Multi-walled carbon nanotube functionalized sludge biochar as well as preparation method and application thereof

Abstract

The invention discloses multi-walled carbon nanotube functionalized sludge biochar as well as a preparation method and application thereof. The method comprises the following steps: firstly, mixing sludge biochar prepared by anaerobic pyrolysis with a multi-walled carbon nanotube, and carrying out ball milling treatment, so as to prepare the sludge biochar functionalized by the multi-walled carbon nanotube; the multi-walled carbon nanotube functionalized sludge biochar prepared by the invention can efficiently activate peroxymonosulfate to degrade trace antibiotics in a water body, and the removal rate of sulfamethoxazole can reach 96% when the reaction is carried out for 60 minutes. According to the method, harmless treatment and resource utilization of the sludge can be realized, and meanwhile, efficient removal of antibiotics in the water body is also realized.

Description

Technical Field

[0001] The invention belongs to the technical field of advanced oxidation water treatment and relates to multi-walled carbon nanotube functionalized sludge biochar and a preparation method and application thereof. Background Art

[0002] Antibiotics are widely used in large quantities to prevent and treat various diseases caused by bacteria. After being ingested by humans and animals, only 10-50% of them can be metabolized and absorbed, and the rest will eventually be excreted from the body in the form of original compounds or metabolites through feces and urine and enter the natural environment. Antibiotics and their long half-life, weak biodegradability and high water solubility allow them to persist in the environment. They can accumulate through the food chain and induce bacteria to produce resistance genes, thereby threatening the safety of the entire ecosystem. Therefore, it is urgent to develop technologies that can efficiently and sustainably remove antibiotics from water.

[0003] In recent years, peroxymonosulfate (PMS)-based advanced oxidation technology has received particular attention, mainly because it has a variety of activation methods (such as heat, ultrasound, ultraviolet, transition metals and carbon-based materials, etc.), and a variety of active groups (such as SO4 •− , • OH, O2 •− , 1 O2, etc.). Among them, carbon-based materials - biochar is considered to be a promising catalytic material due to its abundant raw material sources, low production cost and good biocompatibility.

[0004] At present, the main disposal methods of sludge are incineration and landfill, which will inevitably cause pollution to the air, soil and groundwater. The high organic matter content (30-70%) of sludge provides a good precursor condition for the preparation of biochar. However, the practical application of sludge biochar is still limited by its weak catalytic ability, so it is urgent to develop a modification method that can significantly improve its catalytic performance.

[0005] Multi-walled carbon nanotubes have high mechanical strength, thermal / chemical stability, and abundant oxygen-containing functional groups, but their practical applications are limited by their poor dispersibility and potential nanotoxicity. Loading a small amount of carbon nanotubes onto sludge biochar has the potential to improve the catalytic performance of sludge biochar, and is also beneficial to improve its poor dispersibility and reduce its nanotoxicity. However, how to stably and uniformly graft carbon nanotubes onto sludge biochar for efficient activation of persulfate to degrade antibiotics remains an urgent problem to be solved. Summary of the invention

[0006] The purpose of the present invention is to provide a multi-walled carbon nanotube functionalized sludge biochar (BMWCNT-SBC) capable of efficiently activating peroxymonosulfate to degrade antibiotics, and its preparation method and application. The present invention can not only realize the resource utilization of urban solid waste, but also realize the efficient removal of antibiotics in water, thereby achieving the purpose of treating pollution with waste.

[0007] The technical solution of the present invention is as follows:

[0008] The method for preparing sludge biochar functionalized with multi-walled carbon nanotubes comprises the following steps:

[0009] (1) Preparation of sewage sludge biochar (SBC): The sludge was washed and dried to constant weight, then placed in a tube furnace for anaerobic pyrolysis, ground and sieved to obtain sludge biochar. The anaerobic pyrolysis conditions were: nitrogen (N2) flow rate 0.05-0.5 L / min, heating rate 5-20 °C / min, and continuous pyrolysis at 400-800 °C for 30-240 min.

