A high specific surface area hexagonal boron nitride nanotube material with tunable microporous structure, its preparation method and application

Abstract

This invention discloses a high specific surface area hexagonal boron nitride nanotube material with a tunable microporous structure, its preparation method, and its applications. The preparation method of the hexagonal boron nitride nanotube material is as follows: urea and boric acid are dissolved in ethanol-water, and continuously stirred in a water bath at 75-85°C until the solvent is completely evaporated. After drying, the powder is placed in a graphite mold and heated to 950-1050°C at a heating rate of 500-1200°C / s under inert gas protection, held for 3-8 s, and then naturally cooled to room temperature. This thermal activation process is repeated 5-8 times to finally obtain the hexagonal boron nitride nanotube material. The h-BN-ts material prepared by this invention through a unique preparation process has a specific surface area ≥1000 m². 2 / g, pore size distribution <2 nm, pore volume 0.4–1.5 cm³ 3 The excellent performance of / g effectively solves the technical problems of low adsorption efficiency and poor selectivity of traditional adsorption materials for oils, organic solvents and dye molecules.

Description

Technical Field

[0001] This invention relates to a high specific surface area hexagonal boron nitride nanotube material with a tunable microporous structure, its preparation method, and its applications. Background Technology

[0002] Oil pollutants (including waste engine oil, waste pump oil, etc.), organic solvents (such as toluene, ethylene glycol, etc.), and industrial dyes (such as methylene blue, Congo red, etc.) not only disrupt the ecological balance of aquatic bodies but may also enter the food chain through bioaccumulation. Specifically, oil pollutants form dense oil films on the water surface, severely hindering the reoxygenation process; organic solvents, due to their toxicity and persistence, may cause chronic health hazards; and some synthetic dyes have been proven to have potential carcinogenic and mutagenic risks (RSC advances, 2016, 6(67): 62411-62419; Curr Pharm Des, 2019, 25(34): 3645-3663). Therefore, developing efficient and environmentally friendly new water treatment technologies has become an important topic in the field of environmental engineering (Chemosphere, 2021, 280: 130595.).

[0003] Currently, commonly used adsorbents in the water treatment field mainly include activated carbon, zeolite molecular sieves, metal-organic frameworks (MOFs), and polymer adsorbents (Molecules, 2021, 26(21): 6628.). However, these traditional adsorbents all have obvious performance limitations: although activated carbon has a large specific surface area, its pore size distribution is too wide, resulting in poor selectivity for pollutant molecules of specific sizes, and its adsorption performance decays significantly during regeneration (Carbon, 2002, 40(12):2085-2100.); zeolite molecular sieves are limited by their fixed pore size structure, making it difficult to effectively adsorb large molecular organic pollutants; although the pore structure of MOFs is tunable, they are prone to hydrolysis or structural collapse in actual water treatment environments (Electron, 2025:e70002); and polymer adsorbents generally suffer from insufficient mechanical strength and short service life. These defects seriously restrict the practical application effect of existing adsorbents under complex water quality conditions.

[0004] Hexagonal boron nitride (h-BN), as a novel two-dimensional nanomaterial, has shown great potential in the field of environmental adsorption in recent years due to its unique graphene-like layered structure and excellent physicochemical properties (including high thermal stability, chemical inertness, and mechanical strength) (Chemosphere, 2021, 263: 127970.). However, h-BN materials prepared by traditional methods generally have a low specific surface area (typically <500 m²). 2Bottlenecks such as the difficulty in controlling the pore structure have resulted in the actual adsorption capacity falling far short of the theoretical expectation, making it difficult to meet the high-efficiency purification requirements of industrial wastewater treatment (ES Materials & Manufacturing, 2021, 16(5): 56-65). More importantly, existing h-BN materials lack precisely controllable sub-nanometer pores (<2 nm) in their microstructure, which not only limits their selective adsorption capacity for pollutants of different molecular sizes but also affects the structural stability of the material during high-temperature regeneration.

