A modified nanofiber material, its preparation method and application

Abstract

The present invention belongs to the technical field of adsorption materials, and particularly relates to a modified nanofiber material, a preparation method thereof, and an application. The raw materials for preparing the modified nanofiber material of the present invention include modified nanocellulose, a temperature-responsive monomer, and an initiator; the modified nanocellulose is obtained by modifying nanocellulose with a copper-manganese-iron composite network magnetic auxiliary agent. By using a specific copper-manganese-iron composite magnetic auxiliary agent to modify nanocellulose, the present invention obtains modified nanocellulose, and under the action of an initiator, the modified nanocellulose and the temperature-responsive monomer act together, so that the modified nanofiber material has good adsorption performance, dual magnetic and temperature responses, can be separated by a magnetic field during separation, and at the same time, the adsorbed target pollutants can be eluted by changing the temperature, realizing the low-cost recovery and regeneration of the adsorbent, and solving the problems of difficult recovery of traditional water treatment adsorbents after use and secondary pollution caused by the regeneration of the adsorbent.

Description

Technical Field

[0001] The present invention belongs to the technical field of adsorption materials, and particularly relates to a modified nanofiber material, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of industry and agriculture, a large amount of wastewater and waste gas are discharged, causing certain harm to the atmospheric environment and water environment. Water pollution has become an important problem and challenge that needs to be solved urgently at present.

[0003] Currently, in the field of wastewater treatment, wastewater is mainly treated by adding adsorption materials such as activated carbon and zeolite biodegradable materials. However, after these adsorption materials are added to the wastewater and adsorbed for a certain period of time, generally, filtration or centrifugation is required to separate the adsorption materials from the pollutants in the wastewater, so as to realize the recovery of the adsorption materials. However, this method still has problems such as incomplete separation, resulting in secondary pollution and difficult recovery of the adsorption materials, and further treatment is required to achieve better separation, which correspondingly increases the additional treatment cost. In addition, there is currently a technology that uses hydrogels for wastewater treatment, but the adsorption performance is difficult to meet the usage requirements, and the adsorption performance needs to be further improved. Moreover, after adsorption, an acidic solution needs to be used for soaking to elute the adsorbed pollutants. The use of the acidic solution not only increases the process flow and the post-treatment cost, but also causes pollution to a certain extent.

[0004] Therefore, it is of great significance to provide an adsorption material with good adsorption performance, which can achieve low-cost recovery and regeneration and will not cause secondary pollution. Summary of the Invention

[0005] The present invention aims to solve one or more of the above-mentioned technical problems existing in the prior art, and at least provides a beneficial choice or creates conditions. Specifically, the present invention provides a modified nanofiber material, which has good adsorption performance, can achieve low-cost recovery and regeneration of the adsorption material, and will not cause secondary pollution; it solves the problems of difficult recovery of traditional water treatment adsorbents after use and secondary pollution caused by the regeneration of adsorbents.

[0006] Inventive concept of the present invention: The raw materials for preparing the modified nanofiber material of the present invention include modified nanocellulose, temperature-responsive monomer, and initiator; the modified nanocellulose is obtained by modifying nanocellulose with a copper-manganese-iron composite magnetic aid. By using a specific copper-manganese-iron composite magnetic aid to modify nanocellulose, the present invention obtains modified nanocellulose, and under the action of an initiator, the modified nanocellulose and the temperature-responsive monomer act together, so that the modified nanofiber material has dual responses to magnetism and temperature, and has good adsorption performance; during separation, the magnetic modified nanofiber material can be separated through a magnetic field, and at the same time, the adsorbed target pollutants can be eluted by changing the temperature, realizing the low-cost recovery and regeneration of the adsorbent modified nanofiber material, and solving the problems of difficult recovery of traditional water treatment adsorbents after use and secondary pollution caused by adsorbent regeneration.

[0007] Therefore, a first aspect of the present invention provides a modified nanofiber material.

[0008] Specifically, the raw materials for preparing the modified nanofiber material include modified nanocellulose, temperature-responsive monomer, and initiator;

[0009] The modified nanocellulose is obtained by modifying nanocellulose with a copper-manganese-iron composite magnetic aid.

[0010] Preferably, the copper-manganese-iron composite magnetic aid includes copper chloride, manganese chloride, and iron chloride; the molar ratio of iron chloride to copper chloride and manganese chloride is (0.5-1.5):(0.5-1.5):1.

[0011] More preferably, the copper-manganese-iron composite network magnetic aid includes copper chloride, manganese chloride, and iron chloride; the molar ratio of iron chloride to copper chloride and manganese chloride is (0.8-1.2):(0.8-1.2):1.

