Preparation and application of biodegradable waterborne polyurethane cross-linked carboxymethyl chitosan-cyclodextrin biomass porous material

Abstract

The application provides preparation and application of a biodegradable waterborne polyurethane crosslinked carboxymethyl chitosan-cyclodextrin biomass porous material, which has adsorption and photodegradation performance for methylene blue in wastewater, is prepared by crosslinking waterborne polyurethane with carboxymethyl chitosan and cyclodextrin, and is doped with nano ZnO, and a preparation method of the biodegradable waterborne polyurethane crosslinked carboxymethyl chitosan-cyclodextrin biomass porous material.The waterborne polyurethane modified by carboxymethyl chitosan and cyclodextrin has good adsorption performance for methylene blue.In the biodegradation test, the modified material shows good biodegradation performance.The material is expected to have important application in the field of water treatment, a synthesis route of a biodegradable material is developed, and the research direction of the modified waterborne polyurethane is widened.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of adsorption separation, and relates to preparation and application of a biodegradable aqueous polyurethane cross-linked carboxymethyl chitosan-cyclodextrin biomass porous material. BACKGROUND

[0002] Water is one of the most important material resources for human survival and development. However, according to statistics, more than 700,000 tons of organic dyes are produced globally each year, of which about 20% of the dyes are discharged into industrial wastewater. Methylene blue (MB) is a typical cationic organic dye, which is often used in the fields of textiles, papermaking, medicine, and aquaculture, etc., causing great pollution to water resources. It is reported that methylene blue has good thermal stability and poor biodegradability, which increases the challenge for people in treating industrial wastewater, etc. Methylene blue not only causes visual pollution, but also hinders the propagation of sunlight, seriously affecting the normal survival of aquatic organisms and the photosynthesis of aquatic plants. In addition, many studies have shown that methylene blue dye is extremely harmful to the human body. For example, it can cause shock, nausea, and potential carcinogenic and mutagenic risks.

[0003] Traditional wastewater treatment technologies, such as lime coagulation, reverse osmosis, solvent extraction, chemical precipitation, etc., have problems such as high energy requirement, high manufacturing cost, and secondary pollution to the environment. The main advantages of adsorption are simple design, low cost, and can be used multiple times. Therefore, it is urgent to study a porous adsorption material which not only has low cost, but also is easy to prepare, has excellent performance, and does not cause secondary pollution to the environment to treat dyes in industrial wastewater has become an important topic.

[0004] In recent years, the use of natural and effective low-cost biological materials for removing dyes in wastewater has attracted more and more attention, and the use of biological materials makes the whole adsorption process more environmentally friendly. Chitin is a substance widely existing in the shells of marine organisms such as shrimps and crabs, and chitosan is a product of deacetylation of chitin, which is a natural polysaccharide. It contains a large number of carboxyl groups, which can be deprotonated in an alkaline environment, thereby having the ability to adsorb cationic dyes in wastewater. However, chitosan can only be dissolved in acid aqueous solution, which limits its practical application. Therefore, we used modified chitosan, that is, carboxymethyl chitosan, which improved its water solubility and made its application more widely.

[0005] Cyclodextrin (CD) is a cyclic oligosaccharide derived from the degradation of starch by amylase. Its structure is unique, with a hydrophobic cavity and a hydrophilic outer surface. According to the difference in the structure of the glucose unit, CD is mainly divided into three categories: α-CD, β-CD, and γ-CD. The hydrophobic cavity of CD provides numerous adsorption sites for dye adsorption and can bind to various molecules through host-guest interactions, thereby removing pollutants. Among the three categories of cyclodextrins, β-CD is the most widely used in water treatment due to its good reactivity and lower cost.

[0006] Waterborne polyurethane has become a research hotspot in recent years due to its low cost and environmental friendliness. Waterborne polyurethane-based porous materials contain numerous functional groups that can interact with adsorbate molecules, facilitating the adsorption of adsorbate molecules. Moreover, these functional groups make it easy to modify waterborne polyurethane, thereby enhancing its adsorption capacity for dyes. Therefore, modifying waterborne polyurethane using its numerous functional groups to further enhance its adsorption performance is of great significance in the field of wastewater treatment.

