Cationic surfactant modified porous carbon material and preparation and application thereof

Abstract

The present application relates to a kind of cationic surfactant modified porous carbon material and preparation and application, belong to environmental pollution control technical field.The shell of agricultural biomass solid waste-hazelnut kernel is used as carbon precursor, and the porous carbon material for wastewater treatment is prepared by two-step pore-making-surface modification coupling technology.Potassium hydroxide solution is mixed with hazelnut shell powder after ultrasonic drying, to realize the intercalation reaction and uniform pre-etching of raw material in liquid strong alkali environment.Second, the obtained hazelnut shell-potassium hydroxide solid mixture is carbonized in situ, to obtain high specific surface area biomass porous carbon.Finally, the surface of porous carbon material is modified by loading cationic surfactant through polyethylene glycol grafting method, to enhance the adsorption performance of material.The obtained modified hazelnut shell porous carbon material has the characteristics of large specific surface area and low cost, can efficiently remove nanometer plastic and antibiotics in wastewater, and the removal rate can reach more than 98%, has good environmental application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environmental pollution control, in particular to a cationic surfactant modified porous carbon material and its preparation and application. BACKGROUND

[0002] In recent years, nano-plastics and antibiotics have been widely detected in natural water bodies. Traditional wastewater treatment technologies have obvious deficiencies such as low efficiency and poor selectivity in removing nano-plastics and antibiotics, and it is urgent to develop new high-efficiency adsorption materials. Biomass carbon materials have become a hot spot in the research of nano-plastics and antibiotic adsorption and removal due to their wide sources, adjustable pore structure, and controllable surface function. Hazelnut is a typical crop in Northeast China and South Shaanxi, and a large amount of hazelnut shells will be produced after shelling. As the outer hard protective structure of hazelnut fruit, the total weight of hazelnut shell accounts for about 40% to 60% of the total weight of hazelnut fruit, and it has the advantages of high carbon content, strong thermal stability, and controllable structure, and is a good precursor of carbon materials. By proper pore creation and surface functionalization modification, the adsorption capacity of the material for nano-plastics and antibiotics can be greatly improved. However, the existing methods mostly adopt single activation or loading strategy, and the obtained materials have problems such as insufficient specific surface area, low adsorption selectivity, and limited number of functional groups. The present application proposes a two-step pore creation-surface modification coupling technology to simultaneously improve the specific surface area and surface functional group density of the material, and realize high-efficiency adsorption of nano-plastics and antibiotics, thereby expanding its application potential in the field of efficient water treatment. SUMMARY

[0003] The present application aims to provide a cationic surfactant modified porous carbon material and its preparation and application to solve the problems of small specific surface area of existing carbon materials, insufficient functional groups, and poor adsorption performance for nano-plastics and antibiotics. Meanwhile, the present application also provides the application of the material in wastewater treatment, which has good application prospect and environmental friendliness.

[0004] To achieve the above-mentioned purpose, the technical solutions adopted by the present application are as follows:

[0005] A cationic surfactant modified porous carbon material for removing nano-plastics and antibiotics in wastewater and its preparation method, comprising the following steps:

[0006] (1) Pre-etching treatment: hazelnut shell powder is added into a potassium hydroxide aqueous solution, ultrasonic dispersion is performed, the reaction time is 1-6 h (preferably 2-5 h), then the hazelnut shell-potassium hydroxide solution mixture is placed in an oven and dried at a temperature of 50-80℃ (preferably 60-70℃) to obtain a hazelnut shell-potassium hydroxide solid mixture;

[0007] (2) In-situ carbonization: the solid mixture obtained in step (1) is crushed, placed in a nickel crucible, and subjected to in-situ carbonization treatment at 500-800°C (preferably 600-700°C) in an argon environment in a high-temperature furnace, and after a certain holding time, it is taken out, washed with water until the pH value of the waste liquid is neutral, and a porous carbon material is obtained;

[0008] (3) Surface modification: the porous carbon material obtained in step (2) is mixed with an aqueous surfactant solution, and ultrasonic treatment is performed for 1-6h (preferably 2-4h). During the start of ultrasonic treatment, a polyethylene glycol solution is added, and then dried at 50-80°C (preferably 60-70°C) to obtain a surfactant-modified biomass porous carbon material.

[0009] In step (1), the mass concentration of the potassium hydroxide aqueous solution is 2 wt.%-10 wt.% (preferably 4 wt.%-8 wt.%), and the preparation process is as follows: a certain mass of potassium hydroxide powder is weighed and poured into deionized water, mechanically stirred for 5-20min (preferably 10-15min) until completely dissolved, and a potassium hydroxide aqueous solution is obtained.