[0012] Even more preferably, the copper-manganese-iron composite network magnetic aid includes copper chloride, manganese chloride, and iron chloride; the molar ratio of iron chloride to copper chloride and manganese chloride is 1:1:1.

[0013] Preferably, the copper-manganese-iron composite magnetic aid includes FeCl3·6H2O, CuCl2·2H2O, and MnCl2·4H2O.

[0014] Specifically, the present invention uses a copper-manganese-iron composite magnetic additive prepared by compounding specific types of copper chloride, manganese chloride, and iron chloride. Iron-manganese and manganese-copper can both form a layered structure through hydrothermal reactions. When the three additives of copper chloride, manganese chloride, and iron chloride coexist, the formation of a monoclinic-tetragonal phase interface with a large number of defects inhibits the growth of nanoparticles, which is conducive to maintaining a small crystal size and a high surface area, and finally generates a complex three-dimensional network morphology with excellent adsorption performance. That is, using the copper-manganese-iron composite magnetic additive to modify nanocellulose can not only endow the material with magnetic response ability but also enhance the adsorption performance of the modified nanofiber material.

[0015] Preferably, the diameter of the nanocellulose is 1-110 nm; more preferably, the diameter of the nanocellulose is 1-100 nm.

[0016] Preferably, the nanocellulose is nanofibers prepared by a mechanical method or an acid hydrolysis method using fiber raw materials from natural sources, including at least one of cellulose nanocrystals (CNC) and nanocellulose (CNF).

[0017] Specifically, CNF is obtained by a mechanical method, and CNC is obtained by an acid hydrolysis method.

[0018] Preferably, the mass ratio of the modified nanocellulose to the temperature-responsive monomer is (0.8-12):1; more preferably, the mass ratio of the modified nanocellulose to the temperature-responsive monomer is (0.9-11):1; even more preferably, the mass ratio of the modified nanocellulose to the temperature-responsive monomer is (1-10):1.

[0019] Preferably, the mass ratio of the initiator to the temperature-responsive monomer is 1:(40-120); more preferably, the mass ratio of the initiator to the temperature-responsive monomer is 1:(45-110); even more preferably, the mass ratio of the initiator to the temperature-responsive monomer is 1:(50-100).

[0020] Preferably, the temperature-responsive monomer includes at least one of N-isopropylacrylamide (NIPAM), polyethylene oxide ether (PEO), and polyvinylpyrrolidone (PVP).

[0021] Preferably, the initiator includes at least one of potassium persulfate, ammonium persulfate, and sodium persulfate.

[0022] The second aspect of the present invention provides a preparation method of the modified nanofiber material described in the first aspect of the present invention.

[0023] Specifically, the preparation method of the modified nanofiber material includes the following steps:

[0024] Mix the raw material components and react to obtain the modified nanofiber material.

[0025] Preferably, the temperature of the reaction is 55 - 85°C; the time of the reaction is 0.5 - 2.2 h; more preferably, the temperature of the reaction is 60 - 80°C; the time of the reaction is 0.5 - 2 h.

[0026] Preferably, the preparation method of the modified nanofiber material includes the following steps:

[0027] Mix the modified nanocellulose with the temperature-responsive monomer, stir at a constant temperature, then add the initiator and react to obtain the modified nanofiber material.

[0028] Preferably, the modified nanofiber material is separated by a magnet, washed and then reserved for use.

[0029] Preferably, constant-temperature stirring is maintained during the reaction process.

[0030] Preferably, the preparation method of the modified nanocellulose includes the following steps:

[0031] Mix the nanocellulose, the copper-manganese-iron composite magnetic additive and water, adjust the pH to alkaline, and react to obtain the modified nanocellulose.

[0032] Preferably, a pH regulator is used to adjust the pH to alkaline.

[0033] Specifically, the modified nanocellulose is prepared from nanocellulose, a copper-manganese-iron composite network magnetic additive and a pH regulator through a hydrothermal reaction. Compared with the preparation of modified nanocellulose by solid-phase reaction, the reaction rate of the hydrothermal reaction for preparing modified nanocellulose in the present invention is higher, the equipment requirements are lower, and compared with the preparation of modified nanocellulose by organic-phase reaction, the present invention is environmentally friendly and has no secondary pollution.

[0034] Specifically, the addition amount of water is preferably just enough to disperse the nanocellulose, and the solid content of the nanocellulose is controlled to be less than 5%.

[0035] Preferably, the pH regulator includes ammonia water.

