CN112915984A - Easily-desorbed regenerated open-chain cucurbituril-based material for treating heavy metal water pollution and preparation method thereof - Google Patents

Easily-desorbed regenerated open-chain cucurbituril-based material for treating heavy metal water pollution and preparation method thereof Download PDF

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CN112915984A
CN112915984A CN202110148159.8A CN202110148159A CN112915984A CN 112915984 A CN112915984 A CN 112915984A CN 202110148159 A CN202110148159 A CN 202110148159A CN 112915984 A CN112915984 A CN 112915984A
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heavy metal
nanofiber membrane
open chain
polyvinyl alcohol
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赵润
韦甜
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Jiangsu New Vision Advanced Functional Fiber Innovation Center Co ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
    • B01J20/26—Synthetic macromolecular compounds
    • B01J20/265—Synthetic macromolecular compounds modified or post-treated polymers
    • B01J20/267—Cross-linked polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
    • B01J20/28011—Other properties, e.g. density, crush strength
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B01J20/34—Regenerating or reactivating
    • B01J20/345—Regenerating or reactivating using a particular desorbing compound or mixture
    • B01J20/3475—Regenerating or reactivating using a particular desorbing compound or mixture in the liquid phase
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/285—Treatment of water, waste water, or sewage by sorption using synthetic organic sorbents
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/20—Heavy metals or heavy metal compounds

Abstract

The invention relates to an easy-to-remove regenerated open chain calabash ureido material for treating heavy metal water pollution and a preparation method thereof, wherein polyvinyl alcohol and dialdehyde are used as main raw materials for electrostatic spinning, and then the electrostatic spinning is carried out in a strong acid methanol solution to form a film through crosslinking; and grafting and modifying the open chain cucurbituril on the surface of the nanofiber membrane, wherein the open chain cucurbituril is of a structure with a ureido repeat unit of 2. The open chain cucurbit uril-based material prepared by the method has good mechanical property and tensile strength of 50-80MPa, the elastic modulus is 2000-3000 MPa; the material is used for common heavy metal ion Cu2+、Hg2+、Pb2+、Ni2+The adsorption performance is high, and the maximum adsorption rate reaches more than 95 percent; the material has easy desorption and regeneration, can complete desorption through methanol and water washing, and has the adsorption rate of more than 85 percent after 5 times of adsorption-desorption cycles. The preparation method is efficient and practical; the material prepared by the method has good mechanical property, high adsorbability and easy desorption and regeneration.

Description

Easily-desorbed regenerated open-chain cucurbituril-based material for treating heavy metal water pollution and preparation method thereof
Technical Field
The invention belongs to the technical field of heavy metal water pollution treatment, and relates to an easy-to-remove regenerated open-chain cucurbituril-based material for treating heavy metal water pollution and a preparation method thereof.
Background
Water is a source of life and is closely related to human life. On one hand, the fresh water resources in China are not distributed in balance, and nearly 45% of the land is in a condition that the water resources are distributed quite scarcely; on the other hand, China has a large population and a large demand for water resources, and the average occupancy of people is less than 1/4 in the average world level. The situation makes the problem of water resource shortage increasingly worse. More seriously, with the continuous development of industrial modernization, a large amount of pollutants are discharged into the environment, and the water body is seriously polluted, wherein heavy metals are one of the most dangerous pollutants, the carcinogenicity of the pollutants is high, and the human health is seriously threatened.
Therefore, the research on the treatment of the heavy metal polluted wastewater is more and more focused. The most common treatment methods at present include an electrolysis method, a floating method, an ion flotation method, ion exchange, a membrane separation method and an adsorption method, wherein the adsorption method is widely applied due to the advantages of simple preparation, low cost, wide material source and the like, and the adsorption material with low preparation cost and good adsorption performance is a hot point of research of people. Common adsorbents include kaolin, activated carbon, water-absorbing resins, hydrogels, nanofiber membranes, and the like. As a novel material, the nanofiber membrane is small in diameter and large in specific surface area, and compared with the traditional filter material, the nanofiber membrane also has the advantages of light weight, high porosity and high permeability, the filtering and adsorption functions of the filter material are well combined together, and the filtering efficiency and the adsorption capacity are remarkably improved.
However, the conventional nanofiber membrane does not have the capability of removing heavy metal ions and pollutants by itself due to the limitation of the functional group structure of the polymer itself. The nanofiber membrane is modified by a chemical modification method, and the problem that spinning solution is crosslinked into gel exists, so that a spinning nozzle and a pipeline are blocked in the electrostatic spinning process. Research shows that the mechanical property of the electrostatic spinning chitosan/polyvinyl alcohol (CS/PVA) nanofiber membrane is obviously weakened along with the prolonging of the soaking time.
And for the nano fiber membrane based on the annular main body (such as calixarene, crown ether, pillared arene and cucurbituril), various problems such as poor mechanical property, poor adsorption selectivity or poor solubility of the annular main body, difficulty in electrostatic spinning and the like exist.
Para-tertiary butyl amidated cup [8 ] prepared by electrostatic spinning technology]The addition of arene/polyacrylonitrile nano fiber and calixarene greatly increases the Cu content2+The amount of adsorption of (3). The dibenzo-18-crown-6 with different proportions is doped into polyacrylonitrile and is added into a dimethylformamide solution to be dissolved to prepare an electrospinning solution, and the electrospinning solution is spun into fibers by adopting an electrospinning technology, so that the adsorption active sites of the obtained nanofibers are improved, and the adsorption performance is better. However, the mechanical properties of the nanofiber membrane are poor due to the flexible chemical structures of cyclic main bodies such as calixarene and crown ether, and the surface of the nanofiber membrane treated by modification is easily polluted and easily influenced by external conditions.
Through an electrostatic spinning technology, a MeP5/PA nano-fiber membrane is prepared from methoxy pillar [5] arene/polyacrylate (MeP5/PA) blended emulsion, and the adsorption behavior of the nano-fiber membrane on four p-nitrobenzene derivatives shows that the addition of pillar arene can improve the adsorption capacity of the nano-fiber membrane. However, because the methoxy pillar [5] arene cavity structure is smaller, the host-object identification is difficult to carry out on organic pollutants with larger molecular sizes, so that the application range of the nano-fiber membrane is weakened, the nano-fiber membrane can only adsorb p-nitrobenzene, and the adjacent and meta-nitrobenzene cannot be adsorbed because the size of the nano-fiber membrane is larger than that of the methoxy pillar [5] arene cavity.
The cucurbituril is a small molecular compound, has poor solubility, is only dissolved in a concentrated acid solution, and cannot meet various conditions required by electrostatic spinning.
Besides, the adsorption capacity and the removal efficiency are only index parameters on the one hand for evaluating the adsorption effect of the modified nanofiber membrane on pollutants, and the regeneration performance of the adsorption material is also paid attention. And when the adsorbent is applied to the actual production process, the adsorbent with high desorption rate is more suitable. Therefore, in order to make the adsorption material more economical and efficient in practical application, it is necessary to pay attention to the desorption process and repetitive research of the material.
