Extractant using purified tributyl phosphate

Abstract

To provide an extractant using purified tributyl phosphate that is obtained by efficiently removing the butanol, dibutyl phosphate, etc. contained as impurities in tributyl phosphate.SOLUTION: An extractant includes: tributyl phosphate as a principal component; and hydrocarbons having 6 or more carbon atoms as diluent. The extractant further includes: 0.02 mass% or less butanol and 0.01 mass% or less dibutyl phosphate, as impurities.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing tributyl phosphate, purified tributyl phosphate obtained thereby, and an extractant using the same. More specifically, the present invention relates to a method for producing tributyl phosphate from which impurities and odors have been removed, purified tributyl phosphate obtained thereby, and an extractant using the same. [Background technology]

[0002] Tributyl phosphate (TBP) is an organophosphorus compound represented by the chemical formula (CH3CH2CH2CH2O)3PO, and is generally produced by the esterification reaction of phosphorus pentachloride or phosphoryl chloride with n-butanol (see Non-Patent Document 1). Its applications include various solvents, antifoaming agents for papermaking and textile processing, plasticizers for synthetic rubber, and extraction solvents for rare metals (platinum and uranium).

[0003] Typical impurities contained in such tributyl phosphate include n-butanol, dibutyl phosphate, and odorous components (hydrocarbons such as alkenes). These impurities impair the performance of tributyl phosphate in the above-mentioned applications, resulting in problems such as a decrease in the quality of the resulting product or a decrease in production efficiency, and therefore it is desirable to remove them as much as possible.

[0004] Among the impurities contained in tributyl phosphate, several methods for removing dibutyl phosphate have been proposed in the field of radioactive material recovery. Because tributyl phosphate has excellent performance as a solvent for recovering uranium and plutonium, it is diluted with hydrocarbon solvents and used primarily in nuclear fuel reprocessing facilities. However, in this field, dibutyl phosphate, the primary hydrolysis product of tributyl phosphate, which is produced as tributyl phosphate deteriorates, significantly reduces the purity of the resulting uranium and plutonium, and attempts have been made to remove it. Alkaline washing has traditionally been widely known as a method for removing dibutyl phosphate, but it was not sufficient to remove it.

[0005] Patent Document 1 discloses a method for removing dibutyl phosphate, which is a degradation product of tributyl phosphate used in a nuclear fuel recycling process, by contacting the tributyl phosphate containing dibutyl phosphate with an adsorbent consisting of 40 to 60% by weight of titanium oxide and 60 to 40% by weight of zirconium oxide to adsorb the dibutyl phosphate onto the adsorbent, but this method does not achieve a satisfactory level of removal.

[0006] Furthermore, no particularly established method has been proposed for removing n-butanol, one of the impurities contained in tributyl phosphate. Vacuum distillation is a widely used method for purifying phosphate triesters to remove low-boiling points, including alcohol, but is not preferred because alkyl phosphate esters undergo thermal decomposition when heated.

[0007] Patent Document 2 proposes a method for obtaining a high-purity phosphate ester by treating a crude phosphate ester, which is an ester of phosphoric acid with methanol, ethanol, or an aromatic hydroxy compound, such as trimethyl phosphate, triethyl phosphate, dimethyl monoethyl phosphate, or diethyl monomethyl phosphate, containing a large amount of at least one polar solvent selected from water, methanol, and ethanol as an impurity, with a crystalline hydrous aluminosilicate of an alkali metal or alkaline earth metal. However, the phosphate ester compound targeted by this technology is not suitable for the present invention. does not contain tributyl phosphate, and that a wide range of natural and synthetic zeolites, zeolites, molecular sieves, etc. can be used as crystalline hydrous aluminosilicates of alkali metals or alkaline earth metals as treating agents, and that the shape of the treating agent can be divided into spherical, columnar, powdery, etc., with spherical being preferred, and that spherical treating agents having particle sizes of 4 to 12 mesh (diameter: about 2.1 mm to about 6.2 mm), and even more preferably 7 to 10 mesh (diameter: about 2.5 mm to about 3.6 mm), are particularly preferred, but nothing more is mentioned. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 188693 / 1983 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-351789 [Non-patent literature]