[0010] In step (1), the mass ratio of hazelnut shell to potassium hydroxide aqueous solution is 1:(10-20) (preferably 1:(12-18));

[0011] In step (2), the temperature is raised to 500-800°C (preferably 600-700°C) at a rate of 5-10°C / min (preferably 5-8°C / min) during carbonization, and the temperature is held for 1-3h (preferably 2-3h).

[0012] In step (3), the surfactant is one of octadecyltrimethylammonium chloride (STAC) and hydroxypropyltrimethylammonium chloride chitosan (HTCC);

[0013] In step (3), the aqueous polyethylene glycol solution has a concentration of 1 wt.%-5 wt.% (preferably 2 wt.%-4 wt.%); the mass ratio of the porous carbon material to the aqueous polyethylene glycol solution is 1:(5-20) (preferably 1:(8-18)); the ultrasonic treatment time is 1-6h (preferably 2-4h); during the start of ultrasonic treatment, the aqueous polyethylene glycol solution is divided into 2-6 portions, and each portion is added every 5-6min, and all portions are added within 10-30min; the drying temperature is 50-80°C (preferably 60-70°C).

[0014] In step (3), when the surfactant is STAC, the concentration of the aqueous solution of the surfactant is 1 wt.% to 5 wt.% (preferably 2 wt.% to 4 wt.%); the mass ratio of the porous carbon material to the aqueous solution of the surfactant is 1:(5-20) (preferably 1:(8-18)); the aqueous solution of STAC is prepared by weighing a certain amount of STAC liquid into deionized water, mechanically stirring for 10-30 min (preferably 15-25 min) until completely dissolved, to obtain an aqueous solution of STAC;

[0015] In step (3), when the surfactant is HTCC, the concentration of the aqueous solution of the surfactant is 2 wt.% to 10 wt.% (preferably 4 wt.% to 8 wt.%); the mass ratio of the porous carbon material to the aqueous solution of the surfactant is 1:(5-10) (preferably 1:(5-8)). The aqueous solution of HTCC is prepared by weighing a certain amount of HTCC liquid into deionized water, mechanically stirring for 10-30 min (preferably 15-25 min) until completely dissolved, to obtain an aqueous solution of HTCC.

[0016] A cationic surfactant modified porous carbon material prepared by the above method, characterized in that: the material takes hazelnut shell as a carbon precursor, is prepared by a two-step pore-forming-surface modification coupling technology, has a large specific surface area and abundant surface functional groups.

[0017] The material can be used to remove nanoplastics and antibiotics in wastewater, with a removal rate of more than 98%, and is suitable for treatment scenarios of domestic sewage and industrial wastewater.

[0018] The design principle of the present application is as follows:

[0019] The present application uses hazelnut shell as the carbon source of biomass carbon material, realizes internal structure loosening and pore pre-generation through liquid phase strong alkali (potassium hydroxide) pre-etching, and then forms a developed pore structure through in-situ carbonization at high temperature, thereby significantly improving the specific surface area. Further, a surface cationic surfactant is introduced, and the surface functional groups of the material are enriched through physical adsorption and chemical bonding, thereby effectively enhancing the adsorption capacity of nanoplastics and antibiotics. This synergistic mechanism overcomes the problems of insufficient functional groups of traditional biomass carbon materials and poor adsorption efficiency of nanoplastics and antibiotics.

[0020] The present application has the following benefits:

[0021] The present application modifies the shell of hazelnut kernels by two-step pore-forming-surface modification combined modification, uses hazelnut shells as carbon precursors, and is prepared by two-step pore-forming-surface modification coupling technology, so that it has a large specific surface area and rich surface functional groups, can effectively expose more active sites, significantly increase the specific surface area, and the cationic surfactant can increase the surface functional group density of the porous carbon material by polyethylene glycol grafting loading, and enhance the adsorption capacity of nano-plastic and antibiotics. Compared with the traditional biochar material, the specific surface area is increased from 20~50cm 2 / g to 500~800cm 2 / g, and the removal efficiency of polystyrene nano-plastic and tetracycline antibiotics is increased from 50~70% to more than 98%.

[0022] In order to understand the present application in more detail, the following examples are disclosed and described, but the examples are only for further illustrating the characteristics and advantages of the present application, and are not a limitation on the claims of the present application.