Various adsorbents are required to desorb pollutants after adsorbing the pollutants so as to be recycled. Currently, there are two main types of methods for adsorbent desorption treatment:
for the crystal materials such as activated carbon fiber, glass hollow fiber membrane, column aromatic hydrocarbon and the like, the desorption conditions are generally high-temperature calcination, the energy consumption is high, the material repeatability is obviously influenced, and the method is not suitable for the desorption process of the nano fiber membrane material. For example, in order to elute the heavy metal ions adsorbed on the activated carbon fiber, the activated carbon fiber needs to be placed in a muffle furnace, the temperature of the muffle furnace is controlled at 600-800 ℃, the heating treatment is carried out, and the heating time is controlled at 3 h.
For the nano-fiber and the conventional membrane material, strong acid and strong base solution is generally used for leaching desorption. Although the desorption effect and efficiency of the method are high, the reusability of the material is seriously influenced, and the adsorption performance of a plurality of membrane materials on pollutants is obviously reduced in the second cycle experiment. For example, using HNO3The solution is used as desorption solution, the desorption process of the modified polyacrylonitrile nano-fiber membrane adsorbing copper ions is researched, the copper ions adsorbed to the material are rapidly desorbed in the desorption solution, and almost complete desorption is achieved in about 60 min. After 4 times of recycling, the adsorption efficiency of the modified polyacrylonitrile nano-fiber membrane to copper ions is obviously reduced. Cyclodextrin/polyacrylonitrile (alpha-, beta-, gamma-CD/PAN) nanofiber membrane for Cu respectively2+、Zn2+、Ni2+、Pb2+In the research on desorption and regeneration, the alpha, beta, gamma-CD/PAN fiber membrane after adsorbing heavy metal ions is put into 50mL of HCl solution with the concentration of 1mol/L for desorption, and the adsorption performance of the nanofiber membrane on the heavy metal ions is obviously reduced after 4 times of adsorption-desorption-adsorption.
In summary, it is very important to develop and prepare a novel nanofiber membrane which is easy to desorb and regenerate and can treat heavy metal water pollution. From the above analysis, the current combination of supramolecular chemistry and nanofiber membrane field is limited to basic research and macrocyclic host, and these nanofiber membranes based on macrocyclic host have various disadvantages, though each has advantages. For example, the macrocyclic hosts lack adaptive selectivity for complex substances in the real environment due to self annular closed structures (the hosts are induced to deform by adding an object); and the host-guest action between the macrocyclic host and the pollutant is relatively strong, so that the nanofiber membrane has the problems of relatively harsh conditions, high energy consumption, high desorption difficulty and the like when desorbing the pollutant, thereby causing relatively poor reusable performance. Therefore, the invention adopts the non-annular main body, namely the open chain cucurbituril graft modification nanofiber membrane, and creatively solves the problems of low pollutant adsorption capacity, poor product mechanical property, high desorption regeneration difficulty and the like.
Disclosure of Invention
The invention aims to solve the technical problems of poor pollutant adsorption performance, poor product mechanical property, unstable product quality, narrow application range, poor product regeneration cycle performance caused by pollutant desorption and the like in the prior art, provides an easy-desorption regeneration open-chain cucurbituril-based material for treating heavy metal water pollution and a preparation method thereof, can endow a nanofiber membrane with unique molecular recognition capability, and is applied to the field of heavy metal adsorption separation. The invention solves the problems of the nanofiber membrane in the process of substance separation, adsorption and desorption, such as poor environmental adaptability, low adsorption quantity, low pollutant selectivity, poor pollutant desorption, regeneration and use performance and the like, and has simple synthesis procedure, mild conditions and popularization value.
The invention aims to provide an easy-desorption regeneration open chain cucurbituril carbamido material for treating heavy metal water pollution, in particular to an easy-desorption cyclic regeneration nanofiber membrane based on open chain cucurbituril with molecular recognition capability, which can desorb heavy metals through simple treatment so as to be regenerated and recycled.
The second purpose of the invention is to provide a preparation method of the nanofiber membrane.
The invention relates to an easy-desorption regeneration open chain cucurbituril-based material for treating heavy metal water pollution, which is a nanofiber membrane with the surface grafted with hydroxyl substituted open chain cucurbituril;
the structural formula of the hydroxyl-substituted open chain cucurbituril is shown in the specification
Figure RE-GDA0003015226520000031
The ureido repeat unit is 2.
In the aspect of material structure performance, the chemical modifiability of the hydroxyl-substituted open-chain cucurbituril enables researchers to easily perform functionalization on the hydroxyl-substituted open-chain cucurbituril according to different application conditions, the application field of the nanofiber membrane is wider by changing the hydrophilic and hydrophobic properties of the hydroxyl-substituted open-chain cucurbituril, and the problem caused when a chemical modification method is used for modifying the nanofiber membrane is avoided; the rigid structure of the open chain cucurbituril can also increase the mechanical property of the nanofiber membrane;
in the aspect of heavy metal adsorption of materials, the C-type open chain cucurbituril increases structural adaptability on the basis of not losing the original carbamido rigid skeleton, so that the introduction of the open chain cucurbituril can greatly enhance the adsorption and separation effects of the nanofiber membrane on different chemical environments and chemical substances of different types and sizes. The cavity structure which can change according to the chemical environment can realize the adsorption of the nanofiber membrane on various pollutants and improve the adsorption capacity of the nanofiber membrane, so that the application range of the nanofiber membrane is wider.
In the aspect of material desorption regeneration, the nanofiber membrane based on the open chain cucurbituril is desorbed because the open chain cucurbituril is easy to change from a C-shape to an S-shape under a certain condition, so that the desorption condition in the process is mild, the energy consumption is low, and the influence on the reusability of the membrane material is small.
Compared with the previous research work, the combination of the supermolecule chemistry and the nanofiber membrane field is only limited to the application of the macrocyclic main body to the nanofiber membrane. Just because the nanofiber membrane based on the cucurbituril makes up the defects of the currently known nanofiber membrane, the application of the nanofiber membrane in the aspect of water treatment of pollutant adsorption is more important and urgent.
As a preferred technical scheme:
according to the easily-desorbed and regenerated open-chain cucurbituril-based material for treating heavy metal water pollution, the grafting rate of the open-chain cucurbituril substituted by hydroxyl on the surface of the nanofiber membrane is 60-80%; the nanofiber membrane is a cross-linked polyvinyl alcohol-based nanofiber membrane, the average diameter of the nanofibers is 200-300 nm, the tensile strength of the nanofiber membrane is 50-80 MPa, and the elastic modulus of the nanofiber membrane is 2000-3000 MPa; the crosslinking degree of the crosslinked polyvinyl alcohol-based nanofiber membrane is 40-90%, and a three-dimensional network structure is formed among the polyvinyl alcohol-based nanofibers through aldol condensation chemical crosslinking caused by dialdehyde under a strong acid condition.
