Catalytic material for catalytic activation of persulfate and targeted degradation of typical pollutant in papermaking wastewater and synthesis method and use thereof

Abstract

A porous catalyst for catalytic activating persulfates to decompose typical pollutants in papermaking wastewater is provided, and a synthesis method thereof and a method of degrading the typical pollutants in paper wastewater by using the porous catalyst are also provided. The porous catalyst MIL-88A@MIP is prepared by a molecular imprinting method comprising using metal organic framework MIL-88A as a precursor and using phthalates as templates.

Claims

1. A method of preparing a catalyst for degrading phthalates in water, the method comprising: dissolving phthalates in acetonitrile in a reactor; sequentially adding metal organic framework MIL-88A and methacrylic acid into the reactor and stirring for a first period of time; adding tetraethyl orthosilicate and acetic acid into the reactor; sealing the reactor; heating the reactor at 60-80 C. for a second period of time to form a catalyst containing the phthalates by using the phthalates as template molecules; removing the phthalates from the obtained catalyst by extracting to obtain a porous catalyst MIL-88A@MIP; and drying the porous catalyst MIL-88A@MIP.

2. The method of claim 1, wherein the metal organic framework MIL-88A is prepared by reacting fumaric acid and FeCl.sub.3.6H.sub.2O in water, and a molar ratio of the fumaric acid and the FeCl.sub.3.6H.sub.2O is 1:10 to 20:1.

3. The method of claim 1, wherein the phthalates comprise at least one of dimethyl phthalate, diethyl phthalate, and dibutyl phthalate.

4. The method of claim 1, wherein a molar ratio of the phthalates, the methacrylic acid and the tetraethyl orthosilicate is about 1:40:200.

5. The method of claim 1, wherein the first period of time is about 0.5-3 hours.

6. The method of claim 1, wherein the second period of time is about 10-20 hours.

7. A catalyst for degrading phthalates in water, comprising a porous catalyst MIL-88A@MIP, wherein the porous catalyst MIL-88A@MIP is prepared by the method of claim 1.

8. The catalyst of claim 7, wherein the phthalates comprise at least one of dimethyl phthalate, diethyl phthalate, and dibutyl phthalate.

9. The catalyst of claim 7, wherein a molar ratio of the phthalates, the methacrylic acid and the tetraethyl orthosilicate is about 1:40:200.

10. A method degrading phthalates in water, the method comprising: adding a persulfate and the porous catalyst MIL-88A@MIP of claim 7 into an aqueous solution containing phthalates.

11. The method of claim 10, wherein the persulfate comprises at least one of sodium persulfate, potassium persulfate and ammonium persulfate.

12. The method of claim 10, wherein the phthalates comprise at least one of dimethyl phthalate, diethyl phthalate, and dibutyl phthalate.

13. The method of claim 10, wherein an acidity of the solution is pH 2-7.

14. The method of claim 10, wherein a molar ratio of the persulfate and the phthalates is about 100:1 to 800:1.

15. The method of claim 14, wherein the added amount of the porous catalyst MIL-88A@MIP is about 0.3-2 g/L.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an X-ray crystal diffraction (XRD) diagram of MIL-88A@MIP and MIL-88A.

(2) FIG. 2 is a scanning electron microscope (SEM) image of MIL-88A@MIP.

(3) FIG. 3 is a scanning electron microscope (SEM) image of MIL-88A.

DETAILED DESCRIPTION OF THE PREFERED EMBODIMENT

(4) The present invention mainly uses phthalates (such as DBP) in organic wastewater from the paper industry as a typical pollutant. The specific implementation of the present invention will be further described below by embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

(5) Embodiment 1:

(6) In the present embodiment, a catalytic material MIL-88A@MIP synthesized by a molecular imprinting method using a metal organic framework MIL-88A as a precursor. The MIL-88A@MIP was used as a catalyst to study the effect of the catalytic material on adsorption and degradation of DBP.