[0009] [Non-Patent Document 1] Org. Synth. 1936, 16, 9 Summary of the Invention [Problem to be solved by the invention]

[0010] Therefore, an object of the present invention is to provide a method for producing highly pure tributyl phosphate by a relatively simple method that overcomes the above-mentioned problems of the prior art. Another object of the present invention is to provide a method for producing an extractant that is an application of such a method for producing tributyl phosphate, and the extractant obtained by this production method. [Means for solving the problem]

[0011] As a result of extensive research and investigation into solving the above problems, the present inventors discovered that, as a method for removing n-butanol, dibutyl phosphate, and odorous components contained as impurities in tributyl phosphate, the use of a hydrophobic aluminosilicate compound having a molar ratio of silica to alumina in the zeolite framework (SiO2 / Al2O3) of 10 or more, known as high-silica zeolite, can remove n-butanol, dibutyl phosphate, and odorous components very efficiently compared to other adsorbents such as activated carbon and general zeolites, and thus completed the present invention.

[0012] Tributyl phosphate is preferably used after dilution with hydrocarbons as an extractant for, for example, radioactive elements, rare earth metals, carboxylic acids, etc. In preparing such extractants, the presence of impurities such as n-butanol, dibutyl phosphate, and odorous components contained in tributyl phosphate has adverse effects, such as reduced extraction efficiency and reduced quality of the final product, and therefore is desirable for their removal. It was discovered that when tributyl phosphate, the main component of the extractant, is present together with hydrocarbons as diluents, contact with the above-mentioned high-silica zeolite does not sufficiently adsorb and remove n-butanol and other impurities. The inventors therefore discovered a method for producing an extractant containing tributyl phosphate as the main component and hydrocarbons with a carbon number of 6 or more as diluents by contacting the tributyl phosphate with an aluminosilicate compound having a silica-to-alumina molar ratio (SiO2 / Al2O3) of zeolite framework of 10 or more to remove impurities contained in the components, followed by mixing with the diluent, thereby providing an extractant with excellent properties, leading to the present invention.

[0013] That is, a first aspect of the present invention for solving the above-mentioned problems is a method for producing tributyl phosphate, comprising a step of contacting crude tributyl phosphate with a hydrophobic aluminosilicate compound having a zeolite framework silica to alumina molar ratio (SiO / AlO) of 10 or more.

[0014] In one embodiment of the method for producing tributyl phosphate according to the present invention, the step of contacting crude tributyl phosphate with a hydrophobic aluminosilicate compound is carried out at a space velocity SV of 1 h -1 The following describes a method in which the mixture is passed through the system or contacted for at least 10 hours in a batch or circulation system.

[0015] In one embodiment of the method for producing tributyl phosphate according to the present invention, a butanol concentration is adjusted to 0.02% by mass or less and a dibutyl phosphate concentration is adjusted to 0.01% by mass or less by a step of contacting crude tributyl phosphate with a hydrophobic aluminosilicate compound.

[0016] In yet another embodiment of the method for producing tributyl phosphate according to the present invention, the hydrophobic aluminosilicate compound is a ZSM-5 (Zeolite Socony Mobil-5) type, beta type zeolite.

[0017] In yet another embodiment of the method for producing tributyl phosphate according to the present invention, the hydrophobic aluminosilicate compound has a molar ratio of silica to alumina in the zeolite framework of 10 to 500.

[0018] A second aspect of the present invention that solves the above-mentioned problems is a method for producing an extractant containing tributyl phosphate and a hydrocarbon having 6 or more carbon atoms as a diluent, in which the tributyl phosphate is brought into contact with an aluminosilicate compound having a zeolite framework with a silica to alumina molar ratio of 10 or more to remove impurities contained in the tributyl phosphate, and then the tributyl phosphate is mixed with the diluent.

[0019] In one embodiment of the method for producing an extractant according to the present invention, the step of contacting tributyl phosphate with a hydrophobic aluminosilicate compound is carried out at a space velocity SV=1 h -1 The following describes a method in which the mixture is passed through the system or contacted for at least 10 hours in a batch or circulation system.

[0020] A third aspect of the present invention that solves the above-mentioned problems is a carboxylic acid extractant that contains tributyl phosphate as a main component and a hydrocarbon having six or more carbon atoms as a diluent, and is characterized in that the concentrations of butanol and dibutyl phosphate as impurities are 0.02 mass% or less and 0.01 mass% or less, respectively.