[0007] The present application uses polycaprolactone diol, isophorone diisocyanate, 2,2-dimethylol propionic acid, and hydroxyethyl methacrylate as raw materials to synthesize waterborne polyurethane. Then, the waterborne polyurethane is crosslinked with carboxymethyl chitosan and cyclodextrin, with the addition of nano zinc oxide powder, to prepare a biodegradable waterborne polyurethane crosslinked carboxymethyl chitosan / cyclodextrin biomass porous material (WPU x -CS y -βCD z / ZnO). Through batch adsorption experiments, the effects of adsorption conditions such as solution pH, temperature, initial dye concentration, and adsorption time on the adsorption performance of the adsorbent were investigated, and the optimal WPU x -CS y -βCD z ratio was selected. Through simulation of actual application wastewater and biodegradation experiments, the adsorbent was found to have good adsorption performance in actual application and in the presence of interfering ions. The adsorption process of the adsorbent for methylene blue was analyzed by fitting the experimental data with adsorption kinetics and adsorption isotherm. Under the optimal ratio, the addition of nano zinc oxide powder enabled the adsorbent to have both adsorption performance and photocatalytic degradation performance for methylene blue. In addition, the reusability of the adsorbent was investigated. The results showed that the WPU x -CMCS y -βCD z / ZnO a porous material has both adsorption and photocatalytic degradation performance for methylene blue, making it valuable in wastewater treatment. SUMMARY

[0008] In view of the current situation of water resources and waterborne polyurethane field, a biodegradable waterborne polyurethane cross-linked carboxymethyl chitosan / cyclodextrin biomass porous material for removing methylene blue dye is prepared. The modified material shows excellent adsorption performance and photodegradation performance for methylene blue dye, and has certain selective adsorption for methylene blue. The material still has high adsorption performance in simulated actual application wastewater.

[0009] To achieve the above-mentioned purposes, the present application provides the following technical solutions:

[0010] First aspect:

[0011] The biodegradable waterborne polyurethane cross-linked carboxymethyl chitosan-cyclodextrin biomass porous material is prepared by cross-linking carboxymethyl chitosan / cyclodextrin with waterborne polyurethane.

[0012] The present application also provides a preparation method of the biodegradable waterborne polyurethane cross-linked carboxymethyl chitosan-cyclodextrin biomass porous material, comprising the following steps:

[0013] Step (1): reacting polyol with isocyanate, after the reaction is completed, carrying out chain extension, temperature reduction, neutralization and end capping, and dispersing in deionized water to prepare waterborne polyurethane;

[0014] Step (2): modifying carboxymethyl chitosan with glycidyl methacrylate; modifying cyclodextrin with acryloyl chloride;

[0015] Step (3): mixing the waterborne polyurethane prepared in step (1) with the modified carboxymethyl chitosan and cyclodextrin prepared in step (2) and nano-zinc oxide in different proportions, and adding cross-linking agent drop by drop until a gel is formed.

[0016] Preferably, step (1) satisfies at least one of the following conditions:

[0017] The polyol is polycaprolactone diol;

[0018] The isocyanate is isophorone diisocyanate;

[0019] A catalyst is added during the chain extension process;

[0020] A neutralizing agent is added during the neutralization process;

[0021] An end capping agent is added during the end capping process.

[0022] Preferably, step (1) satisfies at least one of the following conditions:

[0023] The reaction is a constant temperature reaction;

[0024] The temperature of the reaction is 80-95℃, preferably 87℃;

[0025] The time of the reaction is 1-3h, preferably 1.5h;

[0026] The time of the chain extension is 1.5-4h, preferably 2h;

[0027] The cooling is cooling to 45-55℃, preferably 50℃;

[0028] The time of the neutralization is 15-30min, preferably 20min;

[0029] The time of the endcapping is 2.5-4h, preferably 3h.

[0030] Preferably, step (1) satisfies at least one of the following conditions:

[0031] The catalyst comprises bismuth 2-ethylhexanoate;

[0032] The neutralizing agent comprises triethylamine;

[0033] The endcapping agent comprises hydroxyethyl methacrylate.

[0034] Preferably, step (2) satisfies at least one of the following conditions:

[0035] The reaction is carried out at room temperature.

[0036] The reaction time is 48h;

[0037] The molar ratio of glycidyl methacrylate to carboxymethyl chitosan is 0.7:1.

