Preparation process of Ti-MOF / BiOF composite material with excellent photocatalytic performance

Abstract

The invention discloses a preparation process of a Ti-MOF / BiOF composite material, and relates to the field of photocatalysis of nano materials. The preparation method comprises the following steps: putting N, N-dimethylformamide (DMF), methanol, terephthalic acid and tetrabutyl titanate (TBOT) into a reactor lined with polytetrafluoroethylene, keeping the temperature of 150 DEG C for 24 hours, collecting, washing, drying and activating to obtain Ti-MOF. The preparation method comprises the following steps: respectively dissolving bismuth nitrate and NaF in ethylene glycol and water, carrying out ultrasonic dissolution, and then adding a proper amount of Ti-MOF into the bismuth nitrate solution; under stirring, dropwise adding the NaF solution into the bismuth nitrate solution, transferring the mixed solution into a reaction kettle for reaction, cooling, cleaning and drying to obtain the Ti-MOF / BiOF composite material. The material has good adsorption performance and photocatalytic performance, and can efficiently degrade novel perfluorinated / polyfluorinated compounds in water under simulated sunlight.

Description

Technical fields:

[0001] This invention relates to the fields of nanomaterials and environmental photocatalysis, specifically to the preparation process of a Ti-MOF / BiOF composite material with excellent photocatalytic performance and its application in the efficient degradation of novel organic pollutants. Background technology:

[0002] The efficient degradation and removal of toxic organic pollutants in water is a crucial problem and a key technological challenge that urgently needs to be addressed in the field of environmental chemistry. Photocatalysis, which utilizes simulated visible light to degrade novel organic pollutants, is an important technology in the current environmental field.

[0003] Perfluoroalkyl substances (PFASs) are a class of organic compounds in which all hydrogen atoms in the carbon chains of aliphatic hydrocarbons are replaced by fluorine atoms, containing C... n F 2n+1 - Functional groups. Based on the different functional groups, they are mainly divided into perfluoroalkyl acids (PFAAs), perfluoroalkylphosphonates (PFPiAs), and perfluoroalkyl sulfonamides (FOSAs). Due to their special molecular structure, PFASs have excellent chemical stability, thermal stability, and hydrophobic and oleophobic properties, and are widely used in industrial production and daily consumer fields such as food packaging, fire extinguishing materials, semiconductors, metal electroplating, daily detergents, papermaking, and pesticides.

[0004] Globally, perfluorinated compounds (PFASs) have been detected in various environmental samples, including surface water, groundwater, tap water, soil, sediment, rain and snow, and indoor dust. In surface water, PFASs are mainly perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), with concentrations typically ranging from pg / L to ng / L, but reaching mg / L in certain industrially polluted areas. 3M, the world's largest PFAS producer, announced a voluntary phase-out of PFOS and related products starting in 2000. In 2006, eight major PFOA producers signed an agreement to gradually limit PFOA emissions and use by 2015. In 2009, PFOS and related products were officially added to the list of new "persistent organic pollutants." Due to global restrictions on the production and use of PFOS and PFOA, major manufacturers have shifted their focus to the research and production of short-chain PFAAs (carbon chain length between 4 and 6), leading to a significant increase in the concentration and proportion of short-chain PFAAs such as perfluorobutyl sulfonic acid (PFBS), perfluorobutyric acid (PFBA), and perfluorohexyl sulfonic acid (PFHxS) in surface water. Previous research by my group has shown that the contribution of PFHxS in Taihu Lake has surpassed that of PFOA and PFOS, becoming the most prevalent PFAA in the water, with a concentration range of 45.9–351 ng / L. As the production and use of traditional PFASs are restricted or regulated, the huge market demand has spurred the development and trade of many perfluorinated / polyfluorinated compound alternatives, thus new PFASs are continuously entering the market as substitutes for traditional PFASs. For example, hexafluoropropylene oxide trimer acid (HFPO-TA) and 6:2 chlorinated polyfluorinated ether sulfonates (6:2 F-53B) have rapidly developed in the global market as alternatives to PFOA and PFOS, respectively. 6:2 F-53B, as a PFOS alternative, is only produced in China and used as a chromium mist suppressant in metal plating. However, 6:2 F-53B has been detected not only in environmental media in China but also in Arctic marine mammals, indicating its long-distance transmissibility. Recent studies have shown that the concentration of 6:2 F-53B can reach as high as 78.5 ng / L, comparable to the concentration of PFOS in some river waters. 6:2 FTSA, as a PFOS alternative, is used in firefighting foams and is frequently detected in urban waterways.Studies have shown that these novel PFASs exhibit extremely high environmental persistence, bioaccumulation, and biotoxicity, and are frequently detected in various environmental media, wild animals, and even human serum. Given their potential harm to ecosystems and human health, there is an urgent need to develop technologies for the efficient removal of novel PFASs. Summary of the Invention:

[0005] The purpose of this invention is to provide a preparation process for a Ti-MOF / BiOF composite material with excellent photocatalytic performance and its application in the efficient degradation of novel perfluorinated / polyfluorinated compounds. The Ti-MOF / BiOF composite material synthesized by this method exhibits good degradation effects on novel perfluorinated / polyfluorinated compounds, thereby effectively expanding the application range of photocatalytic materials.

[0006] The present invention achieves the above objectives through the following technical solutions:

[0007] 1. A preparation process for a TiMOF / BiOF composite material with excellent photocatalytic performance, the specific steps of which are as follows:

[0008] 1) N,N-dimethylformamide (DMF), methanol, terephthalic acid, and tetrabutyl titanate (TBOT) were placed in a reactor lined with polytetrafluoroethylene and kept at a constant temperature of 150°C for 24 hours. The mixture was then collected, washed, dried, and activated to obtain Ti-MOF.

[0009] 2) Dissolve Bi(NO3)3·5H2O in ethylene glycol to form a solution, and add an appropriate amount of activated Ti-MOF powder;

[0010] 3) Dissolve NaF in H2O and sonicate to prepare a solution;

[0011] 4) Add solution 3 dropwise to solution 2 while stirring continuously;

[0012] 5) Transfer the prepared solution 4 into a high-pressure reactor, place it in an oven for heating, then cool, clean, dry, and place it in a muffle furnace to obtain Ti-MOF / BiOF.

[0013] 2. The preparation process of the Ti-MOF / BiOF composite material as described in claim 1, characterized in that: in step 1), 30 mL of N,N-dimethylformamide (DMF) and methanol solution are mixed in a 100 mL beaker at a volume ratio of 9:1. Then, 9.0 mmol of terephthalic acid is added to the mixture under stirring. After sonication, 0.9 mL of tetrabutyl titanate (TBOT) is slowly added dropwise. After reacting for 30 min, the reactants are transferred to a reactor lined with polytetrafluoroethylene and reacted at 150 °C for 16 hours. After the reaction is completed, the mixture is cooled to room temperature, washed repeatedly by centrifugation with anhydrous ethanol to remove residual solvent, and finally dried overnight at 60 °C to obtain sample MIL-125.

[0014] 3. The preparation process of the Ti-MOF / BiOF composite material as described in claim 1, characterized in that: in step 2), Bi(NO3)3·5H2O is 0.97g, ethylene glycol is 20mL, Ti-MOF powder is 0.18g, and sonication is performed for 30min.

[0015] 4. The preparation process of the Ti-MOF / BiOF composite material as described in claim 1, characterized in that: in step 3), 0.08g NaF is dissolved in 20mL H2O to form a solution, and sonicated for 30 minutes.

[0016] 5. The preparation process of the Ti-MOF / BiOF composite material as described in claim 1, characterized in that: in step 4), NaF solution is added dropwise to Bi(NO3)3 solution while stirring continuously.

[0017] 6. The preparation process of the Ti-MOF / BiOF composite material as described in claim 1, characterized in that: in step 5), the heating temperature is 160℃ and maintained for 24 hours. Then, it is naturally cooled to room temperature, the solid is collected by centrifugation, and washed multiple times with deionized water and ethanol, respectively. Then, the gray powder is dried at 80℃ for 24 hours to obtain the Ti-MOF / BiOF composite material.

[0018] The preparation process of the Ti-MOF / BiOF composite material provided by this invention greatly improves the specific surface area and photoelectric properties of BiOF, and enables effective separation of photogenerated electron pairs, thereby significantly improving the catalytic effect of the photocatalyst. This allows for the efficient removal of novel perfluorinated / polyfluorinated compounds from water under visible light, expanding the application space of photocatalytic materials. Attached image description:

[0019] Figure 1 The X-ray diffraction (XRD) patterns of Ti-MOF, BiOF, and Ti-MOF / BiOF composites with different ratios in Example 1 are shown.