[0036] Preferably, the mass concentration of the ammonia water is 20 - 30%; more preferably, the mass concentration of the ammonia water is 22 - 27%; even more preferably, the mass concentration of the ammonia water is 25%.

[0037] Preferably, the temperature of the reaction is 150 - 250 °C, the time of the reaction is 0.5 - 2.2 h, and the pH of the reaction is 8 - 11; more preferably, the temperature of the reaction is 180 - 220 °C, the time of the reaction is 0.5 - 2 h, and the pH of the reaction is 9 - 10.

[0038] The third aspect of the present invention provides an application of the modified nanofiber material described in the first aspect of the present invention in wastewater or waste gas treatment.

[0039] Compared with the prior art, the beneficial effects of the technical solution provided by the present invention are as follows:

[0040] (1) The preparation raw materials of the modified nanofiber material of the present invention include modified nanocellulose, temperature-responsive monomer, and initiator; the modified nanocellulose is obtained by modifying nanocellulose with a copper-manganese-iron composite magnetic additive. By using a specific copper-manganese-iron composite magnetic additive to modify nanocellulose, the present invention obtains modified nanocellulose, and under the action of an initiator, the modified nanocellulose and the temperature-responsive monomer act together, so that the modified nanofiber material has good adsorption performance, magnetic and temperature dual response. During separation, the magnetic modified nanofiber material can be separated by a magnetic field. At the same time, by changing the temperature, the adsorbed target pollutants can be eluted, realizing the low-cost recovery and regeneration of the adsorbent, and solving the problems of difficult recovery of traditional water treatment adsorbents after use and secondary pollution caused by adsorbent regeneration.

[0041] (2) The preparation process of the present invention is simple and convenient for large-scale production and application. Description of the Drawings

[0042] Figure 1 It is the scanning electron microscope image of the modified nanofiber material prepared in Example 1 of the present invention;

[0043] Figure 2 It is the Fourier transform infrared spectrum of the modified nanofiber material prepared in Example 1 of the present invention;

[0044] Figure 3 It is the atomic force microscope test result image of the nanocellulose and the modified nanofiber material in Example 1 of the present invention;

[0045] Figure 4 It is the adsorption curve graph of the modified nanofiber material prepared in Example 1 of the present invention for methylene blue and copper ions. Detailed Embodiments

[0046] In order to make those skilled in the art more clearly understand the technical solution described in the present invention, the following examples are listed for illustration. It should be noted that the following examples do not limit the protection scope required by the present invention.

[0047] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial channels or can be obtained by existing known methods.

[0048] The raw material components and dosages (g) of Examples 1-6 and Comparative Examples 1-6 of the present invention are shown in Table 1.

[0049] Table 1: Raw material components and dosages (g) of Examples 1-6 and Comparative Examples 1-6

[0050]

[0051] In Table 1, "-" indicates not added.

[0052] Example 1

[0053] A modified nanofiber material, the raw materials for its preparation include modified nanocellulose, N-isopropylacrylamide, and an initiator; the dosages of each component are shown in Table 1.

[0054] A preparation method of a modified nanofiber material, comprising the following steps:

[0055] (1) Add modified nanocellulose and N-isopropylacrylamide to a reaction vessel, set the temperature to 70 °C and keep stirring at a constant temperature, then add the initiator and keep stirring at a constant temperature;

[0056] (2) Set the reaction time to 1 h, after the reaction, separate and take out the product with a magnet and wash it for standby to obtain a hydrogel, which is the modified nanofiber material.

[0057] Among them, the preparation method of the modified nanocellulose includes the following steps:

[0058] Add nanocellulose (CNF) to a reaction vessel and keep stirring at a constant temperature, then add FeCl3·6H2O, CuCl2·2H2O and MnCl2·4H2O, and mix evenly; then add ammonia water with a mass concentration of 25%, adjust the pH value of the solution to 9, continue to stir evenly and then add it to a high-pressure reaction kettle, set the temperature to 200 °C and react for 2 h, and the obtained modified nanocellulose is separated with a magnet and washed for standby.

[0059] The modified nanofiber material prepared in Example 1 was observed by scanning electron microscopy, and the scanning electron micrograph is as Figure 1 shown, from Figure 1 it can be seen that the nanocellulose shows a honeycomb-like porous structure after modification, and at the same time, the magnetically modified magnetic particles are evenly distributed in the pore structure.

[0060] The Fourier transform infrared spectroscopy (FTIR) test was carried out on the modified nanofiber material prepared in Example 1, and the FTIR diagram is as Figure 2 shown.

