Modified carbon nanotube, water treatment agent and application

Abstract

The application belongs to the technical field of water treatment, and discloses modified carbon nanotubes, a water treatment agent and application. The modified carbon nanotubes have a carbon nanotube framework rich in carbon atom vacancy defects, the surface carboxyl groups of which are selectively inactivated by phenylethanone groups, and the surface of which contains carbonyl groups. The modified carbon nanotubes provided by the application contain carbonyl groups and carbon atom vacancy defects as active sites to participate in the activation process of chlorine, and through catalyzing the activation of chlorine, efficient removal of emerging pollutants in water can be achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment, in particular to a modified carbon nanotube, a water treatment agent and application. BACKGROUND

[0002] Emerging contaminants (ECs) are newly discovered, synthetically or naturally occurring chemical substances and microorganisms that have received widespread attention, and lack comprehensive environmental limit standards. ECs are diverse, usually composed of benzene rings or heteroaromatic compounds, such as pharmaceuticals and personal care products (PPCPs), endocrine disruptors (EDCs), and microplastics (MPs). These pollutants have potential harm to the endocrine, nervous, reproductive, and immune systems of humans and animals. The presence of π bonds endows ECs with high thermal and chemical stability, making them difficult to track and naturally degrade. ECs mainly enter the environment through agricultural planting, animal husbandry, domestic sewage and industrial wastewater, and stably exist in water media in trace amounts (ng / L-μg / L), posing a potential threat to human health and natural ecosystems.

[0003] Current conventional biochemical processes cannot meet the requirements of ECs removal in water treatment due to low biodegradability, while various emerging strategies such as adsorption, (electro)chemical oxidation and membrane separation have high cost, high energy consumption and high operation difficulty. Traditional ultraviolet irradiation photolysis chlorination is used as an advanced oxidation process to eliminate micro-pollutants, but there are large energy consumption and potential risks, such as the formation of disinfection by-products and the use of fragile mercury-containing lamps. Therefore, there is an urgent need for an efficient, economically feasible and environmentally friendly technology to remove ECs to ensure water quality safety. SUMMARY

[0004] To solve the problems in the background art, the present application provides a modified carbon nanotube, a water treatment agent and application. The water treatment agent containing the modified carbon nanotube is applied to water treatment, which can efficiently remove emerging contaminants, and has low cost and simple operation.

[0005] To achieve the above-mentioned purpose, the first technical solution adopted by the present application is:

[0006] The modified carbon nanotube has a carbon nanotube skeleton rich in carbon atom vacancy defects, the surface carboxyl groups of which are selectively inactivated by phenone groups, and the surface contains carbonyl groups.

[0007] Preferably, the carbon atom vacancy defects are introduced by sodium borohydride reduction treatment.

[0008] Preferably, the weight ratio of the carbon nanotube to sodium borohydride is 1: (0.2-1.0).

[0009] Preferably, the phenone groups are introduced by 2-bromo-1-phenylethanone treatment.

[0010] Preferably, the mass ratio of the carbon nanotubes to 2-bromo-1-phenyl ethanone is 1: (1.5~2.5).

[0011] The second technical solution adopted by the present application is:

[0012] The water treatment agent contains the modified carbon nanotubes of the first technical solution and sodium hypochlorite; the dosing amount of the water treatment agent in water treatment is that the modified carbon nanotubes are 0.02~0.05 g / L, and the sodium hypochlorite is 10~15 mg / L, based on the volume of the water to be treated.

[0013] The third technical solution adopted by the present application is:

[0014] Application of the water treatment agent in removal of emerging pollutants in water.

[0015] Preferably, the modified carbon nanotubes are used as catalysts to catalyze the activation of sodium hypochlorite to remove the emerging pollutants in water.

[0016] Preferably, the pH value of the system in the application process is 6.5~7.0.

