CN102649044A - Non-oxidative magnetic multi-wall carbon nanotube and preparation method as well as application thereof - Google Patents

Abstract

The invention discloses a non-oxidized magnetic multi-walled carbon nanotube and its preparation method and application. The adsorbent uses non-oxidized multi-walled carbon nanotubes cross-linked with each other as a matrix, and magnetic iron oxide particles are loaded on the matrix; The steps of the preparation method include: under the protection of an inert gas, adding non-oxidized multi-walled carbon nanotubes into a mixed solution of ferric ammonium sulfate and ferrous ammonium sulfate, followed by ultrasonic dispersion, adding ammonia water dropwise while ultrasonic dispersion, and then Adjust the pH value of the suspension, fully stir at a certain temperature, cool the mixture, separate the precipitate, wash and dry it; the steps for this application are: add the above-mentioned adsorption to the atrazine and/or copper ion solution After the oscillating adsorption reaction is carried out at room temperature, the adsorbent can be separated with a magnet. The invention has the advantages of simple operation, wide application range, stable magnetic properties of the adsorbent, easy separation, high adsorption capacity, short equilibration time, reusability and the like.

Description

Non-oxidized magnetic multi-walled carbon nanotubes, preparation method and application thereof

technical field

The invention relates to the application of carbon nanotube materials and the fields of sewage treatment, in particular to a magnetic multi-walled carbon nanotube, its preparation method and its application in treating pollutants.

Background technique

Atrazine is a triazine pesticide with a relatively stable structure. Its mineralization process by microorganisms is very slow, and its half-retention period in soil is as long as 4 to 57 weeks. Since atrazine was registered, it has been widely used in countries all over the world. While the use of atrazine has brought benefits to agriculture, it has also had a certain impact on the environment. Currently, atrazine has been detected in surface water, groundwater, rivers, lakes, fruits and vegetables in many countries. Studies have shown that long-term exposure to atrazine-contaminated environments can affect the human immune system, lymphatic system, reproductive system, and endocrine system, and may even induce deformed mutations. The national first-level drinking water regulations formulated by the United States list atrazine as a pollutant that endangers public health, and limit the standard of atrazine to 3ppb for first-level drinking water. The European Community has banned the use of atrazine. The limit of atrazine in drinking water is 0.1ppb, and the specific standard value of atrazine in surface water I and II waters formulated by my country is 3ppb.

Heavy metal copper is a widely distributed element in nature, and it is also one of the elements commonly used in industry. Copper is an essential trace element for the human body, and copper-containing enzymes exhibit a variety of biochemical functions in the metabolic process. Because copper has important physiological functions, the level of copper in the body will inevitably affect the health status, too much or too little will lead to pathological changes in the human body. Due to the rapid development of modern industry, especially the development of electroplating, mining, mechanical processing and pesticide industry, a large amount of copper ions are discharged into the water body, resulting in serious pollution of the natural water environment. Copper in the environment enters the ecosystem through the food chain, and the harmful copper ions are not easy to dissolve and move, which can easily cause accumulation in organisms, resulting in serious biological toxicity and great harm to human health.

As a new type of material, carbon nanotubes have good adsorption properties due to their huge specific surface area and unique hollow tubular structure, and can adsorb various molecules and ions whose sizes are suitable for their inner diameters. Carbon nanotubes can be divided into single-wall carbon nanotubes and multi-wall carbon nanotubes according to the number of graphite layers in the photo layer. At present, there are more and more reports on the application of carbon nanotubes (especially multi-walled carbon nanotubes) in water environment treatment and restoration at home and abroad. A large number of studies have shown that multi-walled carbon nanotubes can effectively adsorb and remove organic substances in water. Pollutants and heavy metal ions have great application prospects. However, carbon nanotubes are not easy to separate in water, which limits their practical application. As an efficient, fast and economical separation technology, magnetic separation technology has been widely used in the fields of textile, biology and environmental protection. It is applied to the field of adsorbent, which can separate the adsorbent from water in a short time. It does not need to consume a lot of energy and will not produce secondary pollution.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, provide a non-oxidized magnetic multi-walled carbon nanotube with large specific surface area, high saturation magnetization, which can be used to adsorb and treat pollutants, and also provide an easy-to-operate A method for preparing non-oxidized magnetic multi-walled carbon nanotubes.

