Application of thymol-based hydrophobic deep-eutectic solvent in methylene blue extraction

Abstract

The invention belongs to the technical field of eutecticevaporate solvents, and particularly relates to application of a thymol-based hydrophobic eutecticevaporate solvent in methylene blue extraction. The extraction method comprises the following steps: putting the thymol-based hydrophobic deep-eutectic solvent into an aqueous solution containing methylene blue, and extracting the methylene blue under the conditions of constant temperature and stirring; the thymol-based hydrophobic deep-eutectic solvent is synthesized from thymol and n-propyl alcohol according to a molar ratio of 1: 1. The thymol-based hydrophobic eutecticevaporate solvent prepared by the preparation method disclosed by the invention has a relatively strong trapping capability on methylene blue, and meanwhile, the eutecticevaporate solvent also has a relatively good phase forming capability, and phase separation can be achieved under a relatively small dosage. Under the condition that the volume ratio of the thymol-based hydrophobic deep-eutectic solvent to the methylene blue water solution is 1: 4, the recovery efficiency of the methylene blue is as high as 94.34%. The thymol-based hydrophobic deep-eutectic solvent extraction agent is high in separation efficiency, environment-friendly and low in price.

Description

Technical Field

[0001] This invention belongs to the field of eutectic solvent technology, specifically relating to the application of a thymol-based hydrophobic eutectic solvent in the extraction of methylene blue. Background Technology

[0002] Every year, industries such as plastics, printing, textiles, leather, cosmetics, and dye and pigment manufacturing discharge millions of tons of colored wastewater. The release of dyes into the environment is a serious problem because they stain natural water bodies and have harmful effects on humans and animals. Therefore, removing colored dyes from wastewater is crucial for improving water quality and protecting the environment. Methylene blue is a cationic dye found in colored wastewater, making its extraction from colored wastewater essential.

[0003] Eutectic solvents are a novel type of "green solvent" formed by directly mixing hydrogen bond acceptors such as quaternary ammonium salts with hydrogen bond donors such as polyols, amides, and carboxylic acids. Eutectic solvents not only possess physicochemical properties similar to ionic liquids, such as low vapor pressure, low volatility, and customizable structure and properties, but also offer advantages such as low raw material costs, simple preparation, and good biocompatibility, providing a new platform for the development of separation processes.

[0004] Hydrophobic eutectic solvents possess functional groups that interact with methylene blue, exhibiting a strong ability to capture it. Simultaneously, these solvents also demonstrate good phase-forming ability, achieving phase separation with relatively small dosages. Thymol-based hydrophobic eutectic solvents can form hydrogen bonds with methylene blue, exhibiting a strong ability to capture cationic dyes. This provides an effective method for extracting methylene blue from wastewater. Summary of the Invention

[0005] The thymol-based hydrophobic eutectic solvent of this invention can effectively extract methylene blue from wastewater. The method is simple to operate, low in cost, high in purity, and highly stable.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] An application of a thymol-based hydrophobic eutectic solvent in the extraction of methylene blue is described below: The thymol-based hydrophobic eutectic solvent is placed in an aqueous solution containing methylene blue, and the methylene blue is extracted under constant temperature and stirring conditions; the structural formula of the thymol-based hydrophobic eutectic solvent is shown in (I):

[0008] (I).

[0009] Furthermore, in the above application method, the volume ratio of thymol-based hydrophobic eutectic solvent to methylene blue aqueous solution is 1:4, and the concentration of methylene blue in the aqueous solution is 200 ppm.

[0010] Furthermore, in the above application method, the constant temperature is 30°C.

[0011] Furthermore, regarding the application of the aforementioned thymol-based hydrophobic eutectic solvent in the extraction of methylene blue, the preparation method of the thymol-based hydrophobic eutectic solvent is as follows: thymol and n-propanol are mixed and stirred until a homogeneous transparent liquid is formed, which is then vacuum dried to obtain the target eutectic solvent.

[0012] Furthermore, in the above-mentioned method for preparing the thymol-based hydrophobic eutectic solvent, the molar ratio of thymol to n-propanol is 1:1.

[0013] Furthermore, in the above-mentioned method for preparing the thymol-based hydrophobic eutectic solvent, the stirring reaction temperature is 60°C.

[0014] Furthermore, in the above-mentioned method for preparing the thymol-based hydrophobic eutectic solvent, the stirring reaction time is 1 hour.

[0015] Furthermore, in the above-mentioned method for preparing the thymol-based hydrophobic eutectic solvent, the vacuum drying is performed under vacuum conditions of 0.09 MPa and 60°C for 48 h.

[0016] Compared with the prior art, the present invention has the following significant advantages:

[0017] 1. The thymol-based hydrophobic eutectic solvent prepared by this invention has a wide liquid range, is non-volatile, and is an excellent green solvent, reducing energy consumption and environmental pollution.

[0018] 2. The thymol-based hydrophobic eutectic solvent prepared by this invention has a strong ability to capture methylene blue; at the same time, the hydrophobic eutectic solvent also has good phase-forming ability and can achieve phase separation with a small amount.

[0019] 3. The hydrophobic eutectic solvent of thymol prepared by this invention can form hydrogen bonds with methylene blue, thereby achieving the purpose of efficient extraction and separation of methylene blue.

[0020] 4. The thymol-based hydrophobic eutectic solvent prepared by this invention is inexpensive, has good chemical stability, a wide liquid range, and high extraction efficiency. Attached Figure Description

[0021] Figure 1 The image shows the hydrogen spectrum of the thymol-based hydrophobic eutectic solvent prepared in Example 1.