[0010] (2) Preparation of MWCNT-functionalized sludge biochar: The sludge biochar obtained in step (1) and multi-walled carbon nanotubes (MWCNT) were ball-milled at a mass ratio of 1:10 to 1:30 to prepare MWCNT-functionalized sludge biochar.

[0011] Furthermore, in step (1), the sludge includes but is not limited to primary sludge, secondary sludge, activated sludge and residual sludge.

[0012] Furthermore, in step (1), the drying temperature is 70-90°C.

[0013] Furthermore, in step (1), the anaerobic pyrolysis conditions are: nitrogen flow rate 0.2 L / min, heating rate 10 °C / min, pyrolysis at 600 °C for 120 min; and after grinding, the mixture is sieved through a 100-mesh sieve.

[0014] Furthermore, in step (1), the powder is ground and then passed through a 20-200 mesh sieve.

[0015] Furthermore, in step (2), the mass ratio of sludge biochar to multi-walled carbon nanotubes is 1:10~1:20.

[0016] Furthermore, in step (2), the ball milling conditions are as follows: a planetary ball mill is used, the ball milling speed is 300-700 rpm, preferably 500-700 rpm; the ball milling time is 30-120 min, preferably 60-120 min; the ball-to-material ratio is 10-30:1, preferably 20-30:1.

[0017] The present invention provides multi-walled carbon nanotube functionalized sludge biochar prepared by the preparation method.

[0018] Furthermore, the present invention provides the use of the above-mentioned multi-walled carbon nanotube functionalized sludge biochar as a catalyst to activate peroxymonosulfate to degrade antibiotics in water.

[0019] Furthermore, antibiotics include but are not limited to sulfamethoxazole, ciprofloxacin, tetracycline, erythromycin, chloramphenicol and amoxicillin.

[0020] Specifically, the application method is as follows: adding sludge biochar functionalized with multi-walled carbon nanotubes and peroxymonosulfate into a water body containing antibiotics to degrade the antibiotics.

[0021] Furthermore, in the water containing antibiotics, the concentration of the antibiotics is 5-20 mg / L, the pH of the water is 3-11, preferably 3-5; the dosage of the multi-walled carbon nanotube functionalized sludge biochar is 0.1-0.4 g / L; and the concentration of permonosulfate is 0.25-5 mM, preferably 2-5 mM.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) The present invention prepares sludge biochar functionalized with multi-walled carbon nanotubes by ball milling sludge biochar and multi-walled carbon nanotubes. The method is simple and efficient. Compared with other composite methods of sludge biochar and multi-walled carbon nanotubes, the sludge biochar functionalized with multi-walled carbon nanotubes prepared by the method of the present invention has a better catalytic ability for peroxymonosulfate and can efficiently activate peroxymonosulfate. The degradation rate of sulfamethoxazole with a concentration of 10 mg / L can reach 96% at 60 minutes.

[0024] (2) The system of activated permonosulfate by multi-walled carbon nanotube-functionalized sludge biochar prepared by the present invention can not only effectively eliminate antibiotics in water and reduce their ecotoxicity, but also achieve harmless disposal and resource utilization of sludge. It has the advantages of simple operation process, low cost and large-scale application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Surface morphology and energy spectrum of BMWCNT-SBC, where (ac) are SEM images of BMWCNT-SBC, and (d) is the elemental surface scan of BMWCNT-SBC;

[0026] Figure 2 The removal effect of different reaction systems (SBC, BMWCNT-SBC, SBC / PMS and BMWCNT-SBC / PMS) on 10 mg / L sulfamethoxazole within 0-60 min;

[0027] Figure 3 The effect of BMWCNT-SBC dosage (5-20 mg) on ​​the removal capacity of BMWCNT-SBC / PMS system for 10 mg / L sulfamethoxazole in 0-60 min;

[0028] Figure 4 The effect of PMS concentration (0.25-2 mM) on the removal capacity of BMWCNT-SBC / PMS system for 10 mg / L sulfamethoxazole in 0-60 min;