[0017] Preferably, the emerging pollutants include any one of diclofenac, bisphenol A, N,N-diethyl-m-toluamide and 2,4-dichlorophenol.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] The modified carbon nanotubes provided by the present application have a skeleton structure rich in carbon atom vacancy defects, which cooperates with the surface carbonyl groups to jointly form an active center for efficient catalytic chlorine activation. The modified carbon nanotubes can degrade pollutants by forming an active surface-bound complex with chlorine molecules through a non-free radical oxidation pathway. Since the catalytic activity is derived from the stable carbon defect skeleton and carbonyl groups, rather than physically adsorbed active substances, the catalytic performance is stable and not easily disturbed by common matrix components in water bodies. The modified carbon nanotubes can efficiently remove various emerging pollutants with different structures, and exhibit excellent practical application potential. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 TEM image of the modified carbon nanotubes prepared for experimental group 1 in Example 2;

[0021] Figure 2 TEM image of the modified carbon nanotubes prepared for experimental group 2 in Example 2;

[0022] Figure 3 TEM image of the modified carbon nanotubes prepared for control group 2 in Example 2;

[0023] Figure 4The image shows a TEM image of the modified carbon nanotubes prepared in control group 3 in Example 2.

[0024] Figure 5 The image shows a TEM image of the modified carbon nanotubes prepared in control group 4 of Example 2.

[0025] Figure 6 The images show the Raman spectra of the carbon nanotube materials prepared in control groups 1-3 of Example 2.

[0026] Figure 7 Infrared spectra of different samples in Example 2;

[0027] Figure 8 XPS spectra of different samples in Example 2;

[0028] Figure 9 The middle image shows the high-resolution XPS spectrum of Cl 2p of the CNTs-Chlorine-DCF sample in Example 2;

[0029] Figure 10 Raman spectra of different samples in Example 2;

[0030] Figure 11 The images show the Raman spectra of the CNTs-Chlorine sample and sodium hypochlorite in Example 2. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to comparative examples and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The first embodiment of the present invention provides a modified carbon nanotube having a carbon nanotube framework rich in carbon atom vacancy defects, wherein the carboxyl groups on its surface are selectively deactivated by acetophenone groups, and its surface contains carbonyl groups.

[0033] The modified carbon nanotubes provided by this invention catalyze pollution through a non-radical oxidation pathway. They interact with chlorine molecules via an interfacial bond, leveraging the nanotubes' unique surface properties to achieve highly efficient pollutant degradation. The core of this mechanism lies in the modified carbon atom vacancy defects and carbonyl groups.

[0034] In the catalytic process of modified carbon nanotubes, carbon atom vacancy defects and carbonyl groups play a crucial role, which participate in the activation process of chlorine as active sites. Carbonyl groups are responsible for improving the oxidation capacity of the system by forming CNT-C=O-HOCl complexes, while the introduced carbon atom vacancy defects form CNT-D-HOCl complexes, mainly responsible for accelerating the electron transfer process. In contrast, carboxyl (-COOH) groups are not conducive to the chlorine activation process, so it is necessary to selectively inactivate the carboxyl group during the reaction while retaining the carbonyl group that is beneficial to the catalytic process.

[0035] In some preferred embodiments, the carbon atom vacancy defects are introduced by sodium borohydride reduction treatment, and the phenacyl group is introduced by 2-bromo-1-phenylethanone treatment. Specifically, first, the carbon nanotubes are treated with the reducing property of sodium borohydride to introduce abundant carbon atom vacancy defects in the crystal lattice of the carbon nanotubes; then, the carbon nanotubes with defects are treated with 2-bromo-1-phenylethanone (BrPE), and the bromomethyl group (-CH2-Br) in the BrPE molecule reacts with the original carboxyl group (-COOH) and other oxygen-containing functional groups on the surface of the carbon nanotubes to generate phenacyl derivatives (such as CNT-COO-CH2-CO-C6H5).

[0036] For the amount of sodium borohydride, it is determined according to the number of structural defects to be introduced to form electron transfer active sites; for the amount of 2-bromo-1-phenylethanone, it is determined according to the number of carboxyl groups to be inactivated to inhibit their reactivity; as some preferred embodiments, the weight ratio of carbon nanotubes to sodium borohydride is 1: (0.2-1.0), and the mass ratio of carbon nanotubes to 2-bromo-1-phenylethanone is 1: (1.5-2.5).