[0038] The molar ratio of cyclodextrin to acryloyl chloride is 1:8.

[0039] Preferably, in step (3), the mass ratio of the waterborne polyurethane to carboxymethyl chitosan, cyclodextrin is respectively 4:1:1, 4:1:2, 4:1:3, 4:2:1, 4:3:1.

[0040] Preferably, in step (3), the mass fraction of the added nano zinc oxide is respectively 5%, 10%, 15%, 20%.

[0041] The application also provides a biodegradable cross-linked biomass porous material, which is prepared by the method as described above.

[0042] The application also provides the use of the biodegradable cross-linked biomass porous material in the field of wastewater treatment, especially in the removal of methylene blue.

[0043] The second aspect is:

[0044] The application has good porous structure, adsorption performance, renewability, methylene blue photodegradation performance and biodegradability.

[0045] The application has excellent porous structure, green and sustainable foundation, excellent adsorption capacity, photodegradation efficiency, reusability and biodegradability, and provides certain reference value for the practical application of the material in the wastewater treatment field.

[0046] The application has the following positive effects:

[0047] (1) The application provides a technical route, wherein water-based polyurethane synthesized by polycaprolactone diol is used as a matrix, biomass material carboxymethyl chitosan and cyclodextrin are used for modification, a series of water-based polyurethane cross-linked carboxymethyl chitosan / cyclodextrin porous materials with different carboxymethyl chitosan / cyclodextrin contents are prepared, and the influence of various factors, including time, temperature, pH and initial concentration of dyes, on the adsorption performance of the adsorbent is investigated.

[0048] (2) The application modifies water-based polyurethane by using low-cost and pollution-free biomass material carboxymethyl chitosan and cyclodextrin, thereby reducing the cost of water-based polyurethane and being conducive to the industrialized production in the future.

[0049] (3) The water-based polyurethane modified by carboxymethyl chitosan and cyclodextrin prepared by the application has excellent adsorption performance and exhibits selective adsorption capacity for methylene blue dyes. BRIEF DESCRIPTION OF DRAWINGS

[0050] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those of ordinary skill in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0051] Figure 1 Description Figure 1 Description of the successful modification and synthesis of CMCS, A-CMCS.

[0052] Figure 2 Description of the successful modification and synthesis of β-CD, A-β-CD.

[0053] Figure 3 Description of the successful modification and synthesis of WPU4-CS2-βCD1, WPU4-CS2-βCD1 / ZnO.

[0054] Figure 4 Description of the comparison chart of the methylene blue adsorption effect of WPU1-CS1-βCD1~WPU5-CS1-βCD1.

[0055] Figure 5 Description of the pore structure chart of WPU1-CS1-βCD1~WPU5-CS1-βCD1.

[0056] Figure 6 Description of the comparison chart of the adsorption capacity of WPU4-CS1-βCD1~WPU4-CS3-βCD1 under pH environment.

[0057] Figure 7 Description of the comparison chart of the removal capacity of MB of WPU4-CS1-βCD1~WPU4-CS3-βCD1 with temperature change.

[0058] Figure 8 Description of the pore structure and porosity chart of WPU4-CS1-βCD1~WPU4-CS3-βCD1.

[0059] Figure 9 Description of the adsorption process chart of WPU4-CS1-βCD1~WPU4-CS3-βCD1 with time change.

[0060] Figure 10 Description of the comparison chart of the adsorption effect of WPU4-CS1-βCD1~WPU4-CS3-βCD1 at different adsorption concentrations.

[0061] Figure 11 Description of the first-order kinetics fitting curve of WPU4-CS1-βCD1~WPU4-CS3-βCD1.

[0062] Figure 12 Illustration of secondary kinetics fitting curve of WPU4-CS1-βCD1~WPU4-CS3-βCD1.

[0063] Figure 13 Illustration of intra-diffusion model fitting curve of WPU4-CS1-βCD1~WPU4-CS3-βCD1.

[0064] Figure 14 Illustration of adsorption isotherm model fitting curve of WPU4-CS1-βCD1~WPU4-CS3-βCD1.

[0065] Figure 15 Illustration of WPU4-CS2-βCD1 / ZnO 2.5 ~WPU4-CS2-βCD1 / ZnO 10 Effect of adsorbent on methylene blue adsorption without UV lamp irradiation.