[0029] Figure 5 The effect of pH (3-11) on the removal capacity of BMWCNT-SBC / PMS system for 10 mg / L sulfamethoxazole in 0-60 min;

[0030] Figure 6 Cl - Effect of concentration (0-10 mM) on the removal capacity of BMWCNT-SBC / PMS system for 10 mg / L sulfamethoxazole in 0-60 min;

[0031] Figure 7 NO3 - Effect of concentration (0-10 mM) on the removal capacity of BMWCNT-SBC / PMS system for 10 mg / L sulfamethoxazole in 0-60 min;

[0032] Figure 8 HCO3 - Effect of concentration (0-10 mM) on the removal capacity of BMWCNT-SBC / PMS system for 10 mg / L sulfamethoxazole in 0-60 min;

[0033] Fig. 9 For CO3 2- Effect of concentration (0-10 mM) on the removal capacity of BMWCNT-SBC / PMS system for 10 mg / L sulfamethoxazole in 0-60 min;

[0034] Fig.10 The effect of humic acid (HA) concentration (0-10 mg / L) on the removal capacity of BMWCNT-SBC / PMS system for 10 mg / L sulfamethoxazole in 0-60 min;

[0035] Fig.11The effect of the BMWCNT-SBC / PMS system on the removal of 10 mg / L sulfamethoxazole in different actual water bodies within 0-60 min;

[0036] Fig.12 This is the removal effect diagram of 10 mg / L sulfamethoxazole by MWCNT-SBC / PMS, PMWCNT-SBC / PMS and HMWCNT-SBC / PMS systems in 0-60 min;

[0037] Fig.13 This is the removal effect diagram of sulfamethoxazole with a concentration of 10 mg / L by BMWCNT-SBC-1:10 / PMS, BMWCNT-SBC-1:20 / PMS and BMWCNT-SBC-1:30 / PMS systems within 0-60 min;

[0038] Fig.14 This is the removal effect diagram of sulfamethoxazole with a concentration of 10 mg / L by BMWCNT-SBC-300 rpm / PMS, BMWCNT-SBC-500 rpm / PMS, and BMWCNT-SBC-700rpm / PMS systems within 0-60 min;

[0039] Fig.15 This is the removal effect diagram of sulfamethoxazole with a concentration of 10 mg / L by BMWCNT-SBC-30 min / PMS, BMWCNT-SBC-60 min / PMS, and BMWCNT-SBC-120 min / PMS systems within 0-60 min;

[0040] Fig.16 This is the removal effect diagram of sulfamethoxazole with a concentration of 10 mg / L by BMWCNT-SBC-10:1 / PMS, BMWCNT-SBC-20:1 / PMS and BMWCNT-SBC-30:1 / PMS in 0-60 min;

[0041] Fig.17 This is the removal effect diagram of the BMWCNT-SBC / PMS system on different antibiotics. DETAILED DESCRIPTION

[0042] In order to facilitate the understanding of the present invention, the present invention will be further described in detail below in conjunction with embodiments and drawings, but the protection scope of the present invention is not limited to the following specific embodiments.

[0043] Example 1

[0044] (1) The cleaned municipal sludge was placed in a 70 °C oven and dried to constant weight. It was then transferred to a high-temperature tube furnace (N2 flow rate of 0.2 L / min, heating rate of 10 °C / min), pyrolyzed at 600 °C for 120 min, and ground through a 100-mesh sieve to obtain sludge biochar.

[0045] (2) 5 g of sludge biochar and 0.25 g of multi-walled carbon nanotubes were placed in a planetary ball mill and ball milled for 60 min at a ball-to-material ratio of 20:1 and a rotation speed of 500 rpm to obtain BMWCNT-SBC.

[0046] Depend on Figure 1 It can be seen that the network structure is evenly distributed on the surface of BMWCNT-SBC, indicating that the carbon nanotubes are successfully and evenly attached to the surface of SBC; the main elements of BMWCNT-SBC are C, O and Si.