[0023] The shell of hazelnut kernels is widely used in environmental governance due to its high residual carbon rate, low price and adjustable structure. The main components contained in the shell, such as cellulose and lignin, make the carbon component content more than 90wt.% (the data is measured by energy dispersive spectroscopy, Shimadzu, Japan). Therefore, in the following, hazelnut shells are used as source materials to prepare cationic surfactant modified porous carbon materials by two-step pore-forming-surface modification coupling new technology as an embodiment to further illustrate the present application, so as to better understand the present application. Figure 1 The process flowchart is shown in the figure, but the protection scope of the present application is not limited to the embodiment. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The figure is a preparation process flowchart of a cationic surfactant modified porous carbon material.

[0025] Figure 2 The figure is a pore size distribution graph of the porous carbon material and the STAC modified porous carbon material in Example 1.

[0026] Figure 3 The figure is a specific surface area (a) graph of the straw biochar and the STAC modified hazelnut shell porous carbon material in Example 1, and a polystyrene nano-plastic and tetracycline removal effect (b) graph of the STAC modified porous carbon material in Example 1 and the HTCC modified porous carbon material in Example 3.

[0027] Figure 4 The figure is a microstructure graph of the hazelnut shell (a) and the STAC modified porous carbon material (b) in Example 1.

[0028] Figure 5Micro-morphology images of STAC modified biomass porous carbon material (a) and HTCC modified biomass porous carbon material (b) in Example 3.

[0029] Figure 6 Energy spectrum of hazelnut shell and STAC modified biomass porous carbon material in Example 2.

[0030] Figure 7 Pore size distribution of STAC modified biomass porous carbon material in Example 2. DETAILED DESCRIPTION

[0031] Example 1

[0032] The outer shell of hazelnut kernel produced in Tieling, Liaoning Province (hazelnut shell after removing the husk) was used as the carbon precursor. After mechanical crushing for 10 min using a pulverizer, the hazelnut shell powder passing through a 100-mesh sieve was taken for use. 2 g of potassium hydroxide powder was dissolved in 98 g of deionized water, and mechanical stirring was performed for 10 min until a complete solution was obtained, obtaining a 2wt.% potassium hydroxide aqueous solution. 5 g of hazelnut shell powder was mixed with 50 g of potassium hydroxide solution, and ultrasonic dispersion was performed for 2 h. Then, the hazelnut shell-potassium hydroxide solution mixture was placed in an oven and dried at 60°C for 6 h, obtaining a hazelnut shell-potassium hydroxide solid mixture. The obtained mixture was crushed and placed in a high-temperature furnace, and heated to 500°C at a rate of 10°C / min under an argon atmosphere, and held for 2 h. After cooling, the mixture was washed with deionized water until neutral, and dried at 60°C for 3 h, obtaining a porous carbon material after in-situ carbonization. The pore size range was 3.5-44.7 nm, and the pore volume was 1.74 cm 3 / g. 1 g of STAC was dissolved in 99 g of deionized water, and mechanical stirring was performed for 10 min until complete dissolution, obtaining a 1wt.% STAC solution. 2 g of polyethylene glycol was dissolved in 98 g of deionized water, and mechanical stirring was performed for 30 min until complete dissolution, obtaining a 2wt.% polyethylene glycol aqueous solution. 5 g of the porous carbon material was placed in 25 g of the 1wt.% STAC solution and ultrasonic treated for 4 h. During the ultrasonic treatment, 30 g of the polyethylene glycol aqueous solution was divided into 5 equal parts, and added every 5 min, and the addition was completed within 25 min. After the ultrasonic treatment was completed, the sample was filtered and dried in an oven at 60°C for 4 h, obtaining a STAC modified biomass porous carbon material. The pore size range was 7.45-48.4 nm, the pore volume was 2.12 cm 3 / g, and the STAC mass content was 2.23%. The content of each element in the obtained material was 83.1wt.% C, 12.4wt.% O, and 4.5wt.% N (data measured by energy dispersive X-ray spectroscopy, Shimadzu, Japan). Compared with the biochar material prepared by using straw as the carbon source and using the same method, the surface area was increased from 143 m 2 / g to 638 m2 / g Figure 3 a) (The data were measured by a BET specific surface area and pore size analyzer, BSD-660S, Beijing). The specific experimental operation steps for removing pollutants are as follows (the following examples and comparative examples are all operated according to this method, and the difference between experiments is that the material is the biochar material prepared in each example and comparative example), polystyrene plastic with an average particle size of 80 nm is selected as a nano-plastic pollutant (purchased from the Science Compass website), tetracycline is selected as an antibiotic pollutant (purchased from Sigma Company), and a 20 mg / L pollutant aqueous solution is prepared, 0.1 g of STAC modified porous biochar material is placed into 20 mL of the pollutant aqueous solution, and the adsorption is shaken at a speed of 180 rpm / min for 60 min, and the remaining concentration of the polystyrene nano-plastic and tetracycline pollutant aqueous solution is measured by using a UV spectrophotometer at 265 nm and 270 nm ultraviolet light, respectively, and the remaining content is 0.31 mg / L and 0.22 mg / L, respectively, and thus it can be calculated that the removal rate of the prepared STAC modified porous biochar material for polystyrene nano-plastic and tetracycline is 98.5% and 98.9%, respectively. Figure 3 b) (The data were measured by a T700 UV-visible spectrophotometer, Beijing Puxi General Instrument Co., Ltd.).