The easy-to-remove regeneration open chain cucurbituril-based material for treating heavy metal water pollution is used for treating heavy metal ions Cu2+、Hg2+、Pb2+、Ni2+The maximum adsorption rate of the adsorbent reaches more than 95 percent; the easy-desorption regeneration open chain cucurbituril-based material for treating heavy metal water pollution can complete desorption after being washed by methanol and water after adsorbing heavy metal ions, and the adsorption rate is still more than 85% after 5 times of adsorption-desorption cycles.
The invention also provides a preparation method of the easy-desorption regeneration open chain cucurbituril matrix material for treating heavy metal water pollution, which comprises the steps of completely immersing the crosslinked polyvinyl alcohol electrostatic spinning nanofiber membrane into the reaction solution for reaction, taking out and washing to obtain the easy-desorption regeneration open chain cucurbituril matrix material for treating heavy metal water pollution;
the preparation method of the crosslinked polyvinyl alcohol electrostatic spinning nanofiber membrane comprises the following steps:
the method comprises the following steps: dissolving polyvinyl alcohol in deionized water, heating and keeping constant temperature to obtain a uniform solution;
step two: adding dialdehyde to the homogeneous solution;
step three: then carrying out electrostatic spinning to obtain electrospinning;
step four: soaking the electrospinning into a strong acid methanol solution to obtain a crosslinked polyvinyl alcohol electrospinning nanofiber membrane; the strong acid methanol solution can be greatly excessive as long as the soaking can be ensured;
the reaction liquid is an intermediate product obtained by reacting hydroxyl-substituted open chain cucurbituril with isocyanate propyltriethoxysilane in an anhydrous dimethyl sulfoxide solvent;
the structural formula of the hydroxyl-substituted open chain cucurbituril is shown in the specification
Figure RE-GDA0003015226520000041
The structural formula of the intermediate product is
Figure RE-GDA0003015226520000051
The mechanism of the in-situ crosslinking process of the polyvinyl alcohol and the dialdehyde is that hydroxyl of the polyvinyl alcohol and aldehyde group of the dialdehyde have aldol condensation reaction under the condition of strong acid, thereby achieving the crosslinking effect.
As a preferred technical scheme:
in the method, in the first step, the mass fraction of the polyvinyl alcohol is 8-15%, and the heating temperature is 85-95 ℃.
In the method, in the second step, dialdehyde is added and then stirred for 0.5 h; the dialdehyde is glutaraldehyde, hexanedial, heptadialdehyde or octanediol; the mass ratio of the polyvinyl alcohol to the dialdehyde is (2-5): 1.
The method comprises the following steps of: the voltage is 10-20 kV, the aluminum foil is used as a receiving screen, the receiving distance between the needle head and the aluminum foil is set to be 11-15 cm, and the spinning speed is 0.3-0.6 mL.h-1(i.e., using a constant flow injection pump at a rate of 0.3-0.6 mL. h-1Delivery of polymer solution)The inner diameter of the flat-head needle head is 0.5-0.9 mm; the electrospinning is prepared in an environment with the temperature of 20-30 ℃ and the relative humidity of 30-50%.
In the fourth step, the content of the strong acid in the methanol solution of the strong acid is 8-12 wt%, and the time for soaking the electrospinning fiber in the methanol solution of the strong acid is 7-11 days; the strong acid is hydrochloric acid, sulfuric acid, hydroiodic acid, or hydrobromic acid.
In the above method, the specific preparation method of the reaction solution is as follows: adding the cucurbituril into anhydrous dimethyl sulfoxide (DMSO), fully dissolving by magnetic stirring, adding anhydrous pyridine, and introducing nitrogen for protection; then adding isocyanate propyl triethoxysilane, and reacting the obtained mixed solution for 10-15 hours at the temperature of 70-90 ℃; wherein the molar ratio of the hydroxyl-substituted open chain cucurbituril to the isocyanate propyltriethoxysilane is (1-1.5): 1, and the volume ratio of the DMSO to the anhydrous pyridine is (8-10): 1.
In the method, the conditions for completely immersing the crosslinked polyvinyl alcohol electrospun nanofiber membrane into the reaction solution are as follows: oscillating for 4-8 hours at the temperature of 25-35 ℃; the washing is that DMSO, methanol and water are used for washing in sequence, and nitrogen is introduced into a nitrogen blowing instrument for blowing and sweeping after washing.
The mechanism for adsorbing the heavy metal pollutants is carried out in the invention: the molecular recognition ability is derived from the host-guest recognition ability of the cucurbituril. The cucurbituril is in a C-type structure, under specific conditions, through chemical modification, due to the effects of factors such as pi-pi accumulation, anion-cation attraction and the like, the cucurbituril can complex various guest molecules to form a host-guest complex (namely, a host-guest recognition effect exists between the cucurbituril and pollutants), and has environment self-adaptability (the size of a cavity of the cucurbituril can be matched with that of the guest molecules by adjusting the size of the opening of the cucurbituril). Size of open chain cucurbituril and size of common heavy metal ion-Cu2+(73pm)、Hg2+(102pm)、Pb2+(77.5pm)、Ni2+(69pm) matched. Therefore, the existence of the open chain cucurbituril modified by the nanofiber membrane increases the adsorption amount of the nanofiber membrane to pollutants.
The mechanism for desorbing the heavy metal pollutants in the invention is as follows: three methods for desorbing pollutants exist at present-one is to add competitive molecules to form a new host-guest structure (a method adopted by a macrocyclic host); secondly, the external stimulation mainly destroys the acting force of the high temperature, the illumination, the pH regulation and the like (the method adopted by the macrocyclic main body); thirdly, the host molecules are deformed due to the change of external conditions, the sizes of the host and the guest cannot be matched (the method of the invention), and the shape of the macrocyclic host (such as cucurbituril, columnar aromatic hydrocarbon and the like) is difficult to change due to the structural limitation, so that the method cannot be adopted. Specifically, in the invention, the open chain cucurbituril can be changed from a C-type structure to an S-type structure under the condition of external environment stimulation (special solvent, temperature rise and the like), so that the cavity structure of a host is changed, a host-guest complex is damaged, and adsorbed heavy metals are separated, thereby completing the desorption process.
Has the advantages that:
(1) the easily-desorbed regenerated open-chain cucurbituril-based material for treating heavy metal water pollution has good mechanical properties such as high tensile strength and high modulus;
(2) the invention relates to an easy-desorption regeneration open chain cucurbituril-based material for treating heavy metal water pollution, which is used for treating common heavy metal ions Cu2+、 Hg2+、Pb2+、Ni2+The adsorbent has high adsorbability and is easy to desorb, regenerate and recycle;
(3) the preparation method of the easy-desorption regeneration open chain cucurbit uril material for treating heavy metal water pollution avoids the problem that the ureido structure is difficult to dissolve, and modifies the ureido structure to the surface of the nanofiber membrane by using a grafting modification method; and dialdehyde and polyvinyl alcohol are subjected to chemical crosslinking under the condition of strong acid, so that the crosslinking degree of nanofiber electrospinning is enhanced, and the mechanical property and the stability of the material in water are improved.