(7) (1) Preparation of the metal organic framework MIL-88A: 0.9744 g (1 mol) of fumaric acid and 2.2722 g (1 mol) of FeCl.sub.3.6H.sub.2O weighed and dissolved in 42 mL of deionized water, after 1 hour of stirring, a mixture was transferred into a 100 mL polytetrafluoroethylene-lined reaction kettle, the reaction kettle was placed in an air dry oven, after 2 hours of reaction at 65 C., the reaction kettle was taken out and was placed at room temperature for cooling down; after the reaction kettle was cooled down, the mixture was taken out for centrifuging for 10 minutes under a condition of 9000 rpm to separate and obtain a light yellow solid, the light yellow solid was then poured into a beaker, washed for 3 hours with ethanol, centrifuged, and then washed for 3 hours with deionized water, repeated for twice, an obtained solid was put into a vacuum drying oven for drying at 100 C. for 8 hours; and the metal organic framework MIL-88A was obtained and kept for later use;

(8) (2) preparation of the catalytic material MIL-88A@MIP: 0.267 mL of DBP and 20.0 mL of acetonitrile were measured and mixed in a bottle to obtain a solution, 0.1 g of MIL-88A was added into the solution, then 1.7 mL of methacrylic acid was added, after 1 hour of stirring on a magnetic stirring apparatus at 500 rpm, 22.75 mL of tetraethyl orthosilicate and 0.85 mL of acetic acid were added, after sealing the bottle, the bottle was heated in a water bath at a temperature of 60 C. for 20 hours, after centrifuging, a solid was obtained and dried, the dried solid was put into a Soxhlet extractor to extract an exemplary molecule DBP using an extraction agent of ethanol/acetic acid =9:1 (volume ratio), 150mL of the exemplary molecule was extracted each time and the extraction was performed for 6 times, the solid was put into the vacuum drying oven (60 C.) and dried for 12 hours; and the catalytic material MIL-88A@MIP was obtained;

(9) (3) 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution and 0.018 mmol/L DBP solution were prepared for later use;

(10) (4) a conical flask was used as a reactor, 3 mL of 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution and 100 mL of 0.018 mmol/L DBP solution (nNa.sub.2S.sub.2O.sub.8/nDBP=600) were added into the reactor, and meanwhile 0.05 g of the catalytic material MIL-88A@MIP was added into the reactor, the conical flask was placed in a shaker with 200 rpm, the reaction was conducted at room temperature, pH was adjusted to 3.26, and sampling analysis was performed at a fixed point;

(11) (5) the catalytic material MIL-88A@MIP was not added into the reactor, and other conditions were the same as the step (4); and

(12) (6) the Na.sub.2S.sub.2O.sub.8 solution was not added into the reactor, and other conditions were the same as the step (4).

(13) Removal rates of the above three processes are shown in Table 1:

(14) TABLE-US-00001 TABLE 1 Removal rate (%) Time (min) Process (4) Process (5) Process (6) 0 0.0 0.0 0.0 30 20.3 27.9 2.7 60 39.7 34.9 5.3 120 62.0 37.7 7.4 180 65.8 36.1 7.7 240 66.1 34.3 6.0 300 68.9 31.3 3.3 360 74.7 33.9 6.0 480 80.4 33.5 3.4

(15) It can be seen from the above table that, using sodium persulfate alone has basically no degradative effect on DBP, but when the catalytic material MIL-88A@MIP is added, a removal rate of DBP increases, indicating that the catalytic material MIL-88A@MIP has certain adsorption properties for phthalates. When the catalytic material MIL-88A@MIP and sodium persulfate are added at the same time, the removal rate significantly increases. After 8 hours of reaction, the removal rate of DBP can reach around 80%.

(16) Embodiment 2:

(17) In the present embodiment, a catalytic material MIL-88A@MIP synthesized by a molecular imprinting method using a metal organic framework MIL-88A as a precursor was used as a catalyst to study an effect of different molar ratio of Na.sub.2S.sub.2O.sub.8 and DBP (nNa.sub.2S.sub.2O.sub.8/nDBP=200, 400, 600, 800) during reaction on a removal rate of a pollutant.

