Hydrated electron solution for degrading pollutants and application thereof

Abstract

The invention discloses a hydrated electronic solution for degrading pollutants and application thereof, and belongs to the technical field of pollutant degradation, and the hydrated electronic solution is prepared by dropwise adding a PBS solution into [Bmim] PF6 and [C16mim] PF6 under an ultrasonic condition. The ionic liquid reverse micelle containing strong reducing hydration electrons prepared by the preparation method disclosed by the invention can be used for degrading pollutants, the preparation method is simple, the preparation cost is low, and the degradation rates of perfluorooctanoic acid and bromate can respectively reach 75% and 91% or above after potassium iodide is added.

Description

Technical Field

[0001] The invention relates to a hydrated electronic solution for degrading pollutants and application thereof, belonging to the technical field of pollutant degradation. Background Art

[0002] In recent years, a new concept of advanced reduction technology has emerged in the field of water treatment. This technology combines activation methods such as ultraviolet light with reducing agents such as sulfite to produce strong reducing substances (such as hydrated electrons, hydrogen atoms, etc.), which can efficiently reduce and degrade refractory organic pollutants such as chlorinated and fluorinated organics and inorganic pollutants such as perchlorates, bromates, and nitrates. It has broad application prospects in the field of water treatment. When electrons are removed from or accepted by the constituent ions, the ionization of ionic liquids (ILs) usually produces free radicals, anions or neutral free radicals and hydrogen atoms, hydrated electrons. Irradiation is the most common route for advanced reduction technology. In addition, chemical production routes can also prepare hydrated electrons, such as reactions in metals and strongly alkaline aqueous solutions, catalytic hydrogenation reactions of organic matter in alkaline solutions, and sodium amalgam electrode electrolysis reactions. There are experimental reports that 4-hydroxycoumarin can produce hydrated electrons in aqueous solution after being exposed to sunlight. Hydrated electrons promote the reduction of nitrobenzene to 4-aminophenol. Therefore, 4-hydroxycoumarin is a new substance that can produce hydrated electrons. Hydrated electrons will transform in the solution, and will generate reducing hydrogen atoms under the action of hydrogen ions. Hydrated electrons can also directly react with water molecules to generate hydrogen atoms and hydroxyl radicals, and can also react with bisulfite to generate sulfite and hydrogen atoms. The generated hydrogen atoms can combine with hydroxyl radicals to generate water molecules and release hydrated electrons. Adding surfactants to ionic liquids is a simple method for preparing ionic liquid reverse micelles, and the formed reverse micelles can maintain the life of hydrated electrons for a long time. The hydrated electron components in the formed reverse micelles can be separated and prepared by centrifugation and other methods, and their activity can be maintained for a certain period of time. The detection of hydrated electrons can usually be determined by using the absorption spectrum of dye molecules, and the strong reducing properties can also be used to reduce metal ions and then observe the generated metal nanoparticles under an electron microscope. Near-infrared spectroscopy (NIR) is the simplest, most direct and effective technology for studying hydrated electrons. The hydrated electron complex shows direct absorption properties in the near-infrared light range of 1300-2000nm. Summary of the invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a hydrated electronic solution for degrading pollutants and its application.

[0004] Technical solution: The present invention provides a hydrated electronic solution for degrading pollutants, wherein the hydrated electronic solution is provided by adding [Bmim]PF6 and [C 16mim]PF6 was prepared by adding PBS solution dropwise under ultrasonic conditions.

[0005] Furthermore, the ultrasonic conditions are 40KHz, 120W, and the ultrasonic time is 1 to 15 minutes.

[0006] Furthermore, the [Bmim]PF6, [C 16 The ratio of mim]PF6 and PBS solution is 1.5:2.0~10.0:2.0~10.0.

[0007] Furthermore, the [Bmim]PF6, [C 16 The ratio of mim]PF6 and PBS solution was 1.5:2.0:6.0.

[0008] Furthermore, the reaction temperature during the preparation is 30-60°C.

[0009] Furthermore, the PBS solution also includes potassium iodide.

[0010] Furthermore, the concentration range of the potassium iodide is 0.01 to 100 μmol / L.

[0011] Furthermore, the concentration of potassium iodide is 0.1 μmol / L.

