Application of benzyltriethyl formic acid eutectic solvent in iodine extraction

Abstract

The invention discloses application of a benzyltriethyl formic acid eutectic solvent in iodine extraction, and belongs to the technical field of eutectic solvents. The method comprises the following steps: preparing a benzyltriethyl formic acid eutectic solvent from benzyltriethyl ammonium chloride and formic acid under a constant-temperature stirring condition; under the conditions of constant-temperature heating and stirring, iodine is extracted from a cyclohexane solution containing iodine by using a benzyltriethyl formic acid eutectic solvent. The benzyltriethyl formic acid eutectic solvent prepared by the method has the advantages of simplicity in synthesis, low price, good degradability and the like, has relatively strong trapping capability on iodine and high iodine extraction and separation efficiency, and has the iodine extraction efficiency as high as 96.7% under the condition that the mass ratio of the benzyltriethyl formic acid eutectic solvent to a cyclohexane solution containing iodine is 1: 2.

Description

Technical Field

[0001] The invention belongs to the technical field of low eutectic solvents, and particularly relates to application of benzyltriethylformic acid low eutectic solvent in extracting iodine. Background Art

[0002] Nuclear energy does not rely on fossil fuels in its production and use, and therefore does not produce greenhouse gas emissions. It is a new energy source that is expected to replace traditional energy. However, the production process of nuclear energy produces nuclear waste, and the current discharge of nuclear wastewater contains iodine ( 129 I and 131 I), is a radioactive nuclear waste that is easily sublimated, has a long half-life, and is directly harmful to the human body. Therefore, exploring effective extractants is crucial to achieve rapid and efficient capture and stable storage of iodine.

[0003] Low eutectic solvents are composed of hydrogen bond acceptors such as quaternary ammonium salts and hydrogen bond donors such as metal halides, amides, and carboxylic acids. In addition to the advantages of ionic liquids such as "designability", low vapor pressure, wide liquid range, non-flammability, and good conductivity, low eutectic solvents also have the characteristics of lower cost, simpler operation, and better degradability. Therefore, low eutectic solvents are also called "green solvents". Replacing traditional organic solvents with low eutectic solvents is more in line with the concept of "green development".

[0004] Low eutectic solvents can form hydrogen bonds with iodine and successfully extract and separate iodine from organic solvents. Based on experience and experiments, low eutectic solvents with the lowest cost, simplest operation and best extraction effect can be designed to maximize economic benefits. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method for extracting iodine using a benzyltriethylformic acid low eutectic solvent. The method is simple to operate and has excellent effect.

[0006] The technical solution adopted by the present invention is:

[0007] Application of benzyltriethylcarboxylic acid deep eutectic solvent in extracting iodine, the method is as follows: placing benzyltriethylcarboxylic acid deep eutectic solvent in cyclohexane solution containing iodine, extracting iodine under constant temperature heating and stirring conditions;

[0008] The benzyltriethylformic acid deep eutectic solvent is synthesized from benzyltriethylammonium chloride and formic acid;

[0009] The structural formulas of benzyltriethylammonium chloride and formic acid are shown in (Ⅰ) and (Ⅱ) respectively:

[0010]

[0011] Furthermore, in the above application, the mass ratio of benzyltriethylformic acid low eutectic solvent: iodine-containing cyclohexane solution is 1:2.

[0012] Furthermore, in the above application, the concentration of iodine in the iodine-containing cyclohexane solution is 0.2 g / L.

[0013] Furthermore, in the above application, the heating temperature is 60°C.

[0014] In any one of the above applications, the method for preparing the benzyltriethylformic acid deep eutectic solvent comprises the following steps:

[0015] 1) vacuum drying benzyltriethylammonium chloride;

[0016] 2) mixing the dried benzyltriethylammonium chloride and formic acid and stirring to react until a uniform transparent liquid is formed;

[0017] 3) vacuum drying the homogeneous transparent liquid obtained in step 2) to obtain a benzyltriethylformic acid low eutectic solvent.

[0018] Furthermore, in the preparation method of the above-mentioned benzyltriethylformic acid low eutectic solvent, in step 1), the vacuum drying temperature is 60° C. and the time is 12 h.

[0019] Furthermore, in the above-mentioned method for preparing the benzyltriethylformic acid low eutectic solvent, in step 2), the molar ratio of the dried benzyltriethylammonium chloride and formic acid is 1:2.

[0020] Furthermore, in the preparation method of the above-mentioned benzyltriethylformic acid low eutectic solvent, in step 2), the time for stirring the dried benzyltriethylammonium chloride and formic acid to react is 2 hours.

[0021] Furthermore, in the preparation method of the above-mentioned benzyltriethylformic acid low eutectic solvent, in step 3), the vacuum drying temperature is 60° C. and the time is 12 h.

[0022] The beneficial effects of the present invention are:

[0023] 1. The present invention utilizes benzyltriethylformic acid deep eutectic solvent to extract iodine. The synthesis operation of the benzyltriethylformic acid deep eutectic solvent is simple and the price is low.

[0024] 2. The present invention utilizes benzyltriethylformic acid low eutectic solvent to extract iodine. The selected benzyltriethylformic acid low eutectic solvent can form hydrogen bonds with iodine, and iodine can be successfully extracted from the organic solvent with a high extraction rate.

[0025] 3. The present invention utilizes benzyltriethylformic acid as a low eutectic solvent to extract iodine, which is beneficial to the concept of green environmental protection and is more beneficial to the life and survival of humans, animals and plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of the benzyltriethylformic acid deep eutectic solvent of Example 1.