Another object of the present invention is to provide an application of non-oxidized magnetic multi-walled carbon nanotubes with simple operation, wide application range, good removal effect and environmental friendliness in pollutant treatment and removal.

In order to solve the above-mentioned technical problems, the technical solution proposed by the present invention is a non-oxidized magnetic multi-walled carbon nanotube, wherein the non-oxidized magnetic multi-walled carbon nanotube is based on mutually cross-linked non-oxidized multi-walled carbon nanotubes, The substrate is loaded with magnetic iron oxide particles, the specific surface area of the non-oxidized magnetic multi-walled carbon nanotubes is 130m ² /g-160m ² /g, and the saturation magnetization of the non-oxidized magnetic multi-walled carbon nanotubes is 8emu/ g ~ 12emu/g.

As a general technical concept, the present invention simultaneously provides a method for preparing the above-mentioned non-oxidized magnetic multi-walled carbon nanotubes, comprising the following steps:

(1) Under the protection of an inert gas (such as nitrogen), add non-oxidized multi-walled carbon nanotubes to the mixed solution of ferric ammonium sulfate and ferrous ammonium sulfate to obtain non-oxidized multi-walled carbon nanotubes with a concentration of 4g/L～6g/L carbon nanotube suspension;

(2) Ultrasonic disperse the non-oxidized multi-walled carbon nanotube suspension obtained after step (1), add ammonia water drop by drop while ultrasonically dispersing, adjust the pH value of the suspension to 10-12, and keep the temperature at 40°C ~60°C, then fully stir to obtain a mixture;

(3) Cool the mixed solution obtained in step (2), magnetically separate the precipitate, wash with ultrapure water and absolute ethanol, and dry in vacuum to obtain non-oxidized magnetic multi-walled carbon nanotubes.

In the above-mentioned preparation method of non-oxidized magnetic multi-walled carbon nanotubes, the ferric ammonium sulfate and ferrous ammonium sulfate mixed solution in the step (1) are preferably mainly composed of (NH ₄ ) with a molar ratio of 1:(1.5～2). It is prepared by mixing and dissolving ₂ Fe(SO ₄ ) ₂ ·6H ₂ O and NH ₄ Fe(SO ₄ ) ₂ ·12H ₂ O in water.

In the above-mentioned preparation method of non-oxidized magnetic multi-walled carbon nanotubes, in the step (2), the volume fraction of the ammonia water is preferably 30% to 35%, and the amount of the ammonia water is preferably the amount of the non-oxidized multi-walled carbon nanotubes 1/15 to 1/20 of the volume of the tube suspension.

In the above-mentioned preparation method of non-oxidized magnetic multi-walled carbon nanotubes, in the step (2), the time of the ultrasonic dispersion is preferably controlled at 10min to 15min; the full stirring preferably refers to stirring at a speed of 200rpm to 300rpm for 30min ~60min.

As a general technical conception, the present invention also provides a method for removing pollutants with the above-mentioned non-oxidized magnetic multi-walled carbon nanotubes, the pollutants refer to atrazine and/or copper ions, Add the non-oxidized magnetic multi-walled carbon nanotubes into the wastewater, the amount of the non-oxidized magnetic multi-walled carbon nanotubes added is 0.2g/L-0.5g/L, and then adjust the pH value of the wastewater to 5.0-6.0, after ultrasonic After the treatment, an oscillating adsorption reaction is carried out at normal temperature, and finally the non-oxidized magnetic multi-walled carbon nanotubes are separated and recovered by a magnet to complete the removal of pollutants.

In the above method for removing pollutants, the time of the ultrasonic treatment is preferably 1 min to 2 min. The reaction temperature of the oscillation adsorption reaction is preferably controlled at 25°C-30°C, the reaction speed is preferably controlled at 150rpm-160rpm, and the reaction time is preferably 7h-12h.

