Preparation method and application of a MIL68(Fe) / MoS2 composite catalyst

Abstract

The present invention relates to a preparation method and application of a MIL68(Fe) / MoS2 composite catalyst, belonging to the technical field of water purification materials. In the present invention, sodium molybdate dihydrate and thiourea are added to deionized water and mixed evenly to obtain solution A, and the pH value of solution A is adjusted to 5.0 - 5.2 with acetic acid, and the reaction is carried out at a temperature of 190 - 210 °C for 23 - 24 h, followed by solid-liquid separation. The solid is washed successively with deionized water and ethanol, and then dried in vacuo to obtain molybdenum disulfide. Ferric chloride (III) trihydrate and 1,4-benzenedicarboxylic acid are added to N,N-dimethylformamide and mixed evenly to obtain solution B, and molybdenum disulfide is added to solution B and mixed evenly. The reaction is carried out at a temperature of 25 - 40 °C under ultrasonic conditions for 1 - 2 h, and then placed at a temperature of 90 - 110 °C for 110 - 120 h. After cooling to room temperature, solid-liquid separation is carried out. The solid is washed successively with N,N-dimethylformamide and acetone, and then dried in vacuo to obtain the MIL68(Fe) / MoS2 composite catalyst. The MIL68(Fe) / MoS2 catalyst of the present invention has abundant active sites and has an excellent degradation effect on activating persulfate (PMS) to degrade the dye rhodamine B, and the degradation efficiency can reach more than 98%.

Description

Technical Field

[0001] The present invention relates to a preparation method and application of a MIL68(Fe) / MoS2 composite catalyst, belonging to the technical field of water purification materials. Background Art

[0002] The complex aromatic structure of dye molecules is highly stable and can cause several types of diseases in the surrounding environment. In addition, they are soluble in water, have high color rendering in water, and may also cause the production of toxic sludge. Their easy coloring and the presence of other common substances in nature affect continuous dyeing cycles. Therefore, the presence of dyes in water makes it difficult to recycle them. Dyes can be classified according to their structure and use. Dyes can be classified into acid dyes, basic dyes, direct dyes, reactive dyes, etc. according to their use. Rhodamine B (RhB) is a typical artificially synthesized triphenylmethane-based cationic basic dye, also known as rose bengal B, commonly known as pollen pink. Due to its carcinogenicity, it is listed as one of the three carcinogens by the International Agency for Research on Cancer of the World Health Organization and is prohibited from being consumed.

[0003] So far, a series of wastewater treatment technologies have been developed and utilized, such as biodegradation, physical adsorption, and chemical reactions. Among them, sulfate-based advanced oxidation technology (SR-AOP) is a particularly efficient technology for degrading organic pollutants in the water environment. In recent years, many transition metal catalysts have shone in the application of activating PMS to degrade organic pollutants due to their rich redox sites, excellent electrical conductivity, and catalytic performance. However, the stability of PMS results in low pollutant degradation performance. Summary of the Invention

[0004] Aiming at the problems of low efficiency and large consumption of PMS in the degradation of rhodamine B dye in wastewater, the present invention proposes a preparation method and application of a MIL68(Fe) / MoS2 composite catalyst, that is, using molybdenum disulfide as a carrier, which has rich sulfur vacancies and metal sites, and preparing highly catalytic MIL-68(Fe) / MoS2 by in-situ synthesis method. Using the persulfate-based advanced oxidation technology, an excellent degradation effect on the dye rhodamine B can be achieved, and the degradation efficiency can reach about 99% in 15 minutes, which can be used to remove rhodamine B in water.

[0005] A preparation method of a MIL68(Fe) / MoS2 composite catalyst is as follows:

[0006] (1) Sodium molybdate dihydrate and thiourea are added to deionized water and mixed evenly to obtain solution A. The pH value of solution A is adjusted to 5.0 - 5.2 with acetic acid, and the reaction is carried out at a temperature of 190 - 210 °C for 23 - 24 h. After solid-liquid separation, the solid is washed successively with deionized water and ethanol, and then dried in vacuum to obtain molybdenum disulfide;

[0007] (2) Add ferric chloride (III) trihydrate and 1,4-benzenedicarboxylic acid to N,N-dimethylformamide and mix well to obtain solution B. Add the carrier molybdenum disulfide to solution B and mix evenly. React at a temperature of 25-40 °C under ultrasonic conditions for 1-2 h, then react at a temperature of 90-110 °C for 110-120 h. Cool to room temperature, separate the solid and liquid, wash the solid successively with N,N-dimethylformamide and acetone, and dry in vacuo to obtain the MIL68(Fe) / MoS2 composite catalyst.