[0047] Example 2

[0048] 15 mg of SBC and BMWCNT-SBC in Example 1 were added to 50 mL of 10 mg / L sulfamethoxazole solution containing / not containing PMS (1 mM), and stirred continuously on a magnetic stirrer at a speed of 600 rpm. Samples were taken at set time intervals (0-60 min), and the residual sulfamethoxazole concentration was determined by high performance liquid chromatography, and the removal rate of sulfamethoxazole at different times was calculated.

[0049] Depend on Figure 2 It can be seen that the removal rate of sulfamethoxazole by the BMWCNT-SBC / PMS system is significantly higher than that by the SBC / PMS, BMWCNT-SBC and SBC systems. The removal rate of sulfamethoxazole is 92.1% at 60 min, indicating that BMWCNT-SBC can efficiently activate PMS to degrade sulfamethoxazole.

[0050] Example 3

[0051] The dosage of BMWCNT-SBC in the BMWCNT-SBC / PMS system was set to 5-20 mg, the concentration of sulfamethoxazole was 10 mg / L, the volume was 50 mL, and the PMS concentration was 1 mM. The system was stirred continuously on a magnetic stirrer at a speed of 600 rpm. Samples were taken at set time intervals (0-60 min), and the residual concentration of sulfamethoxazole was determined by high performance liquid chromatography to explore the effect of BMWCNT-SBC dosage on the ability of the BMWCNT-SBC / PMS system to remove sulfamethoxazole.

[0052] Depend on Figure 3It can be seen that the removal rate of sulfamethoxazole by the BMWCNT-SBC / PMS system increases with the increase of the BMWCNT-SBC dosage. When the BMWCNT-SBC dosage is 15 and 20 mg, there is no significant difference in the removal rate of sulfamethoxazole by the BMWCNT-SBC / PMS system at 60 min, which are 92.1% and 96.0%, respectively.

[0053] Example 4

[0054] The dosage of BMWCNT-SBC in the BMWCNT-SBC / PMS system was set to 15 mg, the concentration of PMS was 0.25-2 mM, the concentration of sulfamethoxazole was 10 mg / L, and the volume was 50 mL. Stirring was continued on a magnetic stirrer at a speed of 600 rpm. Samples were taken at set time intervals (0-60 min), and the residual concentration of sulfamethoxazole was determined by high performance liquid chromatography to explore the effect of PMS concentration on the ability of BMWCNT-SBC / PMS system to remove sulfamethoxazole.

[0055] Depend on Figure 4 It can be seen that the removal rate of sulfamethoxazole by the BMWCNT-SBC / PMS system increases with the increase of PMS concentration. When the concentration of PMS is 1 and 2 mM, there is no significant difference in the removal rate of sulfamethoxazole by the BMWCNT-SBC / PMS system at 60 min, which are 92.1% and 96.1%, respectively.

[0056] Example 5

[0057] The dosage of BMWCNT-SBC in the BMWCNT-SBC / PMS system was set to 15 mg, the concentration of PMS was 1 mM, the concentration of sulfamethoxazole was 10 mg / L, the volume was 50 mL, and the pH of the solution was set to 3, 5, 7, 9 and 11, respectively. The mixture was stirred continuously on a magnetic stirrer at a speed of 600 rpm. Samples were taken at set time intervals (0-60 min), and the residual concentration of sulfamethoxazole was determined by high performance liquid chromatography to explore the effect of solution pH on the ability of BMWCNT-SBC / PMS system to remove sulfamethoxazole.

[0058] Depend on Figure 5 It can be seen that the removal rate of sulfamethoxazole by the BMWCNT-SBC / PMS system varies with the change of solution pH. Overall, the removal rate of sulfamethoxazole by the BMWCNT-SBC / PMS system under acidic conditions is higher than that under alkaline conditions, and when the solution pH is 5, its removal rate of sulfamethoxazole is the highest, reaching 92.9%.

