U.S. patent application number 16/934066 was filed with the patent office on 2021-09-09 for zirconium-based metal-organic framework material uio-66(zr), rapid room-temperature preparation method and application thereof.
This patent application is currently assigned to Tongji University. The applicant listed for this patent is Tongji University. Invention is credited to Fengting Li, Yinan Wu.
Application Number | 20210277029 16/934066 |
Document ID | / |
Family ID | 1000005795494 |
Filed Date | 2021-09-09 |
United States Patent
Application |
20210277029 |
Kind Code |
A1 |
Li; Fengting ; et
al. |
September 9, 2021 |
ZIRCONIUM-BASED METAL-ORGANIC FRAMEWORK MATERIAL UIO-66(ZR), RAPID
ROOM-TEMPERATURE PREPARATION METHOD AND APPLICATION THEREOF
Abstract
A zirconium-based metal-organic framework material UiO-66(Zr)
and a rapid room-temperature preparation method and application
thereof are procided. The preparation method includes: (1) mixing a
zirconium source and an organic ligand uniformly, then placing in
methanol and stirring at room temperature, centrifuging and then
discarding a supernatant to obtain a transparent gel-like
intermediate product; and (2) heating and drying the intermediate
product to obtain UiO-66(Zr). Compared with the prior art, the
present invention excludes the use of N,N-dimethylformamide and
other toxic organic solvents that are necessary in the traditional
solvothermal method, and only needs to stir in methanol at room
temperature and dry to obtain UiO-66(Zr). The method has mild
conditions and a high yield. Moreover, the product purity is
extremely high, and the product activation step can be omitted. The
product has good adsorption to fluoride ion in water, and can be
applied to the adsorption treatment of fluorine-containing
wastewater.
Inventors: |
Li; Fengting; (Shanghai,
CN) ; Wu; Yinan; (Shanghai, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Tongji University |
Shanghai |
|
CN |
|
|
Assignee: |
Tongji University
Shanghai
CN
|
Family ID: |
1000005795494 |
Appl. No.: |
16/934066 |
Filed: |
July 21, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C07F 7/003 20130101 |
International
Class: |
C07F 7/00 20060101
C07F007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 6, 2020 |
CN |
202010151476.0 |
Claims
1. A rapid room-temperature preparation method of a zirconium-based
metal-organic framework material UiO-66(Zr), comprising the
following steps: (1) mixing a zirconium source and an organic
ligand uniformly to obtain a mixture, then placing the mixture in
methanol to obtain a mixed solution and stirring the mixed solution
at room temperature, centrifuging the mixed solution to obtain a
centrifuged product and then discarding a supernatant of the
centrifuged product to obtain a transparent gel-like intermediate
product; and (2) heating and drying the transparent gel-like
intermediate product obtained in step (1) to obtain the
zirconium-based metal-organic framework material UiO-66(Zr);
wherein the zirconium source is zirconium oxychloride
octahydrate.
2. (canceled)
3. The rapid room-temperature preparation method of the
zirconium-based metal-organic framework material UiO-66(Zr)
according to claim 1, wherein the organic ligand is one selected
from the group consisting of terephthalic acid, 2-bromoterephthalic
acid and aminoterephthalic acid.
4. The rapid room-temperature preparation method of the
zirconium-based metal-organic framework material UiO-66(Zr)
according to claim 1, wherein a molar ratio of the zirconium source
to the organic ligand is (1-2):(2-1).
5. The rapid room-temperature preparation method of the
zirconium-based metal-organic framework material UiO-66(Zr)
according to claim 1, wherein in step (1), a mass ratio of a
mixture of the zirconium source and the organic ligand to the
methanol is 1:(10-100).
6. The rapid room-temperature preparation method of the
zirconium-based metal-organic framework material UiO-66(Zr)
according to claim 1, wherein in step (1), a time for the stirring
is 0.5-2 h.
7. The rapid room-temperature preparation method of the
zirconium-based metal-organic framework material UiO-66(Zr)
according to claim 1, wherein in step (2), a temperature for the
heating and drying is 40-120.degree. C.