[0021] In one embodiment of the extractant according to the present invention, the diluent of the prepared extractant is at least one selected from the group consisting of hexane, benzene, toluene, octane, isooctane, nonane, decane, undecane, dodecane, o-xylene, m-xylene, p-xylene, and ethylbenzene. [Effects of the Invention]

[0022] In the present invention, impurities are removed from crude tributyl phosphate by contacting the crude tributyl phosphate with an aluminosilicate compound having a zeolite framework with a silica to alumina molar ratio of 10 or more. This allows n-butanol, dibutyl phosphate, and odorous components contained as impurities to be efficiently removed by a simple method, and highly purified tributyl phosphate can be efficiently recovered. DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention will be described in more detail below based on preferred embodiments.

[0024] (Method of producing tributyl phosphate) A method for producing tributyl phosphate according to a first aspect of the present invention is characterized by comprising a step of contacting crude tributyl phosphate with a hydrophobic aluminosilicate compound having a molar ratio of silica to alumina in a zeolite framework (SiO / AlO) of 10 or more.

[0025] Crude tributyl phosphate In the method for producing tributyl phosphate according to the first aspect of the present invention, the crude tributyl phosphate to be treated is not particularly limited by its synthesis method, etc. Furthermore, for example, it can be used as the treated material in a process for separating and purifying tributyl phosphate from a waste liquid that has been used as an extractant or the like and in which impurities such as butanol and dibutyl phosphate, which are primary hydrolyzates of tributyl phosphate, have accumulated, and for reusing the tributyl phosphate.

[0026] Although not particularly limited, crude tributyl phosphate to be treated may contain, as impurities, for example, butanol at a concentration (mass fraction) of 0.1% by mass or more, typically, for example, 0.1 to 0.3% by mass, and / or dibutyl phosphate at a concentration (mass fraction) of 0.03% by mass or more, typically, for example, 0.03 to 0.2% by mass, and may further contain odorous components such as butene as trace components, with a concentration (mass fraction) of up to about 0.1% by mass in the gas phase when approximately 30 ml of the sample is placed in a 70 ml sample bottle and the bottle is closed with a septum.

[0027] Aluminosilicate Compounds On the other hand, in the method for producing tributyl phosphate according to the first aspect of the present invention, the adsorbent used for adsorbing and removing impurities by contacting with the above-mentioned crude tributyl phosphate is a hydrophobic aluminosilicate compound having a molar ratio of silica to alumina in the zeolite framework (SiO / AlO) of 10 or more, more preferably 10 to 500, and even more preferably 40 to 300.

[0028] Furthermore, as a hydrophobic aluminosilicate compound, it is desirable to use ZSM-5 (Zeolite Socony Mobil-5) or beta zeolites, whose crystalline framework structure has an MFI topology as defined by the International Zeolite Society using three capital letters, such as that shown in the "Atlas of Zeolite Framework Types, 6th revised edition, Elsevier, Amsterdam, 2007." The use of ZSM-5 or beta zeolites enables more efficient adsorption and removal of impurities such as butanol and dibutyl phosphate.

[0029] The average pore diameter of the hydrophobic aluminosilicate compound, so-called high-silica zeolite, is not particularly limited, but from the viewpoint of the efficiency of capturing impurities in crude tributyl phosphate, it is preferably 7 Å or less, more preferably 4 to 7 Å, and even more preferably 5 to 6 Å. The pore diameter of the high-silica zeolite can be measured as follows.

[0030] <Method for measuring average pore diameter> The average pore diameter can generally be determined by a gas adsorption method such as nitrogen gas adsorption, but can also be measured using a commercially available specific surface area / pore size distribution measuring device (e.g., the Tristar II 3020 series manufactured by Shimadzu Corporation). The values ​​shown in this specification are average pore diameters measured by the nitrogen gas adsorption method using the above device.