[0022] Figure 2 The infrared spectrum is that of the thymol-based hydrophobic eutectic solvent prepared in Example 1.

[0023] Specific implementation methods

[0024] The present invention will be further illustrated by specific examples below. The present invention is not limited to the embodiments described, and minor variations may be made without departing from the scope thereof.

[0025] Example 1: A thymol-based hydrophobic eutectic solvent for extracting methylene blue

[0026] (a) The preparation method is as follows:

[0027] Thymol and n-propanol were weighed according to a molar ratio of 1:1 and placed in a sample bottle. The mixture was stirred at 60°C for 1 h to form a homogeneous and transparent liquid. The mixture was then vacuum dried at 0.09 MPa and 60°C for 48 h to obtain the final product, a hydrophobic eutectic solvent of thymol-n-propanol (molar ratio 1:1).

[0028] (II) Characterization of thymol-based hydrophobic eutectic solvents:

[0029] (1) Proton NMR spectrum: Thymol-n-propanol (molar ratio 1:1) hydrophobic eutectic solvent proton NMR spectrum 1 1H NMR characterization (300MHz, DMSO-d6 solvent) is shown in Figure 1. For 1H NMR analysis, 1 The chemical shifts and number of resonance peaks of the H NMR were consistent with those of the target hydrophobic eutectic solvent, and no impurity peaks were found.

[0030] (2) Infrared spectrum: The infrared characterization of the hydrophobic eutectic solvent thymol-n-propanol (molar ratio 1:1) is shown in Figure 2. Analysis of the infrared spectrum shows that the eutectic solvent's infrared spectrum contains both the characteristic peaks of the hydrogen bond acceptor (n-propanol) and the characteristic absorption peaks of the hydrogen bond donor (thymol), and no new characteristic peaks are generated. This indicates that thymol and n-propanol do not undergo a chemical reaction to produce new substances; they are only bonded through hydrogen bond interactions.

[0031] Example 2: Application of thymol-based hydrophobic eutectic solvent extraction of methylene blue

[0032] (a) Extraction and separation experiment

[0033] A certain amount of methylene blue was dissolved in water to prepare a 200 ppm methylene blue aqueous solution. 1 mL of a thymol-based hydrophobic eutectic solvent was transferred to a 10 mL graduated test tube, followed by 4 mL of the methylene blue aqueous solution. The volume ratio of the thymol-based hydrophobic eutectic solvent to the methylene blue aqueous solution was 1:4. The extraction and separation of methylene blue was carried out under magnetic stirring at 30°C.

[0034] After extraction for 30 min, the sample was allowed to stand for 60 min. The concentration of methylene blue in the aqueous phase at a wavelength of 665 nm was measured using UV-Vis spectrophotometry. At least three samples were taken from the aqueous phase for quantitative determination, and the relative error at equilibrium was controlled within 3% to ensure data accuracy. The extraction efficiency of methylene blue (…) E %) is calculated according to formula (1-1):

[0035] (1-1)

[0036] Where C0 represents the initial concentration of methylene blue in water, C f This represents the concentration of remaining methylene blue in the aqueous phase.

[0037] (ii) Extraction rate of methylene blue by thymol-based hydrophobic eutectic solvent

[0038] After extraction with a thymol-based hydrophobic eutectic solvent, the extraction rate of methylene blue was calculated to be 94.34%.

Claims

1. The application of a thymol-based hydrophobic eutectic solvent in the extraction of methylene blue, characterized in that, The method is as follows: A thymol-based hydrophobic eutectic solvent is placed in an aqueous solution containing methylene blue, and the methylene blue is extracted under constant temperature and stirring conditions; the structural formula of the thymol-based hydrophobic eutectic solvent is shown in (Ⅰ): （Ⅰ）。 2. The application of the thymol-based hydrophobic eutectic solvent according to claim 1 in the extraction of methylene blue, characterized in that, By volume ratio, the ratio of thymol-based hydrophobic eutectic solvent to aqueous solution containing methylene blue is 1:4, and the concentration of methylene blue in the aqueous solution is 200 ppm.

3. The application of the thymol-based hydrophobic eutectic solvent according to claim 1 in the extraction of methylene blue, characterized in that, The constant temperature is 30℃.

4. The application of the thymol-based hydrophobic eutectic solvent according to claim 1 in the extraction of methylene blue, characterized in that, The preparation method of the thymol-based hydrophobic eutectic solvent is as follows: thymol and n-propanol are mixed and stirred until a homogeneous transparent liquid is formed, and then vacuum dried to obtain the target eutectic solvent.

5. The application of a thymol-based hydrophobic eutectic solvent according to claim 4 in the extraction of methylene blue, characterized in that, The molar ratio of thymol to n-propanol is 1:

1.

6. The application of a thymol-based hydrophobic eutectic solvent according to claim 4 in the extraction of methylene blue, characterized in that, The temperature of the stirring reaction is 60°C.

7. The application of a thymol-based hydrophobic eutectic solvent according to claim 4 in the extraction of methylene blue, characterized in that, The stirring reaction was carried out for 1 hour.

8. The application of a thymol-based hydrophobic eutectic solvent according to claim 4 in the extraction of methylene blue, characterized in that, The vacuum drying was carried out under vacuum conditions of 0.09 MPa and 60°C for 48 hours.

Images