the nano-copper and the silica-coated magnetic Fe3O4 nanoparticles were mixed and calcinated at 300 °C by powder metallurgy method. Copper nanoparticles were uniformly dispersed on the FeSi surface by the linkage of Cu3Si, which was formed by the interfacial reaction between surface Cu atoms in the copper nanoparticles and the amorphous Si on the surface of FeSi. Due to the magnetic properties of the Fe3O4 nanoparticles, the adsorbent can be effectively separated from dust waste for further recycling and regeneration. The amorphous silicon in ferrosilicon (FeSi) reacts with copper nanoparticles, producing copper-silicon alloy as a binder to maintain the stability of copper nanoparticles. Besides that, well-dispersed copper nanoparticles prepared by liquid phase reduction have excellent amalgam properties. The characteristics mentioned above make the new composite (MagFeSi-Cu°) a regenerable sorbents for Hg° Removal from flue gas, which was confirmed by mercury removal test conducted in a fix-bed reactor.

1. Introduction Mercury is one of the most dangerous environmental pollutants

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because of its volatility, persistence and bioaccumulation [1]. In general, mercury exists in three forms in coal-fired power plant gases: gaseous oxidized mercury(Hg2+), elemental mercury(Hg0) and

Corresponding author. E-mail address: [email protected] (Y. Diao).

https://doi.org/10.1016/j.colsurfa.2020.124447 Received 3 November 2019; Received in revised form 6 January 2020; Accepted 8 January 2020 Available online 27 January 2020 0927-7757/ © 2020 Elsevier B.V. All rights reserved.

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particulate-bound mercury (Hgp) [2,3], most Hgp and Hg2+ can be removed by the existing wet flue gas desulfurization (WFGD) and electrostatic precipitator (ESP) in the flue gas [4]. However, Hg0 is usually released directly into the atmosphere due to its low solubility in water, it is the most challenging form of mercury to be captured [5–7]. To meet the increasingly stringent mercury emission control legislations, a number of approaches have been devoted to remove Hg0 from coal combustion flue gases, mainly through sorbent injection or catalytic oxidation. The injection of AC-based sorbents has been commercially employed by some power plants [8,9]. One major limitation of using ACbased sorbents is the recovery and recycle of spent sorbents, and therefore they are usually used only once, incurring high operating costs [10]. Noble metals, including Ag, Au, Pb, etc., can capture Hg° by reversible amalgam process, have been well demonstrated to achieve mercury removal efficiency of more than 90 % at flue gas temperature [11–14]. At present, ion exchange method has been employed to incorporate noble metal nanoparticles on the surface of functionalized mesoporous materials, such as natural zeolite, graphene, mesoporous silica [15–18]. They can amalgamate Hg° at the temperatures of coalfired flue gases, the captured Hg° can be readily released through thermal treatment at higher temperatures. Although the noble metal adsorbents have high mercury removal rate and regenerative characteristics, most of them are limited in large-scale application for flue gas due to their high cost. Copper, as a cheap metal, has been proved to amalgamate Hg° in wasted water, and the removal efficiency can be as high as more than 90 %, which can be an alternative to noble metals [19]. At present, modified copper oxides have been commonly applied as catalyst to remove Hg° from flue gas with the existence of Cl and other halogen element [20–23]. However, as a promising adsorbent, elemental Cu was rarely been used to remove Hg° in flue gas. In addition, ion exchange method has the disadvantages of significant metal ion losses in the synthesis process, which makes it difficult in the mass production and complicated synthesis procedures [24]. An alternative method to incorporate copper nanoparticles on the surface of support materials needs to be investigated. Herein, by using powder metallurgy method as an alternative to ion exchange method [25], we develop an innovative, yet simple and robust route for the preparation of a high efficiency and high capacity mercury sorbent (MagFeSi(75)-Cu°), using Ferrosilicon (FeSi) as the support material and copper nanoparticles as the Cu source as shown in Scheme 1. Ferrosilicon (FeSi) acts as good carrier for the binary metal alloy, at normal temperature, most of the metal silicon in FeSi alloy are in the phase of FeSi2 and amorphous Si, their ratio is equivalent, while the remaining Fe-Si compounds exists in the form of metastable Lebeauit [26]. Amorphous Si atoms can be easily combined with metal atoms to form alloy due to their chemical properties. The interfacial reaction was occurred when Cu film was deposited on the surface of Si under ultra-high vacuum conditions, generating Cu3Si as the only copper-silicon compound phase when annealing at 200−800 °C [27–32]. The generated heat value increases with the increase of silicon content in the silicide, which indicates that the silicon-rich silicide is more stable [33,34]. The main purpose of this work is to replace the ion exchange method with powder metallurgy method by incorporating Cu nanoparticles onto the surface of ferrosilicon, and mixing them with silica-coated Fe3O4 particles to develop a novel, simple and reliable high-capacity adsorbent (MagFeSi-Cu°) to remove Hg° from flue gases.

