CN115888658A - Cationized lignocellulose nanofiber adsorbent and preparation method and application thereof - Google Patents
Cationized lignocellulose nanofiber adsorbent and preparation method and application thereof Download PDFInfo
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Abstract
The invention discloses a cationized lignocellulose nanofiber adsorbent and a preparation method and application thereof, wherein bagasse is used as a raw material, the bagasse is sequentially crushed, washed and dried, then placed in a eutectic solvent, 2, 3-epoxypropyltrimethylammonium chloride is added for cationic modification, the mixture is stirred at room temperature for reaction, then centrifugally washed, and then dispersed with water until the solid concentration is 0.5-2 wt%, and the cationized lignocellulose nanofiber adsorbent is prepared under the condition of high-pressure homogenization. The invention takes bagasse as a raw material to prepare the cationized lignocellulose nanofiber adsorbent through pretreatment and mechanical microfibrillation processes, the preparation process is green and simple, the reaction condition is mild, the energy consumption is low, the product has the advantages of reproducibility and degradability and uniform size, and the prepared adsorbent with positive charges on the surface can efficiently adsorb and remove dissolved and colloidal substances in wastewater.
Description
Technical Field
The invention belongs to the technical field of nano-cellulose, and particularly relates to a cationized lignocellulose nano-fiber adsorbent as well as a preparation method and application thereof.
Background
Sugarcane is a gramineous economic crop with wide distribution and large storage capacity, and the annual yield of the sugarcane is billions of tons. Bagasse is a waste produced in the sugar industry, and countless bagasse is produced every year. The components of the composite material are stable and uniform, the content of lignocellulose reaches more than 90%, wherein the content of cellulose is 40% -50%, the content of hemicellulose is 20% -25%, the content of lignin is 16% -25%, and the composite material is an inexhaustible lignocellulose biomass resource. Bagasse is mostly used as a biomass fuel or directly discarded, and a small portion is used for pulp and paper making, feed and fertilizer. In general, bagasse has the prominent problems of low utilization rate and low utilization value.
Generally, the conversion of lignocellulosic biomass into other higher value-added biological or chemical products requires pretreatment, which can destroy the dense hierarchical structure thereof and improve fiber accessibility. The eutectic solvent is a pretreatment solvent which is different from a traditional solvent with high toxicity and poor biocompatibility, and is a liquid eutectic mixture formed by mixing two or three substances capable of forming hydrogen bonds, and the freezing point of the eutectic solvent is lower than that of any one single substance. The eutectic solvent has the characteristics of good biocompatibility, lower vapor pressure, high thermal stability, designability and the like, so that the eutectic solvent becomes a green substitute of the traditional molecular solvent for lignocellulose pretreatment.
The nano-cellulose is a high value-added product obtained by performing nano-crystallization on cellulose fibers by using mechanical, biological, chemical and other methods, the fiber diameter is 3-100 nm, and the length-diameter ratio is more than 10. In recent years, nanocellulose, which has the advantages of high specific surface area, abundant chemical modification sites and the like, has been proposed as a novel adsorbent, and the adsorption performance of the nanocellulose is comparable to that of a commercial adsorbent. However, the removal of lignin and hemicellulose from lignocellulose is required to obtain the cellulose fiber raw material, and the removal processes such as cooking and bleaching have the problems of complicated flow, high consumption and great pollution. Therefore, a scheme for preparing the high-performance nano adsorption material by directly taking lignocellulose as a raw material is provided. At present, the method for preparing nano-cellulose from natural lignocellulose has the limitations of using toxic and harmful chemicals, high energy consumption and high water consumption. In addition, the nano-cellulose prepared by the mechanical method generally has the defects of wide diameter distribution range and nonuniform size, and the natural fibers with compact structure and firm texture are easy to be intertwined to cause the blockage and abrasion of a high-pressure homogenizer.