[0005] Based on the aforementioned technological status, there is an urgent need in this field to develop a technology that combines high specific surface area (>1000 m²) with... 2 A novel h-BN adsorbent material with a pore size of 1 / g and a precisely controllable microporous structure (<2 nm) is proposed. This material should be able to achieve highly efficient and selective adsorption of oils, organic solvents, and dye molecules, while also possessing excellent recyclability, thus providing a stable and reliable technical solution for industrial wastewater treatment. Summary of the Invention

[0006] This invention addresses the technical shortcomings of existing water treatment adsorption materials, such as insufficient specific surface area, uncontrollable pore size distribution, and poor regeneration performance. It provides a high specific surface area hexagonal boron nitride nanotube material with a tunable microporous structure, its preparation method, and its applications. The h-BN-ts material prepared by this invention using a unique process has a specific surface area ≥1000 m². 2 / g, pore size distribution <2 nm, pore volume 0.4-1.5 cm³ 3 The excellent performance of / g effectively solves the technical problems of low adsorption efficiency and poor selectivity of traditional adsorption materials for oils, organic solvents and dye molecules.

[0007] The technical solution adopted in this invention is as follows:

[0008] A method for preparing a high specific surface area hexagonal boron nitride nanotube (h-BN-ts) material with a tunable microporous structure includes the following steps:

[0009] Step 1, Precursor Preparation:

[0010] S1: Dissolve urea and boric acid in an ethanol-water mixed solvent at a molar ratio of 5-20:1. The ethanol-water mixed system can effectively promote the uniform dispersion and full dissolution of the raw materials.

[0011] S2: Stir continuously in a water bath at 75-85℃ until the solvent is completely evaporated; this temperature range ensures rapid evaporation of the solvent while avoiding thermal decomposition of the raw materials.

[0012] S3: The product obtained in step S2 is further dried to obtain a white solid precursor powder;

[0013] Step 2, Joule thermal activation:

[0014] 1) The precursor powder is placed in a graphite mold and stored under an inert gas atmosphere;

[0015] 2) Starting from room temperature, heat to 950-1050 ℃ at a heating rate of 500-1200 ℃ / s, hold for 3-8 s, and then allow to cool naturally to room temperature, preferably holding for 5 s;

[0016] 3) Repeat step 2) 5-8 times for cyclic processing to finally obtain hexagonal boron nitride nanotube (h-BN-ts) material. It is preferable to repeat the cyclic processing 6-7 times.

[0017] Furthermore, in step S1, the molar ratio of urea to boric acid is 8-12:1, and the volume ratio of ethanol to water is 0.5-2:1.

[0018] Furthermore, in step S3, the drying temperature is 70-90℃ and the drying time is 12-24h.

[0019] Furthermore, in step 2), the heating rate is 800-1000℃, and the final heating temperature is 1000℃±20℃.

[0020] The hexagonal boron nitride nanotube (h-BN-ts) material has a specific surface area ≥1000 m². 2 / g, pore size distribution: over 80% of pores are below 2 nm, average pore size is 1.0-2.0 nm, pore volume is 0.4-1.5 cm³. 3 / g.

[0021] This invention also discloses the application of the hexagonal boron nitride nanotube (h-BN-ts) material in the adsorption treatment of organic wastewater. The organic pollutants in the organic wastewater are at least one of dye molecules, organic solvents, and oils. The dye molecules include at least one of methylene blue, rhodamine B, rhodamine 6G, Congo red, and methyl orange. The organic solvents are one or more of toluene, xylene, ethylene glycol, ethanol, acetone, and chloroform. The oils include at least one of waste engine oil, waste pump oil, waste diesel oil, and their derivatives.

[0022] After the adsorption treatment of organic wastewater, the h-BN-ts material of the present invention also includes a material regeneration step, as detailed below:

[0023] Step 1: Centrifuge the organic wastewater containing h-BN-ts material to collect the h-BN-ts material;

[0024] Step 2: In an air atmosphere, the temperature is programmed to rise to 450-550 ℃ at a heating rate of 5-10 ℃ / min, preferably to 500 ℃ at a heating rate of 5 ℃ / min;

[0025] Step 3: Maintain a constant temperature at the target temperature for 1-3 hours to achieve pyrolysis removal of pollutants, and then cool to room temperature.

[0026] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0027] (1) Based on the boric acid-urea precursor system, this invention constructs a layered precursor by solvent ratio directional control and evaporation-induced self-assembly technology, and combines it with a rapid pyrolysis process to prepare a precursor with narrow pore size distribution (<2 nm) and excellent specific surface area (>1000 m²). 2 Microporous h-BN-ts material ( / g).