[0033] Figure 4 a and b are micro-morphology structure diagrams of unmodified and modified hazelnut shells. It can be found that the micro-surface of the hazelnut shell is relatively smooth, the surface of the modified material is rough, and there are pores, the roughness is increased, the pore size range is 6.5-44.7 nm, and the pore volume is 2.74 cm 3 / g. Figure 5 a is a structure scanning diagram of STAC modified porous carbon material adsorbing nano-plastic, and it can be found that the STAC modified porous biochar material surface adsorbs polystyrene nano-plastic.

[0034] Example 2

[0035] The outer shell of hazelnut kernels produced in Tieling, Liaoning Province, was used as a carbon precursor. The hazelnut shell was mechanically broken for 10 minutes using a pulverizer and then sieved through a 100-mesh sieve to obtain hazelnut shell powder. 2 g of potassium hydroxide powder was dissolved in 98 g of deionized water by mechanical stirring for 10 minutes until completely dissolved to obtain a 2 wt.% potassium hydroxide solution. 5 g of hazelnut shell and 75 g of 2 wt.% potassium hydroxide solution were mixed and ultrasonically dispersed for 3 hours to ensure complete wetting. The hazelnut shell-potassium hydroxide mixture was then placed in an oven and dried at 60°C for 6 hours to obtain a hazelnut shell-potassium hydroxide solid mixture. The mixture was then crushed and placed in a high-temperature furnace and heated to 800°C at a rate of 10°C / min and held for 3 hours. The resulting material was then washed with deionized water until neutral and dried at 60°C for 3 hours to obtain a porous carbon material after in-situ carbonization. 5 g of STAC was dissolved in 95 g of deionized water by mechanical stirring for 10 minutes until completely dissolved to obtain a 5 wt.% STAC solution. 2 g of polyethylene glycol was dissolved in 98 g of deionized water by mechanical stirring for 30 minutes until completely dissolved to obtain a 2 wt.% polyethylene glycol solution. 5 g of the porous carbon material was immersed in 50 g of the STAC solution and ultrasonically treated for 5 hours. During the ultrasonic treatment, 30 g of the polyethylene glycol solution was divided into 5 equal parts and added every 6 minutes for a total of 30 minutes. After the ultrasonic treatment was complete, the sample was filtered and dried in an oven at 60°C for 4 hours to obtain a STAC-modified porous carbon material with a STAC content of 2.41%. The elemental content of the resulting material was 85.3 wt.% C, 9.54 wt.% O, and 5.16 wt.% N. The resulting material was used for adsorption experiments with polystyrene nanoplastics and tetracycline. The residual concentrations of polystyrene nanoplastics and tetracycline were 0.11 mg / L and 0.06 mg / L, respectively. The removal rates of polystyrene nanoplastics and tetracycline were 99.5% and 99.7%, respectively. Figure 6 The results show that after the hazelnut shell was modified by the two-step pore-forming-surface modification coupling technology, new N1s (N-O, C=N, C-N) characteristic peaks appeared, confirming that the STAC was successfully loaded on the surface of the porous carbon material and formed new functional groups that can adsorb pollutants through chelation or coordination.