[0020] Figure 2 The images are scanning electron microscope (SEM) images of Ti-MOF, BiOF, and Ti-MOF / BiOF composites with different ratios in Example 1.

[0021] Figure 3 This is a schematic diagram illustrating the performance of the Ti-MOF / BiOF composite material in Example 2 in degrading novel perfluorinated / polyfluorinated compounds. Detailed implementation method:

[0022] The following embodiments are further illustrations of the present invention, but not limitations thereof.

[0023] Example 1: Preparation of Ti-MOF / BiOF composite materials with different ratios

[0024] 1. A preparation process for a Ti-MOF / BiOF composite material with excellent photocatalytic performance, the specific steps of which are as follows:

[0025] 1) N,N-dimethylformamide (DMF), methanol, terephthalic acid, and tetrabutyl titanate (TBOT) were placed in a reactor lined with polytetrafluoroethylene and kept at a constant temperature of 150°C for 24 hours. The mixture was then collected, washed, dried, and activated to obtain Ti-MOF.

[0026] 2) Dissolve Bi(NO3)3·5H2O in ethylene glycol to form a solution, and add an appropriate amount of activated Ti-MOF powder;

[0027] 3) Dissolve NaF in H2O and sonicate to prepare a solution;

[0028] 4) Add solution 3 dropwise to solution 2 while stirring continuously;

[0029] 5) Transfer the prepared solution 4 into a high-pressure reactor, place it in an oven for heating, then cool, clean, dry, and place it in a muffle furnace to obtain Ti-MOF / BiOF.

[0030] 2. The preparation process of the Ti-MOF / BiOF composite material as described in claim 1, characterized in that: in step 1), 30 mL of N,N-dimethylformamide (DMF) and methanol solution are mixed in a 100 mL beaker at a volume ratio of 9:1. Then, 9.0 mmol of terephthalic acid is added to the mixture under stirring. After sonication, 0.9 mL of tetrabutyl titanate (TBOT) is slowly added dropwise. After reacting for 30 min, the reactants are transferred to a reactor lined with polytetrafluoroethylene and reacted at 150 °C for 16 hours. After the reaction is completed, the mixture is cooled to room temperature, washed repeatedly by centrifugation with anhydrous ethanol to remove residual solvent, and finally dried overnight at 60 °C to obtain sample MIL-125.

[0031] 3. The preparation process of the Ti-MOF / BiOF composite material as described in claim 1, characterized in that: in step 2), Bi(NO3)3·5H2O is 0.97g, ethylene glycol is 20mL, Ti-MOF powder is 0.18g, and sonication is performed for 30min.

[0032] 4. The preparation process of the Ti-MOF / BiOF composite material as described in claim 1, characterized in that: in step 3), 0.08g NaF is dissolved in 20mL H2O to form a solution, and sonicated for 30 minutes.

[0033] 5. The preparation process of the Ti-MOF / BiOF composite material as described in claim 1, characterized in that: in step 4), NaF solution is added dropwise to Bi(NO3)3 solution while stirring continuously.

[0034] 6. The preparation process of the Ti-MOF / BiOF composite material as described in claim 1, characterized in that: in step 5), the heating temperature is 160℃ and maintained for 24 hours. Then, it is naturally cooled to room temperature, the solid is collected by centrifugation, and washed multiple times with deionized water and ethanol, respectively. Then, the gray powder is dried at 80℃ for 24 hours to obtain the Ti-MOF / BiOF composite material.

[0035] 7) For composite materials with other doping levels, simply change the amount of Ti-MOF.

[0036] Example 1 shows XRD patterns of a series of materials.