[0028] (2) The microporous boron nitride tube material prepared in this invention utilizes the unique pore topology and the synergistic effect of surface polar groups to simultaneously capture hydrophobic pollutants (mineral oil / vegetable oil, benzene series / halogenated hydrocarbons) and charged dye molecules (cationic methylene blue, anionic Congo red) in wastewater, with an adsorption capacity reaching 15-20 times the weight of the pollutants. Compared with traditional adsorption media, the microporous boron nitride tube material of this invention exhibits significant technical advantages: the adsorption kinetic rate is increased by more than 5 times (equilibrium is reached in 10 minutes), while also possessing excellent regeneration performance (maintaining 94% of the initial efficiency after 5 thermal regenerations).

[0029] (3) This invention solves the technical bottleneck of poor selectivity and difficult regeneration of existing adsorption materials, and provides a new solution for the deep purification of industrial wastewater that is both efficient and economical. Attached Figure Description

[0030] Figure 1A This is the X-ray diffraction (XRD) pattern of the h-BN-ts material in Example 1;

[0031] Figure 1B These are the N2 adsorption-desorption isotherms and corresponding pore size distribution curves of the h-BN-ts material in Example 1;

[0032] Figure 1C This is a scanning electron microscope (SEM) morphology image of the h-BN-ts material in Example 1;

[0033] Figure 1D The image shows a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image (left) and a corresponding structural simulation diagram (right) of the h-BN-ts material in Example 1.

[0034] Figure 1EThe X-ray diffraction (XRD) pattern of the h-BN-wc material in Comparative Example 1 is shown below.

[0035] Figure 1F These are the N2 adsorption-desorption isotherms and corresponding pore size distribution curves of the h-BN-wc material in Comparative Example 1;

[0036] Figure 1G This is a scanning electron microscope (SEM) morphology image of the h-BN-wc material in Comparative Example 1;

[0037] Figure 2A The UV-Vis absorption spectra of MB aqueous solution at different time intervals in the presence of h-BN-ts material in Example 1 are shown.

[0038] Figure 2B The relationship between MB removal rate and time is shown in the presence of h-BN-ts material in Example 1.

[0039] Figure 2C The results are the adsorption isotherm fitting results of MB on microporous boron nitride nanotubes (h-BN-ts);

[0040] Figure 2D The adsorption rate of MB (120 mg / L, 25 ml) aqueous solution on microporous boron nitride nanotubes (h-BN-ts) after five cycles;

[0041] Figure 2E These are the N2 adsorption-desorption isotherms and corresponding pore size distribution curves of h-BN-ts after one regeneration.

[0042] Figure 2F The UV-Vis absorption spectra of MB aqueous solution at different time intervals are shown in the presence of h-BN-wc material in Comparative Example 1.

[0043] Figure 2G The MB removal rate varies with time in the presence of h-BN-wc material in Comparative Example 1.

[0044] Figure 3A The UV-Vis absorption spectra of CR (140 mg / L, 25 ml) aqueous solution in the presence of microporous boron nitride nanotube material (h-BN-ts) at different time intervals are shown.

[0045] Figure 3B The adsorption rate of CR (140 mg / L, 25 ml) aqueous solution on microporous boron nitride nanotube material (h-BN-ts);

[0046] Figure 3C It is the adsorption isotherm of CR on microporous boron nitride nanotube material (h-BN-ts);

[0047] Figure 3D The UV-Vis absorption spectra of h-BN-wc materials synthesized in a conventional tube furnace at different time intervals are those of CR (140 mg / L, 25 ml) aqueous solution.

[0048] Figure 3E The adsorption rate of CR (140 mg / L, 25 ml) aqueous solution on h-BN-wc material synthesized in a conventional tube furnace is denoted as .

[0049] Figure 4 Comparison of absorption capacities between microporous h-BN nanotubes, h-BN-wc synthesized in a conventional tube furnace, commercial h-BN nanosheets, and activated carbon.