[0061] The atomic force microscopy (AFM) test was carried out on the nanocellulose of Example 1 and the modified nanofiber material of Example 1. The AFM test results are as Figure 3 shown, where Figure 3 Figure (a) in Figure 3 is the AFM test result diagram of the nanocellulose in Example 1, and

[0062] From Figure 2 it can be seen that the peaks at 3340 cm -1 , 2898 cm -1 and 1621 cm -1 (corresponding to the stretching vibration of the O-H bond, the stretching vibration of the C-H bond, and the O-H bending respectively) are the peaks of the matrix material nanocellulose; the peaks at 1636 cm -1 and 1556 cm -1 come from poly(N-isopropylacrylamide) (PNIPAM) chains, corresponding to the N-H stretching and C=O stretching of amide I respectively; the peak at 1378 cm -1 is generated by the PNIPAM (-CH(CH3)2) group; the above results indicate that the magnetic-temperature dual-responsive modified nanofiber material was successfully prepared.

[0063] From Figure 3 it can be seen that the nanocellulose showed a linear and uniformly dispersed microstructure before modification. After magnetic modification and temperature-responsive modification, it presented a porous structure, and the magnetic particles were uniformly dispersed in the modified nanocellulose.

[0064] Example 2

[0065] A modified nanofiber material, the preparation raw materials of which include modified nanocellulose, N-isopropylacrylamide, and initiator; the dosages of each component are shown in Table 1.

[0066] A preparation method of a modified nanofiber material, comprising the following steps:

[0067] (1) Add the modified nanocellulose and N-isopropylacrylamide into a reaction vessel, set the temperature to 70 °C and keep stirring at a constant temperature, and then add the initiator and keep stirring at a constant temperature;

[0068] (2) Set the reaction time to 1 h. After the reaction, separate and take out the product with a magnet and wash it for standby to obtain a hydrogel, which is the modified nanofiber material.

[0069] Among them, the preparation method of the modified nanocellulose includes the following steps:

[0070] Add nanocellulose (CNF) into a reaction vessel, keep stirring at a constant temperature, then add FeCl3·6H2O, CuCl2·2H2O and MnCl2·4H2O, and after mixing evenly; then add ammonia water with a mass concentration of 25%, adjust the pH value of the solution to 9, continue to stir evenly and then add it to a high-pressure reaction kettle, set the temperature to 250 °C and react for 2 h, and the obtained modified nanocellulose is separated by a magnet and washed for later use.

[0071] Example 3

[0072] A modified nanofiber material, the preparation raw materials of which include modified nanocellulose, N-isopropylacrylamide, and an initiator; the dosage of each component is shown in Table 1.

[0073] A preparation method of a modified nanofiber material includes the following steps:

[0074] (1) Add the modified nanocellulose and N-isopropylacrylamide into a reaction vessel, set the temperature to 65 °C and keep stirring at a constant temperature, and then add the initiator and keep stirring at a constant temperature;

[0075] (2) Set the reaction time to 0.5 h, separate the product by a magnet after the reaction, take it out and wash it for later use to obtain a hydrogel, which is the modified nanofiber material.

[0076] Among them, the preparation method of the modified nanocellulose includes the following steps:

[0077] Add nanocellulose (CNF) into a reaction vessel, keep stirring at a constant temperature, then add FeCl3·6H2O, CuCl2·2H2O and MnCl2·4H2O, and after mixing evenly; then add ammonia water with a mass concentration of 25%, adjust the pH value of the solution to 9, continue to stir evenly and then add it to a high-pressure reaction kettle, set the temperature to 200 °C and react for 2 h, and the obtained modified nanocellulose is separated by a magnet and washed for later use.

[0078] Example 4

[0079] A modified nanofiber material, the preparation raw materials of which include modified nanocellulose, polyoxyethylene ether, and an initiator; the dosage of each component is shown in Table 1.

[0080] A preparation method of a modified nanofiber material includes the following steps:

[0081] (1) Add the modified nanocellulose and polyoxyethylene ether into a reaction vessel, set the temperature to 70 °C and keep stirring at a constant temperature, and then add the initiator and keep stirring at a constant temperature;

[0082] (2) Set the reaction time to 1 h. After the reaction, use a magnet to separate and take out the product, wash it and set it aside to obtain a hydrogel, which is the modified nanofiber material.

