3.1 Characterization of ZIF-67 (Co)
The lattice data of synthesized ZIF-67 (Co) was analyzed using XRD. As shown in Figure S2, the experimental results conformed to the theory within the literature(Banerjee et al. 2008). The crystal plane diffractions of ZIF-67 (Co) were obtained including 011 (corresponding to 7.31°), 002 (corresponding to 10.36°), 112 (corresponding to 12.72°), 022 (corresponding to 14.40°), 013 (corresponding to 16.45°), 222 (corresponding to 18.04°), 114 (corresponding to 22.15°), 233 (corresponding to 24.53°), 134 (corresponding to 26.70°), 044 (corresponding to 29.62°), 334 (corresponding to 30.62°) and 235 (corresponding to 32.43°).
The morphology of ZIF-67 (Co) was scanned using SEM. At 10000 times magnification (Figure S3A), it could be clearly seen that a large number of ZIF-67 (CO) particles were closely packed together. At a greater magnification, the shape of ZIF-67 (Co) is similar to a rhombic dodecahedron or a ‘chamfered cube’ (Figure S3B-C). It was seen that the morphology of ZIF-67 can be changed by adjusting the molar ratio of ligand to metal ion, and the synthesis time. The rhombic dodecahedron grew when the molar ratio of metal ion to ligand was low (Cravillon et al. 2012). In this study, 1:45 was the molar ratio of metal ion to ligand used to form the rhombic dodecahedron (Figure S3D). This resulted in a favorable formation of ZIF-67 (Co) crystal. Additionally, the choice of metal ion salt could directly affect the size of ZIF (Shao et al. 2014). When cobalt nitrate was used as the source of cobalt, the ZIF-67 (Co) obtained in our work was an average size of approximately 0.5 µm.
The functional groups on the surface of ZIF-67 (Co) were analyzed using infrared spectroscopy (Figure S4). 2-methylimidazole, a ligand found exclusively in the ZIF-67 (Co) structure, was used as a standard comparison because it provided most of the infrared absorption signal of ZIF-67 (Co) (Lashgari et al. 2020). The infrared absorption within the range of 1500-1600 cm−1 was attributable to the stretching vibration and bending vibration of the imidazole ring. The peak at 1584 cm−1 corresponded to the stretching vibration of the C=N bond in 2-methylimidazole. Lastly, the infrared absorption within the range of 3200-2900 cm−1 belonged to the stretching vibration of C-H on the imidazole ring and the aliphatic chain (Lin &Chang 2015).
3.2 Characterization of Co-NPCs
As shown in Figure S5, the XRD characterization was used to obtain the diffraction signal of the synthesized Co-NPC-800 and Co-NPC-800 (Ar). Compared to the XRD spectrum of the original ZIF-67 (Co), a lower resolution and wider particle peaks were observed after carbonization. Meanwhile, there were three obvious diffraction peaks found in both Co-NPC-800 and Co-NPC-800 (Ar), which corresponded well to the elementary substance of β-Co. Among them, 2θ = 43.9°, 51.1° and 75.4° were assigned to (111), (200) and (220) of the crystal plane’s diffraction, respectively. In the XRD spectra of both samples, a relatively weak diffraction peak was found at 2θ = 25°, which belonged to the characteristic peak of the typical (002) graphite laminated structure. This result suggested that the prepared Co-NPXs were partly graphitized. In addition, we observed a faint protrusion at 2θ = 37° belonging to the characteristic peak of COO. This may be caused by the easy oxidation, in air, of Co nanoparticles on the surface of the porous carbon materials (Ma et al. 2016).
The SEM images of Co-NPC-800 and Co-NPC-800 (Ar) are shown in Figure 2. After carbonization, the original shape of the ZIF-67 (Co) crystal remained but the surfaces of the porous carbon particles were distorted and the size of the particles were shrunk. As shown in Figure 2A-B, the surface of Co-NPC-800 (Ar) was obviously roughened, while the crystals were more concentrated. Compared to Co-NPC-800 (Ar), the surface of Co-NPC-800 was smoother, and the crystals were more dispersed. This result was attributed to the fact that defects were formed on the surface of Co-NPC-800 by nitrogen doping, which separated the crystals and made the dispersive crystals difficult to agglomerate. Additionally, more adsorption sites were available after the defects formed and a larger specific surface area was created after the crystals separated. This increased the chance of Co-NPC-800 contacting with pollutants and caused the adsorption performance to improve.