8. The rapid room-temperature preparation method of the
zirconium-based metal-organic framework material UiO-66(Zr)
according to claim 1, wherein in step (2), a time for the heating
and drying is 0.5-4 h.
9. A zirconium-based metal-organic framework material UiO-66(Zr),
wherein the zirconium-based metal-organic framework material
UiO-66(Zr) is obtained by using the rapid room-temperature
preparation method according claim 1.
10. A method of using the zirconium-based metal-organic framework
material UiO-66(Zr) according to claim 9, comprising applying the
zirconium-based metal-organic framework material UiO-66(Zr) in
water containing fluoride ion pollutants.
11. (canceled)
12. The rapid room-temperature preparation method of the
zirconium-based metal-organic framework material UiO-66(Zr)
according to claim 3, wherein a molar ratio of the zirconium source
to the organic ligand is (1-2):(2-1).
13. (canceled)
14. The zirconium-based metal-organic framework material UiO-66(Zr)
according to claim 9, wherein the organic ligand is one selected
from the group consisting of terephthalic acid, 2-bromoterephthalic
acid and aminoterephthalic acid.
15. The zirconium-based metal-organic framework material UiO-66(Zr)
according to claim 9, wherein a molar ratio of the zirconium source
to the organic ligand is (1-2):(2-1).
16. The zirconium-based metal-organic framework material UiO-66(Zr)
according to claim 9, wherein in step (1), a mass ratio of a
mixture of the zirconium source and the organic ligand to the
methanol is 1:(10-100).
17. The zirconium-based metal-organic framework material UiO-66(Zr)
according to claim 9, wherein in step (1), a time for the stirring
is 0.5-2 h.
18. The zirconium-based metal-organic framework material UiO-66(Zr)
according to claim 9, wherein in step (2), a temperature for the
heating and drying is 40-120.degree. C.
19. The zirconium-based metal-organic framework material UiO-66(Zr)
according to claim 9, wherein in step (2), a time for the heating
and drying is 0.5-4 h.
Description
CROSS REFERENCE TO THE RELATED APPLICATIONS
[0001] This application is based upon and claims priority to
Chinese Patent Application No. 202010151476.0, filed on Mar. 6,
2020, the entire contents of which are incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present invention belongs to the technical field of
metal-organic framework materials, and in particular to a
zirconium-based metal-organic framework material UiO-66(Zr), and
its rapid room-temperature preparation method and use in fluoride
removal from water.
BACKGROUND
[0003] A metal-organic framework (MOF), also known as a
metal-organic complex or an organic-inorganic hybrid material, is a
type of porous material formed by self-assembly of a metal salt and
an organic ligand. MOFs have attracted more and more attention
recently because of the characteristics including a high porosity,
a high specific surface area, an adjustable micropore size, a
variable structure, and a diverse structural function. MOFs have
been widely studied and applied in gas adsorption and storage,
sensing and detection, drug delivery and catalysis reaction, and
other fields.
[0004] UiO-66(Zr) is a metal-organic framework material formed by
an inorganic metal unit Zr.sub.6O.sub.4(OH).sub.4 and twelve
terephthalic acid ligands. UiO-66(Zr) has two cage structures,
i.e., tetrahedron and octahedron. Eight faces on each octahedral
cage are each connected to one tetrahedral cage, forming a
three-dimensional structure in turn. Cavka et al. first reported
the synthesis of UiO-66 in 2008. Due to the very strong interaction
between Zr--O, the UiO-66(Zr) has good water stability and thermal
stability. It is stable and maintains its structure in a solution
of pH 1-11. The framework collapses only when the carbon-carbon
bond formed by benzene ring and carboxylic acid breaks at
540.degree. C.
[0005] Research on synthesis of UiO-66 is reported in the following
patent and published documents.
[0006] Chinese patent CN107163258A discloses a preparation method
of a metal-organic framework material UiO-66 in an ethanol phase.
It is characterized in that an intermediate product is obtained by
pretreating a zirconium source and an organic ligand, and then
stirred in ethanol at room temperature to obtain UiO-66. This
method requires a ball mill pretreatment, the process is relatively
cumbersome and time-consuming.