[0083] Among them, the preparation method of the modified nanocellulose includes the following steps:

[0084] Add nanocellulose (CNF) into a reaction vessel, keep stirring at a constant temperature, then add FeCl3·6H2O, CuCl2·2H2O and MnCl2·4H2O, and mix evenly; then add ammonia water with a mass concentration of 25%, adjust the pH value of the solution to 9, continue to stir evenly and then add it to a high-pressure reaction kettle, set the temperature to 200 °C and react for 2 h. The obtained modified nanocellulose is separated by a magnet, washed and set aside.

[0085] Example 5

[0086] A modified nanofiber material, the preparation raw materials of which include modified nanocellulose, polyvinylpyrrolidone, and initiator; the dosage of each component is shown in Table 1.

[0087] A preparation method of a modified nanofiber material includes the following steps:

[0088] (1) Add the modified nanocellulose and polyvinylpyrrolidone into a reaction vessel, set the temperature to 70 °C and keep stirring at a constant temperature, and then add the initiator and keep stirring at a constant temperature;

[0089] (2) Set the reaction time to 1 h. After the reaction, use a magnet to separate and take out the product, wash it and set it aside to obtain a hydrogel, which is the modified nanofiber material.

[0090] Among them, the preparation method of the modified nanocellulose includes the following steps:

[0091] Add nanocellulose (CNF) into a reaction vessel, keep stirring at a constant temperature, then add FeCl3·6H2O, CuCl2·2H2O and MnCl2·4H2O, and mix evenly; then add ammonia water with a mass concentration of 25%, adjust the pH value of the solution to 10, continue to stir evenly and then add it to a high-pressure reaction kettle, set the temperature to 200 °C and react for 2 h. The obtained modified nanocellulose is separated by a magnet, washed and set aside.

[0092] Example 6

[0093] A modified nanofiber material, the preparation raw materials of which include modified nanocellulose, polyvinylpyrrolidone, and initiator; the dosage of each component is shown in Table 1.

[0094] A preparation method of a modified nanofiber material includes the following steps:

[0095] (1) Add the modified nanocellulose and polyvinylpyrrolidone into a reaction vessel, set the temperature at 70 °C and keep stirring constantly. Then add the initiator and keep stirring constantly.

[0096] (2) Set the reaction time to 1 h. After the reaction, separate and take out the product with a magnet and wash it for standby to obtain the hydrogel, which is the magnetic modified nanofiber material.

[0097] Among them, the preparation method of the modified nanocellulose includes the following steps:

[0098] Add nanocellulose (CNF) into a reaction vessel and keep stirring constantly. Then add FeCl3·6H2O, CuCl2·2H2O and MnCl2·4H2O. After mixing evenly; then add ammonia water with a mass concentration of 25%, adjust the pH value of the solution to 9, continue to stir evenly and then add it to a high-pressure reactor. Set the temperature at 200 °C and react for 2 h. The obtained modified nanocellulose is separated with a magnet and washed for standby.

[0099] Comparative Example 1

[0100] The difference between Comparative Example 1 and Example 2 is only that Comparative Example 1 did not use the copper-manganese-iron composite network magnetic auxiliary agent to modify the nanocellulose, that is, an equal amount of nanocellulose was used to replace the modified nanocellulose in Example 1, and the others were the same as Example 2.

[0101] Specifically, the preparation method of the modified nanofiber material in Comparative Example 1 includes the following steps:

[0102] (1) Add nanocellulose and N-isopropylacrylamide into a reaction vessel, set the temperature at 70 °C and keep stirring constantly. Then add the initiator and keep stirring constantly.

[0103] (2) Set the reaction time to 1 h. After the reaction, filter and separate the product with filter paper and wash it for standby to obtain the hydrogel, that is, the modified nanofiber material.

[0104] Comparative Example 2

[0105] The difference between Comparative Example 2 and Example 2 is that the preparation raw materials of the modified nanofiber material in Comparative Example 2 only contain modified nanocellulose and do not contain an initiator and a temperature-responsive monomer.

[0106] The preparation method of the modified nanocellulose in Comparative Example 2 is the same as that in Example 2.

[0107] Comparative Example 3

[0108] The difference between Comparative Example 3 and Example 3 is only that Comparative Example 3 changed the reaction temperature in the preparation process of the modified nanofiber material, and the others were the same as Example 3.

[0109] Specifically, the preparation method of the modified nanofiber material in Comparative Example 3 includes the following steps:

[0110] (1) Add the modified nanocellulose and N-isopropylacrylamide into a reaction vessel, set the temperature at 50 °C and keep stirring at a constant temperature. Then add the initiator and keep stirring at a constant temperature;

[0111] (2) Set the reaction time to 0.5 h. After the reaction, separate and take out the product with a magnet and wash it for standby to obtain a hydrogel, which is the modified nanofiber material.