[0012] Furthermore, the [Bmim]PF6 and PBS solutions need to be deoxygenated with nitrogen before use.

[0013] Furthermore, the pollutant is a perfluorinated compound or a bromate compound.

[0014] The present invention also provides a method for degrading pollutants in water, comprising adding a phosphate buffer solution and potassium iodide to water containing a perfluorinated compound or a bromate compound, and adding [Bmim]PF6 and [C 16 mim]PF6 is enough.

[0015] Furthermore, the pH of the phosphate buffer solution is 2-10.

[0016] The present invention uses [Bmim]PF6 (1-butyl-3-methylimidazolium hexafluorophosphate) as the nitrogen carbene precursor, and [C 16 mim]PF6 is a surfactant, into which a phosphate buffer solution (PBS) of pH=6 is added while ultrasound is applied. Ultrasound is used to allow the substances in the system to fully contact with the PBS solution, forming an ionic liquid reverse micelle system with a W / O structure containing hydrated electrons.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following outstanding and significant advantages: the ionic liquid reverse micelles containing strongly reducing hydrated electrons prepared by the preparation method of the present invention can be used to degrade pollutants, the preparation method is simple, the preparation cost is low, and after adding potassium iodide, the degradation rates of perfluorooctanoic acid and bromate can reach 75% and 91% respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 、[Bmim]PF6-[C 16 mim]PF6-PBS reverse micelle preparation;

[0019] Figure 2 、[Bmim]PF6-[C 16 mim]Near infrared spectrum of PF6-PBS ionic liquid reverse micelles;

[0020] Figure 3 、[Bmim]PF6-[C 16 mim] PF6-PBS ionic liquid reverse micelles reduced gold nanoparticles transmission electron microscopy;

[0021] Figure 4 、[Bmim]PF6-[C 16 mim] PF6-PBS ionic liquid reverse micelle reduced gold nanoparticles elemental analysis characterization diagram;

[0022] Figure 5 、[Bmim]PF6-[C 16 mim]PF6-PBS ionic liquid reverse micelle degradation of perfluorinated compounds product fluoride ion selective electrode standard curve;

[0023] Figure 6 、[Bmim]PF6-[C 16 mim] PF6-PBS ionic liquid reverse micelle degradation bromate absorption spectrum;

[0024] Figure 7 , standard curve of bromate absorption spectrum;

[0025] Figure 8 、[Bmim]PF6-[C 16 mim]PF6-PBS ionic liquid reverse micelles [C 16 mim] The trend of the effect of PF6 content on the degradation of bromate;

[0026] Fig. 9 、[Bmim]PF6-[C 16 mim] The trend of the effect of water content in PF6-PBS ionic liquid reverse micelles on the degradation of bromate;

[0027] Fig.10 , the trend diagram of the effect of temperature on the degradation of bromate during the reaction process;

[0028] Fig.11 , the trend diagram of the effect of pH on the degradation of bromate during the reaction process;

[0029] Fig.12 , the trend diagram of the effect of initial bromate concentration on the degradation of bromate;

[0030] Fig.13 、[Bmim]PF6-[C 16 mim] The trend of the effect of potassium iodide concentration on the degradation of bromate in PF6-PBS ionic liquid reverse micelles;

[0031] Fig.14 、[Bmim]PF6-[C 16 mim] Trend chart of the effect of adding other common anions to the PF6-PBS ionic liquid reverse micelles on the degradation of bromate. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0033] Example 1 [Bmim]PF6-[C 16 Preparation of mim]PF6-PBS reverse micelles

[0034] With [C 16 mim]PF6 is a surfactant, BmimPF6 is a hydrophobic solvent, and [Bmim]PF6 (1.5 mL)-[C 16 mim]PF6 (2.0 mg) was added dropwise into PBS solution (pH = 6) under ultrasound (40 KHz, 120 W, 15 min, 25 ° C), and the turbidity change of the solution was visually observed (all the solutions used needed to be deoxygenated with nitrogen for 30 min to reduce the influence of oxygen on the experiment). Figure 1 The formation process of ionic liquid reverse micelles (IL-RM) is shown. Figure 1 a is to [Bmim]PF6-[C 16 After adding PBS solution to mim]PF6, a layered structure appeared, and after adding ultrasound, a uniform and clear state was formed ( Figure 1 b, this state indicates the formation of reverse micelles, the amount of PBS solution added ≤ 10 μL), and then the PBS solution becomes turbid again with the addition of excessive ionic liquid (1-c, the amount of PBS solution added > 10 μL). Finally, 6 μL of PBS solution was added to the [Bmim]PF6-[C 16 mim]PF6-PBS reverse micelles were used for subsequent experiments.