In order to investigate the changes in the functional groups of ZIF-67 (Co) after carbonization, the infrared spectra of Co-NPC-800 (Ar) and Co-NPC-800 were analyzed (Figure S6). It was found that the infrared spectra of Co-NPC-800 (Ar) and Co-NPC-800 were similar, indicating that their structures were basically the same. Compared to ZIF-67 (Co), Co-NPC retained the normal absorption rate of the aromatic ring in the range of 1500-600 cm−1, which was a result of the fact the imidazole ring remained stable after high temperature carbonization. The characteristic peak at 1500 cm−1 corresponded to C=C on the aromatic ring, and the peaks at 1300-700 cm−1 were the flexural vibration signals of C-H on the aromatic ring. Absorption peaks around 3000 cm−1 were observed in both Co-NPC-800 (Ar) and Co-NPC-800, which may have been caused by the reaction of C and H at the edge of the material during pyrolysis. The broad absorption peaks near 3500 cm−1 indicated the stretching vibration of N-H or O-H. The signal of O-H may have been a result of the moisture absorbed by the material from the air. Nevertheless, the N-H peak of Co-NPC-800 was sharper than the peak of Co-NPC-800 (Ar), indicating that more N elements had been successfully introduced into Co-NPC-800 by carbonization in a N2 atmosphere(Ma et al. 2016).
In order to explain the graphitized carbon signal in the XRD spectrum of Co-NPC, Raman spectroscopy was used to further investigate the C element in Co-NPC (Yang et al. 2021). The relative ratio of the D-band area to the G-band area (ID/IG) in the Raman spectrum is an important parameter to understand the degree of crystallization of the graphitized carbon in the materials. The D-band is a region that characteristically contains structural defects and impurities, which represent the defects and disorder of the materials. The G-band is generated by the stretching vibration of C-C, which represents the internal vibration of SP2 hybrid carbon atoms. The amorphous degree can be expressed by ID/IG, for example, a larger ratio represents a lower degree of order in the graphite materials. The Raman spectra of Co-NPC-800 are shown in Figure S7, and ID/IG=2.34 was obtained by fitting. The results indicate that Co-NPC-800 has a low degree pf graphitization, low order and many defects, which could provide more sites for the adsorption of pollutants.
The XPS was used to investigate the composition and element valence of Co-NPC-800, and to further confirm the successful doping of the N element. In the full spectrum (Figure S8A), we could clearly observe the signals of Co, C, N and O. By fitting the N1s spectrum (Figure S8B), we discovered that it could be divided into four independent peaks and that their binding energies were 398.6, 399.3, 400.7 and 404.1 eV respectively. The results suggested that N elements in Co-NPC-800 existed in four different forms; namely pyridine, pyrrole, graphite and oxidized type. By fitting the N1s spectrum (Figure S8B), it was found that Co element existed in the forms of Co (0) (at 778.3 eV), Co2+ (at 780.8 eV) and Co-OH (at 785.7 eV). This result was consistent with the previous XRD results and results contained in the literature(Huang et al. 2015). The existence of the oxidation state Co (Co2+) verified the partial surface oxidation of Co nanoparticles in the XRD results. The results above showed that high temperature carbonization of ZIF-67 (Co) led to the formation of N-doped magnetic porous carbon materials (Co-NPC), whose magnetic function mainly came from the Co nanoparticles.
The specific surface area, pore type, and adsorption capacity of Co-NPCs were investigated using a N2 adsorption-desorption curve (Fan et al. 2020). N2 adsorption-desorption analysis of Co-NPC-600, Co-NPC-800 and Co-NPC-800 (Ar) were carried out at 77 K. The specific surface areas of all three materials exceeded 200 m2·g−1. Obvious H3 mesoporous hysteresis loops in the N2 adsorption-desorption curves (Figure S9A), indicated that mesopores formed on ZIF-67 (Co) during the carbonization. The pore size distribution of all three materials were mainly below 10 nm (Figure S9B), and the average pore sizes were all less than 10 nm (Table 1); this confirmed that Co-NPCs were mesoporous materials. Comparing Co-NPC-600 with Co-NPC-800, it was found that the pore size, specific surface area and total pore volume all increased alongside the increase in the carbonization temperature. This implied that the higher temperature led to the greater carbonization of ZIF-67 (Co) and more defects on Co-NPCs. Comparing Co-NPC-800 with Co-NPC-800 (Ar), it was found that the pore size, specific surface area and total pore volume of Co-NPC-800 (Ar) were all smaller than those of Co-NPC-800, which showed that Ar was non-reactive with porous carbon materials. Fewer defects and lower parameters were obtained in Ar when compared to N2. Therefore, we concluded that Co-NPC-800 had greater potential in adsorption applications.