[0031] In the present invention, if the average pore size of the hydrophobic aluminosilicate compound serving as the adsorbent is set to the preferred size described above, this size is large enough to accommodate molecules of n-butanol, one of the impurities contained in crude tributyl phosphate, and therefore adsorption and removal of n-butanol is considered to be a reasonable result to some extent. However, surprisingly, in addition to n-butanol, dibutyl phosphate, whose molecules are larger in size than the average pore size, can also be adsorbed at the same time. Although the exact mechanism of action in this regard is not fully clear, since dibutyl phosphate is hydrophilic and has a butanol skeleton, it is thought that it can be removed by the above-mentioned hydrophobic aluminosilicate compound, although not to the same extent as n-butanol.

[0032] Furthermore, odorous components contained in crude tributyl phosphate can be adsorbed and removed well when the average pore diameter of the hydrophobic aluminosilicate compound is set to the preferred size described above. The odorous components contained in crude tributyl phosphate are presumed to be, for example, butene gases produced when tributyl phosphate is thermally decomposed, and this is thought to be because the molecules of these butenes also have a size that matches the average pore diameter described above.

[0033] The shape of the hydrophobic aluminosilicate compound used as an adsorbent is not particularly limited, but is generally preferably granular, cylindrical, or spherical in shape from the viewpoint of contact efficiency. It is desirable to pack such a compound in a predetermined column or the like and bring it into contact with crude tributyl phosphate.

[0034] When the hydrophobic aluminosilicate compound is granular, its average particle size is preferably about 1 to 5 mm, more preferably about 1 to 2 mm, and when it is spherical, its average particle size is preferably about 1 to 5 mm, more preferably about 2 to 3 mm. The average particle size of the hydrophobic aluminosilicate compound can be determined using a laser diffraction / scattering particle size analyzer.

[0035] Contact process The step of contacting crude tributyl phosphate with a hydrophobic aluminosilicate compound may be carried out in a continuous, batch, or circulation manner, as long as the hydrophobic aluminosilicate compound and the crude tributyl phosphate are sufficiently contacted with each other and impurities contained in the crude tributyl phosphate can be adsorbed and removed by the hydrophobic aluminosilicate compound.

[0036] The contacting step is not particularly limited because it depends on the amount and ratio of impurities such as butanol, dibutyl phosphate, and odorous components contained in the crude tributyl phosphate. In the case of a continuous liquid flow type, the space velocity SV is 1 h -1 or less, preferably SV is 0.1 to 0.6 h -1 Alternatively, when the reaction is carried out in a batch or circulation system, the contact is desirably carried out for at least 10 hours, more preferably 17 to 75 hours.

[0037] Here, the term "space velocity" in this specification refers to the velocity at which the adsorbent packed in the adsorption tower is filled with crude tributyl phosphate, which is the liquid to be treated, and is expressed by the following formula: Space velocity SV=Q / V (1 / Hr) where Q is the flow rate (m3 / Hr) V: Amount of adsorbent in the adsorption tower (m 3 ) In the method for producing tributyl phosphate according to the present invention, when crude tributyl phosphate is brought into contact with a hydrophobic aluminosilicate compound, it has been found that the adsorption of each impurity contained in crude tributyl phosphate by the hydrophobic aluminosilicate compound proceeds preferentially with respect to butanol among the impurities over dibutyl phosphate, as will be shown in the Examples described later.

[0038] Therefore, for example, the production method according to the present invention may be configured such that the contact step between crude tributyl phosphate and a hydrophobic aluminosilicate compound is a two- or multi-stage process, with impurities, primarily butanol, being removed in the first stage and impurities, primarily dibutyl phosphate, being removed in the second stage, thereby enabling efficient separation of adsorbed components from the used hydrophobic aluminosilicate compound and efficient regeneration of the hydrophobic aluminosilicate compound.

[0039] The environmental conditions for the step of contacting crude tributyl phosphate with the hydrophobic aluminosilicate compound are not particularly limited, but the step can be carried out satisfactorily, for example, at a temperature of about 10 to 40°C and a pressure of about 101325±20 Pa.