In the above method for removing pollutants, in the pollutant-containing wastewater, the concentration of atrazine is preferably controlled at 1 mg/L to 20 mg/L, and the concentration of copper ions is controlled at 10 mg/L to 100 mg/L. L.

In the application of the above pollutant removal in the present invention, the maximum adsorption capacities of the non-oxidized magnetic multi-walled carbon nanotubes to atrazine and copper ions are respectively 40.16 mg/g and 38.91 mg/g, which can be realized in 10 minutes Adsorption is roughly balanced. Preferably, the non-oxidized magnetic multi-walled carbon nanotubes recovered by the magnet separation can be reused after being washed and desorbed with an acidic ethanol solution.

Compared with the prior art, the present invention has the advantages of:

1. The specific surface area and pore structure of the non-oxidized magnetic multi-walled carbon nanotubes provided by the present invention are conducive to the mass transfer and adsorption of pollutants. The method for preparing the non-oxidized magnetic multi-walled carbon nanotubes is simple, easy to operate, and The obtained non-oxidized magnetic multi-walled carbon nanotubes have stable properties.

2. The method of using non-oxidized magnetic multi-walled carbon nanotubes in the present invention to remove atrazine and copper ion pollutants in water has simple operation, wide application range, and environmental friendliness. Non-oxidized magnetic multi-walled carbon nanotubes are used as adsorbent magnetic Stable, easy to separate, high adsorption capacity, short equilibration time, reusable. Under the conditions of optimal pH value of 6.0, temperature of 25°C, rotation speed of 150rpm, concentration of non-oxidized magnetic multi-walled carbon nanotubes of 0.2g/L, and initial concentrations of atrazine and copper ions of 20mg/L and 100mg/L respectively , the maximum adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes for atrazine and copper ions after ultrasonic treatment can reach 40.16 mg/g and 38.91 mg/g respectively, and the adsorption can be roughly balanced in 10 minutes.

3. The present invention utilizes non-oxidized magnetic multi-walled carbon nanotubes after ultrasonic treatment to remove atrazine and copper ion pollutants in water. The specific surface area and pore structure of multi-walled carbon nanotubes are conducive to the mass transfer and adsorption of pollutants. Therefore, heavy metals and organic complex pollutants in water can be efficiently removed; meanwhile, the adsorbent in the method provided by the invention has the characteristics of easy magnetic separation, simple operation, low operating cost, no energy consumption, and no secondary pollution.

Description of drawings

Fig. 1 is a scanning electron microscope image of non-oxidized magnetic multi-walled carbon nanotubes prepared in Example 1 of the present invention.

Fig. 2 is a graph of magnetization curves of non-oxidized magnetic multi-walled carbon nanotubes prepared in Example 1 of the present invention.

Fig. 3 is an X-ray photoelectron spectroscopy analysis chart of non-oxidized magnetic multi-walled carbon nanotubes prepared in Example 1 of the present invention.

Fig. 4 is a comparison diagram of non-oxidized magnetic multi-walled carbon nanotubes in Example 2 of the present invention after ultrasonic treatment and without ultrasonic treatment.

Fig. 5 is a diagram of desorption and reuse of non-oxidized magnetic multi-walled carbon nanotubes in Example 2 of the present invention.

Fig. 6 is a graph showing the adsorption capacities of non-oxidized magnetic multi-walled carbon nanotubes for different concentrations of atrazine in Example 3 of the present invention.

Fig. 7 is an X-ray photoelectron spectroscopy analysis diagram of non-oxidized magnetic multi-walled carbon nanotubes adsorbed atrazine in Example 3 of the present invention.

Fig. 8 is a graph showing the adsorption capacities of non-oxidized magnetic multi-walled carbon nanotubes with different concentrations of Cu ²⁺ in Example 4 of the present invention.

FIG. 9 is an X-ray photoelectron spectroscopy analysis diagram of non-oxidized magnetic multi-walled carbon nanotubes adsorbing Cu ²⁺ in Example 4 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Example 1

A non-oxidized magnetic multi-walled carbon nanotube as shown in Figure 1, the non-oxidized magnetic multi-walled carbon nanotube is based on non-oxidized multi-walled carbon nanotubes cross-linked with each other, and the matrix is loaded with magnetic iron oxide particles , the specific surface area of the non-oxidized magnetic multi-walled carbon nanotubes in this embodiment is 138.66m ² /g, and the saturation magnetization is 8.06emu/g.