Table 1
Structural parameters fitted by N2 adsorption model at 77 K
Entry
|
Sample
|
Aperture (nm)
|
SBET (m2·g−1)
|
Pore volume (cm3·g−1)
|
1
|
Co-NPC-600
|
6.1517
|
240.8376
|
0.318171
|
2
|
Co-NPC-800
|
9.9545
|
275.5626
|
0.389612
|
3
|
Co-NPC-800 (Ar)
|
9.6441
|
259.8515
|
0.3662
|
As shown in Figure 3, the magnetization curves of Co-NPCs were obtained in the magnetic field range of ±20,000 Oe, at room temperature. It can be seen that four kinds of Co-NPC each had small hysteresis loops. The magnetization of the Co-NPCs rose slowly when the magnetic field exceeded ±10,000 Oe, which explained why Co-NPCs were soft magnetic materials. As the temperature increased, the saturation magnetization (Ms) of Co-NPC rose from 35.05 to 65.25 emu·g−1. The increase of Ms was due to the higher crystallinity of Co nanoparticles embedded in Co-NPCs as the temperature rose (Torad et al. 2014). The high Ms value of Co-NPC-800 came from the large load of Co nanoparticles. Similar studies of magnetic porous carbon materials have also been reported (Hameed 2009, Hameed &Lee 2009, Ji et al. 2009, Ravikumar et al. 2005, Wu et al. 2012), however, the Ms value of Co-NPC-800 was higher than them. As shown in the magnetic separation photo, Co-NPC-800 could be quickly separated by an external magnetic field after being dispersed in water.
3.3 Investigation into the factors affecting the adsorption of TCS and PCMX by Co-NPCs
3.3.1 Effect of carbonization temperature and atmosphere
Temperature can affect the carbonization degree of materials (Guo et al. 2017), while different atmospheres affect the surface reaction during the materials’ carbonization (Ismail et al. 2018). The adsorption capacity of synthesized Co-NPCs within different atmospheres and under different temperatures for TCS and PCMX had been compared (Figure 4). It can be seen that the influence of temperature and atmosphere on the adsorption of TCS and PCMX were almost the same, which related to the same charge properties of both under the experimental conditions (pH=7.0). As the temperature rose, the adsorption capacity of Co-NPC-600, Co-NPC-700 and Co-NPC-800 for TCS and PCMX gradually increased, which mainly because the pore size, specific surface area and total pore volume of Co-NPC all increased with the carbonization temperature. The contact area with pollutants and volume containing pollutants was also increased. Compared with Co-NPC-800 (Ar), the adsorption capacity of the Co-NPC-800 was significantly enhanced. Synthesized in a N2 atmosphere, the Co-NPC-800 doping of N obtained more adsorption sites, which was conducive to the adsorption of TCS and PCMX. Out of all the materials, Co-NPC-800 was selected for follow-up experiments because it had the best adsorption capacity.
3.3.2 Effect of pH
The pH of the solution can affect the existing form of the adsorbate in the solution, and it could also affect the charge properties on the adsorbent's surface (Bernal et al. 2017). The effect of the pH on the adsorption of TCS and PCMX by Co-NPC-800 was investigated. With the increase of pH, it could be seen that the adsorption capacity of Co-NPC-800 for TCS and PCMX both increased firstly and then decreased (Figure 5A&C). The results implied that electrostatic attraction might be the main mechanism Co-NPC-800 for the adsorption of pollutants. In order to verify this conjecture, the existing forms of TCS and PCMX were analyzed at different pH levels (Figure 5B&D). The pKa of TCS and PCMX were 7.68 and 9.21, respectively. The TCS was mainly in form of neutral molecules in the solution when the pH was less than 7.68. Most of the molecules would carry one unit of negative charge after losing a proton where the pH was greater than 7.68. The PCMX was mainly in form of neutral molecules in the solution when the pH was less than 9.21, and most of molecules would carry one unit of negative charge after losing a proton, when the pH was greater than 9.21.