[0037] There is no special limitation on the preparation method of the modified carbon nanotubes, and those skilled in the art can adjust the preparation method according to the structural adaptability. As a specific example, the preparation method can include:

[0038] After mixing the carbon nanotubes and sodium borohydride uniformly in deionized water, stirring, filtering, washing the precipitate, and drying, the carbon nanotubes with defect structures are obtained;

[0039] After mixing the ethanol solution of 2-bromo-1-phenylethanone and the carbon nanotubes with defect structures uniformly, filtering, washing the precipitate, and drying, the modified carbon nanotubes are obtained.

[0040] In the above preparation method, the drying is preferably vacuum drying at 60-80 ℃ for 48-56 h.

[0041] The second embodiment of the present application provides a water treatment agent containing the modified carbon nanotube of the first embodiment and sodium hypochlorite; the dosing amount of the water treatment agent in water treatment is 0.02-0.05 g / L of the modified carbon nanotube and 10-15 mg / L of sodium hypochlorite based on the volume of the water to be treated.

[0042] The applicant finds that the concentration of sodium hypochlorite is too high in the water treatment process to inhibit the catalytic reaction, and therefore the dosing amount of sodium hypochlorite is preferably controlled to be 10-15 mg / L, and the amount of the modified carbon nanotube can be adjusted adaptively by those skilled in the art according to the desired treatment effect.

[0043] In the water treatment agent, the modified carbon nanotube acts as a catalyst to catalyze the chlorine activation to remove emerging pollutants in water, and the mechanism is based on a non-radical oxidation pathway, and high-efficiency pollutant degradation is achieved through interfacial binding interaction. When the modified carbon nanotube contacts with chlorine-containing compounds in an aqueous solution, the O-Cl bond in the chlorine molecule is broken, and a C-Cl bond is formed through interfacial binding interaction to produce a reactive metastable surface-bound complex CNTS-HOCl*. The formation of this surface complex significantly adjusts the charge distribution and electron density configuration of the carbon nanotube surface, thereby activating the chlorine molecule and enhancing its oxidation ability.

[0044] The third embodiment of the present application provides the application of the water treatment agent in removing emerging pollutants in water.

[0045] In the water treatment agent of the present application, the modified carbon nanotube acts as a catalyst to catalyze the chlorine activation, enhances the oxidation ability of chlorine, and achieves the removal of emerging pollutants. The advantage of this catalytic mechanism is that it can achieve high-efficiency degradation of various emerging pollutants such as diclofenac, bisphenol A, N,N-diethyl-m-toluamide, and 2,4-dichlorophenol without external energy input, and is almost not affected by the water matrix, showing excellent practical application potential. The whole process avoids the high energy consumption and potential risk problems of the traditional ultraviolet photolysis chlorine process, and provides an economical and environmentally friendly solution for the removal of emerging pollutants in water treatment.

[0046] The water treatment agent is added to the water to be treated, and the pH value of the system is 6.5-7.0. In order to make the reaction more uniform and fast, stirring can be carried out, and the specific parameters are not specially limited, and those skilled in the art can adjust them adaptively according to the needs. For example, the stirring speed is 600-1000 rpm, the reaction temperature is room temperature, and the reaction time is 10-60 min.

[0047] The preparation and application effect of the modified carbon nanotube and water treatment are described in detail below through multiple specific embodiments.

[0048] Example 1 Preparation of modified carbon nanotube

[0049] In deionized water, 2-3 g of carbon nanotubes were mixed with NaBH4, and stirred magnetically under Ar atmosphere for 4-6 h. The precipitate was washed to neutral and dried in vacuum at 60-70 °C for 48-56 h to obtain carbon nanotubes with defect structure.

[0050] In an ethanol solution of 2-bromo-1-phenylethanone, 1-3 g of carbon nanotubes with defect structure were added, and stirred for 24-48 h. The precipitate was washed and dried in vacuum at 60-80 °C for 48-56 h to obtain modified carbon nanotubes.