[0059] Example 6

[0060] The dosage of BMWCNT-SBC in the BMWCNT-SBC / PMS system was set to 15 mg, the concentration of PMS was 1 mM, the concentration of sulfamethoxazole was 10 mg / L, the volume was 50 mL, and the Cl - 、NO3 - 、HCO3 - and CO3 2- The concentrations were 0~10 mM, respectively. The mixture was stirred continuously on a magnetic stirrer at a speed of 600 rpm. Samples were taken at set time intervals (0~60 min), and the residual concentration of sulfamethoxazole was determined by high performance liquid chromatography to explore the effects of the types and concentrations of inorganic ions in the solution on the ability of the BMWCNT-SBC / PMS system to remove sulfamethoxazole.

[0061] Depend on Figure 6 and Figure 7 It can be seen that the coexistence of Cl - and NO3 - It has no significant effect on the ability of BMWCNT-SBC / PMS system to degrade sulfamethoxazole; Figure 8 and Fig. 9 It can be seen that the coexisting HCO3 - and CO3 2- The inhibitory effect on the degradation of sulfamethoxazole by the BMWCNT-SBC / PMS system increased with the increase of their concentration, which can be mainly attributed to: (1) HCO3 - and CO3 2- Can quench SO4 generated in the system •− and • OH; (2) HCO3 - and CO3 2- Hydrolysis will lead to an increase in the pH of the solution, and alkaline conditions are not conducive to the activation of PMS by BMWCNT-SBC.

[0062] Example 7

[0063] The dosage of BMWCNT-SBC in the BMWCNT-SBC / PMS system was set to 15 mg, the concentration of PMS was 1 mM, the concentration of sulfamethoxazole was 10 mg / L, the volume was 50 mL, and the concentration of humic acid (HA) was 0-10 mg / L. The system was stirred continuously on a magnetic stirrer at a speed of 600 rpm. Samples were taken at set time intervals (0-60 min), and the residual concentration of sulfamethoxazole was determined by high performance liquid chromatography to explore the effect of the coexisting HA concentration on the ability of the BMWCNT-SBC / PMS system to remove sulfamethoxazole.

[0064] Depend on Fig.10It can be seen that the inhibitory effect of the coexisting HA on the degradation ability of sulfamethoxazole by the BMWCNT-SBC / PMS system increases with the increase of HA concentration. When the concentration of HA is 0, 1, 5 and 10 mg / L, the removal rates of sulfamethoxazole at 60 min are 92.1%, 93.1%, 89.1% and 85.6%, respectively. This is because HA, as a macromolecular compound, can compete with sulfamethoxazole for the active oxygen groups generated in the system. But overall, the coexisting HA has no significant effect on the degradation ability of sulfamethoxazole by the BMWCNT-SBC / PMS system.

[0065] Example 8

[0066] The dosage of BMWCNT-SBC in the BMWCNT-SBC / PMS system was set to 15 mg, the concentration of PMS was 1 mM, the concentration of sulfamethoxazole was 10 mg / L, the volume was 50 mL, and the water bodies were drinking water, tap water, river water, lake water and sewage effluent. The mixture was stirred continuously on a magnetic stirrer at a speed of 600 rpm. Samples were taken after 60 min, and the residual concentration of sulfamethoxazole was determined by high performance liquid chromatography to explore the effect of the BMWCNT-SBC / PMS system on the removal ability of sulfamethoxazole in different actual water bodies.

[0067] Depend on Fig.11 It can be seen that after 60 min of reaction, the removal rates of sulfamethoxazole in drinking water, tap water, river water, lake water and sewage by the BMWCNT-SBC / PMS system were 95.4%, 84.8%, 84.1%, 81.7% and 80.1%, respectively, indicating that the BMWCNT-SBC / PMS system has strong anti-interference ability.

[0068] Example 9

[0069] The ability of the BMWCNT-SBC prepared in Example 1 to catalyze PMS was compared with that of the MWCNT-functionalized SBC prepared by other methods.