[0007] A synthesis method of UiO-66(Zr) is reported in a published
document of Journal of the American Chemical Society, 2008,
130(42): 13850-13851. ZrCl.sub.4 and terephthalic acid are
dissolved in an organic solvent of N,N-dimethylformamide,
transferred to an airtight container, heated to 120.degree. C. and
maintained at 120.degree. C. for 24 h, cooled to room temperature,
then filtered, washed repeatedly with N,N-dimethylformamide, and
dried to obtain UiO-66(Zr) powder. This method consumes a large
amount of N,N-dimethylformamide and the reaction temperature is
high.
[0008] An improved synthesis method of UiO-66(Zr) is reported in a
published document of Scientific Reports, 2015, 5. ZrCl.sub.4,
terephthalic acid, water and N,N-dimethylformamide are mixed and
dissolved in a ratio of 1:1:1:500, transferred to a stainless steel
reactor, heated to 120.degree. C. and marinated at 120.degree. C.
for 48 h, cooled to room temperature, then centrifuged to collect
the solid. The solid is washed with ethanol multiple times, and
vacuum dried at 120.degree. C. to obtain UiO-66(Zr) powder.
UiO-66(Zr) synthesized by this method has better crystallization,
but the reaction time is longer.
[0009] A microwave-assisted method of synthesizing UiO-66(Zr) is
reported in a published document of Dalton Transactions, 2015,
44(31):14019-14026. ZrCl.sub.4 and terephthalic acid are dissolved
in N,N-dimethylformamide, and then acetic acid and water are added
as auxiliary agents. The mixture is microwave heated to 120.degree.
C. for reaction for 15 min, cooled to room temperature, centrifuged
to collect the solid. The solid is washed with
N,N-dimethylformamide and acetone in order, and dried at 60.degree.
C. to obtain UiO-66(Zr) powder. This method takes less time, but
needs to add acetic acid and water as auxiliary agents. Moreover,
microwave-assisted heating is difficult to carry out scale-up
experiments, and it is difficult to achieve industrial
production.
[0010] The UiO-66(Zr) synthesis methods reported above each require
heating or pretreating the reactants. The synthesis process is
complicated, the conditions are harsh, and the reaction time is
longer than 24 h. N,N-dimethylformamide and other toxic organic
solvents are used. Moreover, the washing and activation processes
are cumbersome and costly, making it difficult to scale up
production.
SUMMARY
[0011] Objectives of the present invention is to provide a
zirconium-based metal-organic framework material UiO-66(Zr) and its
rapid room-temperature preparation method and application, so as to
overcome the above-mentioned defects existing in the prior art. The
metal-organic framework material UiO-66(Zr) is prepared in a green
solvent system through fast, efficient and simple synthetic means
to realize the industrial production and application of the new
material.
[0012] The objectives of the present invention may be achieved by
the following technical solutions.
[0013] A first aspect of the present invention provides a rapid
room-temperature preparation method of a zirconium-based
metal-organic framework material UiO-66(Zr), including the
following steps:
[0014] (1) mixing a zirconium source and an organic ligand
uniformly, then placing in methanol and stirring at room
temperature, centrifuging and then discarding a supernatant to
obtain a transparent gel-like intermediate product; and
[0015] (2) heating and drying the intermediate product obtained in
step (1) to obtain the zirconium-based metal-organic framework
material UiO-66(Zr).
[0016] Preferably, the zirconium source is zirconium oxychloride
octahydrate.
[0017] Preferably, the organic ligand is terephthalic acid,
2-bromoterephthalic acid or aminoterephthalic acid.
[0018] Preferably, a molar ratio of the zirconium source to the
organic ligand is (1-2):(2-1).
[0019] Preferably, in step (1), a mass ratio of a mixture of the
zirconium source and the organic ligand to the methanol is
1:(10-100).
[0020] Preferably, in step (1), the stirring time is 0.5-2 h.