Drawings
FIG. 1 is a schematic diagram of a process for grafting and modifying hydroxyl-substituted open chain cucurbituril on the surface of a polyvinyl alcohol nanofiber membrane (PVANF); wherein the content of the first and second substances,
Figure RE-GDA0003015226520000061
the expression open chain cucurbiturils,
Figure RE-GDA0003015226520000062
denotes a nanofiber membrane (PVANF).
Detailed Description
The invention will be further illustrated with reference to specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.
The structural formula of the hydroxyl-substituted open chain cucurbituril adopted in the embodiment of the invention is as follows:
Figure RE-GDA0003015226520000063
the reaction liquid prepared in the embodiment is an intermediate product obtained by the reaction of hydroxyl-substituted open chain cucurbituril and isocyanate propyltriethoxysilane in an anhydrous dimethyl sulfoxide solvent, and the structural formula of the reaction liquid is
Figure RE-GDA0003015226520000071
Fig. 1 is a schematic diagram of a process of grafting and modifying hydroxyl-substituted open-chain cucurbituril onto a surface of a polyvinyl alcohol nanofiber membrane (PVANF), specifically: reacting hydroxyl-substituted open chain cucurbituril with isocyanate propyltriethoxysilane in DMSO (dimethylsulfoxide), and reacting the obtained product with a polyvinyl alcohol nanofiber membrane (PVANF) in DMSO to obtain the nanofiber membrane with the surface grafted with the hydroxyl-substituted open chain cucurbituril.
Example 1
A preparation method of an easily-desorbed regenerated open-chain cucurbituril-based material for treating heavy metal water pollution comprises the following specific steps:
(1) preparing a crosslinked polyvinyl alcohol electrostatic spinning nanofiber membrane:
(1.1) dissolving polyvinyl alcohol in deionized water, heating to 90 ℃, and mixing under a constant temperature condition to obtain a uniform solution with the mass fraction of 10%;
(1.2) adding glutaraldehyde into the uniform solution, and stirring for 0.5h to obtain a spinning solution; wherein the mass ratio of the polyvinyl alcohol to the glutaraldehyde is 4: 1;
(1.3) Using a constant flow syringe pump, the flow rate of the spinning solution supplied was 0.5 mL. h-1The polymer solution is conveyed, the voltage is set to be 13kV, the aluminum foil is used as a receiving screen, the receiving distance between the needle head and the aluminum foil is 15cm, and the inner diameter of the flat-head needle head is 0.7 mm; electrospinning at 25 deg.C and relative humidity of 40% to obtain electrospun fiber;
(1.4) soaking the obtained electrospun fiber in a methanol solution of hydrochloric acid for 9 days to obtain a crosslinked polyvinyl alcohol electrospun nanofiber membrane; wherein the mass fraction of the hydrochloric acid in the methanol solution of the hydrochloric acid is 10 wt%;
the crosslinking degree of the crosslinked polyvinyl alcohol-based nanofiber membrane is 45%; wherein the average diameter of the nanofibers is 210 nm; the tensile strength of the nanofiber membrane is 53MPa, and the elastic modulus is 2100 MPa.
(2) Preparation of reaction solution:
adding hydroxyl-substituted open chain cucurbituril into anhydrous dimethyl sulfoxide, stirring by magnetic force to fully dissolve, then adding anhydrous pyridine, and introducing nitrogen for protection; then adding isocyanate propyl triethoxysilane, and reacting the obtained mixed solution at 80 ℃ for 12 hours to obtain a reaction solution; wherein, the molar ratio of the hydroxyl-substituted open chain cucurbituril to the isocyanate propyltriethoxysilane is 1.1:1, and the volume ratio of the anhydrous dimethyl sulfoxide to the anhydrous pyridine is 10: 1;
(3) completely immersing the crosslinked polyvinyl alcohol electrostatic spinning nanofiber membrane prepared in the step (1) into the reaction solution prepared in the step (2) to vibrate for 6 hours at the temperature of 30 ℃ for reaction, taking out and washing with anhydrous dimethyl sulfoxide, methanol and water in sequence, and blowing and sweeping with nitrogen by using a nitrogen blower after washing to obtain the easily-desorbed regenerated open-chain cucurbituril material for treating heavy metal water pollution; wherein the mass ratio of the polyvinyl alcohol electrostatic spinning nanofiber membrane to the hydroxyl-substituted open-chain cucurbituril is 35:1 during reaction.
The prepared easy-to-remove regenerated open chain cucurbituril material for treating heavy metal water pollution is a nanofiber membrane with the surface grafted with hydroxyl substituted open chain cucurbituril, and the grafting rate of the hydroxyl substituted open chain cucurbituril is 61%.
The application of the open chain cucurbituril ureido polyvinyl alcohol nanofiber membrane in treating heavy metal water pollution is as follows:
(I) adsorption test: selecting Hg2+Detecting Hg in the open chain cucurbituril-based polyvinyl alcohol nanofiber membrane as a model molecule2+The adsorption effect of (1). By fixing Hg2+And (3) respectively changing the dosage of the open-chain cucurbituril-ureido polyvinyl alcohol nanofiber membrane of the adsorbent to determine the influence of the quality of the adsorbent on the adsorption efficiency according to the initial concentration of the solution. In the experiment, 5mg, 10mg, 15mg, 20mg, 25mg and 30mg of the open chain cucurbituril-based polyvinyl alcohol nanofiber membrane and the polyvinyl alcohol nanofiber membrane are respectively weighed and added into a mercury-containing aqueous solution (pH 1) with the initial concentration of 25mg/mL, the mixture is placed at room temperature for 36 hours, and then the change of the absorbance of the adsorption solution is tested.
The results show that: hg pair of open chain cucurbit urea-based polyvinyl alcohol nanofiber membranes2+Has obvious adsorption effect, the adsorption rate of heavy metal is gradually increased along with the increase of the dosage of the adsorbent, the dosage of the corresponding adsorbent reaches the balance after 20mg, and the maximum adsorption capacity is 95%. When the dosage of the adsorbent is continuously increased from 20mg to 30mg, the adsorption rate is not obviously changed.
(II) Desorption regenerability test: preparing Hg with proper concentration2+The solution is used as a sample solution to be detected, the open chain cucurbituril ureido polyvinyl alcohol nanofiber membrane is immersed in the solution for 36 hours and then taken out, the detection wavelength is 532nm through an ultraviolet-visible spectrophotometry method, and the change of the absorbance of the residual sample solution is measured. Adsorbing the Hg2+The open chain cucurbituril ureido polyvinyl alcohol nanofiber membrane is washed by methanol for three times, and the washed open chain cucurbituril ureido polyvinyl alcohol nanofiber membrane is immersed into Hg with the same concentration again2+The solution is subjected to an adsorption operation, and the Hg is measured after adsorption is finished2+Absorbance of the solution. The steps are repeated for many times, and the adsorption performance of the open chain cucurbituril-ureido polyvinyl alcohol nanofiber membrane on heavy metals is researched when the open chain cucurbituril-ureido polyvinyl alcohol nanofiber membrane is repeatedly utilized.