[0036] Example 3

[0037] The hazelnut kernel outer shell produced in Tieling, Liaoning Province, was used as a carbon precursor. The hazelnut shell was mechanically broken for 10 min using a pulverizer and then sieved through a 100-mesh sieve to obtain hazelnut shell powder. 10 g of potassium hydroxide powder was dissolved in 90 g of deionized water, and mechanical stirring was performed for 10 min until a complete solution was obtained, obtaining a 10 wt.% potassium hydroxide solution. 5 g of hazelnut shell powder was mixed with 100 g of potassium hydroxide aqueous solution, and ultrasonic dispersion was performed for 2 h. Then, the hazelnut shell-potassium hydroxide mixture was placed in an oven and dried at 70°C for 4 h, obtaining a hazelnut shell-potassium hydroxide solid mixture. The obtained mixture was crushed and placed in a high-temperature furnace, and the temperature was increased to 800°C at a rate of 10°C / min, and held for 2 h. After cooling, the mixture was washed with deionized water until neutral, and then dried at 60°C for 3 h, obtaining a porous carbon material after in-situ carbonization. 10 g of HTCC was dissolved in 90 g of deionized water, and mechanical stirring was performed for 10 min until complete dissolution, obtaining a 10 wt.% HTCC solution. 5 g of polyethylene glycol was dissolved in 95 g of deionized water, and mechanical stirring was performed for 30 min until complete dissolution, obtaining a 5 wt.% polyethylene glycol aqueous solution. The porous carbon material was placed in the HTCC solution and ultrasonically treated for 4 h. During the ultrasonic treatment, 30 g of the polyethylene glycol aqueous solution was divided into two portions, and each portion was added every 5 min, with the addition being completed within 10 min. After the ultrasonic treatment was completed, the sample was filtered and dried in an oven at 60°C for 4 h, obtaining an HTCC-modified porous carbon material. The mass content of HTCC was 2.09%. The elemental content of the obtained material was 83.6 wt.% C, 11.9 wt.% O, and 4.5 wt.% N. Adsorption experiments were performed using the obtained material on polystyrene nanoplastics and tetracycline. The residual concentrations of polystyrene nanoplastics and tetracycline were 0.24 mg / L and 0.16 mg / L, respectively, and the removal efficiencies of polystyrene nanoplastics and tetracycline were 98.8% and 99.2%, respectively. Figure 3 b). The modified material had increased roughness and a porous structure Figure 5 b) with a pore size distribution of 9.15-49.2 nm Figure 7 and a pore volume of 2.43 cm 3 / g.

[0038] Comparative Example 1

[0039] STAC modified acidified biomass char material: The outer shell of hazelnut kernel produced in Tieling, Liaoning Province was used as the carbon precursor. The hazelnut shell was mechanically broken by a pulverizer for 10 min, and then passed through a 100-mesh sieve to obtain the hazelnut shell powder under the sieve. 10 g of hydrochloric acid solution was dissolved in 90 g of deionized water, and mechanically stirred for 5 min until completely dissolved to obtain a 10wt.% hydrochloric acid aqueous solution; 5 g of hazelnut shell was mixed with 100 g of hydrochloric acid aqueous solution, and ultrasonically dispersed for 2 h, then the hazelnut shell-hydrochloric acid solution mixture was filtered, and the obtained material was placed in a 60°C oven for 6 h drying; the acidified hazelnut shell was placed in a high-temperature furnace, and heated to 500°C at 10°C / min under argon environment, and kept for 2 h, then the obtained material was washed with deionized water to neutral, and dried at 60°C for 3 h to obtain an acidified carbon material. 5 g of STAC was dissolved in 95 g of deionized water, and mechanically stirred for 10 min until completely dissolved to obtain a 5wt.% STAC solution, 2 g of polyethylene glycol was poured into 98 g of deionized water, and mechanically stirred for 30 min until completely dissolved to obtain a 2wt.% polyethylene glycol aqueous solution; 5 g of porous carbon material was immersed in 50 g of STAC aqueous solution, and ultrasonically treated for 4 h, during the ultrasonic treatment, 30 g of polyethylene glycol aqueous solution was divided into 5 equal parts, and added once every 5 min, and added within 25 min, after the ultrasonic treatment, the mixture was filtered, and placed in an oven and dried at 60°C for 4 h to obtain a STAC modified acidified carbon material. The content of each element in the obtained material accounted for 80.4wt.% C, 17.9wt.% O, and 1.7wt.% N. The obtained material was subjected to polystyrene nanoplastics and tetracycline removal experiments, and it was found that the removal rates of polystyrene nanoplastics and tetracycline antibiotics were 73.8% and 69.1%, respectively, which was much lower than the effect of Example 1.