[0066] Figure 16 Illustration of WPU4-CS2-βCD1 / ZnO 2.5 ~WPU4-CS2-βCD1 / ZnO 10 Effect of adsorbent on methylene blue adsorption with UV lamp irradiation.

[0067] Figure 17 Illustration of WPU4-CS2-βCD1 / ZnO 2.5 ~WPU4-CS2-βCD1 / ZnO 10 Mass loss curve in enzyme degradation solution.

[0068] Figure 18 Illustration of WPU4-CS2-βCD1 / ZnO 2.5 ~WPU4-CS2-βCD1 / ZnO 10 Effect of reusability under conditions with and without UV lamp irradiation. DETAILED DESCRIPTION

[0069] The present application will be further described below in connection with specific embodiments. The following description is only several embodiments of the present application, and does not limit the present application in any form. Although the present application is disclosed in the preferred embodiments, it is not intended to limit the present application, and any skilled person in the art can make some changes or modifications to the disclosed technical content without departing from the scope of the technical solution of the present application, which are equivalent to the equivalent embodiments and belong to the scope of the technical solution.

[0070] Unless otherwise specified, the raw materials in the embodiments of the present application are purchased through commercial channels and directly used without any special treatment.

[0071] Unless otherwise specified, the analysis method in the examples uses the conventional setting of the instrument or equipment and the conventional analysis method.

[0072] The following is the source of raw materials in the examples, polycaprolactone diol (OH-PCL-OH, M n =2000), isophorone diisocyanate (IPDI), triethylamine (TEA), carboxymethyl chitosan (CMCS) and methylene blue (MB) were purchased from Shanghai Macklin Biochemical Co., Ltd. 2,2-dimethylol propionic acid (DMPA) and bismuth 2-ethylhexanoate (BiR3) were purchased from Shanghai Aldrin Biochemical Technology Co., Ltd. All purchased materials were used directly without further purification. All solutions were prepared with deionized water.

[0073] Example 1

[0074] The preparation method of the biodegradable aqueous polyurethane cross-linked carboxymethyl chitosan-cyclodextrin biomass porous material comprises the following steps:

[0075] (1) Preparation of aqueous polyurethane

[0076] 16.68 g of isophorone diisocyanate (IPDI) and 50 g of polycaprolactone diol (HO-PCL-OH) were added to a three-necked flask, and 0.25 g of bismuth 2-ethylhexanoate (BiR3) was added, and the reaction was carried out at 87 ℃ for 1.5 h, then the temperature was kept unchanged, 4.38 g of 2,2-dimethylol propionic acid (DMPA) was added for chain extension for 2 h, and 0.25 g of bismuth 2-ethylhexanoate (BiR3) was added for catalysis; after the chain extension reaction was completed, the reaction system was cooled to 60 ℃, and 4.56 g of hydroxyethyl methacrylate (HEMA) was added as a capping agent, and a capping reaction was carried out for 3 h. Then continue to cool to 50 ℃, add 3.30 g of triethylamine (TEA) to neutralize the salt, and neutralize for 20 min to prepare a polyurethane prepolymer, and finally the polyurethane prepolymer is dispersed into 181.36 g of deionized water by the action of a shearing machine, thereby successfully synthesizing WPU.

[0077] (2) Modification of carboxymethyl chitosan

[0078] First, 2.96 g of carboxymethyl chitosan (CMCS) was dissolved in deionized water, and stirred until it was completely dissolved, 0.224 g of glycidyl methacrylate was added, and the glycidyl methacrylate was slowly added under the condition of continuous stirring at room temperature, and the reaction was carried out at room temperature for 48 h. After the reaction was completed, 0.1 mol / L NaOH was used to adjust the pH value of the solution to 8.0, and the solution was dialyzed for 24 h to remove the unreacted monomer and small molecules. -1The reaction solution was neutralized by HCl solution. Then the neutralized solution was dialyzed for 1 day. After dialysis, the dialysate was freeze-dried to obtain glycidyl methacrylate modified carboxymethyl chitosan (A-CMCS).