After mercury adsorption at 150 °C for 100 min, the sorbents were regenerated by heating to 350 °C in a pure N2 carrier gas. The heating rate was 2 °C min−1 with a flow rate of 1 l/min of pure N2. After the fixed-bed reactor was cooled down to the room temperature, another cycle of the Hg° adsorption test was started. Five cycles of adsorption–desorption–adsorption were tested in our study.

2. Experimental section

3. Results and discussions

2.1. Materials and preparation

3.1. Ultimate analysis and sorbent surface characterization

All materials used in this study are provided in the supporting information (SI). The procedures for synthesis of magnetic copper-ferrosilicon nanocomposites, MagFeSi-Cu°, are shown in Figure S1. 3 g of Fe3O4 (< 100 nm) was dissolved in solution containing 90 ml of

The SEM images of MagFeSi-Cu° are shown in Fig. 1a and 1b. It can be seen from the figures that the magnetic particles are evenly distributed on the ferrosilicon surface. In the ferrosilicon. Further detailed morphological information of copper nanoparticles supported on the

deionized water, followed by dropwise addition of 1 ml of TEOS. The resulting mixture was stirred for 12 h, followed by magnetic separation and dried directly in an air-circulated oven at 50 °C to obtain Fe3O4@ SiO2 black powder. 0.2 mol L−1 NaH2PO2 solution was poured into a three-necked flask at a constant temperature of 75 °C. The pH was adjusted to 1–2 by adding H3PO4 solution, followed by the addition of 3 g of stearic acid (about 0.01 mol) under magnetic stirring. 0.15 mol L−1 CuSO4 solution was added into the as-prepared solution at a rate of 40 drops per minute in 2 h, followed by filtered and dried at 60 °C for 12 h to obtain stearic acid-modified copper powder. The copper powder, ferrosilicon (< 25 μm) and Fe3O4@SiO2 powder were mixed at a mass ratio of 2:3:5, and calcinated at 300 °C for 1 h to obtain the magnetic adsorbent MagFeSi-Cu°. 2.2. Characterization The physicochemical properties of MagFeSi-Cu° were determined using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). More details on these characterization methods are given in the SI. BET surface area, pore volume and pore size of the FeSi and MagFeSi-Cu° were determined from nitrogen adsorption/desorption isotherms after degassing the samples at 200 °C for 4 h using QuadraSorb (Quantachrome Instruments, USA) under the standard mode. The specific surface area was calculated using multipoint BET method by tagging P/P0 range of 0.05 - 0.30. The total pore volume was measured from the amount of nitrogen adsorbed at P/P0 = 0.99. By collecting the distribution of the valence of Cu atoms and Si atoms on the surface of the adsorbent, the content of Cu° nanoparticles and copper-silicon alloy can be quantitatively investigated. The particle size of the sample surface was measured by using Nano Measurer 1.2 software. 2.3. Mercury breakthrough test The Hg° adsorption performance of MagFeSi-Cu° was evaluated in a fix-bed reactor. The schematic diagram of the experimental setup is shown in Figure S2.The experimental facility consists of a lab-scale fixed-bed reactor, a mercury generator, and a real time online Hg° analyzer (VM3000). The Hg° concentration in the stream was about 38.5 μg m−3. When the concentration of Hg° had fluctuated within 5 % for more than 30 min, the gas was diverted to the adsorbent bed for the test. The sorbent bed height was about 10 mm, with a gas hourly space velocity about 76,394 h−1, The average particle size of the sorbent is 24 μm. To test the effect of temperature on Hg° adsorption performance, the experiments were carried out at temperature range from ambient temperature (25 °C) to 250 °C. The adsorption time for each sample was about 100 min. 2.4. Sorbent regeneration