[0051] Example 2 Application effect of modified carbon nanotubes

[0052] The following groups of carbon nanotube materials were prepared:

[0053] Experimental group 1: CNTs-D 0.2 -BrPE, the preparation method referred to Example 1, the mass ratio of NaBH4 to carbon nanotubes was 0.2:1, and the mass ratio of 2-bromo-1-phenylethanone to carbon nanotubes was 2.0:1. The TEM image of the modified carbon nanotubes prepared in this experimental group is shown in Figure 1 .

[0054] Experimental group 2: CNTs-D 1.0 -BrPE, the preparation method referred to Example 1, the mass ratio of NaBH4 to carbon nanotubes was 1.0:1, and the mass ratio of 2-bromo-1-phenylethanone to carbon nanotubes was 2.0:1. The TEM image of the modified carbon nanotubes prepared in this experimental group is shown in Figure 2 .

[0055] Control group 1: Raw CNTs, an equal amount of carbon nanotubes without modification treatment;

[0056] Control group 2: CNTs-D 0.2 Compared with experimental group 1, the only difference was that only an equal amount of NaBH4 was used to modify the carbon nanotubes; the TEM image of the modified carbon nanotubes prepared in this control group is shown in Figure 3 .

[0057] Control group 3: CNTs-D 1.0 Compared with experimental group 2, the only difference was that only an equal amount of NaBH4 was used to modify the carbon nanotubes; the TEM image of the modified carbon nanotubes prepared in this control group is shown in Figure 4 .

[0058] Control group 4: CNTs-BrPE, compared with experimental group 1, the only difference was that only an equal amount of 2-bromo-1-phenylethanone was used to modify the carbon nanotubes; the TEM image of the modified carbon nanotubes prepared in this control group is shown in Figure 5 .

[0059] From Figures 1-5 It can be seen that the carbon nanotube materials of the experimental group and the control group both maintain typical one-dimensional fibrous network structure, the tube diameter is relatively uniform and interwound to form a three-dimensional network. In the control group sample, CNTs-D 0.2 and CNTs-D 1.0 show the effect of different concentrations of sodium borohydride treatment, in which CNTs-D 1.0 Due to higher concentration of reduction treatment, the surface presents a more rough morphology and more obvious structural defects. CNTS-BrPE sample exhibits the result of 2-bromo-1-phenylethanone modification alone, and the nanotubes maintain good tubular morphology and relatively smooth surface, indicating that BrPE mainly performs surface functionalization treatment.

[0060] The experimental group composite modified sample CNTs-D 0.2 -BrPE and CNT S -D 1.0 -BrPE exhibits the most complex surface morphology characteristics, and granular substances can be observed attached to the surface of the nanotubes, which may be aggregates of functional groups, and the surface modification degree of CNTS-D1.0-BrPE is more obvious. High magnification images further reveal the influence of different modification strategies on the surface morphology: sodium borohydride treatment mainly introduces surface structural defects, while BrPE treatment produces functional modification on the surface. Importantly, all modification processes well maintain the basic tubular structure of carbon nanotubes, ensuring their excellent electronic conductivity performance. This structural integrity combined with surface modification lays a good morphological foundation for subsequent catalytic applications.

[0061] The Raman spectra of each sample were detected using a Thermo Raman DXR3, Figure 6 The Raman spectra of the carbon nanotube materials prepared for the control group 1-3 are shown in the figure, which shows the structural changes of the carbon nanotubes after different degrees of sodium borohydride reduction treatment, directly verifying the design strategy of improving catalytic activity through defect engineering. As can be seen from the figure, the I D / I G ratio of the original carbon nanotubes RawCNTs is 0.909, after sodium borohydride reduction treatment, the I 0.2 / I D ratio of CNTs-D G increases to 0.975, and the I 1.0 / I D ratio of CNTs-D G further improves to 0.955. This I D / I GThe increased ratio indicates that sodium borohydride reduction treatment successfully introduced more structural defects into the carbon nanotube surface. These defect sites are the key active sites of the modified carbon nanotubes, capable of forming CNTs-D-HOCl complexes and accelerating electron transfer processes. Notably, CNTs-D... 1.0 I D / I G Ratio compared to CNTs-D 0.2 The slight decrease may be due to structural rearrangement or partial defect repair caused by excessive reduction. This result provides important guidance for optimizing the amount of sodium borohydride used, namely, that an appropriate amount of reduction treatment can obtain the optimal defect density, laying the foundation for subsequent synergistic treatment with acetophenone groups, and ultimately achieving selective deactivation of carboxyl groups and retention of carbonyl groups, thereby constructing a highly efficient chlorine-activated catalytic system.