[0021] In the present invention, during the stirring process in
step (1), the solution gradually changes from transparent to white
emulsion, the organic ligand completes the deprotonation process,
and the zirconium atom in the zirconium oxychloride octahydrate and
the oxygen atom in the organic ligand form a Zr--O bond. The two
reactions are necessary to form UiO-66. After centrifugation, the
transparent gel-like intermediate product is obtained.
[0022] Zirconium oxychloride octahydrate (ZrOCl.sub.2.8H.sub.2O)
has a very high solubility in methanol and has a structure of
[Zr.sub.4(OH).sub.8(H.sub.2O).sub.16].sup.8+, which is conducive to
the rapid formation of Zr--O clusters
([Zr.sub.6O.sub.4(OH).sub.4].sup.12+) as one of the constituent
units of UiO-66 at the beginning of the reaction. However, other
metal sources such as zirconium chloride and zirconium sulfate have
very low solubility in methanol, and therefore they cannot form
similar structures in methanol and react with the organic ligand.
Therefore, when other zirconium sources are used, the target
product cannot be obtained under the same synthesis conditions.
[0023] According to experiments, the zirconium source used in the
present invention must be zirconium oxychloride octahydrate, and it
cannot be replaced with zirconium sulfate tetrahydrate, zirconium
chloride and other zirconium sources. The solvent must be methanol,
and cannot be replaced with water, ethanol, N,N-dimethylformamide
and other solvents.
[0024] The excessive large mass/volume ratio (solid-liquid ratio)
of the mixture of the zirconium source and the organic ligand to
the methanol results in insufficient stirring and incomplete
deprotonation of the organic ligands, which affects the formation
of Zr--O bonds and reduces the yield and product cleanliness. The
excessive small solid-liquid ratio results in increased solvent
consumption and higher costs. Therefore, the suitable solid-liquid
ratio is 1:(10-100). The stirring time is related to the solubility
of the organic ligand in methanol. The organic ligand with
relatively high solubility, such as aminoterephthalic acid,
brominated terephthalic acid, etc., requires a shorter stirring
time of 0.5-1 h. The organic ligand with relatively small
solubility, such as terephthalic acid, requires a longer stirring
time of 1-2 h. The stirring can be terminated once the solution
becomes a milky white suspension. After centrifugation, the solid
is clearly separated from the liquid, and the supernatant is
completely transparent.
[0025] Preferably, in step (1), an ultrasonic treatment is first
performed before the stirring. That is, after the zirconium source
and the organic ligand are uniformly mixed and placed in methanol,
the mixture is ultrasonically treated and subsequently stirred.
[0026] Preferably, in step (2), a temperature for the heating and
drying is 40-120.degree. C.
[0027] Preferably, in step (2), the time for the heating and drying
is 0.5-4 h.
[0028] In the present invention, the function of heating in step
(2) is to further crystallize the intermediate product to form a
metal-organic framework compound. In this mild heating process, a
primary structural unit Zr.sub.6O.sub.4(OH).sub.4 formed by the
zirconium source and the organic ligand in the reaction solvent at
room temperature is further coordinated with the organic ligand,
the protons contained in the organic ligand can form hydrogen
chloride molecules with chloride ions in the zirconium source, the
hydrogen chloride molecules escape from the system, leading to
continuous coordination and crystallization reactions, and
ultimately forming the zirconium-based metal-organic framework
material UiO-66(Zr). In addition, the heating temperature in this
process needs to be controlled to adjust the solvent volatilization
rate. Excessive low heating temperature causes the solvent
volatilization rate lower than the system crystallization rate,
which may cause the increase in the lattice mismatch ratio and
reduce the crystallinity of the product. Excessive high heating
temperature makes the solvent volatilization rate exceeds the
system crystallization rate, which may cause the incomplete
crystallization process and reduce the crystallinity of the
product. At the same time, high-temperature heating consumes a lot
of energy, increasing the synthesis cost. Therefore, the optimum
temperature is 40-120.degree. C. The regulation of heating time is
contrary to that of temperature, generally controlled within 0.5
h-4 h.