[0040] Comparative Example 2

[0041] STAC modified hydrothermal carbonized hazelnut shell material: The hazelnut shell produced in Tieling, Liaoning Province was used as the carbon precursor. The hazelnut shell was mechanically broken by a pulverizer for 10 min, and then the hazelnut shell powder passing through a 100-mesh sieve was obtained and used as a raw material. 10 g of potassium hydroxide powder was added into 90 g of deionized water, and mechanically stirred for 10 min until completely dissolved to obtain a 10wt.% potassium hydroxide solution. 5 g of hazelnut shell and 100 g of potassium hydroxide solution were mixed, and then ultrasonic treatment was performed for 5 h. Subsequently, the hazelnut shell-potassium hydroxide solution mixture was placed in a reaction kettle, and heated to 200℃ at a rate of 10℃ / min, and then kept at 200℃ for 2 h. The obtained material was washed with deionized water until neutral, and then dried at 60℃ for 3 h to obtain a hydrothermal carbonized material. 5 g of STAC was added into 95 g of deionized water, and mechanically stirred for 10 min until completely dissolved to obtain a 5wt.% STAC solution. 5 g of polyethylene glycol was added into 95 g of deionized water, and mechanically stirred for 30 min until completely dissolved to obtain a 5wt.% polyethylene glycol solution. 5 g of the hydrothermal carbonized material was immersed in 100 g of the STAC solution, and ultrasonic treatment was performed for 4 h. During the ultrasonic treatment, 30 g of the polyethylene glycol solution was evenly divided into 5 portions, and each portion was added every 5 min, and the addition was completed within 25 min. Subsequently, the sample was filtered, and then dried in an oven at 60℃ for 4 h to obtain a STAC modified hydrothermal carbonized material. Through adsorption experiments, the removal rates of polystyrene nanoplastics and tetracycline by the obtained material were 56.7% and 70%, respectively, and the adsorption performance was lower than that of the material obtained in Example 1.

[0042] Comparative Example 3

[0043] STAC modified hazelnut shell charred material: The outer shell of hazelnut kernel produced in Liaoning Tieling was used as a carbon precursor. After mechanical crushing for 10 min using a pulverizer, the hazelnut shell powder passing through a 100-mesh sieve was taken as a standby. 10 g of hazelnut shell was placed in a high-temperature furnace and heated to 800℃ at a rate of 10℃ / min, and then kept for 2 h to obtain hazelnut shell biochar material. 5 g of potassium hydroxide powder was dissolved in 95 g of deionized water by mechanical stirring for 10 min to obtain a 5wt.% potassium hydroxide aqueous solution. 5 g of biochar and 50 g of potassium hydroxide solution were mixed and ultrasonically treated for 2 h. Then the hazelnut shell biochar material-potassium hydroxide mixture was placed in an oven and dried at 60℃ for 6 h to obtain a hazelnut shell biochar material-potassium hydroxide solid mixture. 5 g of STAC was dissolved in 95 g of deionized water by mechanical stirring for 10 min to obtain a 5wt.% STAC solution. 2 g of polyethylene glycol was dissolved in 98 g of deionized water by mechanical stirring for 30 min to obtain a 2wt.% polyethylene glycol aqueous solution. 5 g of hazelnut shell biochar material was immersed in 25 g of STAC aqueous solution and ultrasonically treated for 4 h. During the ultrasonic treatment, 30 g of polyethylene glycol aqueous solution was divided into 5 equal parts and added every 5 min. After 25 min, the ultrasonic treatment was stopped. The sample was filtered and dried in an oven at 60℃ for 4 h to obtain the STAC modified biochar material. The removal efficiencies of polystyrene nanoplastics and tetracycline were 53.8% and 72.1%, respectively, which were lower than those of the material prepared in Example 1.

[0044] Comparative Example 4

[0045] Hazelnut shell derived porous carbon material: The outer shell of hazelnut kernel produced in Liaoning Tieling was used as a carbon precursor. After mechanical crushing for 10 min using a pulverizer, the hazelnut shell powder passing through a 100-mesh sieve was taken as a standby. 2 g of potassium hydroxide powder was dissolved in 98 g of deionized water by mechanical stirring for 10 min to obtain a 2wt.% potassium hydroxide aqueous solution. 5 g of hazelnut shell powder was mixed with 50 g of potassium hydroxide solution and ultrasonically dispersed for 2 h. Then the hazelnut shell-potassium hydroxide solution mixture was placed in an oven and dried at 60℃ for 6 h to obtain a hazelnut shell-potassium hydroxide solid mixture. The obtained mixture was crushed and placed in a high-temperature furnace and heated to 500℃ at a rate of 10℃ / min under an argon atmosphere, and then kept for 2 h. After cooling, the mixture was washed with deionized water until neutral, and then dried at 60℃ for 3 h to obtain a porous carbon material. The content of each element in the obtained material was 88.3wt.% C and 11.7wt.% O. The removal efficiencies of polystyrene nanoplastics and tetracycline in wastewater were 62.8% and 70.1%, respectively, which were lower than those of Example 1.