(18) (1) The preparation method of the metal organic framework MIL-88A was the same as the step (1) in the Embodiment 1;

(19) (2) the preparation method of the catalytic material MIL-88A@MIP was the same as the step (2) in the Embodiment 1;

(20) (3) 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution and 0.018 mmol/L DBP solution were prepared for later use;

(21) (4) a conical flask was used as a reactor, 1 mL of 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution and 100 mL of 0.018 mmol/L DBP solution (nNa.sub.2S.sub.2O.sub.8/nDBP=200) were added into the reactor, and meanwhile 0.05 g of the catalytic material MIL-88A@MIP was added into the reactor, the conical flask was placed in a shaker with 300 rpm, a reaction was conducted at room temperature, pH was adjusted to 3.26, and sampling analysis was perfoiiiied at a fixed point;

(22) (5) 2 mL of 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution and 100 mL of 0.018 mmol/L DBP solution (nNa.sub.2S.sub.2O.sub.8/nDBP=400) were added into the reactor, and others were the same as the step (4);

(23) (6) 3 mL of 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution and 100 mL of 0.018 mmol/L DBP solution (nNa.sub.2S.sub.2O.sub.8/nDBP=600) were added into the reactor, and others were the same as the step (4); and

(24) (7) 4 mL of 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution and 100 mL of 0.018 mmol/L DBP solution (nNa.sub.2S.sub.2O.sub.8/nDBP=800) were added into the reactor, and others were the same as the step (4).

(25) Removal rates of the above four processes are shown in Table 2:

(26) TABLE-US-00002 TABLE 2 Removal rate/% Time/min Process (4) Process (5) Process (6) Process (7) 0 0.0 0.0 0.0 0.0 30 10.8 15.6 20.3 23.1 60 28.6 29.8 39.7 40.1 120 36.3 43.2 62.0 63.8 180 39.4 47.8 65.8 64.9 240 42.3 56.2 66.1 65.7 300 49.6 60.0 68.9 69.7 360 53.1 68.3 74.7 76.4 480 60.2 72.4 80.4 81.3

(27) It can be seen from the above table that, as the ratio of nNa.sub.2S.sub.2O.sub.8/nDBP increases, the removal rate of the pollutant DBP in a papermaking wastewater shows an upward trend. When the ratio is from 200:1 to 600:1, the removal rate increases rapidly, while the ratio is from 600:1 to 800:1, the removal rate does not change substantially, showing a weak trend.

(28) Embodiment 3:

(29) In the present embodiment, a catalytic material MIL-88A@MIP synthesized by a molecular imprinting method using a metal organic framework MIL-88A as a precursor was used as a catalyst to study an effect of an amount used of the catalytic material MIL-88A@MIP (0.03 g, 0.05 g, 0.1 g, 0.2 g) during reaction on a removal rate of a pollutant.

(30) (1) The preparation method of the metal organic framework MIL-88A was the same as the step (1) in the Embodiment 1;

(31) (2) the preparation method of the catalytic material MIL-88A@MIP was the same as the step (2) in the Embodiment 1;

(32) (3) 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution and 0.018 mmol/L DBP solution were prepared for later use;

(33) (4) a conical flask was used as a reactor, 3 mL of 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution and 100 mL of 0.018 mmol/L DBP solution (nNa.sub.2S.sub.2O.sub.8/nDBP=600) were added into the reactor, and meanwhile 0.03 g of the catalytic material MIL-88A@MIP was added into the reactor, the conical flask was placed in a shaker with 300 rpm, a reaction was conducted at room temperature, pH was adjusted to 3.26, and sampling analysis was performed at a fixed point;

(34) (5) 0.05 g of the catalytic material MIL-88A@MIP was added into the reactor, and others were the same as the step (4);

(35) (6) 0.1 g of the catalytic material MIL-88A@MIP was added into the reactor, and others were the same as the step (4); and

(36) (7) 0.2 g of the catalytic material MIL-88A@MIP was added into the reactor, and others were the same as the step (4).