[0029] In the present invention, a white gel is obtained after
heating in step (2). The gel at this time is the primary product
formed by the metal and the ligand and contains a large amount of
methanol solvent. Methanol is volatilized by heating and drying to
obtain UiO-66(Zr) block.
[0030] UiO-66(Zr) synthesized by the method of the present
invention has high purity, and needs no washing and activation
steps, avoiding the use of more organic solvents, greatly
simplifying the process, and reducing costs.
[0031] Compared with the prior art, the present invention adopts
the synthesis strategy of the intermediate product to ultra-rapidly
synthesize nano-sized UiO-66(Zr) under mild conditions, greatly
shortening the synthesis time and simplifying the process.
Moreover, the process is not necessary to perform at high
temperature and needs no use of toxic organic solvents such as
N,N-dimethylformamide. The product has high purity and needs no
washing and activation steps, reducing the amount of solvent phase
used in the preparation process. Further, the synthesis cost is
reduced and the low-yield shortcoming of the traditional method is
overcome. A metal-organic framework material UiO-66(Zr) with
excellent quality is obtained, which makes it possible to
synthesize metal-organic framework materials on a large scale.
[0032] A second aspect of the present invention provides a
zirconium-based metal-organic framework material UiO-66(Zr), which
is obtained by using the preparation method.
[0033] A third aspect of the present invention provides an
application of the zirconium-based metal-organic framework material
UiO-66(Zr), and the zirconium-based metal-organic framework
material UiO-66(Zr) is used for the adsorption of fluoride ion
pollutants in water.
[0034] The application includes the following steps: adding a
predetermined amount of the zirconium-based metal-organic framework
material UiO-66(Zr) to a solution containing fluoride ions,
ultrasonic treating, dispersing uniformly, stirring, and detecting
the fluoride ion concentration at intervals. The results show that
the zirconium-based metal-organic framework material UiO-66(Zr) of
the present invention has more structural defects than UiO-66(Zr)
synthesized by the conventional solvothermal method, and can expose
more active sites such as Zr--OH to adsorb fluoride ions. At the
same time, it also has hierarchical pore structures such as
micro/mesopores, which is advantageous for the rapid diffusion and
adsorption of adsorbate. Therefore, the zirconium-based
metal-organic framework material UiO-66(Zr) obtained by the present
invention has a significant adsorption effect on fluoride ions and
a better adsorption capacity.
[0035] Furthermore, in a solution with an initial fluoride ion
concentration of 19 mg/L, the saturated adsorption capacity of
UiO-66(Zr) synthesized by the present invention is 49.15 mg/g,
which is higher than that of UiO-66(Zr) synthesized by the
conventional solvothermal method (the saturated adsorption capacity
is 38.71 mg/g) by 27.0%. In a solution with an initial fluoride ion
concentration of 38 mg/L, the saturated adsorption capacity of
UiO-66(Zr) synthesized by the present invention is 63.06 mg/g,
which is higher than that of UiO-66(Zr) synthesized by the
conventional solvothermal method (the saturated adsorption capacity
is 45.29 mg/g) by 39.2%. At the same time, the material's fluorine
removal performance is also significantly better than conventional
commercial purification materials such as activated alumina,
showing a better application prospect in fluorine removal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1 is a theoretical simulation X-ray Diffraction (XRD)
graph of UiO-66(Zr);
[0037] FIG. 2 is an XRD graph of the UiO-66(Zr) sample synthesized
in Embodiment 1;
[0038] FIG. 3 is an XRD graph of the UiO-66(Zr) sample synthesized
in Embodiment 2;
[0039] FIG. 4 is an XRD graph of the UiO-66(Zr) sample synthesized
in Embodiment 3;
[0040] FIG. 5 is an XRD graph of the UiO-66(Zr) sample synthesized
in Comparative Example 1;
[0041] FIG. 6 is an XRD graph of the UiO-66(Zr) sample synthesized
in Comparative Example 2;
[0042] FIG. 7 is an XRD graph of the UiO-66(Zr) sample synthesized
in Embodiment 4;
[0043] FIG. 8 is an XRD graph of the UiO-66(Zr) sample synthesized
in Embodiment 5;
[0044] FIG. 9 is a schematic graph showing adsorption performance
of UiO-66(Zr) synthesized in Embodiment 6 of the present invention
and UiO-66(Zr) synthesized by a solvothermal method to fluoride
ions; and
[0045] FIG. 10 is a schematic graph showing comparison of
isothermal adsorptions of UiO-66(Zr) synthesized in Embodiment 7 of
the present invention and UiO-66(Zr) synthesized by the
solvothermal method to fluoride ions.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0046] The present invention will be described in detail below in
conjunction with the drawings and specific embodiments.