The preparation method of the non-oxidized magnetic multi-walled carbon nanotubes of the present embodiment comprises the following steps:

(1) Under the protection of nitrogen, the non-oxidized multi-walled carbon nanotubes are added to the mixed solution of ferric ammonium sulfate and ferrous ammonium sulfate to obtain a suspension of non-oxidized multi-walled carbon nanotubes with a concentration of 5g/L, ferric ammonium sulfate The mixed solution with ferrous ammonium sulfate is mainly obtained by mixing and dissolving (NH ₄ ) ₂ Fe(SO ₄ ) ₂ ·6H ₂ O and NH ₄ Fe(SO ₄ ) ₂ ·12H ₂ O in water with a molar ratio of 1:2 ;

(2) The non-oxidized multi-walled carbon nanotube suspension obtained after the step (1) is subjected to ultrasonic dispersion for 10min to 15min, and while the ultrasonic dispersion is dispersed, it is added dropwise the ammoniacal liquor with a volume fraction of 32%. The volume ratio of the walled carbon nanotube suspension is 1:20, the pH value of the suspension is adjusted to 11, the temperature is kept at 40°C to 60°C, and then stirred at a speed of 250rpm for 45min, fully stirred to obtain a mixed solution;

(3) Cool the mixed solution obtained in step (2), magnetically separate the precipitate, wash with ultrapure water and absolute ethanol, and dry in vacuum to obtain non-oxidized magnetic multi-walled carbon nanotubes.

The non-oxidized magnetic multi-walled carbon nanotubes prepared above were observed under a scanning electron microscope with a power of 70,000, and the scanning electron microscope picture shown in FIG. 1 was obtained. As can be seen from Figure 1, the diameter of the multi-walled carbon nanotubes is about 36nm, and there are many iron oxide particles loaded on the cross-linked tubular shape; the non-oxidized magnetic multi-walled carbon nanotubes prepared above were subjected to _N2 adsorption-desorption experiments , carried out on the ASAP2020M+C automatic specific surface area analyzer, using the BET method to calculate the specific surface area of non-oxidized magnetic multi-walled carbon nanotubes, and obtained that the specific surface area of non-oxidized magnetic multi-walled carbon nanotubes is 138.66m ² /g; The above-mentioned non-oxidized magnetic multi-walled carbon nanotubes are tested for saturation magnetization, and the magnetization curve is as shown in Figure 2. It can be seen that its saturation magnetization value is 8.06emu/g, which shows that the adsorbent has stronger magnetism and can be It is easily separated from the solution by a magnet; the above-mentioned non-oxidized magnetic multi-walled carbon nanotubes are analyzed by X-ray photoelectron spectroscopy, and the results are shown in Figure 3. From Figure 3, it can be known that the non-oxidized magnetic multi-walled carbon nanotubes The surface of carbon nanotubes contains iron, carbon, and oxygen elements, but does not contain nitrogen and copper elements.

Example 2:

A method for removing pollutants with the non-oxidized magnetic multi-walled carbon nanotubes obtained in Example 1, comprising the following steps:

10mg of non-oxidized magnetic multi-walled carbon nanotubes prepared in Example 1 were added to two groups of 50mL atrazine solution or Cu ²⁺ solution respectively, and the initial concentration of atrazine in the atrazine solution was 5mg/ L, the initial concentration of Cu ²⁺ in the Cu ²⁺ solution was 30 mg/L, and the pH value of each group of mixed solutions was adjusted to 6.0. Among the two groups of solutions for each pollutant, one group was not subjected to ultrasonic treatment, and the other group was subjected to ultrasonic treatment. Ultrasonic treatment for 1 min, and then the four groups of solutions were placed in a water bath constant temperature oscillator at a temperature of 25 ° C and a rotation speed of 150 rpm to carry out the adsorption reaction for 24 h, and then the adsorbent was separated from the solution with a magnet, and high performance liquid chromatography and The residual atrazine and Cu ²⁺ concentrations in the solution were determined by flame atomic absorption spectrophotometry, and the results are shown in Table 1. It can be seen from Table 1 that ultrasonic treatment is beneficial to the adsorption of atrazine and Cu ²⁺ on non-oxidized magnetic multi-walled carbon nanotubes.