[0046] Comparative Example 5

[0047] Catalpa bungei shell unmodified porous carbon material: The outer shell of Catalpa bungei nut produced in Liaoning was used as the carbon precursor. The shell was mechanically broken by a pulverizer for 10 min, and then the shell powder was obtained by passing through a 100-mesh sieve. 2 g of potassium hydroxide powder was dissolved in 98 g of deionized water by mechanical stirring for 10 min to obtain a 2wt.% potassium hydroxide aqueous solution. 5 g of the shell powder was mixed with 50 g of the potassium hydroxide solution, and then ultrasonic dispersion was performed for 2 h. The mixture was placed in an oven and dried at 60°C for 6 h to obtain a solid mixture of the shell and potassium hydroxide. The mixture was crushed and placed in a high-temperature furnace, and then heated to 500°C at a rate of 10°C / min under an argon atmosphere. After cooling, the mixture was washed with deionized water until it was neutral, and then dried at 60°C for 3 h to obtain a porous carbon material. 1 g of STAC was dissolved in 99 g of deionized water by mechanical stirring for 10 min to obtain a 1wt.% STAC solution. 5 g of the porous carbon material was placed in 25 g of the STAC solution and ultrasonic treated for 4 h. After ultrasonic treatment, the sample was filtered and dried in an oven at 60°C for 4 h to obtain a STAC-modified biomass porous carbon material. The content of each element in the obtained material was 85.38wt.% C, 13.6wt.% O, and 1.02wt.% N. The removal rates of polystyrene nano-plastic and tetracycline were 73.4% and 82.4%, respectively, which were lower than those of the example.

[0048] Comparative example 6

[0049] STAC modified coconut shell biochar material: The outer shell of hazelnut kernel produced in Tieling, Liaoning Province was used as the carbon precursor. The hazelnut shell was mechanically broken by a grinder for 10 min and then passed through a 100-mesh sieve to obtain the hazelnut shell powder. 5 g of potassium hydroxide powder was dissolved in 95 g of deionized water by mechanical stirring for 10 min to obtain a 5wt.% potassium hydroxide solution. 5 g of coconut shell was mixed with 50 g of potassium hydroxide solution and ultrasonically dispersed for 2 h. Then the coconut shell-potassium hydroxide solution mixture was placed in an oven and dried at 60°C for 6 h to obtain a coconut shell-potassium hydroxide solid mixture with a mass loss of more than 45%. The obtained mixture was crushed and placed in a high-temperature furnace, and heated to 500°C at a rate of 10°C / min under an argon atmosphere, and then kept for 2 h. After cooling, the mixture was washed with deionized water until neutral, and then dried at 60°C for 3 h to obtain a porous carbon material. 2 g of STAC was dissolved in 98 g of deionized water by mechanical stirring for 10 min to obtain a 2wt.% STAC solution. 2 g of polyethylene glycol was dissolved in 98 g of deionized water by mechanical stirring for 30 min to obtain a 2wt.% polyethylene glycol aqueous solution. 5 g of the porous carbon material was placed in 25 g of the STAC solution and ultrasonically treated for 4 h. During the ultrasonic treatment, 30 g of the polyethylene glycol aqueous solution was divided into 5 equal parts and added every 5 min, and the addition was completed within 25 min. After the ultrasonic treatment, the sample was filtered and dried in an oven at 60°C for 4 h to obtain a STAC modified porous carbon material. The specific surface area and adsorption efficiency of the STAC modified porous carbon material were lower than those of Example 1.

[0050] Comparative Example 7

[0051] STAC modified sodium hydroxide carbonized biochar material: The outer shell of hazelnut kernel produced in Tieling, Liaoning Province was used as the carbon precursor. The hazelnut shell was mechanically broken by a pulverizer for 10 min and then sieved through a 100-mesh sieve to obtain hazelnut shell powder. 2 g of sodium hydroxide powder was dissolved in 98 g of deionized water by mechanical stirring for 10 min to obtain a 2wt.% sodium hydroxide aqueous solution. 5 g of hazelnut shell powder was mixed with 50 g of sodium hydroxide solution and ultrasonically dispersed for 2 h. Then the hazelnut shell-sodium hydroxide solution mixture was placed in an oven and dried at 60°C for 6 h to obtain a hazelnut shell-sodium hydroxide solid mixture. The obtained mixture was crushed and placed in a high-temperature furnace, heated to 500°C at 10°C / min under an argon atmosphere, and held for 2 h. After cooling, the mixture was washed with deionized water until neutral and dried at 60°C for 3 h to obtain a porous carbon material after in-situ carbonization. 1 g of STAC was dissolved in 99 g of deionized water by mechanical stirring for 10 min to obtain a 1wt.% STAC solution. 2 g of polyethylene glycol was dissolved in 98 g of deionized water by mechanical stirring for 30 min to obtain a 2wt.% polyethylene glycol aqueous solution. 5 g of the porous carbon material was placed in 25 g of the 1wt.% STAC solution and ultrasonically treated for 4 h. During the ultrasonic treatment, 30 g of the polyethylene glycol aqueous solution was divided into 5 equal parts and added every 5 min, with the addition completed within 25 min. After the ultrasonic treatment was completed, the sample was filtered and dried in an oven at 60°C for 4 h to obtain a STAC modified sodium hydroxide carbonized biochar material with a pore size range of 39.7-68.5 nm. This is because sodium hydroxide modification dissolves silicates and organic matter in the hazelnut shell through corrosion, forming a large-pore pore structure, while potassium hydroxide forms micropores and mesopores through intercalation and oxidation etching, resulting in a higher specific surface area than the porous carbon material modified by sodium hydroxide. The adsorption experiment results showed that the removal rates of polystyrene nanoplastics and tetracycline by the STAC modified sodium hydroxide carbonized biochar material were lower than those of the examples.