[0008] In the step (1), the molar ratio of sodium molybdate dihydrate to thiourea is 2:5, and the concentration of sodium molybdate in solution A is 0.05-0.1 mol / L.

[0009] In the step (2), the molar ratio of ferric chloride (III) trihydrate to 1,4-benzenedicarboxylic acid is 1:2.0-2.5, and the concentration of ferric chloride (III) in solution B is 0.08-0.1 mol / L.

[0010] The addition amount of the carrier molybdenum disulfide is 5-30% of the mass of MIL68(Fe).

[0011] In the step (2), the ultrasonic power is 50-150 W.

[0012] The application of the MIL68(Fe) / MoS2 composite catalyst in activating persulfate for degrading the dye Rhodamine B in water.

[0013] The principle of the iron-based metal-organic framework material (MIL-68(Fe)) / molybdenum disulfide composite catalyst of the present invention for degrading the dye Rhodamine B: Promote the valence state transformation of high-valent metal to low-valent metal ions through sulfur vacancies to support the activation of PMS to generate highly active free radicals and non-free radicals, and then attack Rhodamine B; the reaction formulas include:

[0014] Fe 2+ + HSO5 - → Fe 3+ + SO4 ·- + OH - (1)

[0015] Fe 3+ + HSO5 - → Fe 2+ + SO5 ·- + H + (2)

[0016] Mo 4+ + 2HSO5 - → Mo 5+ + 2HSO4 - +·O2 - (3)

[0017] Mo 5+ + 2HSO5 - → Mo 6+ + 2HSO4 - +·O2 - (4)

[0018] Mo 6+ + ·O2 - →Mo 4+ + 1 O2 (5)

[0019] SO4 ·- + OH - / H2O→ SO4 2- + ·OH (6)

[0020] SO5 ·- + 2H2O→ Mo 6+ + 2HSO4 - +1.5 1 O2 (7)

[0021] Fe 2+ + O2→ Fe 3+ + ·O2 - (8)

[0022] Fe 3+ + ·O2 - → Fe 2+ + O2 (9)

[0023] ·O2 - +2H + → 1 O2 + H2O2 (10)

[0024] 2·O2 - + 2H + → 2·OH + O2 (11)

[0025] Fe 3+ + S 2- / S2 2- → Fe 2+ + Sn 2- / SO x (12)

[0026] Mo 6+ + S 2- / S2 2- → Mo 6+ + Sn 2- / SOx (13)

[0027] SO4 ·- / ·O2 - / ·OH / 1 O2 + pollutants → intermediates + CO2 + H2O (14)

[0028] The beneficial effects of the present invention are as follows:

[0029] (1) The present invention combines the non-toxic iron-based metal-organic framework material (MIL-68(Fe)) with molybdenum disulfide containing abundant sulfur vacancies and metal sites, and uses hydrothermal reaction for in-situ synthesis. The iron-based metal-organic framework material (MIL-68(Fe)) / molybdenum disulfide composite catalyst has good cycling performance;

[0030] (2) The iron-based metal-organic framework material (MIL-68(Fe)) / molybdenum disulfide composite catalyst of the present invention with enriched active sites has excellent degradation effect on the dye Rhodamine B, and the degradation efficiency can reach about 99% in 15 minutes. Description of the Drawings

[0031] Figure 1 It is the degradation diagram of Rhodamine B by different dosages of MIL68(Fe) / MoS2 composite catalyst in the water body of Example 1;

[0032] Figure 2 It is the cycling degradation diagram of Rhodamine B by MIL68(Fe) / MoS2 composite catalyst in the water body of Example 1;