[0040] In addition, there is no particular limitation on the contacting step between such crude tributyl phosphate and the hydrophobic aluminosilicate compound. For example, in order to increase the contact efficiency, after filling the adsorption tower with the liquid, the pressure is reduced (about 2666.45 to 13332.2 Pa), and bubbles are removed from the adsorbent for about 10 minutes, and then the adsorbent is left for a predetermined time or until the SV reaches 1 hour. -1 It is desirable to carry out the liquid-passing or batch treatment under the following conditions: In addition, since the treatment liquid after the contact treatment contains fine powder of the hydrophobic aluminosilicate compound, it is desirable to install a filter to remove the fine powder. The filter to be used is not particularly limited, but for example, a depth filter, a surface type filter, a membrane filter, etc. may be used. In the method for producing tributyl phosphate according to the present invention, after the contact step as described above, the liquid to be treated and the hydrophobic aluminosilicate compound are simply separated into solid and liquid to obtain high-purity tributyl phosphate having an extremely low impurity concentration, specifically, for example, a butanol concentration of 0.02% by mass or less, more preferably 0.01% by mass or less, and a dibutyl phosphate concentration of 0.01% by mass or less, more preferably 0.005% by mass or less.

[0041] (Method of producing extractant) The method for producing an extractant according to the present invention is a method for producing an extractant containing tributyl phosphate and a hydrocarbon having 6 or more carbon atoms as a diluent, characterized in that the tributyl phosphate is brought into contact with an aluminosilicate compound having a zeolite framework with a silica to alumina molar ratio of 10 or more to remove impurities contained in the components, and then mixed with the diluent.

[0042] In the method for producing an extractant according to the present invention, the tributyl phosphate used is first brought into contact with an aluminosilicate compound having a zeolite framework with a silica to alumina molar ratio of 10 or more to remove impurities contained in the components, essentially the same as in the method for producing tributyl phosphate described above, and then mixed with a diluent, thereby obtaining an extractant with extremely low impurities. This is because the adsorption of impurities such as butanol and dibutyl phosphate by the aluminosilicate compound tends not to proceed efficiently in the presence of the diluent, and therefore the adsorption treatment is carried out before mixing with the diluent.

[0043] In the method for producing an extractant according to the present invention, the step of contacting the tributyl phosphate used with the aluminosilicate compound is similar to the step of contacting crude tributyl phosphate with the aluminosilicate compound in the above-described method for producing tributyl phosphate in terms of treatment conditions, suitable ranges, etc., and therefore further description thereof will be omitted here.

[0044] Furthermore, the hydrocarbons having 6 or more carbon atoms used as a diluent to be mixed with tributyl phosphate are appropriately determined depending on the application of the diluent and are not particularly limited as long as they satisfy the above-mentioned conditions. Examples of such hydrocarbons include saturated or unsaturated aliphatic and aromatic hydrocarbons, and among these, preferred are hexane, benzene, toluene, octane, isooctane, nonane, decane, undecane, dodecane, o-xylene, m-xylene, p-xylene, and ethylbenzene, with toluene, octane, and decane being particularly preferred.

[0045] After the step of contacting the tributyl phosphate used with the aluminosilicate compound, the blending ratio and the mixing method when mixing with the diluent as described above are not particularly limited, and can be appropriately selected depending on the application of the resulting extractant, etc.

[0046] (Extractant) The extractant according to the present invention can be produced by the above-described method for producing an extractant, and is an extractant containing tributyl phosphate as a main component and a hydrocarbon having 6 or more carbon atoms as a diluent, and is characterized in that the concentration of butanol as an impurity is 0.02% by mass or less, more preferably 0.014% by mass or less, and the concentration of dibutyl phosphate as an impurity is 0.01% by mass or less, more preferably 0.007% by mass or less.

[0047] Such an extractant having an extremely low content of impurities can be suitably used for various conventionally known applications, including, but not limited to, an extractant for various metals such as rare metals, rare earth metals, and radioactive metals, and an extractant for specific carboxylic acids in a mixed solution. [Example]

[0048] The present invention will be described in more detail below with reference to examples. In the following examples, the analysis of each component was carried out according to the following methods.