[0050] Figure 5 These are photographs showing the changes in microporous boron nitride nanotubes (h-BN-ts) during a 4-minute period of absorbing waste engine oil in Example 5. Detailed Implementation

[0051] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0052] Example 1: A method for preparing a high specific surface area hexagonal boron nitride nanotube (h-BN-ts) material with a tunable microporous structure, comprising the following steps:

[0053] Step 1, Precursor Preparation:

[0054] S1: Weigh urea and boric acid precisely at a molar ratio of 10:1 and dissolve them in 40 mL of a mixed solvent prepared by mixing ethanol and deionized water in a volume ratio of 1:1. Stir thoroughly to ensure complete dissolution and obtain a homogeneous precursor solution.

[0055] S2: Place the precursor solution from step S1 in a heating environment of 80°C and stir continuously until the solvent is completely evaporated to obtain a solid product.

[0056] S3: The product obtained in step S2 is transferred to an oven and dried at 80 °C for 24 h to obtain a white solid precursor;

[0057] Step 2, Joule thermal activation:

[0058] 1) The precursor powder is placed in a graphite mold and placed under nitrogen gas protection;

[0059] 2) Starting from room temperature, heat to 1000 ℃ at a heating rate of 1000 ℃ / s, hold for 5 s, and then allow to cool naturally to room temperature;

[0060] 3) The thermal cycling process in step 2) was repeated 7 times to finally obtain h-BN-ts material.

[0061] The X-ray diffraction (XRD) pattern of the h-BN-ts material in Example 1 is shown below. Figure 1A As shown, the N2 adsorption-desorption isotherms and corresponding pore size distribution curves are as follows: Figure 1B As shown, the scanning electron microscope (SEM) morphology image is as follows. Figure 1C As shown, the high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image (left) and the corresponding structural simulation diagram (right) are as follows. Figure 1D As shown.

[0062] according to Figure 1B Characterization results show that the specific surface area of ​​the h-BN material prepared in Example 1 is 1027.6 m². 2 / g, average pore size: 1.8nm, pore volume: 0.55cm³ 3 / g, the adsorption-desorption curve type is I, and the proportion of pore size below 2nm (<1.93nm) is approximately 86.4%.

[0063] Comparative Example 1: Mesoporous hexagonal boron nitride nanosheets (h-BN-wc) were prepared using a conventional tube furnace pyrolysis method. The preparation steps were the same as in Example 1, except that the pyrolysis method in the second step was changed to a conventional tube furnace. The specific process is as follows:

[0064] 1) The precursor powder is placed in a ceramic boat under nitrogen gas protection;

[0065] 2) Starting from room temperature, heat to 1000 ℃ at a heating rate of 5 ℃ / s, hold for 5 h and then cool naturally to room temperature; finally, mesoporous hexagonal boron nitride nanosheets (h-BN-wc) material synthesized by conventional tube furnace are obtained.

[0066] The X-ray diffraction (XRD) spectrum of the h-BN-wc material in Example 1 is shown below. Figure 1E As shown, the N2 adsorption-desorption isotherms and corresponding pore size distribution curves are as follows: Figure 1F As shown, the scanning electron microscope (SEM) morphology image is as follows. Figure 1G As shown in the figure. The characterization results indicate that the h-BN synthesized by conventional tubular furnace pyrolysis in Control Example 1 has a lamellar structure with a specific surface area of ​​659.6 m². 2 / g, pore volume: 0.41cm³ 3 / g, with an average pore size of 4.1nm, and an adsorption-desorption curve of type IV. The proportion of pores with a size >2nm is approximately 75.5%.

[0067] Example 2.1: Wastewater organic pollutant treatment and regeneration experiment of h-BN-ts material, the steps are as follows:

[0068] 1) Pollutant adsorption treatment:

[0069] First, a 120 mg / L methylene blue (MB) standard aqueous solution was prepared, and 25 mL of this solution was placed in a constant-temperature stirred reactor. Then, 10 mg of the h-BN-ts material from Example 1 was added, and adsorption treatment was carried out at 25 °C and 300 rpm. The absorbance change of the solution at the characteristic absorption peak of 665 nm was monitored in real time using a UV-Vis spectrophotometer. The dye removal rate was calculated according to the Lambert-Beer law, and the calculation formula is: D% = (1 - A t / A0)×100%, where A0 and A t The absorbance values ​​of the solution before and after adsorption are represented, respectively. Experimental results show that the h-BN-ts material can achieve a removal rate of 94.0% for methylene blue. Further fitting of the experimental data using the Langmuir adsorption model shows that its adsorption isotherm conforms to Q... e =Q m bC e / (1+bC e The mathematical relationship between Q and Q. e To achieve the equilibrium adsorption capacity (mg / g), Q m Where b is the maximum adsorption capacity (mg / g), b is the Langmuir constant, and C is the maximum adsorption capacity (mg / g). e The equilibrium concentration is (mg / L).