The results show that: the open chain cucurbituril-based polyvinyl alcohol nanofiber membrane can recover the adsorption capacity again after being simply cleaned by methanol, the adsorption capacity is not obviously reduced after repeated use for many times, and the adsorption rate is 85% after 5 times of adsorption-desorption cycles, which indicates that the material has good reproducibility.
Example 2
A preparation method of an easily-desorbed regenerated open-chain cucurbituril-based material for treating heavy metal water pollution comprises the following specific steps:
(1) preparing a crosslinked polyvinyl alcohol electrostatic spinning nanofiber membrane:
(1.1) dissolving polyvinyl alcohol in deionized water, heating to 85 ℃, and mixing under a constant temperature condition to obtain a uniform solution with the mass fraction of 8%;
(1.2) adding glutaraldehyde into the uniform solution, and stirring for 0.5h to obtain a spinning solution; wherein the mass ratio of the polyvinyl alcohol to the glutaraldehyde is 2: 1;
(1.3) Using a constant flow syringe pump, the flow rate of the spinning solution supplied was 0.3 mL. h-1The polymer solution is conveyed, the voltage is set to be 10kV, the aluminum foil is used as a receiving screen, the receiving distance between the needle head and the aluminum foil is 11cm, and the inner diameter of the flat-head needle head is 0.5 mm; electrospinning at 20 deg.C and relative humidity of 30% to obtain electrospun fiber;
(1.4) soaking the obtained electrospun fiber in a methanol solution of sulfuric acid for 7 days to obtain a crosslinked polyvinyl alcohol electrospun nanofiber membrane; wherein the mass fraction of the sulfuric acid in the methanol solution of the sulfuric acid is 8 wt%;
the crosslinking degree of the crosslinked polyvinyl alcohol-based nanofiber membrane is 40%; wherein the average diameter of the nanofibers is 200 nm; the tensile strength of the nanofiber membrane is 50MPa, and the elastic modulus is 2000 MPa.
(2) Preparation of reaction solution:
adding hydroxyl-substituted open chain cucurbituril into anhydrous dimethyl sulfoxide, stirring by magnetic force to fully dissolve, then adding anhydrous pyridine, and introducing nitrogen for protection; then adding isocyanate propyl triethoxysilane, and reacting the obtained mixed solution for 15 hours at 70 ℃ to obtain a reaction solution; wherein, the molar ratio of the hydroxyl-substituted open chain cucurbituril to the isocyanate propyltriethoxysilane is 1:1, and the volume ratio of the anhydrous dimethyl sulfoxide to the anhydrous pyridine is 8: 1;
(3) completely immersing the crosslinked polyvinyl alcohol electrostatic spinning nanofiber membrane prepared in the step (1) into the reaction solution prepared in the step (2) to vibrate for 8 hours at the temperature of 25 ℃ for reaction, taking out and washing with anhydrous dimethyl sulfoxide, methanol and water in sequence, and blowing and sweeping with nitrogen by using a nitrogen blower after washing to obtain the easily-desorbed regenerated open-chain cucurbituril material for treating heavy metal water pollution; wherein the mass ratio of the polyvinyl alcohol electrostatic spinning nanofiber membrane to the hydroxyl-substituted open-chain cucurbituril is 40: 1.
The prepared easy-to-remove regenerated open chain cucurbituril material for treating heavy metal water pollution is a nanofiber membrane with the surface grafted with hydroxyl substituted open chain cucurbituril, and the grafting rate of the hydroxyl substituted open chain cucurbituril is 60%;
application of easily-desorbed and regenerated open-chain cucurbituril-based material for treating heavy metal water pollution to Cu2+The adsorption and desorption results are: for Cu2+The maximum adsorption rate of the adsorbent reaches 96 percent; easy-to-desorb regenerated open-chain cucurbituril-based material for treating heavy metal water pollution in Cu adsorption2+Then the desorption can be completed by methanol and water washing, and the adsorption rate is 86 percent after 5 times of adsorption-desorption cycles.
Example 3
A preparation method of an easily-desorbed regenerated open-chain cucurbituril-based material for treating heavy metal water pollution comprises the following specific steps:
(1) preparing a crosslinked polyvinyl alcohol electrostatic spinning nanofiber membrane:
(1.1) dissolving polyvinyl alcohol in deionized water, heating to 87 ℃, and mixing under a constant temperature condition to obtain a uniform solution with the mass fraction of 15%;
(1.2) adding adipaldehyde into the uniform solution, and stirring for 0.5h to obtain a spinning solution; wherein the mass ratio of the polyvinyl alcohol to the hexanedial is 3: 1;
(1.3) Using a constant flow syringe pump, the flow rate of the spinning solution supplied was 0.5 mL. h-1The polymer solution is conveyed, the voltage is set to be 16kV, the aluminum foil is used as a receiving screen, the receiving distance between the needle head and the aluminum foil is 14cm, and the inner diameter of the flat-head needle head is 0.8 mm; electrospinning at 30 deg.C and relative humidity of 50% to obtain electrospun fiber；
(1.4) soaking the obtained electrospun fiber in a methanol solution of hydroiodic acid for 8 days to obtain a crosslinked polyvinyl alcohol electrospun nanofiber membrane; wherein the mass fraction of the hydroiodic acid in the methanol solution of the hydroiodic acid is 9 wt%;
the crosslinking degree of the crosslinked polyvinyl alcohol-based nanofiber membrane is 55%; wherein the average diameter of the nanofibers is 220 nm; the tensile strength of the nanofiber membrane is 66MPa, and the elastic modulus of the nanofiber membrane is 2400 MPa.
(2) Preparation of reaction solution:
adding hydroxyl-substituted open chain cucurbituril into anhydrous dimethyl sulfoxide, stirring by magnetic force to fully dissolve, then adding anhydrous pyridine, and introducing nitrogen for protection; then adding isocyanate propyl triethoxysilane, and reacting the obtained mixed solution at 85 ℃ for 14 hours to obtain a reaction solution; wherein, the molar ratio of the hydroxyl-substituted open chain cucurbituril to the isocyanate propyltriethoxysilane is 1.1:1, and the volume ratio of the anhydrous dimethyl sulfoxide to the anhydrous pyridine is 9: 1;
(3) completely immersing the crosslinked polyvinyl alcohol electrostatic spinning nanofiber membrane prepared in the step (1) into the reaction solution prepared in the step (2) to vibrate for 5 hours at the temperature of 30 ℃ for reaction, taking out and washing with anhydrous dimethyl sulfoxide, methanol and water in sequence, and blowing and sweeping with nitrogen by using a nitrogen blower after washing to obtain the easily-desorbed regenerated open-chain cucurbituril material for treating heavy metal water pollution; wherein the mass ratio of the polyvinyl alcohol electrostatic spinning nanofiber membrane to the hydroxyl-substituted open-chain cucurbituril is 32:1 during reaction.