[0062] The carbon nanotube materials prepared in the experimental and control groups were tested for their degradation effect on emerging pollutant (diclofenac DCF) in water by catalytic chlorination. The relative concentration ratio of diclofenac, C / C0, was used for characterization, where C is the concentration of diclofenac at time t, and C0 is the initial concentration of diclofenac before the reaction. C / C0 = 1 indicates no degradation, and C / C0 = 0 indicates complete degradation. The specific method is as follows:

[0063] At room temperature and an initial pH of approximately 6.5, the reaction was carried out in a 150 mL beaker with a reaction volume of 100 mL on a magnetic stirrer at 900 rpm. Taking a typical reaction as an example, DCF (5 µM) was added first, stirred thoroughly, and a sample was taken as the initial concentration before the reaction. Then, sodium hypochlorite (10 mg / L) and carbon nanotubes (0.02 g / L) were added, and timing was started. Sampling was performed at time gradients of 1, 2, 5, 10, 30, 45, and 60 min. Sampling procedure: 1.5 mL of sample was pipetted and filtered through a 0.22 µm polytetrafluoroethylene (PTFE) filter into a high-performance liquid chromatography (HPLC) vial pre-filled with 30 µL of 0.5 mM sodium thiosulfate as a terminator (for samples determining the initial concentration, sodium thiosulfate may not be added to the HPLC vial). The samples were filtered, and the concentration of diclofenac in the samples was detected by high-performance liquid chromatography (HPLC). The C / C0 value was obtained by dividing the detected concentration by the initial concentration. Each experiment was conducted twice as a parallel experiment, and the average value was taken as the experimental data. The results are shown in Table 1.

[0064] Table 1

[0065] .

[0066] Table 1 shows that the removal effects of various carbon nanotube materials on diclofenac (DCF) exhibit significant and regular differences. The effects of dual-modified carbon nanotubes (CNTs-D) are particularly evident. 0.2 -BrPE and CNTs-D 1.0 -BrPE) exhibits the best catalytic performance, among which CNTs-D 0.2 -BrPE showed the best performance, exhibiting the fastest removal rate from the start of the reaction. The C / C0 value dropped to 0.8480 at 1 minute, further to 0.7648 at 2 minutes, and completely removed DCF at 45 minutes. While CNTs-BrPE modified with bromoacetophenone alone had a faster reaction rate in the early stages, its overall removal performance was not as good as the dual-modified material. CNTs-D modified with defect engineering alone... 0.2 and CNTs-D 1.0 The modified carbon nanotubes exhibited moderate catalytic activity, showing better removal efficiency than unmodified raw CNTs, but significantly inferior to the dual-modified material. Unmodified raw CNTs showed the worst removal efficiency and the slowest reaction rate. Notably, regarding sodium borohydride dosage, a weight ratio of 0.2 (sodium borohydride to carbon nanotubes) showed better catalytic performance than a weight ratio of 1.0, indicating an optimal level of defect engineering. The mechanism underlying this phenomenon lies in the non-radical oxidation pathway employed in the chlorine activation catalysis of modified carbon nanotubes. When the material comes into contact with chlorine-containing compounds, chlorine molecules interact through interfacial bonding to form an active metastable surface complex, CNTS-HOCl*, which significantly modulates the surface charge distribution and electron density configuration. During catalysis, the retained carbonyl groups enhance the system's oxidation capacity by forming the CNTS-C=O-HOCl complex, while the carbon atom vacancy defects introduced by sodium borohydride reduction form the CNTS-D-HOCl complex, accelerating electron transfer. Meanwhile, 2-bromo-1-phenylethylone selectively masks the carboxyl groups while retaining beneficial carbonyl groups. However, excessive defect engineering can deplete effective catalytic active sites, leading to CNT-D 1.0 Performance is inferior to CNTs-D 0.2 Overall, the synergistic effect of defect engineering modification and bromoacetophenone modification significantly enhances the catalytic activity of carbon nanotubes by precisely controlling surface chemical properties and vacancy defect structures, providing an economical and environmentally friendly solution for the removal of emerging pollutants in water treatment.