[0070] When MB pollutant adsorption treatment was performed according to the method in step 1) of Example 2.1, the UV-Vis absorption spectra of the MB aqueous solution containing h-BN-ts material at different time intervals are shown in the figure. Figure 2A The results of the change in the ratio of the residual concentration of MB in the MB aqueous solution to the initial concentration over time are shown in the figure. Figure 2B , Figure 2B The inset shows photos of samples taken at different time points, with nine sample photos from left to right corresponding to nine sampling points.

[0071] 2) Material recycling:

[0072] (a) The h-BN-ts material saturated with adsorption in MB solution was separated into solid and liquid by centrifugation at 9500 rpm for 20 min;

[0073] (b) The separated h-BN-ts material was placed in a tube furnace and heated to 500 °C at a heating rate of 5 °C / min in air atmosphere;

[0074] (c) Remove pollutants by pyrolysis at a constant temperature of 500 °C for 2 h;

[0075] (d) The recycled material is obtained after natural cooling to room temperature.

[0076] Example 2.1 Step 2) The regenerated h-BN-ts material was then subjected to an experiment of MB pollutant adsorption treatment according to the method in step 1). Thus, the h-BN-ts material underwent an adsorption-regeneration cycle experiment in sequence according to the operation process of step 1)-step 2).

[0077] Example 2.2: The experimental steps of Example 2.2 are the same as those of Example 2.1, except that "in step 1) pollutant adsorption treatment, the amount of h-BN-ts material added is changed to 50mg", and the other conditions remain unchanged.

[0078] Example 2.2 investigated the experiment involving repeated adsorption of 50 mg of MB (120 mg / L, 25 ml) aqueous solution on microporous boron nitride nanotubes (h-BN-ts). The change in the ratio of the remaining MB concentration to the initial concentration over time after five cycles of adsorption is shown in the figure. Figure 2D As shown. Figure 2D The illustrations, from left to right, show the appearance of fresh h-BN-ts material, h-BN-ts material after the first adsorption of MB to saturation, and h-BN-ts material after the first to fifth pyrolysis regeneration cycles, after drying. Experimental results show that after five complete adsorption-regeneration cycles, the average adsorption capacity retention rate of the h-BN-ts material for MB pollutants is >90%.

[0079] The material's specific surface area change rate after each regeneration was less than 35%, and the pore size distribution remained stable. The N2 adsorption-desorption isotherms and corresponding pore size distribution curves of the h-BN-ts material after the first pyrolysis regeneration following MB adsorption saturation are shown below. Figure 2E As shown, the specific surface area of ​​h-BN-ts after one regeneration is 756.6 m². 2 / g, with an average pore size of 1.8nm. It can be seen that after one application-regeneration cycle, the average pore size of the h-BN-ts material did not change, but the specific surface area decreased. The reason for this is speculated to be: from Figure 2E The pore structure has not collapsed, so the average pore size remains at 1.8 nm. However, a small portion of the BN may have oxidized to boron trioxide, leading to a slight decrease in specific surface area.

[0080] The adsorption isotherm fitting results of MB on microporous boron nitride nanotubes (h-BN-ts) are shown below. Figure 2C . Figure 2C The inset photos, from top to bottom, show the appearance of fresh h-BN-ts material and h-BN-ts material after the first adsorption of MB saturation, respectively, after drying.

[0081] Example 2.3: The experimental steps of Example 2.3 are the same as those of Example 2.1, except that "in step 1) pollutant adsorption treatment, the h-BN-ts material is replaced with the h-BN-wc material of control example 1 of equal mass", and the other conditions remain unchanged.