At the same time, the Zeta potential of Co-NPC-800 was investigated when the pH was between 4.0-9.0 (Figure S10). It could be seen that the Co-NPC-800 was always negative in the whole range, and the negative charge showed a slight downward trend when the pH increased between the range of 4.0-7.0. The negative charge showed an obvious up-trend when the pH increased through the range of 7.0-9.0. Considering the form of the pollutants and the concept of Zeta potential, if there was only an electrostatic effect impacting upon the process, the optimal adsorption pH of Co-NPC-800 for TCS and PCMX should be around 7.0. At this time, Co-NPC-800 had the lowest negative charge and the pollutants were not charged, which are the most beneficial conditions for an electrostatic effect. However, whilst the experimental results showed that best adsorption pH of Co-NPC-800 for PCMX was around 7.0, the best adsorption pH of Co-NPC-800 for TCS was around 6.0. It could be assumed that electrostatic effect was not the only mode of action in the adsorption of Co-NPC-800 to TCS, but also there were π-π and hydrogen bond effects. Under acidic conditions, the π-π effect appeared between the imidazole ring on the surface of Co-NPC-800 and the benzene ring of the TCS molecule, which benzene group could be used as a π donor or acceptor. What’s more, the hydroxyl group of TCS molecules could be used as an H donor to form a hydrogen bond with the N atom on the surface of Co-NPC-800. The chlorine/hydroxyl group of TCS molecules could also be used as an H receptor to form a hydrogen bond with the H atom of Co-NPC-800. In conclusion, the optimal adsorption pH of TCS was 6.0 due to the multiple factors above. Because of the large steric hindrance caused by two methyl groups on the surface of PCMX, π-π and hydrogen bond effects were in the minority during PCMX adsorption. As a result, the pH of PCMX adsorption remained at 7.0.
3.3.3 Effect of ionic strength
A high concentration of salt in industrial waste water might affect the removal of pollutants by Co-NPC. So, the effect of solution ionic strength on the adsorption of TCS and PCMX was we studied by Co-NPC-800. As shown in Figure S11A, the ionic strength had only had a small impact on TCS adsorption. When the NaCl concentration was above 0.2 molŸL−1, the adsorption capacity increased slightly as the NaCl concentration rose. According to the existing form of TCS and the surface charge of Co-NPC-800, the Na+ between the Co-NPC-800 and TCS molecules would generate a shielding effect, which was beneficial to the interaction between adsorbate and adsorbent, and enhanced the adsorption of Co-NPC-800 to TCS. On the contrary, the adsorption capacity of Co-NPC-800 for PCMX became weaker and tended to be stable when more NaCl was added (Figure S11B). This result might be attributed to the fact that the adsorption of Co-NPC-800 for PCMX had, for the most part, an electrostatic effect rather than π-π effect, while NaCl would compete with PCMX for the adsorption sites on Co-NPC-800. Therefore, the binding sites of PCMX and Co-NPC-800 were partially occupied by NaCl, resulting in a decrease in its adsorption capacity. Nevertheless, under experimental conditions, the salt ion concentration had a very little effect on the adsorption of TCS and PCMX by Co-NPC-800.
3.4 Study on the Adsorption Kinetics of Co-NPC-800 on TCS and PCMX
By investigating the change of absorbance between Co-NPC-800, TCS and PCMX, the time taken to reach adsorption equilibrium could be determined. In addition, the adsorption mechanism could be better understood by fitting the kinetic model. As shown in Figure 6A&D, the equilibrium time of adsorption on Co-NPC-800 (0.1 mg·mL−1) with TCS (20 mg·L−1) and PCMX (10 mg·L−1) were both 3 mins. Although both TCS and PCMX were highly concentrated, Co-NPC-800 showed excellent adsorptive power for these two targets.
Fitting the experimental data with the quasi-first-order and the quasi-second-order kinetic equation respectively, the fitting curves obtained are showing in Figure 6B-C&E-F, while the kinetic parameters and correlation coefficients for TCS and PCMX adsorbed by Co-NPC-800 are summarized in Table S1. It can be seen that the adsorption kinetics of Co-NPC-800 on TCS and PCMX were more in line with quasi-second-order kinetic model (R2>0.99), the adsorption capacity calculated by the quasi-second-order kinetic equation were closer to the experimental value as well. Above results suggested that the quasi-second-order kinetic model could be applied to the adsorption process of TCS and PCMX.