2

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Fig. 1. (a, b) SEM images of MagFeSi-Cu0 nanocomposites; (c, d) STEM dark field image of MagFeSi-Cu0 and EDX spectrum (inset); (e, f) STEM dark field image of MagFeSi-Cu0 nanocomposites and size distribution of copper nanoparticles on FeSi.

Fig. 2. N2 adsorption and desorption isotherm for FeSi and MagFeSi-Cu0 (Ads and Des, are the abbreviation of adsorption and desorption, respectively). 3

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in different samples. The binding energy of Si 2p in copper-silicon alloy is 99.3 and 99.0 eV, respectively. Hence, the peak at 99.3 eV can be considered as a signature for the presence of Cu3Si, in addition, the peak at 99.0 eV can be assigned to the Si 2p of Cu5Si [37]. As anticipated, the content of Cu° and copper-silicon alloy in MagFeSi(75)-Cu° are higher than that in MagFeSi(50)-Cu°, indicating that the coppersilicon alloy was synthesized successfully on the surface of FeSi. Furthermore, the binding energy between Si and Cu increases as the silicon content in FeSi increases, that is, the silicon-rich silicide has a higher formation heat, which indicates that the Cu3Si in MagFeSi(75)-Cu° is more stable. The content of Cu° and copper-silicon alloy were determined by calculating the corresponding peak areas in MagFeSi(50)Cu° and MagFeSi(75)-Cu°. The results show that the content of Cu° and copper-silicon alloy in MagFeSi(50)-Cu° are approximately 92.86 % and 98.6 % of that in MagFeSi(75)-Cu°, respectively. In summary, the content of Cu particles supported on the surface of FeSi increases as the amount of Si increases. In addition, the specific composition of copper in MagFeSi (75) -Cu0 was also analyzed by XPS. The results were shown in Figure S4. The peak of Cu 2p3/2 at 934.7 eV and the peak of Cu 2p1/2 at 954.8 eV are the characteristics of Cu2 + species, the peaks at 932.8 eV for Cu 2p3/2 and 952.6 eV for Cu 2p1/2 represented the Cu0 species [36]. The results show that the copper oxides exist in the form of the mixed states of Cu2+ in the samples. Copper mainly exists in the form of Cu0, accompanied by CuO.