[0035] Example 2 [Bmim]PF6-[C 16 mim] PF6-PBS reverse micelle near infrared spectrum

[0036] The above was measured using a Cary 5000 near-infrared (NIR) absorption spectrometer. Figure 1 -b NIR spectrum (see Figure 2 ). Figure 2 1406, 1609, 1901cm can be found in -1 The absorption peak of the hydrated electron complex is at 400 nm, indicating the successful preparation of hydrated electrons. However, other ionic liquids, such as BmimAc and BmimNTf2, have no obvious NIR absorption peak.

[0037] Example 3 [Bmim]PF6-[C 16 Transmission electron microscopy and elemental analysis of gold nanoparticles reduced by mim]PF6-PBS reverse micelles

[0038] In order to further confirm that [Bmim]PF6-[C 16 mim] PF6-PBS reverse micelles contain hydrated electrons. After adding chloroauric acid to the PBS aqueous phase, the formation of gold nanoparticles is confirmed. The main steps for preparing ionic liquid reverse micelles are as follows: weigh 1.4 mg of [C 16 mim]PF6 in a 50 mL centrifuge tube, and then add 1.0 mL of [Bmim]PF6 ionic liquid and 1.0 mL of 1 mg mL -1 The reagent wherein the [Bmim]PF6 ionic liquid and the chloroauric acid solution are prepared in a volume ratio of 1:1, ultrasonicated for 15 minutes, and then heated at 4000 r·min -1 Centrifuge at a speed of 15 minutes to obtain reverse micelles and then separate them into layers. Then take the lower layer of ionic liquid on ITO glass and dry it in a vacuum oven for 24 hours. Finally, measure SEM ( Figure 3 ). Figure 3 The production of gold nanoparticles was clearly observed. Figure 4 The EDS image of the reverse micelle is shown in Figure 1. Gold nanoparticles are clearly identified in the EDS measurement results.

[0039] Example 4 [Bmim]PF6-[C 16 Application of mim]PF6-PBS reverse micelles in the degradation of perfluorinated compounds

[0040] Fluorine products are used in a variety of fields, including traditional industries, electronics, energy, environmental protection, information, and biomedicine. While driving economic growth, they also pose a certain threat to the ecological environment. 16The hydrated electron reduction degradation of a new fluorinated environmental pollutant, perfluorooctanoic acid, in mim]PF6-PBS reverse micelles was carried out in the following steps: using a pH=6 phosphate buffer solution to prepare a 140 μmol·L -1 PFOA solution was added to [Bmim]PF6 (1.5 mL)-[C 16 mim]PF6 (2.0 mg) was added with the prepared perfluorooctanoic acid solution (6 μL) and ultrasonicated. The fluoride ions produced by degradation were determined by ion selective electrode method, and the degradation rate was calculated ( Figure 5 is the standard curve of ion selective potentiometry for fluoride ion, y = -57.22257x + 9.8937, R 2 =0.9978).

[0041] According to the measured potential results ( Figure 5 ) and the fluoride ion standard curve, the fluoride ion concentration of each sample can be obtained. It is also known that the initial concentration of the reagent is 140 μmol·L -1 PFOA has 15 fluorine atoms, so the degradation rate is calculated as follows:

[0042]

[0043] The results showed that the reduction degradation rate of perfluorooctanoic acid by hydrated electrons prepared under the above conditions reached 75.8% (Table 1).