3.5 Adsorption isotherms of TCS and PCMX
The adsorption isotherms of TCS and PCMX by Co-NPC-800 were studied at 298, 308, and 318 K. The concentration range of TCS and PCMX were 8-40 and 1-25 mg·L−1, respectively. As the concentration of TCS and PCMX increased, the adsorption capacity increased rapidly and tended to balance. Under experimental conditions, the adsorption capacity of Co-NPC-800 for TCS and PCMX also increased as the temperature rose (Figure 7A&D). In line with the Langmuir adsorption isotherm equation and Freundlich adsorption isotherm equation, it was possible to obtain fitted linear diagrams (Figure 7B-C&E-F). The related parameters are shown in Table S2.
Only single-layer with physical adsorption was assumed in the Langmuir model. However, in the Freudlich model, single-layer and multi-layer adsorption were combined and both chemical and physical adsorption was considered. According to the fitted results, it could be seen that the adsorption of TCS and PCMX by Co-NPC-800 were more in line with the Langmuir isotherm adsorption model (R2>0.99), while the Freundlich model fit relatively poorly. The results suggested that the type of adsorption of TCS and PCMX by Co-NPC-800 was physical adsorption with a single-layer covering, which was also in line with the results of kinetics (qm ≈ q2e). As the temperature increased, the adsorption constant of the Langmuir model (KL) gradually increased. The maximum adsorption capacity (qm) of TCS increased from 163 to 263 mg·g−1, and the maximum adsorption capacity of PCMX increased from 39 to 56 mg·g−1. These results show that the adsorption of TCS and PCMX by Co-NPC-800 is an endothermic process. Additionally, the adsorption constant of the Freundlich model (KF) also increased as the temperature rose, and the value of n was greater than 1 at all the temperature, indicating that the adsorption of both pollutants by Co-NPC-800 was a preferential adsorption process.
3.6 Study on the adsorption thermodynamics of TCS and PCMX
In order to further understand the adsorption mechanism of TCS and PCMX on Co-NPC-800, we calculated thermodynamic parameters including Gibbs free energy change (ΔG0), enthalpy change (ΔH0) and entropy change (ΔS0). The ΔG0 value indicated the priority in the adsorption process and the magnitude of the adsorption driving force. The adsorption process could not be carried out spontaneously when ΔG0>0, but the adsorption process could be carried out spontaneously when ΔG0<0 (Tran et al. 2020). As listed in Table 2, the ΔG0 of Co-NPC-800 adsorbing TCS and PCMX were both negative in the range of 298-318 K. This indicated that that both processes could proceed spontaneously. Meanwhile, the ΔG0 decreased as the temperature rose, suggesting that the temperature rise enhanced the driving force of adsorption and promoted the adsorption progress. This result also inferred that the adsorption of TCS and PCMX on Co-NPC-800 was an endothermic process. Further, the ΔH0>0 also proved that the two processes were endothermic. The results calculated for ΔG0 and ΔH0 confirmed the results of adsorption isotherm. In general, having ΔG0 between -80 and 400 kJ·mol−1 was considered to be chemical adsorption, while ΔG0 between -20 and 0 kJ·mol−1 was regarded as physical adsorption (Özcan et al. 2005). In this study, the ΔG0 values of the two adsorption processes were in the range of -20-0 kJ·mol−1, suggesting that both of them were physical adsorption. These results were also in line with the results of kinetics and adsorption isotherms.
Table 2
Thermodynamic parameters of adsorption on Co-NPC-800 to TCS and PCMX
Target
|
Temperature (K)
|
K
|
ΔGo (kJ·mol−1)
|
ΔHo (kJ·mol−1)
|
ΔSo (kJ·mol−1·K−1)
|
TCS
|
298
|
21.558
|
-7.608
|
27.843
|
-0.119
|
308
|
29.282
|
-8.647
|
|
|
318
|
40.93
|
-9.814
|
|
|
PCMX
|
298
|
19.057
|
-7.302
|
9.019
|
-0.0547
|
308
|
20.737
|
-7.512
|
|
|
318
|
23.113
|
-7.781
|
|
|
The ΔS0 value reflects a change in system disorder. It was a process of entropy increase when ΔS0>0, while it was a process of entropy decrease when ΔS0<0. The ΔS0 was below 0 in the adsorption process of Co-NPC-800 on TCS and PCMX, indicating that, after adsorption, the disorder of the system was reduced.