Table 1: Effect of ultrasonic treatment on the adsorption of atrazine and Cu ²⁺ on non-oxidized magnetic multi-walled carbon nanotubes

Fig. 4 is the non-oxidized magnetic multi-walled carbon nanotubes prepared in Example 1 through the comparison diagram of ultrasonic treatment and without ultrasonic treatment, as can be seen from Fig. 4, after ultrasonic treatment, non-oxidized magnetic multi-walled carbon nanotubes The fine particles of the non-oxidized magnetic multi-walled carbon nanotubes exfoliate and fragment evenly in the solution, thereby increasing the adsorption sites and area of the non-oxidized magnetic multi-walled carbon nanotubes, while the fine particles of the non-oxidized magnetic multi-walled carbon nanotubes without ultrasonic treatment It is mainly deposited at the bottom of the Erlenmeyer flask.

After the non-oxidized magnetic multi-walled carbon nanotubes were reacted with atrazine and Cu ²⁺ solutions respectively, the separated non-oxidized magnetic multi-walled carbons were washed with 20% acidic ethanol solution (pH value 3.0) respectively. Nanotubes, desorbed non-oxidized magnetic multi-walled carbon nanotubes were reacted with atrazine or Cu ²⁺ solution again under the same conditions to test the reusability of non-oxidized magnetic multi-walled carbon nanotubes, the results are shown in Figure 5 It can be seen from the figure that with the increase of repeated use times, although the adsorption effect of non-oxidized magnetic multi-walled carbon nanotubes on atrazine and Cu ²⁺ has decreased, it still has a greater effect after 4 repeated uses. The adsorption capacity, especially for Cu ²⁺ , its adsorption capacity decreases very little. This indicates that the non-oxidized magnetic multi-walled carbon nanotubes have certain operational stability and can be reused.

Example 3: Using non-oxidized magnetic multi-walled carbon nanotubes to remove atrazine from water.

A method for removing atrazine in water bodies with different pH values by utilizing the non-oxidized magnetic multi-walled carbon nanotubes obtained in Example 1, comprising the following steps:

10 mg of non-oxidized magnetic multi-walled carbon nanotubes prepared in Example 1 were added to 7 groups of 50 mL atrazine solutions, the initial concentration of atrazine was 5 mg/L, and the pH value of each group of mixed solutions was adjusted respectively 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 and 9.0, after ultrasonic treatment for 1min, place in a water bath constant temperature oscillator at a constant temperature of 25°C, shake at a speed of 150rpm for adsorption reaction for 24h, and then use a magnet to separate the adsorbent from the solution Come out, and measure the residual atrazine concentration in the solution with high performance liquid chromatography, the results are shown in Table 2. It can be seen from Table 2 that when the pH is 3.0-6.0, as the pH value increases, the adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes for atrazine is increasing; when the pH is 6.0-9.0, With the increase of pH value, the adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes for atrazine remained basically unchanged.

Table 2: Adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes for atrazine at different pH values

pH value 3.0 4.0 5.0 6.0 7.0 8.0 9.0 Adsorption capacity (mg/g) 15.78 17.84 18.05 18.80 18.74 18.82 18.61

A method utilizing the non-oxidized magnetic multi-walled carbon nanotubes prepared in Example 1 to remove atrazine in water under different adsorption times, comprising the following steps:

Take 10 mg of non-oxidized magnetic multi-walled carbon nanotubes and add them to several assembled 50 mL atrazine solutions (initial concentration is 5 mg/L, pH value is 6.0), sonicate for 1 min and shake at 25 °C at a speed of 150 rpm From 0 min to 720 min, the residual atrazine concentration in the solution was measured after magnetic separation, and the results are shown in Table 3. It can be seen from Table 3 that the adsorption effect is very obvious within 10 minutes, and the adsorption rate is rapid. The adsorption capacity fluctuates slightly after 10 minutes, and the adsorption equilibrium is basically achieved after 420 minutes. Therefore, the preferred oscillation adsorption time determined in the above technical solution is 7h-12h, and the optimum adsorption time is 7h.