[0070] The preparation methods of the other two MWCNT functionalized SBCs are as follows:

[0071] (1) PMWCNT-SBC: The preparation of SBC was the same as in Example 1. 5 g of SBC was placed in a solution containing 0.25 g of MWCNT, subjected to ultrasonic dispersion for 60 min, dried in a 70 °C oven, and then transferred to a high-temperature tube furnace (N2 flow rate of 0.2 L / min, heating rate of 10 °C / min) for pyrolysis at 600 °C for 120 min, and ground through a 100-mesh sieve to obtain PMWCNT-SBC.

[0072] (2) HMWCNT-SBC: The preparation of SBC was the same as in Example 1. 5 g of SBC was placed in a solution containing 0.25 g of MWCNT, and then placed in a reactor for hydrothermal reaction at 220°C for 720 min, and then dried in an oven at 70°C, ground and passed through a 100-mesh sieve to obtain HMWCNT-SBC.

[0073] According to the method of Example 2, BMWCNT-SBC / PMS, PMWCNT-SBC / PMS and HMWCNT-SBC / PMS systems were constructed respectively. The dosage of BMWCNT-SBC, PMWCNT-SBC and HMWCNT-SBC was 15 mg, the concentration of PMS was 1 mM, the concentration of sulfamethoxazole was 10 mg / L, the volume was 50 mL, and the stirring was continued on a magnetic stirrer at a speed of 600 rpm. Samples were taken at set time intervals (0-60 min), and the residual concentration of sulfamethoxazole was determined by high performance liquid chromatography. The catalytic ability of BMWCNT-SBC, PMWCNT-SBC and HMWCNT-SBC on PMS was compared.

[0074] Depend on Fig.12 It can be seen that the removal capacity and efficiency of BMWCNT-SBC / PMS system for sulfamethoxazole are significantly higher than those of PMWCNT-SBC / PMS and HMWCNT-SBC / PMS systems. After 60 min of reaction, the removal rates of sulfamethoxazole by BMWCNT-SBC / PMS, PMWCNT-SBC / PMS and HMWCNT-SBC / PMS systems were 92.1%, 38.1% and 51.3%, respectively, indicating that the BMWCNT-SBC prepared by the present invention has a stronger catalytic ability for PMS.

[0075] Example 10

[0076] This example investigates the effect of the mass ratio of MWCNT to SBC on the ability of BMWCNT-SBC to catalyze PMS.

[0077] According to the method of Example 1, the mass ratios of MWCNT and SBC were adjusted to 1:10 (0.5 g / 5 g), 1:20 (0.25 g / 5 g) and 1:30 (0.167 g / 5 g), respectively, to prepare BMWCNT-SBC-1:10, BMWCNT-SBC-1:20 and BMWCNT-SBC-1:30.

[0078] The masses of BMWCNT-SBC-1:10, BMWCNT-SBC-1:20 and BMWCNT-SBC-1:30 were set to 15 mg, the concentrations of PMS were 1 mM, the concentrations of sulfamethoxazole were 10 mg / L, and the volume was 50 mL. The mixture was stirred continuously on a magnetic stirrer at a speed of 600 rpm. Samples were taken at set time intervals (0-60 min), and the residual concentration of sulfamethoxazole was determined by HPLC. The catalytic abilities of BMWCNT-SBC-1:10, BMWCNT-SBC-1:20 and BMWCNT-SBC-1:30 on PMS were compared.

[0079] Depend on Fig.13 It can be seen that the removal ability of BMWCNT-SBC / PMS system for sulfamethoxazole increases with the increase of MWCNT doping ratio. At t=60 min, the removal rates of sulfamethoxazole by BMWCNT-SBC-1:10 / PMS, BMWCNT-SBC-1:20 / PMS and BMWCNT-SBC-1:30 / PMS were 95.7%, 92.1% and 59.9%, respectively. This shows that there is no significant difference in the activation ability of BMWCNT-SBC-1:10 and BMWCNT-SBC-1:20 for PMS, so the mass ratio of MWCNT to SBC was selected as 1:20 for the preparation of BMWCNT-SBC.