[0079] (3) Modification of cyclodextrin

[0080] First, 2 g of cyclodextrin (β-CD) was dissolved in DMF, then 1.48 g of triethylamine was added to the solution, and then nitrogen was introduced into the reaction system for 30 min to remove air in the system. The reaction was placed in an ice bath at 0-5°C, and 1.47 g of acryloyl chloride (AC) was weighed and slowly added to the reaction solution, and the addition process lasted for 30 min. After the addition was completed, the reaction system was transferred to room temperature and reacted for 24 h. After the reaction was completed, the reaction solution was concentrated by vacuum distillation, and the solvent, unreacted AC and triethylamine in the reaction were removed to obtain the concentrated product, which was then added dropwise to a large amount of acetone solution for precipitation treatment, and washed with a large amount of acetone to remove possible impurities on the surface of the precipitate. The white precipitate after washing was vacuum dried for 24 h to obtain the final product A-β-CD.

[0081] (4) Preparation of porous material

[0082] WPU, A-CMCS and A-β-CD prepared in steps (1), (2) and (3) were fully stirred and mixed at room temperature, and then a crosslinking agent ethylenediamine (EDA) was added dropwise until a gel was formed. Then the formed gel was freeze-dried for 48 h to obtain WPU4-CS2-βCD1 / ZnO x -CS y -βCD z Biomass porous material, wherein x 、 y and z respectively represent the mass ratio of the three added. WPU4-CS2-βCD1 / ZnO a The preparation method of WPU4-CS2-βCD1 / ZnO a After WPU, A-CMCS and A-β-CD were fully stirred and mixed at room temperature, different mass fractions of nano-zinc oxide were doped, then a crosslinking agent EDA was added dropwise until a gel was formed, and then the formed gel was freeze-dried for 48 h to obtain WPU4-CS2-βCD1 / ZnO a composite porous material, wherein a represents the mass fraction of added ZnO.

[0083]

[0084] Effect Example 1

[0085] The adsorbents were measured, and the test results are shown in Table 2.

[0086] Table 2

[0087]

[0088] From the attached Figure 1 , the attached Figure 2 and the attached Figure 3 , it can be seen that A-CMCS, A-β-CD and the successful modification and synthesis of the adsorbent.

[0089] From the attached Figure 4 , first, the content of carboxymethyl chitosan and cyclodextrin is fixed, and the content of waterborne polyurethane is adjusted to screen out the best ratio of waterborne polyurethane. From the experimental results, it can be seen that WPU4-CS1-βCD1 has the best adsorption effect on methylene blue. Therefore, the ratio of WPU to carboxymethyl chitosan and cyclodextrin is 4:1, which is the best dosage.

[0090] From the attached Figure 5 , all WPU x -CS1-βCD1 has a good porous structure, and WPU4-CS1-βCD1 has the most excellent porous structure, which is consistent with the adsorption experiment.

[0091] From the attached Figure 6 , by controlling the content of WPU, changing the content of carboxymethyl chitosan and cyclodextrin respectively, five kinds of adsorbents are prepared, and all of them have good adsorption performance. When the pH value is low, the concentration of H + + is high, and H + will compete with cationic dyes for adsorption sites on the surface of the adsorbent, so the adsorption capacity is low. With the gradual increase of pH value, the concentration of H + gradually decreases, resulting in a decrease in competitive adsorption, so the adsorption capacity of the adsorbent for methylene blue increases. Therefore, we choose pH=7 for subsequent testing.

[0092] From the attached Figure 7 , when the temperature is 35℃, the removal rate of the adsorbent for MB is the highest. This is because as the temperature rises, the movement of dye molecules increases, thereby increasing the possibility of interaction between dye molecules and adsorbents. However, as the temperature further increases, the removal rate of the adsorbent for MB remains unchanged, because the adsorption sites of the adsorbent are limited, and more interactions cannot further increase the removal rate of the adsorbent for dyes.

[0093] From the attached Figure 8and Table 2, it can be seen that the adsorbent has good porous structure and porosity. Excellent porous structure and porosity are conducive to the adsorption process of the adsorbent to the dye.

[0094] From the attached Figure 9 , it can be seen that with the extension of time, the adsorbent WPU4-CS x -βCD y adsorption process is first a fast adsorption, then gradually slow, and finally tends to adsorption equilibrium process, and the adsorption performance of the adsorbent WPU4-CS2-βCD1 is the most excellent.