[0112] Among them, the preparation method of the modified nanocellulose includes the following steps:

[0113] Add nanocellulose (CNF) into a reaction vessel and keep stirring at a constant temperature. Then add FeCl3·6H2O, CuCl2·2H2O and MnCl2·4H2O. After mixing evenly; then add ammonia water with a mass concentration of 25%, adjust the pH value of the solution to 9, continue to stir evenly and then add it to a high-pressure reaction kettle. Set the temperature at 200 °C and react for 2 h. The obtained modified nanocellulose is separated with a magnet and washed for standby.

[0114] Comparative Example 4

[0115] The difference between Comparative Example 4 and Example 1 is only that Comparative Example 4 uses an equal amount of MnCl2·4H2O to replace CuCl2·2H2O, that is, it does not contain CuCl2·2H2O, and the others are the same as Example 1.

[0116] The preparation methods of the modified nanofiber material and the modified nanocellulose in Comparative Example 4 are the same as those in Example 1.

[0117] Comparative Example 5

[0118] The difference between Comparative Example 5 and Example 1 is only that Comparative Example 5 uses an equal amount of CuCl2·2H2O to replace MnCl2·4H2O, that is, it does not contain MnCl2·4H2O, and the others are the same as Example 1.

[0119] The preparation methods of the modified nanofiber material and the modified nanocellulose in Comparative Example 5 are the same as those in Example 1.

[0120] Comparative Example 6

[0121] The difference between Comparative Example 6 and Example 1 is only that Comparative Example 6 uses an equal amount of CuCl2·2H2O to replace FeCl3·6H2O, that is, it does not contain FeCl3·6H2O, and the others are the same as Example 1.

[0122] The preparation methods of the modified nanofiber material and the modified nanocellulose in Comparative Example 6 are the same as those in Example 1.

[0123] Performance Test

[0124] 1. Adsorption performance and response performance tests

[0125] The adsorption performance and response performance of the modified nanofiber materials prepared in Examples 1-6 and Comparative Examples 1-6 were tested. The test methods are as follows:

[0126] Adsorption performance test: The adsorption performance of the modified nanofiber materials prepared in Examples 1-6 and Comparative Examples 1-6 was tested using the dye methylene blue (MB) as an indicator. First, a stock solution of the dye with a concentration of 1000 mg / L was prepared and then diluted to 20 mg / L to obtain the test solution (dye solution). During the experiment, at 25 °C, 10 mg of the modified nanofiber materials prepared in Examples 1-6 and Comparative Examples 1-6 were respectively added to 10 mL of the dye solution with a concentration of 20 mg / L to obtain a mixture. Then, the mixture was placed on a TS110X30 vibrating sieve and tested at a stirring speed of 150 rpm. After a predetermined time (1 h), the concentration of the dye was measured using a UV spectrophotometer. According to the test results, the saturated adsorption capacity of the dye (Qe, mg / g of modified nanofiber material) can be obtained.

[0127] Response performance test: 10 mg of each of the modified nanofiber materials prepared in Examples 1-6 and Comparative Examples 1-6 were respectively added to 10 mL of the dye solution (the same dye solution as in the adsorption performance test) with a concentration of 20 mg / L (initial concentration C0) to obtain a mixture. The mixture was placed on the above-mentioned TS110X30 vibrating sieve at a temperature of 25 °C and kept for 2 hours to reach equilibrium. The concentration of the dye was measured using a UV spectrophotometer and denoted as C1. Then, the removal efficiency R1% of the dye was calculated according to the initial concentration (R1% = (C0 - C1) / C0 × 100%); the temperature was fixed at 37 °C and kept for another 2 hours to reach equilibrium. The concentration of the dye was measured using a UV spectrophotometer and denoted as C2, and the removal efficiency R2% of the dye was calculated (R2% = (C0 - C2) / C0 × 100%). Then, the temperature was fixed at 25 °C and kept for another 2 hours to reach equilibrium. The concentration of the dye was measured using a UV spectrophotometer and denoted as C3, and the removal efficiency R3% of the dye was calculated (R3% = (C0 - C3) / C0 × 100%).

[0128] The performance test results of the modified nanofiber materials prepared in Examples 1-6 and Comparative Examples 1-6 are shown in Table 2.