[0047] FIG. 1 is a theoretical simulation XRD graph of
UiO-66(Zr).
Embodiment 1
[0048] 0.996 g of terephthalic acid and 1.932 g of zirconium
oxychloride octahydrate are separately weighed and placed into a
150 ml beaker, 100 ml of methanol is added, and the mixture is
stirred at a stirring speed of 350 rpm under a magnetic stirring
for 1 h. After a reaction is completed, white emulsion obtained
after the stirring is centrifuged and a supernatant is discarded to
obtain a transparent gel-like intermediate product. The
intermediate product is transferred to a blast oven, and heated and
dried at 80.degree. C. for 1 h to obtain 1.421 g of a final product
with a yield of 85%. Analyzed by XRD characterization (FIG. 2), the
product synthesized by this embodiment is a typical zirconium-based
metal-organic framework material UiO-66(Zr).
Embodiment 2
[0049] 0.996 g of terephthalic acid and 1.932 g of zirconium
oxychloride octahydrate are separately weighed and placed into a
150 ml beaker, 100 ml of methanol is added, and the mixture is
stirred at a stirring speed of 350 rpm under a magnetic stirring
for 1 h. After a reaction is completed, white emulsion obtained
after the stirring is centrifuged and a supernatant is discarded to
obtain a transparent gel-like intermediate product. The
intermediate product is transferred to a blast oven, and heated and
dried at 40.degree. C. for 4 h to obtain 1.036 g of a final product
with a yield of 62%. Analyzed by XRD characterization (FIG. 3), the
product synthesized by this embodiment is a typical zirconium-based
metal-organic framework material UiO-66(Zr).
Embodiment 3
[0050] 1.992 g of terephthalic acid and 1.932 g of zirconium
oxychloride octahydrate are separately weighed and placed into a
150 ml beaker, 100 ml of methanol is added, and the mixture is
stirred at a stirring speed of 350 rpm under a magnetic stirring
for 1 h. After a reaction is completed, white emulsion obtained
after stirring is centrifuged and a supernatant is discarded to
obtain a transparent gel-like intermediate product. The
intermediate product is transferred to a blast oven, and heated and
dried at 80.degree. C. for 4 h to obtain 1.487 g of a final product
with a yield of 89%. Analyzed by XRD characterization (FIG. 4), the
product synthesized by this embodiment is a typical zirconium-based
metal-organic framework material UiO-66(Zr).
COMPARATIVE EXAMPLE 1
[0051] 0.996 g of terephthalic acid and 1.397 g of zirconium
tetrachloride are separately weighed and placed into a 150 ml
beaker, 100 ml of dimethylformamide (DMF) is added, and the
solution is stirred at a stirring speed of 350 rpm under a magnetic
stirring until uniform. The stirred solution is transferred to a
self-pressurizing hydrothermal reactor and sealed, and the reactor
is placed in a 120.degree. C. blast oven and heated for 24 h. After
a reaction is completed, the resulting solution is centrifuged and
a supernatant is discarded to obtain a product, the product is
washed three times with DMF and three times with methanol, and then
the resulting product is transferred to a vacuum drying oven and
vacuum dried at 120.degree. C. for 4 h to obtain 1.367 g of
UiO-66(Zr) product with a yield of 80%. Analyzed by XRD
characterization (FIG. 5), the product synthesized by this
comparative example is a typical zirconium-based metal-organic
framework material UiO-66(Zr). This comparative example, however,
uses the solvothermal method, namely, the synthesis is realized at
high temperature and high pressure and takes a long time.