Table 3: Adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes for atrazine at different adsorption times

A method utilizing the non-oxidized magnetic multi-walled carbon nanotubes obtained in Example 1 to remove the atrazine of different initial concentrations in water, comprising the following steps:

10 mg of non-oxidized magnetic multi-walled carbon nanotubes prepared in Example 1 were added to 6 groups of 50 mL atrazine solutions, and the initial concentrations of atrazine were 1 mg/L, 3 mg/L, 5 mg/L, and 10 mg /L, 15mg/L, 20mg/L, adjust the pH value of each group of mixed solution to 6.0, after ultrasonic treatment for 1min, place it in a constant temperature oscillator in a water bath at a constant temperature of 25°C, shake at a speed of 150rpm for adsorption reaction for 12h, and measure after magnetic separation The concentration of residual atrazine in the solution was used to calculate the adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes to atrazine at different concentrations of atrazine, and the results are shown in Figure 6. It can be seen from Figure 6 that with the increase of the initial concentration of atrazine, the adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes for atrazine gradually increases, and the maximum adsorption capacity is 40.16 mg/g. Among them, the non-oxidized magnetic multi-walled carbon nanotubes after absorbing atrazine at an initial concentration of 5 mg/L were analyzed by X-ray photoelectron spectroscopy, and Figure 7 was obtained. It can be seen from Figure 7 that the non-oxidized magnetic multi-walled carbon nanotubes Nitrogen element was newly added on the surface of the tube, and nitrogen element is one of the main elements of atrazine, which indicated that atrazine was indeed adsorbed on the surface of non-oxidized magnetic multi-walled carbon nanotubes.

Example 4:

A kind of non-oxidized magnetic multi-walled carbon nanotubes that utilize embodiment 1 to remove Cu in ^the water body of different pH values The method comprises the following steps:

10mg of non-oxidized magnetic multi-walled carbon nanotubes prepared in Example 1 were added to 5 groups of 50mL Cu ²⁺ solutions respectively, the initial concentration of Cu ²⁺ was 30mg/L, and the pH value of each group of mixed solutions was adjusted to 3.0～ 6.0, after ultrasonic treatment for 1min, put it in a constant temperature oscillator in a water bath at a constant temperature of 25°C, and oscillate at a speed of 150rpm for adsorption reaction for 24h, then use a magnet to separate the adsorbent from the solution, and use flame atomic absorption spectrophotometry to measure the residual The Cu ²⁺ concentration, the results are shown in Table 4. It can be seen from Table 4 that as the pH value increases, the adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes to Cu ²⁺ increases, and the maximum adsorption capacity is reached when the pH value is 6.0.

Table 4: Cu ²⁺ adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes at different pH values

pH value 2.0 3.0 4.0 5.0 6.0 Adsorption capacity (mg/g) 4.8 11.6 14.2 15.6 19.1

A kind of non-oxidized magnetic multi-walled carbon nanotube that utilizes embodiment 1 to make is ^removed the method for Cu in water body under different adsorption time, comprises the following steps:

Take 10 mg of non-oxidized magnetic multi-walled carbon nanotubes and add them to several solutions assembled with 50 mL of Cu ²⁺ (initial concentration is 30 mg/L, pH value is 6.0). After 720 min, the residual Cu ²⁺ concentration in the solution was measured after magnetic separation, and the results are shown in Table 5. It can be seen from Table 5 that with the passage of time, the adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes to Cu ²⁺ also increases correspondingly, and the adsorption equilibrium is achieved in 2 h. Therefore, the optimal adsorption time is 2h.