[0033] Figure 3 It is the degradation diagram of Rhodamine B by MIL68(Fe) / MoS2 composite catalyst in the water body of Example 1 containing different concentrations of humic acid;

[0034] Figure 4 It is the degradation diagram of Rhodamine B by MIL68(Fe) / MoS2 composite catalysts with different MoS2 contents;

[0035] Figure 5 It is the SEM diagram of MIL68(Fe), MoS2 and MIL68(Fe) / MoS2 composite catalyst in Example 1, a is MIL68(Fe), b is MoS2, c is MIL68(Fe) / MoS2;

[0036] Figure 6 It is the FT-IR diagram of MIL68(Fe) / MoS2 composite catalyst in Examples 1 to 4. Detailed Embodiments

[0037] The present invention will be further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the described content.

[0038] Example 1: A preparation method of a MIL68(Fe) / MoS2 composite catalyst, the specific steps are as follows:

[0039] (1) Sodium molybdate dihydrate and thiourea were added to deionized water and mixed evenly to obtain solution A. The pH value of solution A was adjusted to 5.0 with acetic acid with a concentration of 0.04 mol / L, and it was placed in a stainless-steel autoclave with a polytetrafluoroethylene lining. The reaction was carried out at a temperature of 190 °C for 24 h, and solid-liquid separation was performed. The solid was washed successively with deionized water and ethanol, and then dried in vacuum to obtain molybdenum disulfide; the molar ratio of sodium molybdate dihydrate to thiourea was 2:5, and the concentration of sodium molybdate in solution A was 0.05 mol / L;

[0040] (2) Iron(III) chloride trihydrate and 1,4-benzenedicarboxylic acid were added to N,N-dimethylformamide and mixed evenly to obtain solution B. The carrier molybdenum disulfide was added to solution B and mixed evenly. The reaction was carried out at a temperature of 40 °C and under ultrasonic conditions (power 100 W) for 1 h, and then placed in a stainless-steel autoclave with a polytetrafluoroethylene lining. The reaction was carried out at a temperature of 95 °C for 118 h, cooled to room temperature, and solid-liquid separation was performed. The solid was washed successively by centrifugation (8000 rpm) with N,N-dimethylformamide and acetone, and then dried in vacuum to obtain the MIL68(Fe) / MoS2 composite catalyst; the molar ratio of iron(III) chloride trihydrate to 1,4-benzenedicarboxylic acid was 1:2, the concentration of iron(III) chloride in solution B was 0.08 mol / L; the addition amount of the carrier molybdenum disulfide was 10% of the mass of MIL68(Fe);

[0041] The SEM images of the MIL68(Fe), MoS2 and MIL68(Fe) / MoS2 composite catalysts in this example are shown in Figure 5 , from Figure 5 it can be seen that MIL-68(Fe) and molybdenum disulfide are successfully compounded, and the MIL-68(Fe) / molybdenum disulfide composite catalyst has abundant active sites;

[0042] The FT-IR images of the MIL68(Fe) / MoS2 composite catalyst in this example are shown in Figure 6 , from Figure 6 it can be seen that the results of FT-IR show that the material has abundant functional groups and is similar to the reported results of other metal-organic framework materials MIL-68(Fe) and molybdenum disulfide. The functional groups of the iron-based metal-organic framework material (MIL-68(Fe) / molybdenum disulfide composite catalyst) correspond to the functional groups of the two monomer materials, proving the successful synthesis of the composite material;

[0043] Performance test of the iron-based metal-organic framework material (MIL-68(Fe) / molybdenum disulfide composite catalyst) in this example for activating persulfate to degrade rhodamine B in water: 2.5 - 20 mg of the catalyst was put into 50 ml of rhodamine B solution with a concentration of 10 mg / L, and rapidly stirred at 500 rpm for 30 min to reach the adsorption-desorption equilibrium. Then, 3 mg of PMS was added, and the supernatant was filtered out with a 0.22 μm filter head at certain time intervals during the reaction to measure the remaining concentration of rhodamine B.