COMPARATIVE EXAMPLE 2
[0052] 0.996 g of terephthalic acid and 1.932 g of zirconium
oxychloride octahydrate are separately weighed and placed into a
150 ml beaker, 100 ml of ethanol is added, and the mixture is
stirred at a stirring speed of 350 rpm under a magnetic stirring
for 1 h. After a reaction is completed, white emulsion obtained
after the stirring is centrifuged and a supernatant is discarded to
obtain a transparent gel-like intermediate product. The
intermediate product is transferred to a blast oven, and heated and
dried at 80.degree. C. for 1 h to obtain 1.170 g of a final product
with a yield of 70%. Analyzed by XRD characterization (FIG. 6),
replacing methanol with ethanol fails to obtain a crystalline
product, that is, a typical zirconium-based metal-organic framework
material UiO-66(Zr) cannot be successfully synthesized.
COMPARATIVE EXAMPLE 3
[0053] 0.996 g of terephthalic acid and 2.131 g of zirconium
sulfate tetrahydrate are separately weighed and placed into a 150
ml beaker, 100 ml of methanol is added, and the mixture is stirred
at a stirring speed of 350 rpm under a magnetic stirring for 1 h.
The reaction is ended and put aside, and a supernatant is discarded
to obtain a white substance. The substance is transferred to a
blast oven, and heated and dried at 80.degree. C. for 4 h. The
characterization shows the final product of the reaction is the raw
material zirconium sulfate and the target product UiO-66(Zr) is not
obtained because the zirconium sulfate is insoluble in methanol.
Therefore, it is demonstrated that replacing the zirconium
oxychloride octahydrate with zirconium sulfate tetrahydrate fails
to obtain a typical zirconium-based metal-organic framework
material UiO-66(Zr).
Embodiment 4
[0054] 1.086 g of 2-aminoterephthalic acid and 1.932 g of zirconium
oxychloride octahydrate are separately weighed and placed into a
150 ml beaker, 100 ml of methanol is added, and the mixture is
stirred at a stirring speed of 350 rpm under a magnetic stirring
for 1 h. After a reaction is completed, white emulsion obtained
after the stirring is centrifuged and a supernatant is discarded to
obtain a transparent gel-like intermediate product. The
intermediate product is transferred to a blast oven, and heated and
dried at 80.degree. C. for 1 h to obtain 1.455 g of a final product
with a yield of 83%. Analyzed by XRD characterization (FIG. 7), in
this embodiment, a typical zirconium-based metal-organic framework
material UiO-66(Zr) with amino groups can be successfully
synthesized.
Embodiment 5
[0055] 1.469 g of 2-bromoterephthalic acid and 1.932 g of zirconium
oxychloride octahydrate are separately weighed and placed into a
150 ml beaker, 100 ml of methanol is added, and the mixture is
stirred at a stirring speed of 350 rpm under a magnetic stirring
for 1 h. After a reaction is completed, white emulsion obtained
after the stirring is centrifuged and a supernatant is discarded to
obtain a transparent gel-like intermediate product. The
intermediate product is transferred to a blast oven, and heated and
dried at 80.degree. C. for 1 h to obtain 1.534 g of a final product
with a yield of 72%. Analyzed by XRD characterization (FIG. 7), in
this embodiment, a typical bromide-functionalized zirconium-based
metal-organic framework material UiO-66(Zr) can be successfully
synthesized.
Embodiment 6
[0056] 100 mL of fluoride ion solution with an initial
concentration of 19 mg/L is prepared, and the pH is adjusted to
about 7.0 with HCl and NaOH. 10 mg of UiO-66(Zr) synthesized in
Embodiment 1 is added, and an ultrasonic treatment is carried out
for 10 s so that UiO-66(Zr) is uniformly dispersed in the solution.