[0067] The infrared spectrum, X-ray photoelectron spectrum (XPS) and Raman spectrum of the above original carbon nanotubes and reacted carbon nanotubes were determined, specifically including: ①Control group 1 original carbon nanotubes Raw CNTs; ②CNTs-Chlorine: Raw CNTs (0.02 g / L) were contacted with sodium hypochlorite (10 mg / L) under the above reaction conditions, but no DCF was added, and the sample was taken, filtered and dried after 60 min of reaction; ③CNTs-Chlorine-DCF: Raw CNTs (0.02 g / L), sodium hypochlorite (10 mg / L) and DCF (5 µM) were reacted together under the above reaction conditions for 60 min, and the obtained carbon nanotube sample was filtered and dried. The infrared spectrum of each sample was detected by an infrared spectrometer (FTIR) Thermo Fisher Nicolet Is5), and the results are shown in Figure 7 The XPS spectrum measurement parameters are as follows: Sommerfei K-ALPHA excitation source: Al ka (hv=1486.8 eV), beam spot: 400 um, analysis chamber vacuum degree: 2x10-9 mbar, working voltage: 15KV, filament current: 10mA, full spectrum scan: pass energy is 150ev, step 1eV, sub-spectrum scan: pass energy is 50ev, step 0.1eV, sub-spectrum at least 5 cycles of signal accumulation (different elements have different scanning times), binding energy calibration: taking C1s=284.8ev binding energy as the standard, and the results are shown in Figures 8-9 , Figure 8 Used CNTs-1 corresponds to the sample CNTs-Chlorine, and Used CNTs-2 corresponds to the sample CNTs-Chlorine-DCF, Figure 9 is the Cl 2p high-resolution XPS spectrum of the CNTs-Chlorine-DCF sample. The Raman spectrum of each sample was detected by Sommerfei Raman DXR3, and the results are shown in Figure 10 , 11 , Figure 10 Chlorine / CNTs corresponds to the sample CNTs-Chlorine, and Chlorine / CNTs / DCF corresponds to the sample CNTs-Chlorine-DCF. Figure 11 Chlorine / CNTs corresponds to the sample CNTs-Chlorine, and Chlorine is sodium hypochlorite itself.

[0068] From Figure 7 it can be seen that the original carbon nanotubes show a characteristic absorption peak of C-OH group at 3443 cm -1 , a C=O stretching vibration peak at 1655 cm -1 , and a C=C stretching vibration peak at 1583 cm -1at 1062 cm -1 at 1062 cm -1 A new absorption peak appeared at 802 cm -1 after chlorination, indicating the interaction between chlorine and the surface of pristine carbon nanotubes, suggesting the possible formation of CNTs-HOCl* surface complex. When DCF molecules were involved in the reaction, a new C=C peak appeared at 1617 cm -1 and the peak position characteristics changed at 802 cm Figure 8 XPS analysis further supported this observation. The XPS full spectrum showed that the UsedCNTs-2 sample detected a chlorine content of 0.15%, Figure 9 The Cl 2p high-resolution XPS spectrum identified the presence of C-Cl bonds, confirming the combination of chlorine atoms with pristine carbon nanotubes.

[0069] Figure 10 The structural evolution of pristine carbon nanotubes during the catalytic chlorine activation process was demonstrated by the change in the ratio of D peak and G peak intensity, reflecting the progress of the catalytic reaction. From Figure 10 It can be seen that the I D / I G of pristine carbon nanotubes was 0.909, which increased to 0.947 after the action of chlorine, and reached 0.994 after further catalytic DCF degradation reaction. This gradual increasing trend indicates that the surface defect density of carbon nanotubes is increasing continuously during the chlorine activation catalysis process.