[0044] The MIL68(Fe) / MoS2 composite catalyst in this example has a good degradation effect on rhodamine B (15 min, 99%);

[0045] The degradation diagram of rhodamine B by different dosages of MIL68(Fe) / MoS2 composite catalyst in water is shown in Figure 1 , from Figure 1 it can be seen that when the catalyst dosage is only 0.2 g / L, it has a good degradation effect on rhodamine B (15 min, 99%);

[0046] The cyclic degradation diagram of rhodamine B by MIL68(Fe) / MoS2 composite catalyst (0.2 g / L) in water is shown in Figure 2 , from Figure 2 it can be seen that the MIL-68(Fe) / MoS2 catalyst still has a good removal effect after being recycled 5 times (degradation rate of 91 - 99%). Thus, it can be known that the iron-based metal-organic framework material (MIL-68(Fe) / molybdenum disulfide composite catalyst) has good recyclability;

[0047] Humic acid widely exists in nature, and its impact on degradation cannot be ignored. The degradation diagram of rhodamine B by MIL68(Fe) / MoS2 composite catalyst in water containing different concentrations of humic acid is shown in Figure 3 , from Figure 3 it can be seen that in rhodamine B solutions containing different concentrations of humic acid (10 - 40 mg / L), the catalyst has a certain promoting effect on the removal effect of 10 mg / L rhodamine B solution. Due to the large pore structure of HA, it has the ability to adsorb RhB.

[0048] Example 2: A preparation method of a MIL68(Fe) / MoS2 composite catalyst, the specific steps are as follows:

[0049] (1) Sodium molybdate dihydrate and thiourea were added to deionized water and mixed evenly to obtain solution A. The pH value of solution A was adjusted to 5.1 with acetic acid at a concentration of 0.04 mol / L. It was placed in a stainless-steel autoclave with a polytetrafluoroethylene liner and reacted at 200 °C for 23.5 h. After solid-liquid separation, the solid was washed successively with deionized water and ethanol, and dried in vacuum to obtain molybdenum disulfide; the molar ratio of sodium molybdate dihydrate to thiourea was 2:5, and the concentration of sodium molybdate in solution A was 0.08 mol / L;

[0050] (2) Iron(III) chloride trihydrate and 1,4-benzenedicarboxylic acid were added to N,N-dimethylformamide and mixed evenly to obtain solution B. The carrier molybdenum disulfide was added to solution B and mixed evenly. It was reacted at 40 °C under ultrasonic conditions (power 100 W) for 1.5 h, and then placed in a stainless-steel autoclave with a polytetrafluoroethylene liner and reacted at 100 °C for 115 h. After cooling to room temperature, solid-liquid separation was carried out. The solid was washed successively by centrifugation (8000 rpm) with N,N-dimethylformamide and acetone, and dried in vacuum to obtain the MIL68(Fe) / MoS2 composite catalyst; the molar ratio of iron(III) chloride trihydrate to 1,4-benzenedicarboxylic acid was 1:2.2, and the concentration of iron(III) chloride in solution B was 0.085 mol / L; the addition amount of the carrier molybdenum disulfide was 5% of the mass of MIL68(Fe);

[0051] The FT-IR diagram of the MIL68(Fe) / MoS2 composite catalyst in this example is shown in Figure 6 , from Figure 6 it can be seen that the results of FT-IR show that the material has rich functional groups and is similar to the reported results of other metal-organic framework materials MIL-68(Fe) and molybdenum disulfide. The functional groups of the iron-based metal-organic framework material (MIL-68(Fe) / molybdenum disulfide composite catalyst) correspond to the functional groups of the two monomer materials, proving the successful synthesis of the composite material;

[0052] The performance test of the iron-based metal-organic framework material (MIL68(Fe) / molybdenum disulfide composite catalyst) in this example for activating persulfate to degrade rhodamine B in water: 10 mg of the catalyst was put into 50 ml of a rhodamine B solution with a concentration of 10 mg / L, and rapidly stirred at 500 rpm for 30 min to reach the adsorption-desorption equilibrium. 3 mg of PMS was added, and the supernatant was filtered out with a 0.22 μm filter head at certain reaction time intervals to test the remaining rhodamine B concentration;

[0053] Example 3: A preparation method of a MIL68(Fe) / MoS2 composite catalyst, the specific steps are as follows:

[0054] (1) Sodium molybdate dihydrate and thiourea were added to deionized water and mixed evenly to obtain solution A. The pH value of solution A was adjusted to 5.2 with acetic acid at a concentration of 0.04 mol / L. It was placed in a stainless-steel autoclave with a polytetrafluoroethylene lining and reacted at a temperature of 205 °C for 24 h. Solid-liquid separation was carried out, and the solid was washed successively with deionized water and ethanol and then dried in vacuo to obtain molybdenum disulfide; the molar ratio of sodium molybdate dihydrate to thiourea was 2:5, and the concentration of sodium molybdate in solution A was 0.06 mol / L;

[0055] (2) Iron(III) chloride trihydrate and 1,4-benzenedicarboxylic acid were added to N,N-dimethylformamide and mixed evenly to obtain solution B. The carrier molybdenum disulfide was added to solution B and mixed evenly. It was reacted at a temperature of 40 °C and under ultrasonic conditions (power 100 W) for 2 h, and then placed in a stainless-steel autoclave with a polytetrafluoroethylene lining and reacted at a temperature of 105 °C for 118 h. It was cooled to room temperature, and solid-liquid separation was carried out. The solid was centrifuged (8000 rpm) and washed successively with N,N-dimethylformamide and acetone and then dried in vacuo to obtain the MIL68(Fe) / MoS2 composite catalyst; the molar ratio of iron(III) chloride trihydrate to 1,4-benzenedicarboxylic acid was 1:2.3, the concentration of iron(III) chloride in solution B was 0.09 mol / L; the addition amount of the carrier molybdenum disulfide was 20% of the mass of MIL68(Fe);

[0056] The FT-IR diagram of the MIL68(Fe) / MoS2 composite catalyst in this example is shown in Figure 6 , and from Figure 6 it can be seen that the results of FT-IR show that this material has rich functional groups and is similar to the reported results of other metal-organic framework materials MIL-68(Fe) and molybdenum disulfide. The functional groups of the iron-based metal-organic framework material (MIL-68(Fe) / molybdenum disulfide composite catalyst correspond to the functional groups of the two monomer materials, proving the successful synthesis of the composite material;

[0057] The performance test of the iron-based metal-organic framework material (MIL-68(Fe) / molybdenum disulfide composite catalyst) in this example for activating persulfate to degrade rhodamine B in water: 10 mg of the catalyst was put into 50 ml of a rhodamine B solution with a concentration of 10 mg / L, and it was rapidly stirred at 500 rpm for 30 min to reach the adsorption-desorption equilibrium. 3 mg of PMS was added, and at certain reaction time intervals, the clear liquid was filtered out with a 0.22 μm filter head to test the remaining rhodamine B concentration;

[0058] Example 4: A preparation method of a MIL68(Fe) / MoS2 composite catalyst, the specific steps are as follows:

[0059] (1) Sodium molybdate dihydrate and thiourea were added to deionized water and mixed evenly to obtain solution A. The pH value of solution A was adjusted to 5.2 with acetic acid at a concentration of 0.04 mol / L. It was placed in a stainless-steel autoclave with a polytetrafluoroethylene liner and reacted at 210 °C for 23.6 h. After solid-liquid separation, the solid was washed successively with deionized water and ethanol and dried in vacuum to obtain molybdenum disulfide. The molar ratio of sodium molybdate dihydrate to thiourea was 2:5, and the concentration of sodium molybdate in solution A was 0.1 mol / L;

[0060] (2) Ferric chloride (III) trihydrate and 1,4-benzenedicarboxylic acid were added to N,N-dimethylformamide and mixed evenly to obtain solution B. The carrier molybdenum disulfide was added to solution B and mixed evenly. It was reacted at 40 °C under ultrasonic conditions (power 100 W) for 1.5 h, and then placed in a stainless-steel autoclave with a polytetrafluoroethylene liner and reacted at 110 °C for 120 h. After cooling to room temperature, solid-liquid separation was carried out. The solid was washed successively by centrifugation (8000 rpm) with N,N-dimethylformamide and acetone and dried in vacuum to obtain the MIL68(Fe) / MoS2 composite catalyst. The molar ratio of ferric chloride (III) trihydrate to 1,4-benzenedicarboxylic acid was 1:2.5, and the concentration of ferric chloride (III) in solution B was 0.1 mol / L. The addition amount of the carrier molybdenum disulfide was 30% of the mass of MIL68(Fe);