[0082] In step 1) of Example 2.3, the UV-Vis absorption spectra of the MB aqueous solution containing h-BN-wc material at different time intervals during MB pollutant adsorption treatment are shown below. Figure 2F The results of the change in the ratio of the residual concentration of MB in the MB aqueous solution to the initial concentration over time are shown in the figure. Figure 2G .

[0083] Example 3: Wastewater organic pollutant treatment using h-BN-ts material. The steps are as follows: First, 140 mg of Congo Red (CR) dye was dissolved in deionized water to prepare a 140 mg / L standard CR solution. 25 mL of this solution was placed in a constant-temperature magnetic stirrer, and 10 mg of h-BN-ts material from Example 1 was added. Adsorption was performed at 300 rpm under 25 ± 1 °C. The absorbance of the solution was monitored periodically at a characteristic wavelength of 498 nm using a UV-Vis spectrophotometer. The dye removal rate was calculated according to Beer-Lambert's law, using the formula: D% = (1 - A) / ( ... t / A0)×100%, where A0 and A t The absorbance values ​​of the solution before and after adsorption are represented respectively. Experimental results show that the microporous boron nitride nanotube material (h-BN-ts) can achieve a removal rate of 98.5% for Congo red dye. Further fitting analysis of the experimental data using the Langmuir adsorption model shows that its adsorption isotherm conforms to Q... e =Q m bC e / (1+bC e The mathematical relationship between Q and Q. e To achieve the equilibrium adsorption capacity (mg / g), Q m b is the theoretical maximum adsorption capacity (mg / g), b is the Langmuir adsorption constant (L / mg), and C is the theoretical maximum adsorption capacity (mg / g). e The equilibrium concentration is (mg / L).

[0084] When performing CR pollutant adsorption treatment, the UV-Vis absorption spectra of the CR aqueous solution containing h-BN-ts material at different time intervals are shown in the figure. Figure 3A The results of the change in the ratio of the residual CR concentration to the initial concentration in the CR aqueous solution over time are shown in the figure. Figure 3B , Figure 3B The inset shows photos of samples taken at different time points, with nine sample photos from left to right corresponding to nine sampling points.

[0085] The adsorption isotherm fitting results of CR on microporous boron nitride nanotubes (h-BN-ts) are shown below. Figure 3C . Figure 3C The inset photos, from top to bottom, show the appearance of fresh h-BN-ts material and h-BN-ts material after the first adsorption CR saturation, respectively, after drying.

[0086] As a comparative experiment, we conducted the same wastewater organic pollutant treatment experiment on the h-BN-wc material synthesized in a conventional tube furnace as on the h-BN-ts material. The wastewater organic pollutant treatment process was repeated, with the only difference being that "the h-BN-ts material of Example 1 was replaced with an equal mass of the h-BN-wc material of Control Example 1," while all other conditions remained unchanged. The final experimental results are as follows:

[0087] 1) When performing CR pollutant adsorption treatment, the UV-Vis absorption spectra of the CR aqueous solution containing h-BN-wc material at different time intervals are shown in the figure. Figure 3D ;

[0088] 2) The change in the ratio of the residual CR concentration to the initial concentration in the CR aqueous solution over time under the adsorption of h-BN-wc material is shown in the figure. Figure 3E .

[0089] Example 4: A method for removing organic pollutants (ethanol, toluene, ethylene glycol, waste pump oil, and waste engine oil) from wastewater using h-BN-ts materials. The specific operating steps are as follows:

[0090] 1) Place 20 mg of h-BN-ts material from Example 1 into a stoppered graduated cylinder (the empty stoppered graduated cylinder needs to be weighed in advance), and add an excess (20-25 mL) of solvent or oil (ethanol, toluene, ethylene glycol, waste pump oil or waste engine oil) to ensure that the solvent or oil completely submerges the h-BN-ts material.

[0091] 2) After sealing, let stand at room temperature overnight to ensure h-BN-ts adsorption saturation;

[0092] 3) Slowly pour out the unadsorbed liquid on the top layer, retain the saturated h-BN-ts material, and quickly measure the weight to avoid evaporation of the absorbed solvent or oil.