[0095] From the attached Figure 10 , it can be seen that with the increase of concentration, the adsorbent of Example 1 (WPU4-CS x -βCD y ) adsorption capacity is gradually increased with the increase of concentration, but the adsorption capacity is not unlimited increase, because the adsorption site of the adsorbent is limited.

[0096] From the attached Figure 11 , attached Figure 12 and Table 3, it can be seen that the adsorption kinetics is well fitted with the adsorption process data, wherein the R 2 of pseudo-first-order kinetics is higher, which shows that the pseudo-first-order kinetics is more consistent with the adsorption process, indicating that the adsorption rate is mainly affected by the remaining adsorption sites on the surface of the adsorbent, and with the progress of the adsorption process, the remaining adsorption sites are reduced, and the adsorption rate is gradually slowed down. In the adsorption process, the diffusion of dye molecules from the solution body to the adsorption site of the adsorbent may be the rate-limiting step. In the experimental study, it is usually necessary to consider the fitting results of pseudo-first-order kinetics and second-order kinetics, as well as the related experimental conditions, to accurately judge the mechanism, control step and adsorption performance of the adsorption process, and to provide theoretical basis for the optimization of adsorption process and the design of adsorption material.

[0097] From the attached Figure 13 and Table 4, it can be seen that the adsorption process is divided into three stages, first, the adsorption of dye molecules on the surface of the adsorbent, at this time the adsorption site is sufficient, the adsorbent quickly adsorbs methylene blue. In the second stage, the adsorption rate slows down, because the adsorption site on the surface of the adsorbent is insufficient, the dye molecules diffuse to the inside of the adsorbent, and then gradually reach the third stage, the adsorption gradually reaches adsorption equilibrium.

[0098] From the attached Figure 14 and Table 5, it can be seen that the Langmuir model R 2 is higher, which shows that the adsorption process is more consistent with the Langmuir model, which shows that the adsorption process is monolayer adsorption, and the adsorbent is uniformly distributed in the active center. In addition, the R2 The difference is not big, which shows that the adsorption process is affected by many factors. L And 1 / n f Always less than 1, the two parameters further illustrate that the adsorption process is easy to proceed.

[0099] From the attached Figure 15 And the attached Figure 16 It can be seen that the attached Figure 15 The adsorption rate of methylene blue of the ZnO doped adsorbent without ultraviolet lamp irradiation changes with time, the attached Figure 16 The adsorption efficiency of methylene blue of the ZnO doped adsorbent with ultraviolet lamp changes with time. Compared with the two, compared with no ultraviolet lamp irradiation, under the ultraviolet lamp irradiation, the removal rate of methylene blue of the adsorbent is higher, and the adsorption equilibrium is reached in a shorter time.

[0100] From the attached Figure 17 It can be seen that in the aqueous solution of lysozyme and amylase, the lysozyme can specifically recognize the glycosidic bond on the chitosan and its derivatives (such as carboxymethyl chitosan), combine with it and catalyze its degradation, and the amylase can catalyze the degradation of β-cyclodextrin, and the PCL polyol in the waterborne polyurethane can be hydrolyzed. Through the biodegradation experiment, it can be seen that with the increase of the content of ZnO, its degradation performance gradually decreases, because nano ZnO is difficult to be degraded, so in the same time, WPU4-CS2-βCD1 / ZnO 2.5 Has higher mass loss. The results show that the adsorbent has good biodegradation performance, so it has the advantages of being more green, environmentally friendly and friendly to the environment.

[0101] From the attached Figure 18 It can be seen that by comparing the recyclability of undoped nano ZnO and doped nano ZnO under the conditions of ultraviolet lamp irradiation and non-ultraviolet lamp irradiation, it can be seen that under all conditions, the recyclability of nano ZnO doped and ultraviolet lamp irradiation is the best. And after four adsorption-desorption cycles, the adsorbent still has good removal efficiency, which shows that the adsorbent has good reusability.

[0102] From the above data, it can be seen that in the present application, the adsorption performance of WPU4-CS2-βCD1 and WPU4-CS2-βCD1 / ZnO 7.5 Is the best, WPU4-CS2-βCD1 / ZnO 2.5 Has the best biodegradation performance. And the adsorbent is a biomass adsorbent material with excellent porous structure, green and sustainable and excellent biodegradation performance, which can adsorb and photodegrade dyes in wastewater, and has important research significance in the field of water treatment and environmental protection.