The dissolved and colloidal substances are pollutants which are continuously accumulated in the closed circulation system of the white water for papermaking along with the rising of the recycling degree, and the existence of the dissolved and colloidal substances can influence the stable operation of a paper machine, weaken the quality performance of paper and weaken the effect of papermaking additives. Polygalacturonic acid is a representative model contaminant of dissolved and colloidal matter in papermaking wastewater, and its removal, and most other dissolved and colloidal matter, are negatively charged in water, is a serious problem facing the papermaking industry. The traditional methods for dissolving and removing colloidal substances include air floatation, mechanical screening, chemical fixation, biological enzyme method, etc. Compared with the methods, the adsorption method has the advantages of low cost, simple and convenient operation and mature technology, but also has the limitations of low adsorption efficiency, low adsorption quantity and unrenewable materials. In order to overcome the defects, a natural polymer adsorbent which is nontoxic, degradable, renewable and efficient is rapidly researched. Therefore, a green preparation method for efficiently converting the bagasse, which is an agricultural waste, into a natural, renewable and lignocellulose nanofiber adsorbent with high adsorption efficiency is urgently needed, and the green preparation method is applied to dissolution in wastewater and efficient removal of colloidal substances.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a cationized lignocellulose nanofiber adsorbent and a preparation method thereof.
Another object of the present invention is to provide the use of the cationized lignocellulose nanofiber adsorbent.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
(1) Collecting raw materials: crushing, washing and drying bagasse;
(2) Pretreatment: adding the bagasse treated in the step (1) into a eutectic solvent synthesized by tetraethylammonium hydroxide (TEAOH) solution and 1, 3-dimethylurea (1, 3-DMU), uniformly mixing, adding 2, 3-epoxypropyltrimethylammonium chloride for cationic modification, reacting for a period of time under the conditions of mechanical stirring and room temperature, and adding excessive deionized water to terminate the reaction;
(3) Washing: washing the bagasse treated in the step (2) to be neutral by centrifugation;
(4) Mechanical microfibrillation: and (4) collecting the bagasse treated in the step (3), re-dispersing the bagasse in deionized water, and performing high-pressure homogenization treatment to obtain the cationized lignocellulose nanofiber adsorbent.
And (2) crushing the bagasse in the step (1), and collecting bagasse powder with the mesh number of 40-80 meshes for washing.
And (2) washing the bagasse in the step (1) by soaking and washing with clear water and soaking and washing with ethanol, and repeating the steps for multiple times until the washing liquid is clear.
The drying temperature of the bagasse in the step (1) is 50-70 ℃.
The eutectic solvent in the step (2) is synthesized by tetraethylammonium hydroxide solution and 1, 3-dimethylurea, wherein the concentration of the tetraethylammonium hydroxide solution is 35%, and the molar ratio of the tetraethylammonium hydroxide to the 1, 3-dimethylurea is 1: and 2, uniformly mixing to obtain a transparent colorless solution, namely the eutectic solvent.
The mass ratio of the bagasse adding amount in the step (2) to the eutectic solvent is 1:9.
the mass ratio of the adding amount of the 2, 3-epoxypropyltrimethylammonium chloride in the step (2) to the bagasse is (1-3): 1.
the reaction formula of the reaction in step (2) is as follows:
the reaction process of the step (2) is carried out for 8-24 h under the mechanical stirring with the rotating speed of 200-500 rpm.
The reaction temperature in the step (2) is 20-30 ℃.
And (3) adding deionized water which is 3-10 times of the volume of the reaction mixture after the reaction in the step (2) is finished to terminate the reaction.
The rotation speed of the centrifugation in the step (3) is 4000-6000 rpm, and the centrifugation time is 10-20 min.
And (3) in the washing process, the precipitate is collected by centrifugation and then dispersed in deionized water again for centrifugation, and the operation is repeated until the pH value of the supernatant is neutral, so that the precipitate can be collected for the next step.
And (4) adding deionized water into the bagasse collected in the step (4) to prepare a suspension with the concentration of 0.5-2 wt%.
The high-pressure homogenizing condition in the step (4) is 900-1100 bar, and the cycle time is 3-15 times.
The cationized lignocellulose nanofiber adsorbent prepared by any one of the methods described above.
The prepared cationized lignocellulose nanofiber adsorbent is applied to removal of dissolved and colloidal substances in wastewater.