[0049] (dibutyl phosphate) The amount of dibutyl phosphate component was measured by gas chromatography after derivatization treatment using a silylating agent under the following conditions. A BSTFA solution containing 1 g of bis(trimethylsilyl)trifluoroacetamide (Kanto Chemical Co., Ltd., hereafter referred to as BSTFA) and 9 g of n-decane (Kanto Chemical Co., Ltd.) was used as the silylating agent. Approximately 0.5 g of the silylating agent was added to approximately 2 g of sample liquid, and the mixture was heated in a constant temperature bath at 80°C for 1 hour before being analyzed by gas chromatography. The amount of dibutyl phosphate was quantified using the calibration curve method. Equipment: GC-2014 (Shimadzu Corporation) Detector: Hydrogen flame ionization detector (FID) Column: G-100 (inner diameter: 1.2 mm, length: 40 m, film thickness: 3.0 μm) Column temperature rise conditions: 80°C → 10°C / min temperature rise → 240°C (hold for 44 minutes) Injection port conditions: 250°C, Carrier gas flow rate: 15 ml / min

[0050] (moisture) The moisture content was determined using a Karl Fischer moisture meter.

[0051] (butanol) The amount of butanol component was quantified by the absolute calibration curve method, and the gas chromatography analysis conditions were as follows. Equipment: GC-2014 (Shimadzu Corporation) Detector: Hydrogen flame ionization detector (FID) Column: G-100 (inner diameter: 1.2 mm, length: 40 m, film thickness: 3.0 μm) Column temperature rise conditions: 80°C → 10°C / min temperature rise → 240°C (hold for 44 minutes) Injection port conditions: 250°C, Carrier gas flow rate: 15 ml / min

[0052] (Other volatile components including odorous components) For volatile components including other odorous components, approximately 30 ml of sample was placed in a 70 ml sample bottle, and a syringe needle was inserted into the sample bottle with the septum capped. 50 ml of the gas phase was collected using a 100 ml syringe equipped with NEEDLEx (Shinwa Chemical Industry, for organic solvents). The NEEDLEx was then replaced with a gas-tight syringe, and 0.5 ml was injected into the gas chromatograph, concentrating the headspace (gas phase) 100 times for analysis. Quantitative analysis was then performed using a gas chromatograph under the following conditions: Equipment: GC-2014 (Shimadzu Corporation) Detector: Hydrogen flame ionization detector (FID) Column: DB-WAX (inner diameter: 0.25 mm, length: 60 m, film thickness: 0.5 μm) Column temperature rise conditions: 80°C → 10°C / min temperature rise → 220°C (hold for 44 minutes) Injection port conditions: 250°C, Carrier gas flow rate: 100 ml / min

[0053] (tributyl phosphate) The amount of tributyl phosphate was determined by gas chromatography, and the remainder after subtracting the amounts of other components.

[0054] Examples 1 to 4 and Comparative Examples 1 to 6 Crude tributyl phosphate to be treated was provided by a partner company. When this crude tributyl phosphate was analyzed using the method described above, it was found to contain 0.1214 mass% butanol as an impurity. Furthermore, when approximately 30 ml of the sample was placed in a 70 ml sample bottle and the bottle was capped with a septum, the concentrations of volatile components in the gas phase were found to be 0.022 mass% butene, 0.038 mass% chlorobutane, and 0.009 mass% butyl ether (hereinafter, this crude tributyl phosphate will be referred to as "liquid to be treated 1"). The adsorbent shown in Table 1 was added to the sample solution 1 at 5% by mass, and the mixture was shaken for 18 hours using a shaker (Thomas Scientific Instruments, T-25). The supernatant was then collected and the concentrations of each component were measured under the analytical conditions described above, and the adsorption amounts of each component were compared. The results are shown in Table 1. In Example 1 and Comparative Example 5, high-silica zeolite Na was used as the adsorbent. + In Examples 2 to 4 and Comparative Example 6, high-silica zeolite H + In Comparative Example 1, WH2C (manufactured by Osaka Gas Chemicals, coconut shell-derived activated carbon) was used, in Comparative Example 2, WH5C (manufactured by Osaka Gas Chemicals, coal-derived activated carbon) was used, and in Comparative Example 3, KL (manufactured by Osaka Gas Chemicals, charcoal-derived activated carbon) was used.