[0093] The adsorption capacity is calculated by the mass difference of the material before and after adsorption. The formula is: Adsorption capacity (mg / g) = [(m3-m1)-(m2-m1)]×1000 / m2. Where: m1 is the mass of the empty graduated cylinder (g), m2 is the mass of h-BN-ts material + empty graduated cylinder (g), and m3 is the total mass after adsorption (g).

[0094] As a comparative experiment, the same testing procedure was used to conduct parallel tests on commercial non-porous boron nitride nanosheets (i.e., commercial h-BN), h-BN-wc synthesized in a conventional tube furnace as control example 1, and activated carbon to compare the adsorption performance of different adsorbent materials. The aforementioned commercial h-BN was purchased from Hangzhou Jigong Biotechnology Co., Ltd., brand: Macklin (CAS No.: 10043-11-5).

[0095] The absorption capacity comparison results of microporous h-BN-TS material in Example 1, h-BN-WC synthesized in a conventional tube furnace in Control Example 1, commercial h-BN nanosheets, and activated carbon are shown in the figure. Figure 4 .

[0096] Example 5: A method for treating waste oil pollution on the water surface using h-BN material. The specific implementation steps are as follows: Take 20 mg of h-BN-ts material from Example 1 and evenly spread it on the surface of seawater contaminated with waste oil. Due to its superhydrophobicity and high specific surface area, this microporous boron nitride nanotube material can quickly adsorb waste oil pollutants diffused on the water surface. During the natural adsorption process, the microporous boron nitride nanotube material gradually changes from white to dark, indicating its continuous adsorption of waste oil. After adsorption saturation (approximately 2-3 hours), use a filter or other tools to retrieve and recover the microporous boron nitride nanotube material after adsorbing organic pollutants from the water surface. Testing shows that this method can achieve a removal efficiency of over 95% for waste oil on the water surface, and the recovered microporous boron nitride nanotube material can be recycled through heat treatment (400-550 °C). Compared with traditional activated carbon adsorbents, the microporous boron nitride nanotube material used in this invention has higher adsorption selectivity, faster adsorption rate and better water surface dispersibility, making it particularly suitable for emergency response to sudden oil pollution events such as marine oil spills.

[0097] The images show the changes in microporous boron nitride nanotubes (h-BN-ts) during a 4-minute period of absorbing waste engine oil, such as... Figure 5 As shown.

[0098] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.

Claims

1. Application of a hexagonal boron nitride nanotube material in the adsorption treatment of organic wastewater, characterized in that, The specific surface area of the hexagonal boron nitride nanotube material is ≥1000 m 2 / g, and the pore size distribution is that the pore size of 80% or more is below 2 nm, and the pore volume is 0.4-1.5 cm 3 / g; The preparation method of the hexagonal boron nitride nanotube material comprises the following steps: Step 1, preparation of a precursor: S1: Dissolve urea and boric acid in an ethanol-water mixed solvent according to a molar ratio of 8-12:1; S2: Stir continuously in a 75-85℃ water bath until the solvent is completely evaporated; S3: Further dry the product obtained in step S2 to obtain a white solid precursor powder; Step 2, Joule heat activation: 1) Put the precursor powder into a graphite mold under inert gas protection; 2) Start from room temperature, heat to 950-1050℃ at a heating rate of 800-1000℃ / s, keep for 3-8s, and then naturally cool to room temperature; 3) Repeat the operation of step 2) for 5-8 times for cyclic treatment, and finally obtain the hexagonal boron nitride nanotube material, denoted as: h-BN-ts.

2. Use according to claim 1, wherein In step S1, the volume ratio of ethanol-water is 0.5-2:

1.

3. The use according to claim 1, wherein In step S3, the drying temperature is 70-90℃, and the drying time is 12-24h.

4. The use according to claim 1, characterized in that In step 2), the final heating temperature is 1000℃±20℃.

5. The use according to claim 1, characterized in that The organic pollutants in the organic wastewater are at least one of dye molecules, organic solvents and oil substances.

6. The use according to claim 5, characterized in that The dye molecules include at least one of methylene blue, rhodamine B, rhodamine 6G, congo red and methyl orange, the organic solvents are one or more of toluene, xylene, ethylene glycol, ethanol, acetone and chloroform, and the oil substances include at least one of waste engine oil, waste pump oil, waste diesel oil and derivatives thereof.

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