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) The production strategy of the cationized lignocellulose nanofiber adsorbent provided by the invention has the advantages of low cost and high utilization rate of raw materials. Compared with the conventional fiber raw materials such as cotton, wood and the like, the bagasse belongs to agricultural industrial waste, and the cost of the raw materials is almost zero; meanwhile, the processes of delignification and hemicellulose removal with high consumption and high pollution are avoided, the reserved lignin and hemicellulose can participate in cation modification to become a source of adsorbability of the nano adsorbent, the utilization rate of raw materials is effectively improved, and the method is suitable for expanded production.
(2) The production strategy of the cationized lignocellulose nanofiber adsorbent provided by the invention also has the advantages of environmental friendliness and low energy consumption. The used fiber pretreatment solvent is a eutectic solvent synthesized by tetraethyl ammonium hydroxide solution and 1, 3-dimethyl urea, which is a low-toxicity biodegradable green environment-friendly solvent. The compound can fully swell lignocellulose, provides an alkaline environment to deprotonate hydroxyl groups of the cellulose, hemicellulose and lignin, has higher activity on the ring opening reaction of a cationizing agent 2, 3-epoxypropyltrimethylammonium chloride, and effectively grafts a quaternary ammonium group; compared with the traditional mechanical method for preparing the nano-cellulose, the charged groups introduced on the fibers by modification can generate electrostatic repulsion among the fibers, effectively promote the dissociation of the fibers, obviously reduce the energy consumption of high-pressure homogenization, and simultaneously, the reserved lignin component can also reduce the energy consumption required by the high-pressure homogenization.
(3) The cationized lignocellulose nanofiber adsorbent produced by the invention has the advantages of uniform size, high adsorption efficiency, large adsorption capacity and natural reproducibility. The quaternary ammonium groups grafted on the fibers are modified to have positive charges, so that the size of the produced cationized lignocellulose nanofiber adsorbent can be promoted to be more uniform, and electronegative dissolution and colloid in wastewater can be efficiently adsorbed through electrostatic interaction; meanwhile, the raw material of the nanofiber adsorbent is bagasse, and the storage capacity in the nature is huge and is continuous.
Drawings
FIG. 1 is a flow diagram of the preparation of a cationized lignocellulosic nanofiber adsorbent;
FIG. 2 is a pictorial representation of a cationized lignocellulosic nanofiber prepared in example 1;
FIG. 3 is a transmission electron micrograph (a) and a particle size distribution (b) of the cationized lignocellulosic nanofibers prepared in example 1;
FIG. 4 is an optical microscope photograph of bagasse as it is (a) after pretreatment in example 4 (b);
FIG. 5 is a Fourier transform infrared spectrum of non-cationized lignocellulosic nanofibers from bagasse as such, in a comparative example, and the cationized lignocellulosic nanofibers from example 4;
FIG. 6 shows the adsorption removal rate of polygalacturonic acid, a representative model contaminant for both soluble and colloidal species, for each adsorbent.
Detailed Description
The present invention will be described in more detail and clearly in the following examples, which should not be construed as limiting the invention.
Example 1
The embodiment provides a preparation method of a cationized lignocellulose nanofiber adsorbent, which comprises the following specific steps:
(1) Collecting raw materials: crushing bagasse by using a crusher, collecting 40-60-mesh bagasse by using 40-mesh and 60-mesh screens, repeatedly soaking and washing with deionized water and ethanol until washing liquid is clear, and then completely drying in a 60 ℃ drying oven;
(2) Pretreatment: and (2) adding 36g of bagasse treated in the step (1) into a eutectic solvent with the mass being 9 times that of the bagasse, wherein the eutectic solvent is prepared by mixing the components in a molar ratio of 1:2, mixing a 35% tetraethylammonium hydroxide solution and 1, 3-dimethylurea, uniformly mixing bagasse and a eutectic solvent, adding 2, 3-epoxypropyltrimethylammonium chloride with the mass being 2 times that of the bagasse to perform cationic modification, performing reaction at room temperature of 20 ℃ for 24 hours under mechanical stirring of 200rpm, and adding deionized water with the volume being 3 times that of the reaction mixture into the reaction mixture to terminate the reaction;
(3) Washing: repeatedly carrying out centrifugal washing at 6000rpm for 10min on the bagasse treated in the step (2) until washing liquid is neutral;
(4) Mechanical microfibrillation: and (4) collecting the bagasse treated in the step (3), re-dispersing the bagasse in deionized water to prepare a suspension with the concentration of 2wt%, uniformly stirring, and performing high-pressure homogenization treatment with the pressure of 900bar and the cycle number of 3 times to obtain the cationized lignocellulose nanofiber adsorbent.