[0044] Table 1 Potentiometric determination results of fluoride ions

[0045]

[0046] Example 5 [Bmim]PF6-[C 16 Application of mim]PF6-PBS reverse micelles in the degradation of bromate

[0047] 1. [Bmim]PF6-[C 16 mim] PF6-PBS reverse micelles degrade bromate

[0048] Bromate is a disinfection byproduct and a potential carcinogen. - ) is oxidized by ozone. In this example, the degradation of bromate by hydrated electron reduction prepared in Example 1 was investigated. Specifically, potassium bromate solutions of different concentrations were prepared using a pH = 6 phosphate buffer solution and [Bmim]PF6 (1.5 mL)-[C 16 Add the prepared potassium bromate solution (6 μL) to mim]PF6 (2.0 mg) and perform ultrasonication to reduce and degrade the bromate. The remaining bromate can react with iodide ions in an acidic medium to generate iodine and react with excess iodine ions to generate I3 -Based on this property, the ultraviolet spectrophotometry method was used to determine the trace bromate content in water. - The UV spectrophotometer was used to measure the bromate degradation rate at 288 nm and calculate the degradation rate of bromate ( Figure 6 and Figure 7 They are absorption spectra of bromate with different concentrations in aqueous solution and the standard curve of bromate (y=20276.38191x+0.08317, R 2 =0.998). Preliminary experimental results show that [Bmim]PF6-[C 16 mim]PF6-PBS reverse micelles can degrade bromate, and the relevant factors affecting the degradation rate will be explored later.

[0049] 2. [C 16 Effect of mim]PF6 content on bromate degradation rate

[0050] To investigate [C 16 The effect of the content of [C mim]PF6 surfactant on the degradation of bromate was investigated by adding different contents of [C mim]PF6 surfactant in the range of 2.0-10.0 mg under the conditions of hydrated electron preparation in Example 1. 16 mim]PF6, the concentration of potassium bromate is 2.08×10 -5 mol / L PBS for degradation ( Figure 8 ). The results show that [C 16 When the content of [Bmim]PF6 was 3.8-4.2 mg, the degradation rate of bromate was high, and the degradation rate was the highest when the content was 4.0 mg. This shows that when the same volume of [Bmim]PF6 contained [C 16 When the mim]PF6 content is too high, the size of the reverse micelles will be limited, thereby reducing the degradation rate of bromate.

[0051] 3. Effect of PBS addition on bromate degradation rate

[0052] To investigate the effect of water content on the degradation of bromate, the hydrated electron preparation conditions of Example 1 were investigated by adding PBS (potassium bromate concentration was 2.08×10 -5 mol / L) to the degradation rate of bromate ( Fig. 9 ). The results showed that [Bmim]PF6-[C 16 When 5-8 μL PBS was added to mim]PF6, the degradation rate of bromate was high, and the highest degradation rate was obtained when 6.0 μL PBS was added. Figure 8 The reason for the result is the same. When the PBS content in the same volume of [Bmim]PF6 is too high, the size of the reverse micelles will be limited, resulting in a lower degradation rate of bromate.

[0053] 4. Effect of reaction temperature on bromate degradation rate

[0054] In order to investigate the effect of reaction temperature on the degradation of bromate, the effect of changing the ultrasonic temperature in the range of 20-80°C on the degradation rate of bromate was investigated under the conditions of hydrated electron preparation in Example 1. 16 The concentration of potassium bromate added to mim]PF6 is 2.08×10 -5 mol / L PBS solution for degradation ( Fig.10 The results show that the reverse micelles prepared at 30-60°C have a higher degradation rate for bromate, and the reverse micelles prepared at 50°C have the highest bromate degradation rate, indicating that the reverse micelle system produces the most hydrated electrons at this temperature.

[0055] 5. Effect of pH on bromate degradation rate during the reaction

[0056] In order to investigate the effect of the pH of the reaction system on the degradation of bromate, the effect of the hydrated electrons prepared in Example 1 on the degradation rate of potassium bromate solutions with different initial pH values ​​(2-10) was investigated. 16 The concentration of potassium bromate added to mim]PF6 is 2.08×10 -5 mol / L, pH 2-10 PBS solution for degradation ( Fig.11 The results show that the degradation rate exceeds 70% under acidic and neutral conditions when the initial concentration of bromate is high, and decreases under alkaline conditions. The highest degradation rate is measured when the pH of PBS is 6, indicating that the surviving hydrated electrons generated by the reverse micelle system are at the highest level.