[0129] Table 2: Performance test results of the modified nanofiber materials prepared in Examples 1-6 and Comparative Examples 1-6

[0130]

[0131]

[0132] As can be seen from Table 2, the modified nanofiber material of the present invention has good adsorption performance. When the temperature rises to 37 °C, the removal rate of the modified nanofiber material for dyes decreases. When the temperature drops back to 25 °C, the removal rate of the modified nanofiber material for dyes increases significantly again, indicating that the modified nanofiber material of the present invention has good temperature response performance.

[0133] It can be seen from Example 1, Example 4 and Example 5 that changing the type of temperature-responsive monomer has little difference in the influence on the adsorption performance and responsiveness, but the adsorption performance is the best when N-isopropylacrylamide is used as the temperature-responsive monomer. It can be seen from Example 1 and Example 2 that increasing the proportion of the temperature-responsive monomer during the reaction can increase the temperature response characteristics of the modified nanofiber material. At the same time, magnetic modification makes there be more Fe-OH bonds in the structure of the modified nanofiber material, further increasing its dye adsorption performance. It can be seen from Example 2 and Example 3 that increasing the amount of initiator within a certain range will improve the performance of the modified nanofiber material.

[0134] In Comparative Example 1, the nanocellulose was not modified, resulting in the poor dye adsorption performance of the modified nanofiber material in Comparative Example 1 compared to Example 2, indicating that magnetic modification can not only endow the modified nanofiber material with magnetic response ability, but also enhance the ability of the modified nanofiber material to adsorb dyes.

[0135] In Comparative Example 2, no temperature-responsive monomer was added, resulting in no obvious change in the removal rate of the modified nanofiber material for dyes when the temperature changes, indicating that the modified nanofiber material in Comparative Example 2 has no temperature response behavior for dye adsorption.

[0136] In Comparative Example 3, the reaction temperature during the preparation of the modified nanofiber material was changed, resulting in the modified nanofiber material in Comparative Example 3 not only having no temperature responsiveness but also having poor adsorption ability, indicating that the preparation process of the modified nanofiber material needs to be carried out under specific conditions.

[0137] It can be seen from Comparative Example 4, Comparative Example 5 and Comparative Example 6 that the lack of any one of CuCl2·2H2O, FeCl3·6H2O and MnCl2·4H2O will reduce the adsorption performance of the modified nanofiber material, indicating that the formation of the copper-manganese-iron composite network is the guarantee for the excellent adsorption performance of the modified nanofiber material, and none of the three can be missing.

[0138] In addition, the present invention also tested the maximum adsorption capacities of the modified nanofiber materials of Example 1, Example 2, and Comparative Examples 1-6 for MB and Cu 2+ Specifically, a 500 mg / L MB solution and a solution containing Cu 2+The solution was used as the mother liquor, and 1 g of the modified nanofiber material of Example 1, Example 2, and Comparative Examples 1-6 was added to 10 mL of the mother liquor at 25° C. to obtain a mixture, and then the mixture was placed on a TS110X30 vibrating screen and tested at a stirring speed of 150 rpm; after a predetermined time (2 h), MB and Cu were tested using an ultraviolet spectrophotometer and an inductively coupled plasma mass spectrometer (ICP-MS). 2+ The concentration of MB and Cu in each group of modified nanofiber materials was calculated. 2+ The actual maximum adsorption capacity of the modified nanofiber material for MB and Cu is shown in Table 3. 2+ The adsorption curve of Figure 4 shown.

[0139] Table 3: Effect of modified nanofiber materials of Example 1, Example 2, Comparative Examples 1-6 on MB and Cu 2+ The maximum adsorption capacity

[0140]

[0141] It can be seen from Table 3 that the modified nanofiber material of the present invention has a significant effect on the performance of MB and Cu 2+ All of them have high maximum adsorption capacity, indicating that their adsorption performance is good.

[0142] Comparative Example 1 did not modify the nanocellulose, so that the modified nanofiber material of Comparative Example 1 had no significant effect on MB and Cu 2+ The maximum adsorption capacity of the modified nanofiber material is significantly lower than that of Example 2, indicating that the magnetic modification gives the modified nanofiber material a stable three-dimensional network structure, which not only gives the modified nanofiber material magnetic responsiveness, but also enhances the ability of the modified nanofiber material to adsorb dyes. 2+ The maximum adsorption capacity of the modified nanofiber material is significantly lower than that of Example 2. Comparative Example 3 changes the reaction temperature during the preparation of the modified nanofiber material, so that the modified nanofiber material of Comparative Example 3 has a high adsorption capacity for MB and Cu. 2+ The maximum adsorption capacity is low. Compared with Example 1, Comparative Examples 4-6 lack one of CuCl2·2H2O, FeCl3·6H2O, and MnCl2·4H2O, respectively, that is, no copper-manganese-iron composite network is formed, and the adsorption effect is worse than that of Example 1, indicating that only by using copper chloride, manganese chloride and ferric chloride to modify nanocellulose, forming a copper-manganese-iron composite network and the modified nanocellulose and the temperature-responsive monomer work together, and are prepared at a certain reaction temperature, can the modified nanofiber material have a higher adsorption capacity and achieve effective adsorption of pollutants.