(37) Removal rates of the above four processes are shown in Table 3:

(38) TABLE-US-00003 TABLE 3 Removal rate/% Time/min Process (4) Process (5) Process (6) Process (7) 0 0.0 0.0 0.0 0.0 30 16.8 20.3 29.8 30.2 60 30.3 39.7 36.7 38.9 120 56.4 62.0 63.2 65.1 180 60.2 65.8 69.3 69.9 240 63.7 66.1 74.2 75.2 300 69.4 68.9 76.9 77.9 360 70.1 74.7 80.1 80.3 480 73.5 80.4 83.2 84.1

(39) It can be seen from the above table that, with the increase of the used amount of the catalytic material MIL-88A@MIP, the removal rate of the pollutant DBP increases.

(40) Embodiment 4:

(41) In the present embodiment, a catalytic material MIL-88A@MIP synthesized by a molecular imprinting method using a metal organic framework MIL-88A as a precursor was used as a catalyst to study an effect of a pH value (2.68, 3.26, 4.79, 6.94) in a reaction system on a removal rate of a pollutant DBP.

(42) (1) The preparation method of the metal organic framework MIL-88A was the same as the step (1) in the Embodiment 1;

(43) (2) the preparation method of the catalytic material MIL-88A@MIP was the same as the step (2) in the Embodiment 1;

(44) (3) 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution and 0.018 mmol/L DBP solution were prepared for later use;

(45) (4) a conical flask was used as a reactor, 3 mL of 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution and 100 mL of 0.018 mmol/L DBP solution (nNa.sub.2S.sub.2O.sub.8/nDBP=600) were added into the reactor, and meanwhile 0.05 g of the catalytic material MIL-88A@MIP was added into the reactor, the conical flask was placed in a shaker with 300 rpm, a reaction was conducted at room temperature, pH was adjusted to 2.68, and sampling analysis was perfomied at a fixed point;

(46) (5) pH was adjusted to 3.26, and others were the same as the step (4);

(47) (6) pH was adjusted to 4.79, and others were the same as the step (4); and

(48) (7) pH was adjusted to 6.94, and others were the same as the step (4).

(49) Removal rates of the above four processes are shown in Table 4:

(50) TABLE-US-00004 TABLE 4 Removal rate/% Time/min Process (4) Process (5) Process (6) Process (7) 0 0.0 0.0 0.0 0.0 30 10.1 20.3 8.9 5.1 60 15.6 39.7 10.5 7.3 120 38.7 62.0 12.4 8.9 180 40.9 65.8 13.9 9.7 240 45.2 66.1 15.6 12.3 300 59.1 68.9 17.2 15.9 360 65.4 74.7 18.9 17.3 480 68.2 80.4 25.6 19.8

(51) It can be seen from the above table that, the pH value in the system has a great influence on the removal rate of DBP. The pH value of over-acid or neutrality is not ideal for a degradation effect of pollutants, but the removal rate of DBP is highest when pH=3 .26.

(52) Embodiment 5:

(53) In the present embodiment, a catalytic material synthesized by a molecular imprinting method using a metal organic framework MIL-88A as a precursor was used as a catalyst to study an effect of the precursor MIL-88A, a catalytic material MIL-88A@NIP synthesized with no template molecule added and a catalytic material MIL-88A@MIP synthesized with a template molecule added on a removal rate of a pollutant DBP.

(54) (1) The preparation method of the metal organic framework MIL-88A was the same as the step (1) in the Embodiment 1;

(55) (2) the preparation method of the catalytic material MIL-88A@MIP was the same as the step (2) in the Embodiment 1;