Fig. 2 is a pictorial view of a representation of the cationized lignocellulosic nanofiber prepared in example 1, which has a yellow jelly-like appearance.
Fig. 3 is a transmission electron micrograph (a) and a particle size distribution (b) of the cationized lignocellulose nanofibers prepared in example 1. According to a transmission electron microscope image, the diameter of the prepared cationized lignocellulose nanofiber reaches the nanometer level, and the average diameter of the cationized lignocellulose nanofiber is 5.9 +/-1.1 nm as shown in a particle size distribution diagram obtained by randomly measuring 150 nanofibers, so that the cationized lignocellulose nanofiber has a narrow diameter distribution range and a uniform size.
Comparative example
This comparative example provides a comparison of a method of making non-cationized lignocellulosic nanofibers, comprising the steps of:
(1) Collecting raw materials: crushing bagasse by using a crusher, collecting 60-80-mesh bagasse by using 60-mesh and 80-mesh screens, repeatedly soaking and washing the bagasse by using deionized water and soaking and washing the bagasse by using ethanol until washing liquid is clear, and then completely drying the bagasse in a 60 ℃ drying oven;
(2) Pretreatment: and (2) adding 10g of bagasse treated in the step (1) into a eutectic solvent with the mass being 9 times that of the bagasse, wherein the eutectic solvent is prepared from a mixture of a raw material and a solvent, wherein the molar ratio of the eutectic solvent is 1:2, mixing a 35% tetraethylammonium hydroxide solution and 1, 3-dimethylurea, uniformly mixing bagasse and a eutectic solvent, then adding no 2, 3-epoxypropyltrimethylammonium chloride, reacting at room temperature of 30 ℃ for 8 hours under mechanical stirring of 400rpm, and after the reaction is finished, adding deionized water which is 10 times of the volume of the reaction mixture into the reaction mixture to terminate the reaction;
(3) Washing: repeatedly carrying out centrifugal washing on the bagasse treated in the step (2) at 4000rpm for 20min until a washing liquid is neutral;
(4) Mechanical microfibrillation: collecting the bagasse treated in the step (3), re-dispersing the bagasse in deionized water to prepare 0.5wt% suspension, mechanically crushing the suspension by a shearing machine with the rotating speed of 3000rpm and the time of 2 hours, uniformly stirring the suspension, and performing high-pressure homogenization treatment with the pressure of 1100bar and the cycle number of 15 times to obtain the non-cationized lignocellulose nanofiber.
Example 2
The embodiment provides a preparation method of a cationized lignocellulose nanofiber adsorbent, which comprises the following specific steps:
(1) Collecting raw materials: crushing bagasse by using a crusher, collecting 60-80-mesh bagasse by using 60-mesh and 80-mesh screens, repeatedly soaking and washing the bagasse by using deionized water and soaking and washing the bagasse by using ethanol until washing liquid is not obviously turbid, and completely drying the bagasse in a 50 ℃ drying oven;
(2) Pretreatment: and (2) adding 10g of bagasse treated in the step (1) into a 9-time mass eutectic solvent, wherein the eutectic solvent is prepared by mixing the components in a molar ratio of 1:2, mixing a 35% tetraethylammonium hydroxide solution and 1, 3-dimethylurea, uniformly mixing bagasse and a eutectic solvent, adding 2, 3-epoxypropyltrimethylammonium chloride with the mass being 1 time that of the bagasse to perform cationic modification, performing reaction at room temperature of 30 ℃ for 8 hours under mechanical stirring of 400rpm, and adding deionized water with the volume being 10 times that of the reaction mixture into the reaction mixture to terminate the reaction;
(3) Washing: repeatedly carrying out centrifugal washing on the bagasse treated in the step (2) at 4000rpm for 10min until a washing liquid is neutral;
(4) Mechanical microfibrillation: and (4) collecting the bagasse treated in the step (3), re-dispersing the bagasse in deionized water to prepare 0.5wt% suspension, uniformly stirring, and performing high-pressure homogenization treatment at the pressure of 1000bar and the cycle number of 15 times to obtain the cationized lignocellulose nanofiber adsorbent.