[0027] Figure 2 This is the infrared spectrum of the benzyltriethylformic acid deep eutectic solvent of Example 1. DETAILED DESCRIPTION

[0028] The present invention is further described below by way of specific examples. The present invention is not limited to the examples, and is also applicable to other deep eutectic solvents, and may be slightly modified without departing from the described scope.

[0029] Example 1 Benzyltriethylformic acid deep eutectic solvent for extracting iodine

[0030] (I) Preparation method:

[0031] 1) drying benzyltriethylammonium chloride under vacuum at 60° C. for 12 h;

[0032] 2) mixing the dried benzyltriethylammonium chloride and formic acid in a molar ratio of 1:2 and stirring for 2 hours until a uniform transparent liquid is formed;

[0033] 3) The homogeneous transparent liquid obtained in step 2) is vacuum dried at 60° C. for 12 h to obtain a benzyltriethylformic acid low eutectic solvent.

[0034] (II) Characterization methods:

[0035] 1) H NMR spectrum: H NMR spectrum of benzyltriethylformic acid eutectic solvent 1 H NMR characterization (300 MHz, solvent: DMSO-d6) Figure 1 . Analysis of the nuclear magnetic resonance hydrogen spectrum revealed that 1 The chemical shift, number of resonance peaks and integrated area of ​​H NMR were consistent with those of the target deep eutectic solvent, and no impurity peaks were found.

[0036] 2) Infrared spectrum: infrared characterization of benzyltriethylformic acid eutectic solvent is shown in Figure 2 . Analysis of the infrared spectrum shows that the infrared spectrum of the low eutectic solvent contains both the characteristic peaks of the hydrogen bond acceptor (benzyltriethylammonium chloride) and the characteristic absorption peaks of the hydrogen bond donor (formic acid), and no new characteristic peaks are generated, indicating that there is no chemical reaction between benzyltriethylammonium chloride and formic acid to produce new substances, but they are only combined through hydrogen bond interactions.

[0037] Example 2 Application of benzyltriethylformic acid deep eutectic solvent in iodine extraction

[0038] (I) Extraction and separation experiment

[0039] A certain amount of iodine was dissolved in cyclohexane to prepare a cyclohexane solution with an iodine concentration of 0.2 g / L for later use. 1 g of benzyltriethylcarboxylic acid low eutectic solvent was weighed into a 10 mL graduated test tube, 2 g of iodine-containing cyclohexane solution was added, and an iodine extraction and separation experiment was carried out at 60°C with magnetic stirring.

[0040] After 60 minutes of extraction, the mixture was allowed to stand for 2 hours. The iodine concentration in the cyclohexane phase was measured at a wavelength of 523 nm using UV-visible spectrophotometry. The average value of three measurements was taken, and the relative error was controlled within 3% to ensure the accuracy of the data.

[0041] The iodine extraction efficiency (E%) is calculated according to the following formula (1-1):

[0042] E%=[(C0-C f ) / C0] × 100% (1-1)

[0043] Where C0 represents the initial concentration of iodine in the iodine-containing cyclohexane solution, C f is the concentration of residual iodine in the cyclohexane phase.

[0044] (II) Extraction rate of iodine by benzyltriethylformic acid eutectic solvent

[0045] After extraction with the benzyltriethylcarboxylic acid deep eutectic solvent, it was calculated that the extraction efficiency of the benzyltriethylcarboxylic acid deep eutectic solvent for iodine was 96.7%.

Claims

1. The application of benzyltriethylformic acid deep eutectic solvent in extracting iodine is characterized in that: The method is as follows: placing a benzyl triethyl formate deep eutectic solvent in a cyclohexane solution containing iodine, and extracting iodine under constant temperature heating and stirring conditions; the benzyl triethyl formate deep eutectic solvent is synthesized from benzyl triethyl ammonium chloride and formic acid, and the structural formulas of benzyl triethyl ammonium chloride and formic acid are shown in (Ⅰ) and (Ⅱ), respectively:

2. The use according to claim 1, characterized in that: In terms of mass ratio, benzyltriethylformic acid low eutectic solvent: iodine-containing cyclohexane solution = 1:

2.

3. The use according to claim 1, characterized in that: The concentration of iodine in the cyclohexane solution containing iodine is 0.2 g / L.

4. The use according to claim 1, characterized in that: The heating temperature is 60°C.

5. The use according to any one of claims 1 to 4, characterized in that: The preparation method of the benzyltriethylformic acid deep eutectic solvent comprises the following steps: 1) vacuum drying benzyltriethylammonium chloride; 2) mixing the dried benzyltriethylammonium chloride and formic acid and stirring to react until a uniform transparent liquid is formed; 3) vacuum drying the homogeneous transparent liquid obtained in step 2) to obtain a benzyltriethylformic acid low eutectic solvent.

6. The use according to claim 5, characterized in that: In step 1), the vacuum drying temperature is 60° C. and the time is 12 h.

7. The use according to claim 5, characterized in that: In step 2), the molar ratio of the dried benzyltriethylammonium chloride to formic acid is 1:

2.

8. The use according to claim 5, characterized in that: In step 2), the dried benzyltriethylammonium chloride and formic acid are stirred and reacted for 2 hours.

9. The use according to claim 5, characterized in that: In step 3), the vacuum drying temperature is 60° C. and the time is 12 h.

Images