[0070] From Figure 11 It can be seen that when the modified carbon nanotubes are in contact with chlorine-containing compounds in aqueous solution, the O-Cl bond in the chlorine molecule is broken, and a C-Cl bond is formed through interfacial bonding interaction, producing an active metastable surface-bound complex CNT-HOCl*.

[0071] These results support the mechanism of the catalytic chlorine activation of pristine carbon nanotubes through a non-radical oxidation pathway, in which oxygen-containing functional groups may act as active sites to participate in the activation process of chlorine, achieving the degradation of emerging pollutants such as DCF.

[0072] Example 3 Water treatment and application effect

[0073] The following groups of different water treatment agents were prepared:

[0074] Experimental group 1: sodium hypochlorite (10 mg / L) and modified carbon nanotubes CNTs-D in experimental group 1 of Example 2 0.2-BrPE (0.02 g / L); this group of samples is named as chlorine / CNTs;

[0075] Control group 1: only sodium hypochlorite (10 mg / L), without carbon nanotubes; this group of samples is named as chlorine oxidaion;

[0076] Control group 2: only modified carbon nanotubes CNTs-D of experimental group 1 in Example 2 0.2 -BrPE (0.02 g / L), without sodium hypochlorite; this group of samples is named as CNTs adsorption.

[0077] The water treatment was carried out using the above water treatment agents, and the specific method was as follows: first, DCF (5 µM) was added, and after stirring, the sample was taken as the initial concentration before reaction, then the corresponding water treatment agent was added and the timing was started, and the sampling operation was carried out according to the time gradient of 1, 2, 5, 10, 30, 45, 60 min. Sampling operation: 1.5 mL of sample was sucked and filtered into a high-performance liquid chromatography bottle (for samples for determining the initial concentration, 30 µL of 0.5 mM sodium thiosulfate can not be added in the liquid chromatography bottle) in advance with a 0.22 µm polytetrafluoroethylene (PTFE) filter head as a terminator. The sample filtering treatment was carried out, and the concentration of diclofenac in the sample was detected by high-performance liquid chromatography (HPLC), and the detected concentration was divided by the initial concentration to obtain the C / C0 value. Each group of experiments was carried out twice as parallel experiments and the average value was taken as the experimental data, and the experimental results are shown in Table 2.

[0078] Table 2

[0079] .

[0080] As can be seen from Table 2, the water treatment system of sodium hypochlorite / modified carbon nanotubes has a significant synergistic catalytic effect, and its removal effect is much higher than the simple addition of sodium hypochlorite oxidation and modified carbon nanotube adsorption alone, which verifies that the modified carbon nanotubes can effectively catalyze the activation of chlorine and realize the efficient degradation of emerging pollutants.

[0081] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. Modified carbon nanotubes, characterized in that, The carbon nanotube framework is rich in carbon atom vacancy defects. Its surface carboxyl groups are selectively deactivated by acetophenone groups, and its surface contains carbonyl groups.

2. The modified carbon nanotube as described in claim 1, characterized in that, The carbon atom vacancy defects were introduced by sodium borohydride reduction treatment.

3. The modified carbon nanotube as described in claim 2, characterized in that, The weight ratio of carbon nanotubes to sodium borohydride is 1:(0.2~1.0).

4. The modified carbon nanotube as described in claim 1, characterized in that, The acetophenone group is introduced by treatment with 2-bromo-1-phenylacetophenone.

5. The modified carbon nanotube as described in claim 4, characterized in that, The mass ratio of carbon nanotubes to 2-bromo-1-phenylethyl ketone is 1:(1.5~2.5).

6. A water treatment agent, characterized in that, Contains modified carbon nanotubes as described in any one of claims 1-5 and sodium hypochlorite; the dosage of the water treatment agent during water treatment is, based on the volume of water to be treated, 0.02~0.05 g / L of modified carbon nanotubes and 10~15 mg / L of sodium hypochlorite.

7. The application of the water treatment agent as described in claim 6 in the removal of emerging pollutants in water, characterized in that, The emerging pollutants include any one of diclofenac, bisphenol A, N,N-diethyl-m-toluamide, and 2,4-dichlorophenol.

8. The application as described in claim 7, characterized in that, The pH value of the system during application is 6.5~7.0.

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