[0103] The above merely describes several embodiments of the present application, and does not limit the present application in any form. Although the present application is disclosed with the preferred embodiments, it is not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the disclosed technical contents without departing from the scope of the present application, and the equivalent embodiments are equivalent to the equivalent embodiments, which are within the scope of the technical solutions.

Claims

1. Biodegradable aqueous polyurethane cross-linked carboxymethyl chitosan-cyclodextrin biomass porous material, characterized by, Prepared from waterborne polyurethane cross-linked carboxymethyl chitosan and cyclodextrin; The preparation method of the biodegradable waterborne polyurethane cross-linked carboxymethyl chitosan-cyclodextrin biomass porous material comprises the following steps: Step (1): reacting polyol with isocyanate, after the reaction is completed, chain extension, temperature reduction, neutralization and end capping are carried out, and the waterborne polyurethane is prepared by dispersing in deionized water; Step (2): glycidyl methacrylate is used to modify carboxymethyl chitosan; acryloyl chloride is used to modify cyclodextrin; Step (3): the waterborne polyurethane prepared in step (1) is mixed with modified carboxymethyl chitosan, cyclodextrin and nano zinc oxide prepared in step (2) in different proportions, and a crosslinking agent is added drop by drop until a gel is formed; The end capping agent is hydroxyethyl methacrylate.

2. The biodegradable, aqueous polyurethane cross-linked carboxymethyl chitosan-cyclodextrin biomass porous material according to claim 1, characterized in that, Step (1) satisfies at least one of the following conditions: The polyol is polycaprolactone diol; The isocyanate is isophorone diisocyanate; A catalyst is added during step (1); A neutralizing agent is added during the neutralization process; An end capping agent is added during the end capping process.

3. The biodegradable, aqueous polyurethane cross-linked carboxymethyl chitosan-cyclodextrin biomass porous material according to claim 1, characterized in that, Step (1) satisfies at least one of the following conditions: The reaction is a constant temperature reaction; The temperature of the reaction is 80-95℃; The reaction time is 1-3h; The chain extension time is 1.5-4h; The temperature reduction is to 45-55℃; The neutralization time is 15-30min; The end capping reaction time is 2.5-4h; The dispersion time is 20-40min.

4. The biodegradable, aqueous polyurethane cross-linked carboxymethyl chitosan-cyclodextrin biomass porous material according to claim 3, characterized in that, Step (1) satisfies at least one of the following conditions: The temperature of the reaction is 87℃; The reaction time is 1.5h; The chain extension time is 2h; The temperature reduction is to 50℃; The neutralization time is 20min; The end capping reaction time is 3h; The dispersion time is 30min.

5. The biodegradable, aqueous polyurethane cross-linked carboxymethyl chitosan-cyclodextrin biomass porous material according to claim 2, characterized in that, Step (1) satisfies at least one of the following conditions: The catalyst includes bismuth 2-ethylhexanoate; The neutralizing agent includes triethylamine.

6. The biodegradable, aqueous polyurethane cross-linked carboxymethyl chitosan-cyclodextrin biomass porous material according to claim 1, characterized in that, Step (2) satisfies at least one of the following conditions: The reaction of glycidyl methacrylate modifying carboxymethyl chitosan is carried out at room temperature; The reaction time of glycidyl methacrylate modifying carboxymethyl chitosan is 48h; The molar ratio of glycidyl methacrylate to carboxymethyl chitosan is 0.7:1; The molar ratio of cyclodextrin to acryloyl chloride is 1:

8.

7. The biodegradable, aqueous polyurethane cross-linked carboxymethyl chitosan-cyclodextrin biomass porous material according to claim 1, characterized in that, Step (3) satisfies at least one of the following conditions: The mass ratio of the waterborne polyurethane to carboxymethyl chitosan and cyclodextrin is 4:1:1, 4:1:2, 4:1:3, 4:2:1 or 4:3:1; The mass fraction of nano zinc oxide is 5%, 10%, 15% or 20%.

8. The biodegradable, aqueous polyurethane cross-linked carboxymethyl chitosan-cyclodextrin biomass porous material according to claim 1, characterized in that, Application in the field of wastewater treatment as adsorption material and photodegradation dye material, application in adsorption and photodegradation of methylene blue.

Images