Example 3
The embodiment provides a preparation method of a cationized lignocellulose nanofiber adsorbent, which comprises the following specific steps:
(1) Collecting raw materials: crushing bagasse by using a crusher, collecting 60-80-mesh bagasse by using 60-mesh and 80-mesh screens, repeatedly soaking and washing with deionized water and ethanol until washing liquid is not obviously turbid, and completely drying in a 60 ℃ drying oven;
(2) Pretreatment: and (2) adding 10g of bagasse treated in the step (1) into a 9-time mass eutectic solvent, wherein the eutectic solvent is prepared by mixing the components in a molar ratio of 1:2, mixing a 35% tetraethylammonium hydroxide solution and 1, 3-dimethylurea, uniformly mixing bagasse and a eutectic solvent, adding 2, 3-epoxypropyltrimethylammonium chloride with the mass being 2 times that of the bagasse to perform cationic modification, performing reaction at room temperature of 30 ℃ for 8 hours under mechanical stirring of 400rpm, and adding deionized water with the volume being 10 times that of the reaction mixture to terminate the reaction;
(3) Washing: repeatedly carrying out centrifugal washing on the bagasse treated in the step (2) at 5000rpm for 15min until washing liquid is neutral;
(4) Mechanical microfibrillation: and (4) collecting the bagasse treated in the step (3), re-dispersing the bagasse in deionized water to prepare 0.5wt% suspension, uniformly stirring, and performing high-pressure homogenization treatment at the pressure of 1000bar and the cycle number of 15 times to obtain the cationized lignocellulose nanofiber adsorbent.
Example 4
The embodiment provides a preparation method of a cationized lignocellulose nanofiber adsorbent, which comprises the following specific steps:
(1) Collecting raw materials: crushing bagasse by using a crusher, collecting 60-80-mesh bagasse by using 60-mesh and 80-mesh screens, repeatedly soaking and washing the bagasse by using deionized water and soaking and washing the bagasse by using ethanol until washing liquid is clear, and completely drying the bagasse in a 70 ℃ drying oven;
(2) Pretreatment: and (2) adding 10g of bagasse treated in the step (1) into a 9-time mass eutectic solvent, wherein the eutectic solvent is prepared by mixing the components in a molar ratio of 1:2, mixing a 35% tetraethylammonium hydroxide solution and 1, 3-dimethylurea, uniformly mixing bagasse and a eutectic solvent, adding 2, 3-epoxypropyltrimethylammonium chloride with the mass being 3 times that of the bagasse to perform cationic modification, performing reaction at room temperature of 30 ℃ for 8 hours under mechanical stirring of 500rpm, and adding deionized water with the volume being 10 times that of the reaction mixture into the reaction mixture to terminate the reaction;
(3) Washing: repeatedly carrying out centrifugal washing on the bagasse treated in the step (2) at 4000rpm for 20min until washing liquid is neutral;
(4) Mechanical microfibrillation: and (4) collecting the bagasse treated in the step (3), re-dispersing the bagasse in deionized water to prepare 0.5wt% suspension, uniformly stirring, and performing high-pressure homogenization treatment at the pressure of 1000bar and the cycle number of 15 times to obtain the cationized lignocellulose nanofiber adsorbent.
Example 5
This example presents the results of measurements of surface charge density of non-cationized lignocellulosic nanofibers in comparative example and the cationized lignocellulosic nanofibers in examples 2,3, 4, zeta potential of 0.1wt% suspension, nanofiber yield and relative crystallinity by centrifugation, as shown in table 1.