Table 5: Cu ²⁺ adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes at different times

A kind of non-oxidized magnetic multi-walled carbon nanotube that utilizes embodiment 1 to remove ^the Cu of different initial concentration in water body The method comprises the following steps:

10 mg of non-oxidized magnetic multi-walled carbon nanotubes prepared in Example 1 were added to 6 groups of 50 mL Cu ²⁺ solutions respectively, and the initial concentrations of Cu ²⁺ were 10 mg/L, 20 mg/L, 30 mg/L, 50 mg/L, 75mg/L, 100mg/L, adjust the pH value of each mixed solution to 6.0, place it in a water bath constant temperature oscillator at a constant temperature of 25°C after ultrasonic treatment for 1min, and oscillate at a speed of 150rpm for adsorption reaction for 12h, and measure the residual in the solution after magnetic separation The Cu ²⁺ concentration was calculated, and the adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes to Cu ²⁺ was calculated at different Cu ²⁺ concentrations, and the results are shown in Figure 8. It can be seen from the figure that with the increase of the initial concentration of Cu ²⁺ , the adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes to Cu ²⁺ gradually increases, and the maximum adsorption capacity is 38.91 mg/g. Among them, the non-oxidized magnetic multi-walled carbon nanotubes after adsorbing Cu ²⁺ under the initial concentration of 30mg/L were analyzed by X-ray photoelectron spectroscopy, and Figure 9 was obtained. It can be seen from Figure 9 that the non-oxidized magnetic multi-walled carbon nanotubes Copper elements were added to the surface, indicating that Cu ²⁺ was indeed adsorbed on the surface of non-oxidized magnetic multi-walled carbon nanotubes.

Example 5:

A kind of non-oxidized magnetic multi-walled carbon nanotube that utilizes embodiment 1 to make simultaneously removes the method for atrazine and ^Cu in water, can divide following two kinds of implementation modes to carry out:

(1) 10 mg of non-oxidized magnetic multi-walled carbon nanotubes prepared in Example 1 were added to 4 groups of 50 mL solutions respectively, the initial concentration of atrazine was 5 mg/L, and the initial concentration of Cu ²⁺ was 0 mg/L respectively , 10mg/L, 30mg/L, 50mg/L, adjust the pH value of each group of mixed solution to 6.0 respectively, after ultrasonic treatment for 1min, place it in a constant temperature oscillator in a water bath at a constant temperature of 25°C, oscillate at a speed of 150rpm for adsorption reaction for 12h, magnetic After separation, the concentration of residual atrazine in the solution was measured, and the adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes for atrazine at different initial concentrations of Cu ²⁺ was calculated, and the results are shown in Table 6. It can be seen from Table 6 that with the increase of the initial concentration of Cu ²⁺ , the adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes for atrazine gradually decreases, indicating that the presence of Cu ²⁺ inhibits the adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes. The adsorption of atrazine, and the greater the Cu ²⁺ concentration, the stronger the inhibition.

Table 6: Adsorption capacities of non-oxidized magnetic multi-walled carbon nanotubes for atrazine at different initial concentrations of Cu ²⁺

Cu ²⁺ initial concentration (mg/L) 0 10 30 50 Adsorption capacity (mg/g) 18.80 18.17 17.37 17.08

(2) 10mg of non-oxidized magnetic multi-walled carbon nanotubes prepared in Example 1 were added to 5 groups of 50mL solutions respectively, the initial concentration of Cu ²⁺ was 30mg/L, and the initial concentration of atrazine was 0mg/L respectively , 3mg/L, 6mg/L, 10mg/L, 14mg/L, adjust the pH value of each group of mixed solution to 6.0 respectively, after ultrasonic treatment for 1min, place it in a constant temperature oscillator in a water bath at a constant temperature of 25°C, and oscillate at a speed of 150rpm for adsorption After reacting for 12 hours, the residual Cu ²⁺ concentration in the solution was measured after magnetic separation, and the adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes to Cu ²⁺ was calculated at different initial concentrations of atrazine. The results are shown in Table 7. It can be seen from Table 7 that with the increase of the initial concentration of atrazine, the adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes to Cu ²⁺ changes little, indicating that the presence of atrazine has a significant effect on the adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes. Tube adsorption of Cu ²⁺ has little effect.