[0055] Examples 5-6 The crude tributyl phosphate to be treated was a different lot provided by a cooperating company. When this crude tributyl phosphate was analyzed by the above method, the result was that it contained a butanol concentration of 0.1691 mass% as an impurity (hereinafter, this crude tributyl phosphate will be referred to as "liquid to be treated 2"). The adsorbent shown in Table 1 was added to the sample solution 2 at 5% by mass, and the mixture was shaken for 18 hours in a shaker in the same manner as in Examples 1 to 4. The supernatant was then collected and the concentration of each component was measured under the above-mentioned analytical conditions, and the amount of adsorption of each component was compared. The results are shown in Table 1. In Example 5, high-silica zeolite Na was used as the adsorbent. + Example 6 is high silica zeolite H + A mold was used.

[0056] Comparative Example 7 The crude tributyl phosphate to be treated was a different lot provided by a cooperating company. When this crude tributyl phosphate was analyzed by the above method, the result was that it contained butanol as an impurity at a concentration of 0.0826 mass% (hereinafter, this crude tributyl phosphate will be referred to as "liquid to be treated 3"). The adsorbent shown in Table 1 was added to the sample solution 3 in an amount of 5 mass %, and the solution was shaken for 18 hours in a shaker in the same manner as in Examples 1 to 4. The supernatant was then collected and the concentration of each component was measured under the above-mentioned analytical conditions, and the amount of adsorption of each component was compared. The results obtained are shown in Table 1. In Comparative Example 7, Molecular Sieve 5A (a reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the adsorbent.

[0057] [Table 1]

[0058] As shown in Table 1, in Examples 1 to 6 according to the present invention, a higher butanol adsorption rate was obtained compared to Comparative Examples 1 to 7. The odor of the treated liquid after adsorbent treatment was significantly improved in Examples 1 to 6 compared to the liquid to be treated before treatment, and when the gas phase was actually analyzed by gas chromatography under the above conditions, the peak areas of all odorous components were smaller. Table 2 shows the odorous component concentrations in the liquid to be treated 1 before adsorption treatment, obtained from the results of the above gas chromatography, and the odorous component concentrations in the treated liquid after adsorption treatment in Examples 1 and 2 and Comparative Example 2.

[0059] [Table 2]

[0060] Example 7 In order to investigate the removal rate of dibutyl phosphate by the adsorbent according to the present invention, various liquids to be treated were prepared as simulations by adding n-butanol (manufactured by Kanto Chemical Co., Ltd.) and dibutyl phosphate (manufactured by Sigma-Aldrich Co., Ltd.) to reagent-grade n-tributyl phosphate (manufactured by Kanto Chemical Co., Ltd.) in the ratios shown below. Liquid to be treated 4: Reagent-grade tributyl phosphate with 0.1% by mass of n-butanol and dibutyl phosphate added Liquid to be treated 5: Reagent-grade tributyl phosphate to which 0.1% by mass of n-butanol and 0.05% by mass of dibutyl phosphate have been added Liquid to be treated 6: Reagent-grade tributyl phosphate to which 0.02% by mass of n-butanol and 0.1% by mass of dibutyl phosphate have been added To these treated liquids, 5% by mass of the same high-silica zeolite as used in Example 5 was added, and the liquids were shaken for 18 hours using a shaker (Thomas Scientific Instruments, T-25). The supernatant was then collected and the concentrations of each component were measured under the analytical conditions described above, and the adsorption amounts of each component were compared. The results are shown in Table 3.

[0061] [Table 3]

[0062] As shown in Table 3, it was found that in Example 7 of the present invention, even if the concentrations of dibutyl phosphate and butanol, which are impurities contained in tributyl phosphate, were different, both impurity components could be adsorbed and removed. In the adsorption treatment with the ZSM-5 type high silica zeolite used in Example 7, there was a tendency for butanol to be preferentially removed, but even when either butanol or dibutyl phosphate was contained in excess, there was no tendency for either to be completely unadsorbed.

[0063] Examples 8 and 9 To investigate the effect of the crystal structure of the adsorbent on the removal rate of dibutyl phosphate on the dibutyl phosphate, 5% by mass of the same high-silica zeolite as used in Example 3 (Example 8) or the same high-silica zeolite as used in Example 4 (Example 9) was added to the treated liquid 6 prepared in Example 7. The mixture was shaken for 18 hours using a shaker (Thomas Scientific Co., Ltd., T-25). The supernatant was collected and the concentrations of each component were measured under the analytical conditions described above. The adsorption amounts of each component were compared. The results are shown in Table 4.