The massive desorption of water molecules arranged on the surface of Co-NPC-800 would increase the disorder of the entire system and increase the entropy in the adsorption process. However, when TCS and PCMX were adsorbed from the solution to the solid-liquid interface of the adsorbent, some translational and rotational degrees of freedom were lost, which led to a decrease in entropy. The entropy decrease in this process was greater than the entropy increase caused by the massive desorption of water molecules. Therefore, overall, the entire adsorption process showed a decrease in entropy.
3.7 Adsorption mechanism
As mentioned above, the adsorption of Co-NPC-800 to TCS and PCMX was mainly physical adsorption, which included electrostatic, π-π and hydrogen bond effects. Electrostatic interaction is one of the most common. In order to further verify the role of π-π and the hydrogen bond, an infrared spectrometer was used to investigate Co-NPC-800 after adsorption of TCS and PCMX. As shown in Figure 8A&B, obvious infrared absorptions at 1500-700 cm−1, 3000 cm−1 and 3500 cm−1 were observed. Compared with the spectra of pure TCS and PCMX, the characteristic peaks were weaker, despite the fact it implied that TCS and PCMX were successfully adsorbed on Co-NPC-800. The slight shift of the characteristic hydroxyl peak at 3500 cm−1 was attributed to the formation of a hydrogen bond, which is between the N atom on the surface of Co-NPC-800 and the hydroxyl groups in the TCS/PCMX molecules. The characteristic peak of the C=C skeleton vibration in the aromatic ring (about 1600 cm−1) also shifted slightly, and became wider after adsorption. This could be attributed to the π-π effect between TCS/PCMX molecules and the imidazole ring that remained after carbonization. Due to the large steric hindrance in the PCMX molecule caused by multiple substituents on the benzene ring, the π-π effect between Co-NPC-800 and PCMX was suppressed. So, the adsorption capacity of Co-NPC-800 for PCMX was inferior to that of TCS, which meant the steric hindrance was lesser.
In addition, the hydrogen bond acceptors and donors of TCS and PCMX at different pH were analyzed, and the results are shown in Figure 8C&D. There were one hydrogen bond acceptor and two hydrogen bond donors in TCS when pH<6.0. This was consistent with the best adsorption capacity of Co-NPC-800 to TCS at pH=6. The results confirmed that the adsorption of Co-NPC-800 to TCS had several modes of action. For example, there was one hydrogen bond acceptor and two hydrogen bond donors in PCMX when pH<7.0. These were consistent with the best adsorption capacity of Co-NPC-800 to PCMX at pH=7.0. The results indicated that the hydrogen bond was also important in the adsorption of Co-NPC-800 to PCMX. The mechanism diagram of the adsorption on Co-NPC-800 to TCS and PCMX was drawn according to above-mentioned experimental and theoretical results (Figure 9). Co-NPC-800 was also highly able to remove TCS and PCMX due to the combined of electrostatic, π-π and hydrogen bond effects.
3.8 Investigation on the reusability
As shown in Figure S12, the adsorption capacity of Co-NPC-800 for TCS remained above 150 mg·g−1 even after being recycled 5 times, showing that Co-NPC-800 has good reusability. However, the adsorption capacity of Co-NPC-800 for PCMX decreased from 40 to 25 mg·g−1 after being recycled 5 times. This could be explained by the fact that the adsorption capacity of Co-NPC-800 for PCMX was originally small, and the sites where Co-NPC-800 adsorbed PCMX were partially deactivated during the cycles.
3.9 Application of Co-NPC in actual water samples
In order to verify the ability to practically apply this method in this work, we investigated the removal performance of Co-NPC-800 for TCS and PCMX in actual water samples. Both TCS and PCMX were not detected in the collected lake water, river water and tap water, so TCS with spiked concentration of 20 mg·L−1 and PCMX with spiked concentration of 10 mg·L−1 were added in the three water samples. The results of pollutant absorption are shown in Figure 10. The maximum adsorption capacity of Co-NPC-800 for TCS and PCMX in the three water samples was close to the theoretical values, which were about 160 and 40 mg·L−1. Co-NPC-800 could be used as an adsorbent for the removal of TCS and PCMX in sewage, and it has a great potential to be applied more broadly.