[0057] 6. Effect of initial bromate concentration on its degradation rate

[0058] In order to investigate the effect of the initial concentration of bromate on the degradation of bromate, the effect of the degradation rate of potassium bromate solution with different initial concentrations (5-25 μmol / L) was investigated by using the hydrated electrons prepared in Example 1 (ultrasonic temperature was changed to 50°C). Fig.12 The results showed that the degradation rate was higher than 70% when the initial bromate concentration was in the range of 5.0-25.0 μmol / L, and the highest degradation rate was obtained when the bromate concentration was 5.0 μmol / L, indicating that the concentration range of the surviving hydrated electrons generated by the reverse micelle system was at the μmol / L level.

[0059] 7. Effect of potassium iodide additive on bromate degradation rate

[0060] From the above experiments, it can be seen that the concentration range of viable hydrated electrons generated by the reverse micelle system is at the μmol / L level. It is predicted that the degradation of bromate at a higher concentration will be inhibited due to the lack of hydrated electrons. To investigate the effect of potassium iodide additive on the degradation rate of bromate, 1.5 mL BmimPF6 + 4 mg C 16 6.0 μL of PBS (pH=6, potassium bromate concentration of 2.08×10 -5 mol / L)( Fig.13 ). Fig.13 The results show that the degradation rate of bromate ion can reach up to 92% when the potassium iodide additive is 0.1 μmol / L. The reason may be that the trace concentration of iodide ion may act as a hydrate electron amplifier.

[0061] 8. Effects of other common anion additives on bromate degradation rate

[0062] In order to investigate the effect of other common anion additives on the concentration of hydrated electrons in reverse micelles, other common anions (sulfate, sulfite, nitrate, carbonate) at a level of 1.0 μmol / L were added to the PBS aqueous solution used to prepare reverse micelles, and the degradation rate of bromate ( Fig.14 ). The results showed that the common anions investigated, such as sulfate, sulfite, nitrate, and carbonate, did not amplify the hydrated electrons.

[0063] From the similar chemical properties of iodide and bromide, it can be inferred that bromide should also have a similar effect on hydrated electrons as iodide. However, bromide, as a product of bromate degradation, can be considered Fig.14 The degradation rate without adding other anion hydrated electron amplifiers already includes the amplification effect of bromide ions. Based on the above results, it can be determined that [Bmim]PF6-[C 16 mim]PF6 ionic liquid reverse micelles can be used for the reduction and degradation of fluoride and bromate pollutants.

Claims

1. A hydrated electronic solution for degrading pollutants, characterized in that: The hydrated electronic solution is prepared by adding [Bmim]PF6 and [C 16 mim]PF6 was prepared by adding PBS solution dropwise under ultrasonic conditions.

2. The hydrated electronic solution for degrading pollutants according to claim 1, characterized in that: The ultrasonic conditions are 40 KHz, 120 W, and the ultrasonic time is 1 to 15 minutes.

3. The hydrated electronic solution for degrading pollutants according to claim 1, characterized in that: The [Bmim]PF6, [C 16 The ratio of mim]PF6 and PBS solution is 1.5:2.0~10.0:2.0~10.

0.

4. The hydrated electronic solution for degrading pollutants according to claim 1, characterized in that: The reaction temperature during the preparation is 30-60°C.

5. The hydrated electronic solution for degrading pollutants according to claim 1, characterized in that: The PBS solution also includes potassium iodide.

6. The hydrated electronic solution for degrading pollutants according to claim 5, characterized in that: The concentration of the potassium iodide is 0.01-100 μmol / L.

7. The hydrated electronic solution for degrading pollutants according to claim 1, characterized in that: The [Bmim]PF6 and PBS solutions also need to be deoxygenated with nitrogen before use.

8. The hydrated electronic solution for degrading pollutants according to claim 1, characterized in that: The pollutant is a perfluorinated compound or a bromate compound.

9. A method for degrading pollutants in water, characterized in that: The following steps are involved: Phosphate buffer solution and potassium iodide were added to water containing perfluorinated compounds or bromate compounds, and [Bmim]PF6 and [C 16 mim]PF6 is enough.

10. The method for degrading pollutants in water according to claim 8, characterized in that: The pH of the phosphate buffer solution is 2-10.

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