The prepared easy-to-remove regenerated open chain cucurbituril material for treating heavy metal water pollution is a nanofiber membrane with the surface grafted with hydroxyl substituted open chain cucurbituril, and the grafting rate of the hydroxyl substituted open chain cucurbituril is 68%;
application of easily-desorbed and regenerated open-chain cucurbituril-based material for treating heavy metal water pollution to Hg2+The adsorption and desorption results are: for Hg2+The maximum adsorption rate of the adsorbent reaches 96 percent; easy-to-desorb regenerated open-chain cucurbituril-based material for treating heavy metal water pollution in adsorption of Hg2+Then the desorption can be completed through methanol and water washing, andthe adsorption rate after 5 adsorption-desorption cycles was 90%.
Example 4
A preparation method of an easily-desorbed regenerated open-chain cucurbituril-based material for treating heavy metal water pollution comprises the following specific steps:
(1) preparing a crosslinked polyvinyl alcohol electrostatic spinning nanofiber membrane:
(1.1) dissolving polyvinyl alcohol in deionized water, heating to 95 ℃, and mixing under a constant temperature condition to obtain a uniform solution with the mass fraction of 10%;
(1.2) adding heptanediol into the uniform solution, and stirring for 0.5h to obtain a spinning solution; wherein the mass ratio of the polyvinyl alcohol to the heptanediol is 4: 1;
(1.3) Using a constant flow syringe pump, the flow rate of the spinning solution supplied was 0.4 mL. h-1The polymer solution is conveyed, the voltage is set to be 13kV, the aluminum foil is used as a receiving screen, the receiving distance between the needle head and the aluminum foil is 12cm, and the inner diameter of the flat-head needle head is 0.6 mm; electrospinning at 22 deg.C and relative humidity of 34% to obtain electrospun fiber;
(1.4) soaking the obtained electrospun fiber in a methanol solution of hydrobromic acid for 9 days to obtain a crosslinked polyvinyl alcohol electrospun nanofiber membrane; wherein the mass fraction of the hydrobromic acid in the methanol solution of the hydrobromic acid is 10 wt%;
the crosslinking degree of the crosslinked polyvinyl alcohol-based nanofiber membrane is 76%; wherein the average diameter of the nanofibers is 250 nm; the tensile strength of the nanofiber membrane is 69MPa, and the elastic modulus of the nanofiber membrane is 2500 MPa.
(2) Preparation of reaction solution:
adding hydroxyl-substituted open chain cucurbituril into anhydrous dimethyl sulfoxide, stirring by magnetic force to fully dissolve, then adding anhydrous pyridine, and introducing nitrogen for protection; then adding isocyanate propyl triethoxysilane, and reacting the obtained mixed solution for 13 hours at the temperature of 75 ℃ to obtain reaction solution; wherein, the molar ratio of the hydroxyl-substituted open chain cucurbituril to the isocyanate propyltriethoxysilane is 1.3:1, and the volume ratio of the anhydrous dimethyl sulfoxide to the anhydrous pyridine is 10: 1;
(3) completely immersing the crosslinked polyvinyl alcohol electrostatic spinning nanofiber membrane prepared in the step (1) into the reaction solution prepared in the step (2) to react by oscillation for 4.5 hours at 32 ℃, taking out and washing with anhydrous dimethyl sulfoxide, methanol and water in sequence, and blowing with nitrogen by using a nitrogen blowing instrument after washing to obtain the easily-desorbed regenerated open-chain cucurbituril-based material for treating heavy metal water pollution; wherein the mass ratio of the polyvinyl alcohol electrostatic spinning nanofiber membrane to the hydroxyl-substituted open-chain cucurbituril is 28: 1.
The prepared easy-to-remove regenerated open chain cucurbituril material for treating heavy metal water pollution is a nanofiber membrane with the surface grafted with hydroxyl substituted open chain cucurbituril, and the grafting rate of the hydroxyl substituted open chain cucurbituril is 72%;
application of easily-desorbed and regenerated open-chain cucurbituril-based material for treating heavy metal water pollution to Pb2+The adsorption and desorption results are: for Pb2+The maximum adsorption rate of the catalyst reaches 97 percent; easy-to-desorb regenerated open-chain cucurbituril-based material for treating heavy metal water pollution in adsorption of Pb2+Then the desorption can be completed by methanol and water washing, and the adsorption rate is 92 percent after 5 times of adsorption-desorption cycles.
Example 5
A preparation method of an easily-desorbed regenerated open-chain cucurbituril-based material for treating heavy metal water pollution comprises the following specific steps:
(1) preparing a crosslinked polyvinyl alcohol electrostatic spinning nanofiber membrane:
(1.1) dissolving polyvinyl alcohol in deionized water, heating to 93 ℃, and mixing under a constant temperature condition to obtain a uniform solution with the mass fraction of 11%;
(1.2) adding octanediol into the uniform solution, and stirring for 0.5h to obtain a spinning solution; wherein the mass ratio of the polyvinyl alcohol to the octanediol is 5: 1;
(1.3) Using a constant flow syringe pump, the flow rate of the spinning solution supplied was 0.6 mL. h-1The polymer solution is conveyed, the voltage is set to be 20kV, the aluminum foil is used as a receiving screen, the receiving distance between the needle head and the aluminum foil is 15cm, and the inner diameter of the flat-head needle head is 0.9 mm; electrospinning at 28 deg.C and relative humidity of 46% to obtain electrospun fiber;
(1.4) soaking the obtained electrospun fiber in a methanol solution of hydrochloric acid for 10 days to obtain a crosslinked polyvinyl alcohol electrospun nanofiber membrane; wherein the mass fraction of the hydrochloric acid in the methanol solution of the hydrochloric acid is 11 wt%;
the crosslinking degree of the crosslinked polyvinyl alcohol-based nanofiber membrane is 90%; wherein the average diameter of the nanofibers is 300 nm; the tensile strength of the nanofiber membrane is 80MPa, and the elastic modulus is 3000 MPa.