(56) (3) a preparation method of the catalytic material MIL-88A@NIP was as follows: 0.1 g of MIL-88A was added into 20.0 mL of acetonitrile in a bottle, 1.7 mL of methacrylic acid was then added, after being stirred on a magnetic stirring apparatus at 500 rpm for 1 hour, 22.75 mL of tetraethyl orthosilicate and 0.85 mL of acetic acid were added, after sealing the bottle, it was heated in a water bath at a temperature of 60 C. for 20hours, after centrifuging, a solid was obtained and then dried, the dried solid was put into a Soxhlet extractor to be extracted using an extraction agent of ethanol/acetic acid =9:1 (volume ratio), 150 mL extraction agent was used each time and the extraction was performed for 6 times, the solid was put into the vacuum drying oven (60 C.) and dried for 12 hours; and the catalytic material MIL-88A@NIP was obtained;

(57) (4) 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution and 0.018 mmol/L DBP solution were prepared for later use;

(58) (5) a conical flask was used as a reactor, 3 mL of 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution and 100 mL of 0.018 mmol/L DBP solution (nNa.sub.2S.sub.2O.sub.8/nDBP=600) were added into the reactor, and meanwhile 0.05 g of the catalytic material MIL-88A@MIP was added into the reactor, the conical flask was placed in a shaker with 300 rpm, a reaction was conducted at room temperature, pH was adjusted to 3.26, and sampling analysis was performed at a fixed point;

(59) (6) 0.05 g of the precursor material MIL-88A was added into the reactor, and others were the same as the step (5); and

(60) (7) 0.05 g of MIL-88A@NIP synthesized with no template molecule was added into the reactor, and others were the same as the step (5).

(61) Removal rates of the above three processes are shown in Table 5:

(62) TABLE-US-00005 TABLE 5 Removal rate/% Time/min Process (4) Process (5) Process (6) 0 0.0 0.0 0.0 60 39.7 13.2 3.1 180 65.8 16.7 5.9 300 68.9 21.6 12.5 480 80.4 39.4 17.0

(63) It can be seen from the above table that, the precursor, the metal organic framework MIL-88A, has a certain effect on the removal of DBP. However, compared to the catalytic material MIL-88A@MIP, its effect is relatively weak, and the removal effect of MIL-88A@NIP on DBP is basically small, indicating that the catalytic material MIL-88A@MIP can effectively increase the removal rate of DBP.

(64) Embodiment 6:

(65) In the present embodiment, a catalytic material MIL-88A@MIP synthesized by a molecular imprinting method using a metal organic framework MIL-88A as a precursor was used as a catalyst to study an effect of the catalyst on a removal rate of different phthalates (DBP, DEP, DMP) in a papermaking wastewater.

(66) (1) The preparation method of the metal organic framework MIL-88A was the same as the step (1) in the Embodiment 1;

(67) (2) The preparation method of the catalytic material MIL-88A@MIP was the same as the step (2) in the Embodiment 1;

(68) (3) 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution, 0.018 mmol/L DBP solution, 0.018 mmol/L DEP solution, and 0.018 mmol/L DMP solution were prepared;

(69) (4) a conical flask was used as a reactor, 3 mL of 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution and 100 mL of 0.018 mmol/L DBP solution (nNa.sub.2S.sub.2O.sub.8/nDBP=600) were added into the reactor, and meanwhile 0.05 g of the catalytic material MIL-88A@MIP was added into the reactor, the conical flask was placed in a shaker with 300 rpm, a reaction was conducted at room temperature, pH was adjusted to 3.26, and sampling analysis was performed at a fixed point;

(70) (5) 3 mL of 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution and 100 mL of 0.018 mmol/L DEP solution (nNa.sub.2S.sub.2O.sub.8/nDEP=600) were added into the reactor, and others were the same as the step (4); and

(71) (6) 3 mL of 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution and 100 mL of 0.018 mmol/L DMP solution (nNa.sub.2S.sub.2O.sub.8/nDMP=600) were added into the reactor, and others were the same as the step (4).