The experimental temperature is kept at 25.degree. C., a reaction
is carried out under a magnetic stirring and a stirring speed of
400 rpm, samples are taken at regular intervals, and a fluoride ion
selective electrode is used to detect the fluoride ion
concentration. A kinetic curve of UiO-66(Zr) absorbing fluoride
ions is shown in FIG. 9. UiO-66(Zr) synthesized either by the
present invention or the conventional solvothermal method can
quickly reach the saturation of adsorption. Among them, the
adsorption capacity of UiO-66(Zr) synthesized by the present
invention is 49.15 mg/g, which is higher than that of UiO-66(Zr)
synthesized by the conventional solvothermal method (the saturated
adsorption capacity is 38.71 mg/g) by 27.0%.
Embodiment 7
[0057] A series of 100 mL of fluoride ion solutions with an initial
concentration range of 1.5-90 mg/L are prepared, and the pH is
adjusted to about 7.0 with HCl and NaOH. 10 mg of UiO-66(Zr)
synthesized in Embodiment 1 is sadded to each solution, and an
ultrasonic treatment is carried out for 10 s so that UiO-66(Zr) is
uniformly dispersed in the each solution. The experimental
temperature is kept at 25.degree. C., a reaction is carried out
under a magnetic stirring and a stirring speed of 400 rpm for 24 h,
and a fluoride ion selective electrode is used to detect the
fluoride ion concentration after absorption for 24 h. Isothermal
adsorption curves of UiO-66(Zr) absorbing fluoride ions are shown
in FIG. 10. UiO-66(Zr) synthesized either by the present invention
or the conventional solvothermal method exhibits excellent fluoride
ion adsorption capacity, specifically, UiO-66(Zr) synthesized by
the present invention shows better adsorption performance than
UiO-66(Zr) synthesized by conventional solvothermal method in any
fluoride ion equilibrium concentration range. Compared with the
published documents, the UiO-66(Zr) synthesized by the present
invention is significantly better than conventional commercial
purification materials such as activated alumina in the fluorine
removal performance.
Embodiment 8
[0058] This embodiment is basically the same as Embodiment 1,
except that in this embodiment, the organic ligand is weighed to
enable a molar ratio of the zirconium source to the organic ligand
is 1:2.
Embodiment 9
[0059] This embodiment is basically the same as Embodiment 1,
except that in this embodiment, the organic ligand is weighed to
enable a molar ratio of the zirconium source to the organic ligand
is 2:1.
Embodiment 10
[0060] This embodiment is basically the same as Embodiment 1,
except that in this embodiment, the methanol is weighed to enable a
mass ratio of a mixture of the zirconium source and the organic
ligand to the methanol is 1:10.
Embodiment 11
[0061] This embodiment is basically the same as Embodiment 1,
except that in this embodiment, the methanol is weighed to enable a
mass ratio of a mixture of the zirconium source and the organic
ligand to the methanol is 1:100.
Embodiment 12
[0062] This embodiment is basically the same as Embodiment 1,
except that in this embodiment, the magnetic stirring time is 2
h.
Embodiment 13
[0063] This embodiment is basically the same as Embodiment 1,
except that in this embodiment, the magnetic stirring time is 1.5
h.
Embodiment 14
[0064] This embodiment is basically the same as Embodiment 4,
except that in this embodiment, the magnetic stirring time is 0.5
h.
Embodiment 15
[0065] This embodiment is basically the same as Embodiment 4,
except that in this embodiment, the magnetic stirring time is 45
min.
Embodiment 16
[0066] This embodiment is basically the same as Embodiment 1,
except that in this embodiment, the temperature for the heating and
drying is 40.degree. C., and the time for the heating and drying is
4 h.
Embodiment 17
[0067] This embodiment is basically the same as Embodiment 1,
except that in this embodiment, the temperature for the heating and
drying is 120.degree. C., and the time for the heating and drying
is 0.5 h.
[0068] The above description of the embodiments is to facilitate
those of ordinary skill in the art to understand and use the
invention. It is obvious that those skilled in the art can easily
make various modifications to these embodiments, and apply the
general principles described herein to other embodiments without
creative efforts. Therefore, the present invention is not limited
to the above embodiments, and the improvements and modifications
made by those skilled in the art according to the disclosure of the
present invention without departing from the scope of the present
invention should fall within the protection scope of the present
invention.
* * * * *