[0080] Embodiment 11

[0081] This example investigates the effects of ball milling speed, ball milling time and ball-to-material ratio on the catalytic PMS capability of BMWCNT-SBC.

[0082] According to the method of Example 1, the ball milling conditions were adjusted: the ball milling speeds were 300, 500 and 700 rpm, respectively, the ball milling time was 60 min, the ball-to-material ratio was 20:1, and BMWCNT-SBC-300 rpm, BMWCNT-SBC-500 rpm, and BMWCNT-SBC-700 rpm were obtained.

[0083] According to the method of Example 1, the ball milling conditions were adjusted: the ball milling time was 30, 60 and 120 min, the ball milling speed was 500 rpm, the ball-to-material ratio was 20:1, and BMWCNT-SBC-30 min, BMWCNT-SBC-60 min, and BMWCNT-SBC-120min were obtained.

[0084] According to the method of Example 1, the ball milling conditions were adjusted: the ball-to-material ratio was 10:1, 20:1 and 30:1, respectively, the ball milling speed was 500 rpm, and the ball milling time was 60 min to obtain BMWCNT-SBC-10:1, BMWCNT-SBC-20:1 and BMWCNT-SBC-30:1.

[0085] The catalyst mass of BMWCNT-SBC-300 rpm / PMS, BMWCNT-SBC-500 rpm / PMS, BMWCNT-SBC-700 rpm / PMS, BMWCNT-SBC-30 min / PMS, BMWCNT-SBC-60 min / PMS, BMWCNT-SBC-120 min / PMS, BMWCNT-SBC-10:1 / PMS, BMWCNT-SBC-20:1 / PMS and BMWCNT-SBC-30:1 / PMS was 15 mg, the concentration of PMS was 1 mM, the concentration of sulfamethoxazole was 10 mg / L, the volume was 50 mL, and the stirring was continued on a magnetic stirrer at a speed of 600 rpm. The mixture was stirred for 2 h at set time intervals (0-60 min). The residual concentration of sulfamethoxazole was determined by HPLC, and the effects of ball milling speed, ball milling time and ball-to-material ratio on the catalytic PMS ability of BMWCNT-SBC were compared.

[0086] Depend on Fig.14 It can be seen that the catalytic ability of BMWCNT-SBC on PMS first increases with the increase of ball milling speed, and then weakens with the increase of ball milling speed. At t=60 min, the removal rates of BMWCNT-SBC-300 rpm / PMS, BMWCNT-SBC-500 rpm / PMS and BMWCNT-SBC-700 rpm / PMS on sulfamethoxazole were 65.9%, 92.1% and 89.7%, respectively. Therefore, the ball milling speed of 500 rpm was selected as the optimal ball milling speed. Fig.15 It can be seen that, similar to the effect of ball milling speed, the catalytic ability of BMWCNT-SBC on PMS first increases with the increase of ball milling time, and then weakens with the increase of ball milling time. At t=60 min, the removal rates of BMWCNT-SBC-30 min / PMS, BMWCNT-SBC-60 min / PMS and BMWCNT-SBC-120 min / PMS on sulfamethoxazole were 70.1%, 92.1% and 87.6%, respectively. Therefore, the ball milling time of 60 min was selected as the optimal ball milling time. Fig.16It can be seen that the catalytic ability of BMWCNT-SBC to PMS increases with the increase of ball milling ratio. At t=60 min, BMWCNT-SBC-10:1 / PMS, BMWCNT-SBC-20:1 / PMS and BMWCNT-SBC-30:1 / PMS are 71.1%, 92.1% and 92.7% respectively. Therefore, the ball-to-material ratio of 20:1 is selected as the best ball-to-material ratio.

[0087] Example 12

[0088] This example investigates the degradation effect of the BMWCNT-SBC / PMS system on different antibiotics.