surface of mineral ferrosilicon in MagFeSi-Cu° is revealed by STEM imaging. A large number of spherical Cu nanoparticles (black dots) with sizes (diameters) ranging from 0 to 35 nm are visible on the external surface of FeSi as shown in Fig. 1e. The results of EDX analysis at location (1) and (2) confirm that the observed nanoparticles are Cu nanoparticles, as anticipated. The copper with higher atomic number than silicon is shown as black spots on the STEM bright field image. The magnified image of MagFeSi-Cu° clearly shows that many copper nanoparticles distribute on the surface of ferrosilicon. The particle size of the copper nanoparticles was measured by Nano Measurer 1.2 software. The mean particle size of copper nanoparticles was calculated to be 10.72 nm as shown in Fig.1f. In fig.S3, it is more intuitively to see the distribution of Cu° particles on the surface of ferrosilicon, as anticipated, the copper particles are tightly bonded to FeSi, which can be explained by the interfacial reaction and diffusion of Cu atoms on the surface of FeSi. In conclusion, Cu nanoparticles were successfully supported on FeSi by powder metallurgy. The International Union of Pure and Applied Chemistry (IUPAC) has developed six classifications for adsorption isotherms [35]. The adsorption isotherms for all samples were close to Type I of the IUPAC classification as shown in Fig.2, which implies that pores in FeSi were micropores. Compared with FeSi, MagFeSi-Cu0 showed a higher specific surface area, total pore volume and lower average pore diameter (Table 1), which indicated that Fe3O4@SiO2 and Cu0 were successfully loaded onto FeSi. The decreased average pore diameter suggests that Cu atoms were interfacially reacted with amorphous Si atoms, generating Cu3Si. The magnetic adsorbent tested in this experiment can be regarded as a system with various phases. X-ray diffraction analysis can be used to identify various phases, crystallinity of the phases and degree of crystal dispersion. In the characterization, FeSi(75) and FeSi(50) are used as carriers to determine the content of nano-copper and copper-silicon alloy with different silicon content. In addition, the composition of copper-silicon alloy produced in the interfacial reaction can be regarded as a reference to quantitatively analyze the adhesion of Cu° nanoparticles on the surface of FeSi. The results are shown in Fig. 3. The phase constitution of the deposited layer on FeSi spheres was studied. It can be seen from Fig. 3a and b that the diffraction characteristic peaks of Cu° and Fe3O4 appeared after the nano-Cu° particles and Fe3O4@SiO2 were supported on the surface of FeSi(75) by powder metallurgy. Fig. 3b shows the XRD patterns of MagFeSi(75)-Cu°. The peaks at 43.3° and 74.1° in Fig. 3b were assigned to the (111) and (220) planes of cubic Cu phase (JCPDS card no. 01-070-3039), respectively. According to the shape and intensity of the peaks, the Cu shell has a good crystallinity. Comparing the MagFeSi(75)-Cu° patterns with pure FeSi(75) patterns, there is a slight decrease in the intensity of the peaks, which can be attributed to a pore-filling effect of Cu and Fe3O4@SiO2 nanoparticles in the channels, reducing the signal of X-ray scattering to a certain extent. However, the diffraction peaks corresponding to Cu3Si were not appear. This was attributed to the fact that Cu3Si was in an amorphous or poorly crystalline state. In order to further confirm the structure and component of the cooper-silicon alloy spheres, XPS spectrum was measured. Fig. 3c presents the XPS spectrum of the MagFeSi(75)-Cu° and MagFeSi(50)-Cu°. The binding energy of Cu 2p for Cu° is 932.8 and 952.6 eV, respectively [36]. Fig. 3d presents the XPS spectrum of Si 2p for copper-silicon alloy

3.2. Mercury removal performance of sorbents 3.2.1. Mercury breakthrough test Fig. 4a shows the mercury breakthrough characteristics of different samples under varied temperature. The experimental samples are Fe3O4, Fe3O4@SiO2, FeSi and MagFeSi-Cu°, respectively. The content of copper is 20.4 % in MagFeSi-Cu°. As expected, the original Fe3O4 nanoparticles does not adsorb mercury at all even at room temperature (25 °C), in which the Hg° breakthrough is about 96.1 %. After the silica coating is applied to Fe3O4 to form Fe3O4@SiO2, Hg° breakthrough remains as high as 92.2 %, which indicates that Fe3O4@SiO2 does not adsorb Hg°. FeSi(75) as a binary metal alloy has good loading capacity but few micropores, which can not provide enough active sites for Hg° adsorption, and the Hg° breakthrough is about 89.4 % at 25 °C. The effect of Cu content on Hg° removal can be seen in Fig.4b. Five samples with different copper loading are set as P1, P2, P3, P4, and P5 with copper contents of 5.3 %, 10.5 %, 20.4 %, 23.3 %, and 25.7 %, respectively. The adsorption efficiency increased from 44.5%–91.5 %, when the copper content is 20.4 %, the adsorption efficiency tends to saturate. This may be related to the diffusion concentration of mercury on the surface of the adsorbent, at a certain reaction temperature and a certain initial mercury concentration, the diffusion concentration of mercury on the adsorbent surface is relatively stable. The results in Fig. 5 shows that the Cu° nanoparticles on the surface of FeSi can significantly improve the ability for mercury capture, the mercury breakthrough is reduced to 5 % at normal temperature, and the adsorption efficiency is 90 % at 150 °C with an adsorption capacity of 804.6 μg g−1. The poor performance of the MagFeSi-Cu° at high temperature was attributed to the mercury amalgamation mechanism. The Cu–Hg alloy was formed on the surface of FeSi, which showed low thermostability. Therefore, the MagFeSi-Cu° showed poor performance at high temperature. The results above indicate that MagFeSi-Cu° has excellent performance for Hg° removal under general temperature (135−180 °C), which proves the importance of copper nanoparticles in mercury capture. The amount of Hg° captured by MagFeSi-Cu° over 100 min in flue gases at 150 °C was calculated to be 804.6 μg g−1. This represents a significantly higher Hg° capture capacity than some other sorbents such as structured Au/C regenerable sorbent (328.3 μg g−1) [38], Ag-SBA-15 (457.3 μg g−1) [39] and MagZAg° (15.7 μg g−1) [40]. MagFeSi-Cu° also outperforms many carbon-