(2) Preparation of reaction solution:
adding hydroxyl-substituted open chain cucurbituril into anhydrous dimethyl sulfoxide, stirring by magnetic force to fully dissolve, then adding anhydrous pyridine, and introducing nitrogen for protection; then adding isocyanate propyl triethoxysilane, and reacting the obtained mixed solution at 80 ℃ for 12 hours to obtain a reaction solution; wherein, the molar ratio of the hydroxyl-substituted open chain cucurbituril to the isocyanate propyltriethoxysilane is 1.2:1, and the volume ratio of the anhydrous dimethyl sulfoxide to the anhydrous pyridine is 10: 1;
(3) completely immersing the crosslinked polyvinyl alcohol electrostatic spinning nanofiber membrane prepared in the step (1) into the reaction solution prepared in the step (2) to vibrate for 7 hours at the temperature of 27 ℃ for reaction, taking out and washing with anhydrous dimethyl sulfoxide, methanol and water in sequence, and blowing and sweeping with nitrogen by using a nitrogen blower after washing to obtain the easily-desorbed regenerated open-chain cucurbituril material for treating heavy metal water pollution; wherein the mass ratio of the polyvinyl alcohol electrostatic spinning nanofiber membrane to the hydroxyl-substituted open-chain cucurbituril is 15: 1.
The prepared easy-to-remove regenerated open chain cucurbituril material for treating heavy metal water pollution is a nanofiber membrane with the surface grafted with hydroxyl substituted open chain cucurbituril, and the grafting rate of the hydroxyl substituted open chain cucurbituril is 80%;
application of easily-desorbed and regenerated open-chain cucurbituril-based material for treating heavy metal water pollution to Ni2+The adsorption and desorption results are: for Ni2+The maximum adsorption rate of the catalyst reaches 97 percent; easy-to-desorb regenerated open-chain cucurbituril-based material for treating heavy metal water pollution in process of adsorbing Ni2+Then the desorption can be completed by methanol and water washing, and the adsorption rate is 88 percent after 5 times of adsorption-desorption cycles.
Example 6
A preparation method of an easily-desorbed regenerated open-chain cucurbituril-based material for treating heavy metal water pollution comprises the following specific steps:
(1) preparing a crosslinked polyvinyl alcohol electrostatic spinning nanofiber membrane:
(1.1) dissolving polyvinyl alcohol in deionized water, heating to 89 ℃, and mixing under a constant temperature condition to obtain a uniform solution with the mass fraction of 12%;
(1.2) adding heptanediol into the uniform solution, and stirring for 0.5h to obtain a spinning solution; wherein the mass ratio of the polyvinyl alcohol to the heptanediol is 2: 1;
(1.3) Using a constant flow syringe pump, the flow rate of the spinning solution supplied was 0.4 mL. h-1The polymer solution is conveyed, the voltage is set to be 15kV, the aluminum foil is used as a receiving screen, the receiving distance between the needle head and the aluminum foil is 13cm, and the inner diameter of the flat-head needle head is 0.7 mm; electrospinning at 24 deg.C and relative humidity of 38% to obtain electrospun fiber;
(1.4) soaking the obtained electrospun fiber in a methanol solution of sulfuric acid for 11 days to obtain a crosslinked polyvinyl alcohol electrospun nanofiber membrane; wherein the mass fraction of the sulfuric acid in the methanol solution of the sulfuric acid is 12 wt%;
the crosslinking degree of the crosslinked polyvinyl alcohol-based nanofiber membrane is 80%; wherein the average diameter of the nanofibers is 280 nm; the tensile strength of the nanofiber membrane is 72MPa, and the elastic modulus is 2600 MPa.
(2) Preparation of reaction solution:
adding hydroxyl-substituted open chain cucurbituril into anhydrous dimethyl sulfoxide, stirring by magnetic force to fully dissolve, then adding anhydrous pyridine, and introducing nitrogen for protection; then adding isocyanate propyl triethoxysilane, and reacting the obtained mixed solution for 10 hours at 90 ℃ to obtain reaction solution; wherein, the molar ratio of the hydroxyl-substituted open chain cucurbituril to the isocyanate propyltriethoxysilane is 1.4:1, and the volume ratio of the anhydrous dimethyl sulfoxide to the anhydrous pyridine is 8: 1;
(3) completely immersing the crosslinked polyvinyl alcohol electrostatic spinning nanofiber membrane prepared in the step (1) into the reaction solution prepared in the step (2) to vibrate for 6 hours at 29 ℃ for reaction, taking out and washing with anhydrous dimethyl sulfoxide, methanol and water in sequence, and blowing and sweeping with nitrogen by using a nitrogen blower after washing to obtain the easily-desorbed regenerated open-chain cucurbituril material for treating heavy metal water pollution; wherein the mass ratio of the polyvinyl alcohol electrostatic spinning nanofiber membrane to the hydroxyl-substituted open-chain cucurbituril is 25: 1.
The prepared easy-to-remove regenerated open chain cucurbituril material for treating heavy metal water pollution is a nanofiber membrane with the surface grafted with hydroxyl substituted open chain cucurbituril, and the grafting rate of the hydroxyl substituted open chain cucurbituril is 73%;
application of easily-desorbed and regenerated open-chain cucurbituril-based material for treating heavy metal water pollution to Cu2+The adsorption and desorption results are: for Cu2+The maximum adsorption rate of the adsorbent reaches 98 percent; easy-to-desorb regenerated open-chain cucurbituril-based material for treating heavy metal water pollution in Cu adsorption2+Then, the desorption can be completed through methanol and water washing, and the adsorption rate is 87 percent after 5 times of adsorption-desorption cycles.
Example 7
A preparation method of an easily-desorbed regenerated open-chain cucurbituril-based material for treating heavy metal water pollution comprises the following specific steps:
(1) preparing a crosslinked polyvinyl alcohol electrostatic spinning nanofiber membrane:
(1.1) dissolving polyvinyl alcohol in deionized water, heating to 92 ℃, and mixing under a constant temperature condition to obtain a uniform solution with the mass fraction of 13%;
(1.2) adding octanediol into the uniform solution, and stirring for 0.5h to obtain a spinning solution; wherein the mass ratio of the polyvinyl alcohol to the octanediol is 4: 1;
(1.3) Using a constant flow syringe pump, the flow rate of the spinning solution supplied was 0.5 mL. h-1The polymer solution is conveyed, the voltage is set to be 18kV, the aluminum foil is used as a receiving screen, the receiving distance between the needle head and the aluminum foil is 14cm, and the inner diameter of the flat-head needle head is 0.8 mm; electrospinning at 26 deg.C and relative humidity of 42% to obtain electrospun fiber;
(1.4) soaking the obtained electrospun fiber in a methanol solution of hydroiodic acid for 9 days to obtain a crosslinked polyvinyl alcohol electrospun nanofiber membrane; wherein the mass fraction of the hydroiodic acid in the methanol solution of the hydroiodic acid is 9 wt%;
the crosslinking degree of the crosslinked polyvinyl alcohol-based nanofiber membrane is 88%; wherein the average diameter of the nanofibers is 290 nm; the nanofiber membrane had a tensile strength of 78MPa and an elastic modulus of 2800 MPa.