Table 7: Cu ²⁺ adsorption capacity of non-oxidized magnetic multi-walled carbon nanotubes at different initial concentrations of atrazine

Initial concentration of atrazine (mg/L) 0 3 6 10 14 Adsorption capacity (mg/g) 19.0 18.9 18.8 18.8 18.7

Claims (10)

1. A non-oxidized magnetic multi-walled carbon nanotube, characterized in that: the non-oxidized magnetic multi-walled carbon nanotube is based on the cross-linked non-oxidized multi-walled carbon nanotube, and the matrix is loaded with magnetic iron oxide Particles, the specific surface area of the non-oxidized magnetic multi-walled carbon nanotubes is 130m ² /g-160m ² /g, and the saturation magnetization of the non-oxidized magnetic multi-walled carbon nanotubes is 8emu/g-12emu/g. 2. a preparation method of non-oxidized magnetic multi-walled carbon nanotubes as claimed in claim 1, comprising the following steps: (1) Under the protection of an inert gas, add non-oxidized multi-walled carbon nanotubes to the mixed solution of ferric ammonium sulfate and ferrous ammonium sulfate to obtain a suspension of non-oxidized multi-walled carbon nanotubes with a concentration of 4g/L-6g/L liquid; (2) Ultrasonic disperse the non-oxidized multi-walled carbon nanotube suspension obtained after step (1), add ammonia water drop by drop while ultrasonically dispersing, adjust the pH value of the suspension to 10-12, and keep the temperature at 40°C ~60°C, then fully stir to obtain a mixture; (3) Cool the mixed solution obtained in step (2), magnetically separate the precipitate, wash with ultrapure water and absolute ethanol, and dry in vacuum to obtain non-oxidized magnetic multi-walled carbon nanotubes. 3. preparation method according to claim 2, is characterized in that: ferric ammonium sulfate and ferrous ammonium sulfate mixed solution in the described step (1) are mainly composed of (NH ₄ ) ₂ Fe(SO ₄ ) ₂ ·6H ₂ O and NH ₄ Fe(SO ₄ ) ₂ ·12H ₂ O are mixed and dissolved in water. 4. The preparation method according to claim 2 or 3, characterized in that: in the step (2), the volume fraction of the ammonia water is 30% to 35%, and the amount of the ammonia water is the amount of the non-oxidized multi-walled 1/15-1/20 of the volume of the carbon nanotube suspension. 5. The preparation method according to claim 2 or 3, characterized in that: in the step (2), the time of the ultrasonic dispersion is controlled at 10min～15min; Stir for 30min to 60min. 6. a method for removing pollutants with non-oxidized magnetic multi-walled carbon nanotubes according to claim 1, characterized in that: said pollutants refer to atrazine and/or copper ions, in the waste water containing pollutants Add the non-oxidized magnetic multi-walled carbon nanotubes in the water, the amount of the non-oxidized magnetic multi-walled carbon nanotubes is 0.2g/L～0.5g/L, then adjust the pH value of the waste water, and start to cool at room temperature after ultrasonic treatment The vibration adsorption reaction is carried out, and finally the non-oxidized magnetic multi-walled carbon nanotubes are separated and recovered by a magnet to complete the removal of pollutants. 7. The method according to claim 6, characterized in that: the time of the ultrasonic treatment is 1 min-2 min; the pH value of the wastewater is 5.0-6.0. 8. The method according to claim 6 or 7, characterized in that: in the waste water containing pollutants, the concentration of atrazine is controlled at 1 mg/L to 20 mg/L, and the concentration of copper ions Control at 10mg/L～100mg/L. 9. The method according to claim 6 or 7, characterized in that: the non-oxidized magnetic multi-walled carbon nanotubes recovered by the magnet separation can be reused after being washed and desorbed with an acidic ethanol solution. 10. The method according to claim 6 or 7, characterized in that: the reaction temperature of the oscillation adsorption reaction is controlled at 25°C-30°C, the reaction speed is controlled at 150rpm-160rpm, and the reaction time is 7h-12h.

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