[0061] The FT-IR diagram of the MIL68(Fe) / MoS2 composite catalyst in this example is shown in Figure 6 , and it can be seen from Figure 6 that the results of FT-IR show that this material has rich functional groups and is similar to the reported results of other metal-organic framework materials MIL-68(Fe) and molybdenum disulfide. The functional groups of the iron-based metal-organic framework material (MIL-68(Fe) / molybdenum disulfide composite catalyst correspond to the functional groups of the two monomer materials, proving the successful synthesis of the composite material;

[0062] Performance test of the iron-based metal-organic framework material (MIL-68(Fe) / molybdenum disulfide composite catalyst in this example for activating persulfate to degrade rhodamine B in water: 10 mg of the catalyst was put into 50 ml of a rhodamine B solution with a concentration of 10 mg / L, and it was rapidly stirred at 500 rpm for 30 min to reach the adsorption-desorption equilibrium. Then 3 mg of PMS was added, and the clear liquid was filtered out with a 0.22 μm filter head at certain reaction time intervals to test the remaining rhodamine B concentration;

[0063] The removal effect diagrams of the iron-based metal-organic framework materials (MIL-68(Fe) / molybdenum disulfide composite catalysts in Examples 1 to 4 for rhodamine B are shown in Figure 4 , and it can be seen from Figure 4It can be seen that when MoS2 (molybdenum disulfide) is added at 10% of the mass of MIL-68(Fe) to prepare the composite material, the MIL68(Fe) / MoS2 composite catalyst has the best removal effect on rhodamine B. It can be seen that when the composite ratio ranges from 5% to 30%, the degradation efficiency of RhB shows a trend of increasing first and then decreasing; this indicates that adding an appropriate amount of MoS2 can increase more active sites, which is beneficial to improving the catalytic activity of the catalyst.

[0064] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the scope of knowledge possessed by those of ordinary skill in the art.

Claims

1. Application of MIL68(Fe) / MoS2 composite catalyst in activating persulfate for degrading dye rhodamine B in water body, characterized in that, The preparation method of the MIL68(Fe) / MoS2 composite catalyst is as follows: (1) Sodium molybdate dihydrate and thiourea are added to deionized water and mixed evenly to obtain solution A. The pH value of solution A is adjusted to 5.0 - 5.2 with acetic acid, and the reaction is carried out at a temperature of 190 - 210 °C for 23 - 24 h. After solid-liquid separation, the solid is washed successively with deionized water and ethanol, and then dried in vacuum to obtain molybdenum disulfide; (2) Ferric chloride (III) trihydrate and 1,4-benzenedicarboxylic acid are added to N,N-dimethylformamide and mixed evenly to obtain solution B. The carrier molybdenum disulfide is added to solution B and mixed evenly. The reaction is carried out at a temperature of 25 - 40 °C under ultrasonic conditions for 1 - 2 h, and then placed at a temperature of 90 - 110 °C for 110 - 120 h. After cooling to room temperature, solid-liquid separation is carried out, and the solid is washed successively with N,N-dimethylformamide and acetone, and then dried in vacuum to obtain the MIL68(Fe) / MoS2 composite catalyst; the molar ratio of ferric chloride (III) trihydrate to 1,4-benzenedicarboxylic acid is 1:2.0 - 2.5, and the concentration of ferric chloride (III) in solution B is 0.08 - 0.1 mol / L; the addition amount of the carrier molybdenum disulfide is 5 - 30% of the mass of MIL68(Fe).

2. The application according to claim 1, wherein: In step (1), the molar ratio of sodium molybdate dihydrate to thiourea is 2:5, and the concentration of sodium molybdate in solution A is 0.05 - 0.1 mol / L.

3. The application according to claim 1, wherein: In step (2), the ultrasonic power is 50 - 150 W.

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