TABLE 1 Performance index
From the data in Table 1, it was found that by increasing the amount of 2, 3-epoxypropyltrimethylammonium chloride used as a cationizing agent during the preparation, the surface charge density and the Zeta potential gradually increased and shifted from the negative value of the comparative example to a positive value, it was confirmed that the cationizing agent introduced positively charged groups into the bagasse, and as the amount of the cationizing agent added increased, the number of the charged groups grafted onto the fibers also increased accordingly; along with the increase of the using amount of the cationizing agent, the yield of the nano-fiber is gradually increased, which shows that the content of the fiber with the size reaching the nanometer level in the final product is increased, but the comparative example without the cationizing agent has the phenomenon of blocking a cavity in the high-pressure homogenizing process, the high-pressure homogenizing is difficult to carry out without mechanical crushing in advance by a shearing machine, and the bagasse which is subjected to cation modification in an adverse way can easily pass through the high-pressure homogenizing machine, which shows that the charged groups introduced on the fiber can generate electrostatic repulsion among the fibers, effectively promote the dissociation of the fiber and obviously reduce the energy consumption of the high-pressure homogenizing; as the amount of cationizing agent used increases, the relative crystallinity of the cationized lignocellulose nanofibers decreases due to the destruction and partial depolymerization of the crystalline regions of the cellulose caused by electrostatic repulsion after the fibers are grafted with charged groups, and the more charged groups are grafted, the more significant the destruction and depolymerization.
Fig. 4 is an optical microscope image of bagasse as it is (a) and bagasse (b) pretreated in example 4, and comparing the two images, it can be observed that the size of bagasse fiber is significantly reduced and its compact and complete hierarchical structure is also dissociated by the pretreatment with the eutectic solvent and the cationizing agent.
FIG. 5 is a Fourier transform infrared spectrum of virgin bagasse, non-cationized lignocellulosic nanofibers in the comparative example, and the cationized lignocellulosic nanofibers in example 4, and it was found that the non-cationized lignocellulosic nanofibers in the comparative example were 1733cm in comparison to virgin bagasse -1 The characteristic vibrational peak at (C = O) disappears because the natural ester bonds (acetyl of hemicellulose, ferulic acid of lignin/hemicellulose and ester bonds to carboxyl groups in coumaric acid) are destroyed by pretreatment with eutectic solvents; in example 4, the cationized lignocellulose nanofibers were compared to bagasse as is, except 1733cm -1 The characteristic vibration peak at (C = O) disappears, and is also at 1484cm -1 A C-N telescopic vibration band representing quaternary ammonium groups appears, which indicates that the bagasse is pretreated by the eutectic solvent and the cationizing agent, the natural ester bond is damaged, and the quaternary ammonium groups are introduced into the bagasse.
Example 6
The embodiment provides an application of the cationized lignocellulose nanofiber adsorbent in removing dissolved and colloidal substances in wastewater, and the specific implementation mode is as follows:
adsorbent the cationic lignocellulose nanofibers of example 2, example 3 and example 4 were selected as the control, the non-cationic lignocellulose nanofibers of the control were used as the control, and the adsorbent was selected as the representative model of colloidal substances dissolved in wastewater, polygalacturonic acid was used as the contaminant. The amount of adsorbent in the adsorption experiment was 1g/L and the concentration of polygalacturonic acid was 400mg/L (i.e. 10mL of 0.5wt% adsorbent solution was mixed with 40mL of 500mg/L polygalacturonic acid solution) and the adsorption was carried out at 25 deg.C for 6h with stirring at 300 rpm. After adsorption, the mixed solution is centrifuged, supernatant fluid is obtained and filtered by a filter membrane with the diameter of 0.22 mu m, 1mL of filtered supernatant fluid is absorbed and transferred into a test tube, and 0.5mL of 0.1wt% carbazole is addedAnd (5) continuously shaking the ethanol solution until white precipitates appear. Adding 6mL concentrated sulfuric acid in 7s quickly, putting into water bath at 85 deg.C immediately, reacting for 10min, taking out, cooling from water bath to room temperature, and measuring its absorbance at 530nm with ultraviolet-visible spectrophotometer immediately. By standard curve (R) 2 = 0.9998) the change in contaminant concentration before and after adsorption was calculated, and the adsorption capacity and removal rate of each adsorbent were obtained.