(72) Removal rates of the above three processes are shown in Table 6:

(73) TABLE-US-00006 TABLE 6 Removal rate/% Time/min Process (4) Process (5) Process (6) 0 0.0 0.0 0.0 30 20.3 23.2 19.7 60 39.7 40.7 36.2 120 62.0 65.7 59.5 240 66.1 69.2 65.9 360 74.7 77.2 70.1 480 80.4 84.5 77.4

(74) It can be seen from the above table that, MIL-88A@MIP has a relatively high removal rate for the phthalates in the papermaking wastewater, and the removal rates DEP>DBP>DMP, which illustrates that catalytic material MIL-88A@MIP has high feasibility and effectiveness in degradation of refractory pollutants in the papermaking wastewater.

(75) Embodiment 7:

(76) In the present embodiment, a catalytic material MIL-88A@MIP synthesized by a molecular imprinting method using a metal organic framework MIL-88A as a precursor was used as a catalyst to study an effect of recycling the catalyst on a removal rate of DBP.

(77) (1) The preparation method of the metal organic framework MIL-88A was the same as the step (1) in the Embodiment 1;

(78) (2) The preparation method of the catalytic material MIL-88A@MIP was the same as the step (2) in the Embodiment 1;

(79) (3) 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution and 0.018 mmol/L DBP solution were prepared for later use;

(80) (4) a conical flask was used as a reactor, 3 mL of 360 mmol/L Na.sub.2S.sub.2O.sub.8 solution and 100 mL of 0.018 mmol/L DBP solution (nNa.sub.2S.sub.2O.sub.8/nDBP=600) were added into the reactor, and meanwhile 0.05 g of the catalytic material MIL-88A@MIP was added into the reactor, the conical flask was placed in a shaker with 300 rpm, a reaction was conducted at room temperature, pH was adjusted to 3.26, and sampling analysis was performed at a fixed point;

(81) (5) after the step (4) was completed, the catalyst in the conical flask was centrifuged and separated, dried in an oven at 65 C., and put into the same reactor as a system of the step (4), and other conditions are the same as in the step (3); and

(82) (6) The catalyst was recycled in accordance with the step (4) and the step (5) for four times, and results of the removal rate of DBP in each cycle are shown in Table 7:

(83) TABLE-US-00007 TABLE 7 Removal rate (%) Time (min) 1st 2nd 3rd 4th 0 0.0 0.0 0.0 0.0 30 20.3 36.3 26.4 19.2 60 39.7 49.6 43.2 35.3 120 62.0 70.1 65.1 58.3 240 66.1 75.4 68.2 59.1 360 74.7 79.3 75.3 70.2 480 80.4 84.1 80.0 73.7

(84) It can be seen from the above table that: after four cycles, and in the case where the catalyst loses, the removal rate of the targeting material MIL-88A@MIP for degradation of DBP still remains at 70% or more, indicating that MIL-88A@MIP has good recyclability.

(85) Characterization of Catalyst:

(86) FIG. 1 is an X-ray crystal di fiaction (XRD) diagram of MIL-88A@MIP. Compared with the XRD diagram of the precursor MIL-88A, it can be seen that a peak of the catalytic material around 2=7.2 changed, while a peak position of a main peak around 2=10.3 did not change but the peak intensity weakened. Through these changes, it can be inferred that some changes have occurred in a crystalline form of the metal organic framework during a synthesis of the catalytic material, and it can be considered that the catalytic material synthesized by the molecular imprinting method is a material different from the metal organic framework itself, but a modified material based on the metal organic framework.

(87) FIG. 2 and FIG. 3 are a scanning electron microscope (SEM) image of MIL-88A@MIP and a scanning electron microscope (SEM) image of MIL-88A, respectively. Through comparing surfaces of the two images, it can be seen that the surface of FIG. 2 has a greater change than the surface of FIG. 3, and it can be seen that the catalytic material forms many small cavities on its surface for adsorption of pollutant molecules in the process of removing pollutants and then activation and degradation of pollutants using active metal sites of the metal organic framework. In combination with its XRD diagram, it can be considered that the catalytic material MIL-88A@MIP has synthesized successfully.

(88) The above-described embodiments are preferred implementations of the present invention, but the implementations of the present invention are not limited by the above-described embodiments, any other changes, modifications, replacements, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent displacements, and shall all be included in the scope of protection of the present invention.