(2) Preparation of reaction solution:
adding hydroxyl-substituted open chain cucurbituril into anhydrous dimethyl sulfoxide, stirring by magnetic force to fully dissolve, then adding anhydrous pyridine, and introducing nitrogen for protection; then adding isocyanate propyl triethoxysilane, and reacting the obtained mixed solution for 11 hours at 79 ℃ to obtain a reaction solution; wherein, the molar ratio of the hydroxyl-substituted open chain cucurbituril to the isocyanate propyltriethoxysilane is 1.5:1, and the volume ratio of the anhydrous dimethyl sulfoxide to the anhydrous pyridine is 9: 1;
(3) completely immersing the crosslinked polyvinyl alcohol electrostatic spinning nanofiber membrane prepared in the step (1) into the reaction solution prepared in the step (2) to vibrate for 4 hours at 35 ℃ for reaction, taking out and washing with anhydrous dimethyl sulfoxide, methanol and water in sequence, and blowing and sweeping with nitrogen by using a nitrogen blower after washing to obtain the easily-desorbed regenerated open-chain cucurbituril material for treating heavy metal water pollution; wherein the mass ratio of the polyvinyl alcohol electrostatic spinning nanofiber membrane to the hydroxyl-substituted open-chain cucurbituril is 20: 1.
The prepared easy-to-remove regenerated open chain cucurbituril material for treating heavy metal water pollution is a nanofiber membrane with the surface grafted with hydroxyl substituted open chain cucurbituril, and the grafting rate of the hydroxyl substituted open chain cucurbituril is 75 percent;
application of easily-desorbed and regenerated open-chain cucurbituril-based material for treating heavy metal water pollution to Hg2+The adsorption and desorption results are: for Hg2+The maximum adsorption rate of the adsorbent reaches 95 percent; easy-to-desorb regenerated open-chain cucurbituril-based material for treating heavy metal water pollution in adsorption of Hg2+Then the desorption can be finished by methanol and water washing, and the adsorption rate is 85 percent after 5 times of adsorption-desorption cycles.

Claims (10)

1. The easy-to-desorb regenerated open chain cucurbituril-based material for treating heavy metal water pollution is characterized in that: is a nanofiber membrane with the surface grafted with hydroxyl substituted open chain cucurbituril;
the structural formula of the hydroxyl-substituted open chain cucurbituril is shown in the specification
Figure FDA0002931494160000011
2. The easy-to-detach regenerated open chain cucurbituril-based material for treating heavy metal water pollution according to claim 1, wherein the grafting rate of the hydroxyl-substituted open chain cucurbituril on the surface of the nanofiber membrane is 60-80%; the nanofiber membrane is a cross-linked polyvinyl alcohol-based nanofiber membrane; the average diameter of the nano-fibers is 200-300 nm; the tensile strength of the nanofiber membrane is 50-80 MPa, and the elastic modulus is 2000-3000 MPa; the crosslinking degree of the crosslinked polyvinyl alcohol-based nanofiber membrane is 40-90%.
3. The easy-to-desorb regenerated open chain cucurbituril-based material for treating heavy metal water pollution according to claim 1, wherein the maximum adsorption rate of the easy-to-desorb regenerated open chain cucurbituril-based material for treating heavy metal water pollution to heavy metal ions is more than 95%; the easy-desorption regeneration open chain cucurbituril-based material for treating heavy metal water pollution can complete desorption after being washed by methanol and water after adsorbing heavy metal ions, and the adsorption rate is more than 85 percent after 5 times of adsorption-desorption cycles; the heavy metal ion is Cu2+、Hg2+、Pb2+、Ni2+。
4. A preparation method of an easy-desorption regeneration open chain cucurbituril-based material for treating heavy metal water pollution is characterized by comprising the following steps: completely immersing the crosslinked polyvinyl alcohol electrostatic spinning nanofiber membrane into the reaction solution for reaction, taking out and washing to obtain the easily-desorbed regenerated open-chain cucurbituril-based material for treating heavy metal water pollution;
the preparation method of the crosslinked polyvinyl alcohol electrostatic spinning nanofiber membrane comprises the following steps:
the method comprises the following steps: dissolving polyvinyl alcohol in deionized water, heating and keeping constant temperature to obtain a uniform solution;
step two: adding dialdehyde to the homogeneous solution;
step three: then carrying out electrostatic spinning to obtain electrospinning;
step four: soaking the electrospinning into a strong acid methanol solution to obtain a crosslinked polyvinyl alcohol electrospinning nanofiber membrane;
the reaction liquid is an intermediate product obtained by reacting hydroxyl-substituted open chain cucurbituril with isocyanate propyltriethoxysilane in an anhydrous dimethyl sulfoxide solvent;
the structural formula of the hydroxyl-substituted open chain cucurbituril is shown in the specification
Figure FDA0002931494160000021
The structural formula of the intermediate product is
Figure FDA0002931494160000022
5. The method according to claim 4, wherein in the first step, the mass fraction of the polyvinyl alcohol is 8-15%, and the heating temperature is 85-95 ℃.
6. The method according to claim 4, wherein in step two, the dialdehyde is added and then stirred for 0.5 h; the dialdehyde is glutaraldehyde, hexanedial, heptadialdehyde or octanediol; the mass ratio of the polyvinyl alcohol to the dialdehyde is (2-5): 1.
7. The method according to claim 4, wherein in the third step, the spinning process of the electrostatic spinning is as follows: the voltage is 10-20 kV, the aluminum foil is used as a receiving screen, the receiving distance between the needle head and the aluminum foil is 11-15 cm, and the spinning speed is 0.3-0.6 mL.h-1The inner diameter of the flat-head needle head is 0.5-0.9 mm; the electrospinning is prepared in an environment with the temperature of 20-30 ℃ and the relative humidity of 30-50%.
8. The method of claim 4, wherein in the fourth step, the content of the strong acid in the methanol solution of the strong acid is 8 to 12 wt%, and the time for immersing the electrospinning filament in the methanol solution of the strong acid is 7 to 11 days; the strong acid is hydrochloric acid, sulfuric acid, hydroiodic acid, or hydrobromic acid.
9. The method according to claim 4, wherein the reaction solution is prepared by a specific method comprising: adding hydroxyl-substituted open chain cucurbituril into anhydrous dimethyl sulfoxide, stirring by magnetic force to fully dissolve, then adding anhydrous pyridine, and introducing nitrogen for protection; then adding isocyanate propyl triethoxysilane, and reacting the obtained mixed solution for 10-15 hours at the temperature of 70-90 ℃; wherein the molar ratio of the hydroxyl-substituted open chain cucurbituril to the isocyanate propyltriethoxysilane is (1-1.5): 1, and the volume ratio of the anhydrous dimethyl sulfoxide to the anhydrous pyridine is (8-10): 1.
10. The method according to claim 4, wherein the conditions for completely immersing the crosslinked polyvinyl alcohol electrospun nanofiber membrane in the reaction solution are as follows: oscillating for 4-8 hours at the temperature of 25-35 ℃; the washing is that anhydrous dimethyl sulfoxide, methanol and water are used for washing in sequence, and a nitrogen blowing instrument is used for introducing nitrogen for blowing and sweeping after washing.
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