The adsorption performance of the non-cationized lignocellulose nanofibers in the comparative example and the cationized lignocellulose nanofibers in examples 2,3 and 4 are shown in table 2.
TABLE 2 adsorption Performance of the adsorbents
From the data in table 2 and the adsorption removal rate of polygalacturonic acid by each adsorbent in fig. 6, it can be seen that the effect of non-cationized lignocellulose nanofibers on removing polygalacturonic acid in wastewater is very small in comparative example, while the cationized lignocellulose nanofibers in examples 2,3 and 4 are all subjected to cation modification to effectively adsorb and remove polygalacturonic acid in wastewater, and the cationized lignocellulose nanofiber adsorbent prepared in example 3 shows the best adsorption performance, and the adsorption removal rate is as high as 89.94%.
The above examples are only for further detailed and clear explanation of the present invention, but are not limited to the above embodiments. Any other simplification, modification and replacement without departing from the spirit and principle of the present invention should be considered as the protection scope of the present invention.
Claims (10)
1. The preparation method of the cationized lignocellulose nanofiber adsorbent is characterized in that bagasse is used as a raw material and is prepared through the following steps:
(1) Collecting raw materials: crushing, washing and drying bagasse;
(2) Pretreatment: adding the bagasse treated in the step (1) into a eutectic solvent, uniformly mixing, adding 2, 3-epoxypropyltrimethylammonium chloride, stirring, and adding excessive deionized water to terminate the reaction after the reaction is finished;
(3) Washing: washing the bagasse treated in the step (2) to be neutral by centrifugation;
(4) Mechanical microfibrillation: and (4) collecting the bagasse treated in the step (3), re-dispersing the bagasse in deionized water, and performing high-pressure homogenization treatment to obtain the cationized lignocellulose nanofiber adsorbent.
2. The preparation method of the cationized lignocellulose nanofiber adsorbent as claimed in claim 1, wherein the crushing is to crush bagasse into bagasse powder with 40-80 meshes; the washing mode is that the washing is carried out by soaking in clean water and soaking in ethanol, and the washing is repeated for a plurality of times until the washing liquid is clear; the drying temperature is 50-70 ℃.
3. The method of claim 1, wherein the eutectic solvent is synthesized from a tetraethylammonium hydroxide solution and 1, 3-dimethylurea, wherein the concentration of the tetraethylammonium hydroxide solution is 35%, and the molar ratio of the tetraethylammonium hydroxide to the 1, 3-dimethylurea is 1:2.
4. the preparation method of the cationized lignocellulose nanofiber adsorbent according to claim 1, wherein the mass ratio of the bagasse to the eutectic solvent is 1:9.
5. the preparation method of the cationized lignocellulose nanofiber adsorbent as claimed in claim 1, wherein the mass ratio of the added amount of the 2, 3-epoxypropyltrimethylammonium chloride to the bagasse is 1-3: 1;
the reaction formula of the reaction in step (2) is as follows:
6. the method for preparing the cationized lignocellulose nanofiber adsorbent according to claim 1, wherein the stirring conditions in the step (2) are as follows: stirring for 8-24 h at the rotating speed of 200-500 rpm; the reaction conditions are as follows: 20 to 30 ℃; the addition amount of the ionic water is 3-10 times of the volume of the reaction mixture.
7. The method for preparing the cationized lignocellulose nanofiber adsorbent according to claim 1, wherein the rotation speed of the centrifugation in the step (3) is 4000-6000 rpm, and the time is 10-20 min.
8. The method for preparing the cationized lignocellulose nanofiber adsorbent as recited in claim 1, wherein the step (4) is performed by the following method: the collected bagasse is added with deionized water to prepare a suspension with the concentration of 0.5-2 wt%.
9. The method for preparing the cationized lignocellulose nanofiber adsorbent as recited in claim 1, wherein the high pressure homogenization condition is 900-1100 bar, and the cycle number is 3-15.
10. Use of the cationized lignocellulose nanofiber adsorbent as recited in claim 1 for removing dissolved and colloidal substances in wastewater.
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