Table 1 Specific surface area, total pore volume and average pore diameter measured from nitrogen physisorption on FeSi and MagFeSi-Cu0. Samples

Surface area, m2/g

Total pore volume, cm3/g

Average pore diameter, nm

FeSi MagFeSi-Cu0

0.59 1.41

0.002 0.003

11.3 8.36

4

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Fig. 3. (a,b) XRD patterns; (c) XPS narrow-scan spectra of Cu 2p (Cu0); (d) XPS narrow-scan spectra of Si 2p.

based sorbents and non-carbon-based sorbents (see Table S1 for the summary of sorbents on Hg° removal). The XPS analysis was employed to explore the chemical state and the relative portion of Cu and Hg on the surface of sorbents before and after Hg0 removal, and the results were shown in Fig. 6. It can be seen from the Fig. 6 (a) that the peak position of Cu 2p in the spent MagFeSiCu0 sample was negatively shifted by 0.3 eV compared with the pristine sample, which may indicate the formation of Cu-Hg amalgam. Fig. 6(b) shows the XPS spectra of Hg4f in the MagFeSi-Cu0 after Hg capture. As can be seen from the Fig. 6(b), there is Hg0 in MagFeSi-Cu0 after its exposure to elemental mercury, since 4f 7/2 peaks is clearly within the 99.9 eV reference point for elemental mercury [41]. Since Si2p and Hg4f will partially overlap in XPS, in order to eliminate the interference of Si2p on the Hg4f result, XPS analysis was performed on the amorphous silicon in spent MagFeSi (75)-Cu0. The results were shown in Figure S5. The value of the two specific peaks differs from the value of Hg4f 7/2 by 0.5 eV. The interference of amorphous silicon on the elemental analysis of mercury can be ruled out. The observed difference in Hg 4f binding energy is probably due to the different mercury binding environment, leading to chemical shift of Hg 4f inMagFeSi-Cu0. Hg-TPD was used to identify the mercury species present in the spent sorbent and the desorption profiles of Hg was shown in Figure S6. During the experiment, nitrogen was used as the carrier gas, the total gas volume was 1 L/min, and the heating rate was 10°C/min. In the

Fig. 5. Hg0 removal efficiency and capacity of MagFeSi(75)-Cu0 at different temperature.

experiment, the mercury content of the pure substance was set to 80 μg, and the mercury adsorption form in the adsorbent was determined by the mercury desorption curve of the adsorbent. There was a well-resolved peak at about 230°C, which could ascribe to the release of Hg° [42].

Fig. 4. a) Hg0 breakthrough of different adsorption samples at different temperature; b) Hg0 adsorption efficiency of samples under different Cu loading. 5

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Fig. 6. (a) Cu 2p, (b) Hg 4f XPS spectra of MagFeSi-Cu before and after Hg0 removal test.

Fig. 7. a) Analysis of magnetic properties of magnetic adsorbent, b) Regeneration and adsorption efficiency of MagFeSi-Cu0 under heat treatment at 350 °C.

3.2.2. Regeneration performance A key feature of the new magnetic adsorbent MagFeSi-Cu° is its magnetic property. It can be seen from the Fig. 7a that the residual magnetization and coercive force of MagFeSi-Cu° is almost zero, showing typical superparamagnetism. When the magnetic field strength decrease to zero, the magnetization is not zero, but equal to the residual magnetization. The maximum saturation magnetization of MagFeSi-Cu° is 30 emu g−1. The adsorbent can be easily separated from various nonmagnetic substances (such as fly ash) by its superparamagnetism to achieve the purpose of recycling. Using P3 as the research object, the adsorption efficiency of Hg° was analyzed after heat treatment at 350 °C, as shown in Fig. 7b. The result shows that the adsorption efficiency of the adsorbent decrease from 90 % to 81 % after 5 times regeneration. The decrease of adsorption efficiency may be due to the decreased adsorption capacity with mercury residue.