[0064] [Table 4]

[0065] As shown in Table 4, the adsorption amount of dibutyl phosphate in tributyl phosphate was higher in Example 9. As described above, although there was a difference in the adsorption amounts of butanol and dibutyl phosphate due to the difference in the crystal structure of the adsorbent according to the present invention, both the beta type and the ZSM-5 type adsorbed butanol and dibutyl phosphate.

[0066] Reference example 1 In order to confirm the adsorption efficiency of the adsorbent of the present invention for an extractant containing tributyl phosphate and a diluent, the same treated liquid 2 as used in Examples 5 and 6 and a simulated extractant (hereinafter referred to as "treated liquid 7") prepared by mixing this treated liquid 2 with reagent-grade decane (manufactured by Kanto Chemical Co., Ltd.) in a mass ratio of 75:25 were prepared. The same adsorbent as used in Example 1 was added to these sample solutions 2 and 7 in the proportions shown in Table 5, and after shaking for 18 hours in a shaker as in Examples 1 to 4, the supernatant was collected and the concentrations of each component were measured under the above-mentioned analytical conditions, and the adsorption amounts of each component were compared. The results obtained are shown in Table 5.

[0067] [Table 5]

[0068] As shown in Table 5, in the presence of decane as a diluent, the amount of butanol adsorbed from tributyl phosphate tended to decrease by about 60%.

[0069] Examples 10 and 11 To investigate the effect of different liquid flow rates on the adsorption efficiency of butanol and dibutyl phosphate, adsorption treatment was carried out under the following conditions. The crude tributyl phosphate to be treated was a different lot provided by a partner company. Analysis of this crude tributyl phosphate using the above method revealed that it contained 0.1930% by mass of butanol as an impurity. This crude tributyl phosphate was mixed with 0.1% by mass of dibutyl phosphate reagent to form the treated liquid 8. 12.0 g of the adsorbent shown in Example 5 was added to a PFA adsorption column with an inner diameter of 17.5 mm and a length of 120 mm. The adsorption column was filled with the treated liquid 8, and the pressure was reduced to 13,332.2 Pa to remove air bubbles from the adsorbent for 10 minutes. The liquid was then pumped through the adsorption column using a metering pump (Iwaki Corporation, EHN-R) at a flow rate of 0.08 g / min (SV = 0.3) (Example 10) and at a flow rate of 0.91 g / min (SV = 3.2) (Example 11). The butanol and dibutyl phosphate concentrations were measured under the above analytical conditions, and the relationship between the flow rate and the adsorption amount was compared. The results obtained are shown in Table 6.

[0070] [Table 6]

[0071] Example 12 To investigate the relationship between the contact time of the adsorbent and the amount of butanol adsorbed, an adsorption treatment was carried out under the following conditions. 60.0 g of the adsorbent described in Example 5 was added to a SUS304 adsorption column with an inner diameter of 28.4 mm and a length of 200 mm. The adsorption column was filled with 60.0 g of sample liquid 2. A 1000 g Erlenmeyer flask was charged with sample liquid 2. While stirring with a stirrer, sample liquid 2 was pumped into the adsorption column at a flow rate of 7.1 g / min using a metering pump (Iwaki, EHN-R). The liquid after pumping through the adsorption column was mixed with the Erlenmeyer flask containing sample liquid 2. The liquid in the Erlenmeyer flask was sampled at regular intervals, and the butanol concentration was measured under the analytical conditions described above. The relationship between the liquid circulation time and the amount of butanol adsorbed was compared. The results are shown in Table 7.

[0072] [Table 7]

[0073] As shown in Table 7, the amount of butanol adsorbed tended to increase in proportion to the contact time with the adsorbent.

Claims

1. An extractant containing tributyl phosphate as a main component and hydrocarbons having six or more carbon atoms as a diluent, characterized in that the concentrations of butanol and dibutyl phosphate as impurities are 0.02% by mass or less and 0.01% by mass or less, respectively.

2. 2. The extractant according to claim 1, wherein the diluent is at least one selected from the group consisting of hexane, benzene, toluene, octane, isooctane, nonane, decane, undecane, dodecane, o-xylene, m-xylene, p-xylene, and ethylbenzene.

Images