[0037] Simulated Ti-MOF, prepared Ti-MOF, BiOF, and 10-40% Ti-MOF / BiOF heterojunction photocatalysts were compared. The XRD diffraction peaks of the prepared Ti-MOF largely matched the simulated spectrum, confirming its pure phase. Meanwhile, the XRD diffraction peaks of the prepared BiOF were consistent with those of the standard card. In Ti-MOF / BiOF composites with different doping ratios (10-40%), the main characteristic peaks of BiOF were clearly observed, while the characteristic peaks of Ti-MOF were not obvious. With increasing Ti-MOF doping concentration, the peak intensity of BiOF diffraction in the composite material significantly decreased, indicating that the introduction of Ti-MOF affected the crystallinity of the material, and also confirming the successful preparation of the Ti-MOF / BiOF heterojunction photocatalyst.

[0038] Example 2: Performance of Ti-MOF / BiOF composite material in degrading novel perfluorinated / polyfluorinated compounds

[0039] Under optimized conditions, using a 20% Ti-MOF / BiOF composite material as the photocatalyst, four typical PFASs (PFOA, PFOS, HFPO-TA, and 6:2Cl-PFESA) were selected as reaction substrates. PFOS, PFOA, and 6:2Cl-PFESA (15 mg / L) were 100% removed within 90, 150, and 150 min of illumination, respectively, while HFPO-TA (15 mg / L) was degraded by approximately 92% within 180 min of illumination. The degradation rate constants for PFOA, PFOS, HFPO-TA, and 6:2Cl-PFESA were 0.0141, 0.0861, 0.0126, and 0.0615 min, respectively. -1 The order of degradation performance was PFOS > 6: 2Cl-PFESA > PFOA > HFPO-TA. 20% Ti-MOF / BiOF showed good degradation performance for PFOS, which has historically been more difficult to degrade than PFOA in previous studies.

Claims

1. A preparation process for a Ti-MOF / BiOF composite material with excellent photocatalytic performance, the specific steps of which are as follows: 1) N,N-dimethylformamide (DMF), methanol, terephthalic acid, and tetrabutyl titanate (TBOT) were placed in a reactor lined with polytetrafluoroethylene and kept at 150°C for 24 hours. The mixture was then collected, washed, dried, and activated to obtain Ti-MOF. 2) Dissolve Bi(NO3)3·5H2O in ethylene glycol to form a solution, and add an appropriate amount of activated Ti-MOF powder; 3) Dissolve NaF in H2O and sonicate to prepare a solution; 4) Add solution 3 dropwise to solution 2 while stirring continuously; 5) Transfer the prepared solution 4 into a high-pressure reactor, place it in an oven for heating, then cool, clean, dry, and place it in a muffle furnace to obtain Ti-MOF / BiOF.

2. The preparation process of the Ti-MOF / BiOF composite material as described in claim 1, characterized in that: In step 1), 30 mL of N,N-dimethylformamide (DMF) and methanol solution were mixed in a 100 mL beaker at a volume ratio of 9:

1. Then, 9.0 mmol of terephthalic acid was added to the mixture with stirring. After sonication, 0.9 mL of tetrabutyl titanate (TBOT) was slowly added dropwise. After reacting for 30 min, the reactants were transferred to a polytetrafluoroethylene-lined reactor and reacted at 150 °C for 16 hours. After the reaction was complete, the mixture was allowed to cool to room temperature, washed repeatedly by centrifugation with anhydrous ethanol to remove residual solvent, and finally dried overnight at 60 °C to obtain sample MIL-125.

3. The preparation process of the Ti-MOF / BiOF composite material as described in claim 1, characterized in that: In step 2), Bi(NO3)3·5H2O is 0.97g, ethylene glycol is 20mL, Ti-MOF powder is 0.18g, and the mixture is sonicated for 30min.

4. The preparation process of the Ti-MOF / BiOF composite material as described in claim 1, characterized in that: In step 3), 0.08g NaF is dissolved in 20mL H2O to form a solution, and then sonicated for 30 minutes.

5. The preparation process of the Ti-MOF / BiOF composite material as described in claim 1, characterized in that: In step 4), NaF solution should be added dropwise to Bi(NO3)3 solution while stirring continuously.

6. The preparation process of the Ti-MOF / BiOF composite material as described in claim 1, characterized in that: In step 5), the heating temperature was 160℃ and maintained for 24 hours. The mixture was then allowed to cool naturally to room temperature, and the solid was collected by centrifugation. It was washed multiple times with deionized water and ethanol, respectively. The gray powder was then dried at 80℃ for 24 hours to obtain the Ti-MOF / BiOF composite material.

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