[0089] The dosage of BMWCNT-SBC in the BMWCNT-SBC / PMS system was set to 15 mg, the concentration of PMS was 1 mM, ciprofloxacin, erythromycin, tetracycline, chloramphenicol, and amoxicillin were set as the target antibiotics, and the concentrations of ciprofloxacin, erythromycin, tetracycline, chloramphenicol, and amoxicillin were 10 mg / L, respectively. The volume was 50 mL, and the mixture was stirred continuously on a magnetic stirrer at 600 rpm. Samples were taken after 60 min, and the residual concentrations of ciprofloxacin, tetracycline, erythromycin, chloramphenicol, and amoxicillin were determined by high performance liquid chromatography to verify the broad-spectrum removal ability of the BMWCNT-SBC / PMS system for micropollutants in water.

[0090] Depend on Fig.17 It can be seen that at t=60 min, the removal rates of BMWCNT-SBC / PMS for ciprofloxacin, tetracycline, erythromycin, chloramphenicol and amoxicillin were 90.5%, 86.7%, 87.1%, 93.5% and 88.2%, respectively, indicating that the system has high efficiency and broad-spectrum removal ability for antibiotics in water.

[0091] The above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and changes can be made without departing from the principle of the present invention, and these improvements and changes are also regarded as the protection scope of the present invention.

Claims

1. A method for preparing sludge biochar functionalized with multi-walled carbon nanotubes, characterized in that: The following steps are included: (1) Preparation of sludge biochar: The sludge was washed and dried to constant weight, then placed in a tube furnace for anaerobic pyrolysis, ground and sieved to obtain sludge biochar. The anaerobic pyrolysis conditions were: nitrogen flow rate 0.05-0.5 L / min, heating rate 5-20 °C / min, and continuous pyrolysis at 400-800 °C for 30-240 min. (2) Preparation of MWCNT-functionalized sludge biochar: The sludge biochar obtained in step (1) and MWCNTs were ball-milled at a mass ratio of 1:10 to 1:30 to prepare MWCNT-functionalized sludge biochar.

2. The preparation method according to claim 1, characterized in that In step (1), the sludge is primary sludge, secondary sludge, activated sludge or residual sludge, the drying temperature is 70-90°C, and the sludge is ground and passed through a 20-200 mesh sieve; in step (2), the mass ratio of sludge biochar to multi-walled carbon nanotubes is 1:10-1:20; the ball milling conditions are: a planetary ball mill is used, the ball milling speed is 300-700 rpm; the ball milling time is 30-120 min; and the ball-to-material ratio is 10-30:

1.

3. The preparation method according to claim 1, characterized in that In step (1), the anaerobic pyrolysis conditions are: nitrogen flow rate 0.2 L / min, heating rate 10 °C / min, continuous pyrolysis at 600 °C for 120 min; after grinding, the mixture is sieved through a 100-mesh sieve.

4. The preparation method according to claim 1, characterized in that In step (2), the ball milling conditions are: ball milling speed is 500-700 rpm; ball milling time is 60-120 min; ball to material ratio is 20-30:

1.

5. The sludge biochar functionalized with multi-walled carbon nanotubes prepared by the preparation method according to any one of claims 1 to 4.

6. Use of the sludge biochar functionalized with multi-walled carbon nanotubes according to claim 5 as a catalyst to activate peroxymonosulfate to degrade antibiotics in water.

7. The use according to claim 6, characterized in that: Antibiotics are sulfamethoxazole, ciprofloxacin, tetracycline, erythromycin, chloramphenicol, or amoxicillin.

8. The use according to claim 6, characterized in that: The specific application method is: adding multi-walled carbon nanotube functionalized sludge biochar and peroxymonosulfate into water bodies containing antibiotics to degrade the antibiotics.

9. The use according to claim 8, characterized in that In the water containing antibiotics, the concentration of antibiotics was 5~20 mg / L, and the pH of the water was 3~11; the dosage of sludge biochar functionalized with multi-walled carbon nanotubes was 0.1~0.4 g / L; and the concentration of permonosulfate was 0.25~5 mM.

10. The use according to claim 8, characterized in that In water bodies containing antibiotics, the pH of the water is 3~5; the concentration of permonosulfate is 2~5 mM.

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