3.2.3. Effect of different gas composition The effect of flue gas components, including O2, SO2, NO on Hg0 removal performance over MagFeSi-Cu0 was investigated. The results are summarized in Fig. 8. The sorbent lose part of their Hg° capacity due to the competitive adsorption of SO2 and NO which may compete with Hg° for the active sites. The experimental simulated flue gas atmosphere is 6 % O2, 500 ppm SO2, and 200 ppm NO and N2. There exists both physical and chemical adsorption in MagFeSi-Cu° for mercury removal, of which copper amalgam mechanism dominates. As illustrated in Fig. 8, SO2 and NO have lower inhibitory effect on Hg° adsorption. There is little change in adsorption efficiency with the existence of SO2 and NO. In the atmosphere of 6 % O2, the adsorption efficiency decreases by 7 %. The results showed that SO2 and NO have nearly no effects on Hg° removal, the Hg capacity was almost the same as that in purity N2. It was believed that O2 might inhibit the adsorption of Hg° to some extent. The reason was that Cu–Hg alloy could be easily affected by O2 under ambient atmosphere, the surface of Cu during the amalgamation process could be occupied by oxygen atoms. In order to further study the adsorption mechanism of Hg0, some

Fig. 8. Effect of various gases on MagFeSi-Cu0.

active elements such as Fe and O in the adsorbent were investigated before and after the removal of mercury in 6 % O2 atmosphere. It can be seen from Fig. 6(b) that the Hg4f XPS analysis also further proves that the main component of mercury after adsorption by the adsorbent in a nitrogen atmosphere is Hg0, which demonstrates that elemental copper is the main adsorption carrier. In 6 % O2 atmosphere, it can be seen from Figure S7(a) and S7(b) that part of Fe3O4 particles were oxidized to Fe2O3. Only a small amount of Hg0 was removed by the oxidation of Hg0 to Hg2+. It can be seen from Figure S7(c) and S7(d) that The content of lattice oxygen increased for used MagFeSi-Cu0. It was speculated that Fe3O4 particles were oxidized to Fe2O3, At the same time, some copper nanoparticles combined with oxygen atoms to generate CuO in the gas phase, leading to the increase of the lattice oxygen. 6

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4. Conclusion [11]

The novel sorbent MagFeSi-Cu0 showed promising results for capturing elemental mercury from mercury-containing gas phase. MagFeSiCu0 was successfully synthesized in a facile method based on the results of XPS, XRD, BET and TEM. Cu particles were dispersed on the surface of FeSi. Hg atoms transported on the surface of FeSi and combined with Cu particles into Cu–Hg alloy. Mercury as a resource could be collected from the MagFeSi-Cu0 by a thermal regeneration method. The regeneration property makes it potential sorbent for Hg0 control in the future.

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CRediT authorship contribution statement

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Fashan Zhou: Methodology, Investigation, Validation, Writing original draft. Yongfa Diao: Conceptualization, Writing - review & editing.

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Declaration of Competing Interest [19]

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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Acknowledgements

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This work is supported by the National Key Research and Development Program of China (2018YFC0705300), the Special Funds and Key Projects of Fundamental Scientific Research Business Fees in Central Universities (2232017A-09, CUSF-DH-D-2017097) and the Fundamental research of Shanghai Science and Technology Commission (14XD1424700).The financial support for this work from School of Environmental Science and Engineering of Donghua University, is gratefully acknowledged. The authors also would like to thank Mr Jianmao Yang of the test Center of Donghua University for collecting SEM images and EDX data, Mrs Yue Wu of the test Center of Donghua University for collecting XPS and XRD data, Nanjing Polymeric Analysis and Test Center for collecting TEM images.

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Appendix A. Supplementary data

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Supplementary material related to this article can be found, in the online version, at doi:https://doi.org/10.1016/j.colsurfa.2020.124447.

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