[0143] 2. Cycle performance test

[0144] In Example 1 and Comparative Example 4, the modified nanofiber material was regenerated through an elution step (adding the adsorbed modified nanofiber material to 100 mL of 0.01 mol / L dilute hydrochloric acid, raising the temperature to 37 °C, and performing elution at a stirring speed of 150 rpm. After a predetermined time (2 h), the modified nanofiber material was separated by a magnet, washed 3 times with deionized water, and set aside), and then used again for the adsorption of MB and Cu 2+ . The adsorption was carried out for a total of 5 regeneration cycles, and the saturated adsorption capacity of each regeneration cycle was tested. The test method for the saturated adsorption capacity was the same as the test method for the dye saturated adsorption capacity in the above adsorption performance and response performance tests. The experimental data of the saturated adsorption capacity of each regeneration cycle are shown in Table 4.

[0145] Table 4: Saturated adsorption capacities of the modified nanofiber materials in Example 1 and Comparative Example 4 for MB and copper ions (5 regeneration cycles)

[0146]

[0147] As can be seen from Table 4, after five regeneration cycles, the modified nanofiber material in Example 1 of the present invention still has good adsorption effect, and its adsorption capacity slightly decays, showing good recyclability. The recyclability of the modified nanofiber material in Comparative Example 4 is poor.

[0148] In summary, the present invention modifies nanocellulose by using a specific copper-manganese-iron composite magnetic additive to obtain modified nanocellulose. Under the action of an initiator, the modified nanocellulose and the temperature-responsive monomer act together, so that the modified nanofiber material has good adsorption performance, magnetic and temperature dual-responsive performance. The modified nanofiber material with magnetism can be separated by a magnetic field during separation. At the same time, by changing the temperature, the adsorbed target pollutants can be eluted, realizing the low-cost recovery and regeneration of the adsorbent, and solving the problems of difficult recovery of traditional water treatment adsorbents after use and secondary pollution caused by the regeneration of adsorbents.

[0149] The above embodiments are only used to illustrate the technical solutions of the present invention and do not limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A modified nanofiber material, characterized in that, The raw materials for its preparation include modified nanocellulose, temperature-responsive monomer, and initiator; The modified nanocellulose is prepared by a hydrothermal reaction from nanocellulose, a copper-manganese-iron composite network magnetic aid, and a pH regulator; The copper-manganese-iron composite magnetic aid includes copper chloride, manganese chloride, and iron chloride; the molar ratio of iron chloride, copper chloride, and manganese chloride is (0.5 - 1.5):(0.5 - 1.5):

1.

2. The modified nanofiber material according to claim 1, wherein The mass ratio of the modified nanocellulose to the temperature-responsive monomer is (0.8 - 12):

1.

3. The modified nanofiber material according to claim 1, wherein The mass ratio of the initiator to the temperature-responsive monomer is 1:(40 - 120).

4. The modified nanofiber material according to any one of claims 1-3, characterized in that The temperature-responsive monomer includes at least one of N-isopropylacrylamide, polyethylene oxide ether, and polyvinylpyrrolidone; and / or, the initiator includes at least one of potassium persulfate, ammonium persulfate, and sodium persulfate.

5. The preparation method of the modified nanofiber material according to any one of claims 1-4, characterized in that, It includes the following steps: Mix the raw material components and react to obtain the modified nanofiber material.

6. The preparation method according to claim 5, characterized in that, The temperature of the reaction is 55 - 85 °C; the time of the reaction is 0.5 - 2.2 h.

7. The preparation method according to claim 5, wherein The preparation method of the modified nanocellulose includes the following steps: Mix the nanocellulose, copper-manganese-iron composite magnetic aid, and water, adjust the pH to alkaline, and react to obtain the modified nanocellulose.

8. The preparation method according to claim 7, characterized in that, The temperature of the reaction is 150 - 250 °C, the time of the reaction is 0.5 - 2.2 h, and the pH of the reaction is 8 - 11.

9. The application of the modified nanofiber material according to any one of claims 1 - 4 in wastewater or waste gas treatment.

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