Claims

1. Preparation of a cationic surfactant modified porous carbon material, characterized by: The method comprises the following steps: (1) Pre-etching treatment: mixing hazelnut shell powder with a potassium hydroxide aqueous solution, mixing evenly and then drying to obtain a hazelnut shell-potassium hydroxide solid mixture; (2) In-situ carbonization: The solid mixture obtained in step (1) is crushed, placed in a high-temperature furnace under a protective atmosphere for in-situ carbonization treatment, and then washed with water to obtain a porous carbon material; (3) Surface modification: The porous carbon material obtained in step (2) is mixed with an aqueous solution of a surfactant and then ultrasonically shaken. During the ultrasonication, a polyethylene glycol solution is added, and the mixture is dried to obtain a surfactant-modified porous carbon material. In the step (3), the surfactant is one of octadecyltrimethylammonium chloride STAC and hydroxypropyltrimethylammonium chloride chitosan HTCC; When the surfactant is STAC, the concentration of the surfactant aqueous solution is 1 wt.% to 5 wt.%; and the mass ratio of the porous carbon material to the surfactant aqueous solution is 1:(5-20); When the surfactant is HTCC, the concentration of the surfactant aqueous solution is 2 wt.% to 10 wt.%; and the mass ratio of the porous carbon material to the surfactant aqueous solution is 1:(5 to 10).

2. The preparation of the cationic surfactant modified porous carbon material according to claim 1, characterized in that: In the step (1), the mass concentration of the potassium hydroxide aqueous solution is 2 wt.% to 10 wt.%; the hazelnut shell powder is crushed and passed through an 80-120 mesh sieve, and the hazelnut shell powder under the sieve is taken; the mass ratio of the crushed hazelnut shell powder to the potassium hydroxide aqueous solution is 1:(10-20); the mixing step is ultrasonic dispersion for 1-6 h; and the drying temperature is 50-80°C.

3. The preparation of the cationic surfactant modified porous carbon material according to claim 1, characterized in that: In the step (2), the in-situ carbonization process is: heating to 500-800°C at 5-10°C / min and keeping warm for 1-3 hours; the protective atmosphere is one of helium, neon and argon.

4. The preparation of the cationic surfactant modified porous carbon material according to claim 1, characterized in that: In the step (3), the concentration of the polyethylene glycol aqueous solution is 1 wt.% to 5 wt.%; the mass ratio of the porous carbon material to the polyethylene glycol aqueous solution is 1:(5-20); the ultrasonic treatment time is 1 to 6 h; during the start of the ultrasonic treatment, the polyethylene glycol aqueous solution is divided into 2 to 6 portions and added once every 5 to 6 minutes, and the addition is completed within 10 to 30 minutes; the drying temperature is 50 to 80°C.

5. The preparation of the cationic surfactant modified porous carbon material according to claim 1, characterized in that: The specific surface area of ​​the cationic surfactant modified porous carbon material is 500-800 cm 2 / g and N-containing functional groups including NO, CN and C=N.

6. The preparation of the cationic surfactant modified porous carbon material according to claim 1, characterized in that: The porous carbon material obtained in step (2) has a pore size range of 23 to 65 nm and a pore volume range of 1.65 to 2.49 cm³ / g; the surfactant-modified porous carbon material obtained in step (3) has a pore size range of 6 to 50 nm and a pore volume range of 1.78 to 3.17 cm³ / g.

7. A cationic surfactant-modified porous carbon material prepared by the method for preparing a cationic surfactant-modified porous carbon material according to any one of claims 1 to 6.

8. Use of the cationic surfactant-modified porous carbon material according to claim 7 in wastewater treatment, characterized in that: Cationic surfactant-modified porous carbon materials are used to remove plastics and / or antibiotics from wastewater, with a removal rate exceeding 98%, and are suitable for the treatment of domestic sewage and / or industrial wastewater; the plastic is one or both of polystyrene and polyethylene nanoplastics; and the antibiotic is a tetracycline antibiotic.

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