JPS6261900B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the concentration of a volatile component in a non-aqueous liquid, and is aimed at rapid and accurate measurement.

Non-aqueous liquids containing volatile components include, for example, in the oil and fat industry, liquid oils and fats that contain volatile components dispersed or dissolved, liquid organic compounds that require purification, etc. A method for rapidly and accurately measuring the concentration of volatile components in a continuous or discontinuous manner is extremely important, and the development of an excellent method has been strongly desired.

For example, in the deodorizing process of refining oils and fats in the oil and fat industry, oils and fats are conventionally heated with a high-temperature heat medium in a deodorizing can so that the odoriferous volatile components contained therein are reduced to below a predetermined concentration. Once the liquid has dropped, it is assumed that the prescribed treatment in the deodorizing process has been completed and the liquid is sent to the next process. In most cases, this treatment is generally carried out in a batch or semi-batch manner, but there is no suitable industrial measuring method to detect when the concentration of odorous volatile components has fallen below a predetermined level. Some of the deodorized fats and oils had to be taken out of the system, and after the fats and oils were cooled to an appropriate temperature, the odor and taste were examined mainly through sensory tests to determine whether deodorization was appropriate. Therefore, when strict process control is carried out, the deodorized fats and oils are retained in the apparatus until the sensitivity test is completed, significantly reducing the operating rate. In order to reduce this time loss and improve the operating rate of the equipment, an accurate and rapid method for measuring the concentration of odorous volatile components in fats and oils is required in place of the above-mentioned sensitive testing method. The present inventor has arrived at the present invention as a result of intensive research into a method for quickly and accurately measuring the concentration of a volatile component in a non-aqueous liquid. That is, the method of the present invention involves contacting one side of a liquid-repellent continuous microporous porous partition with a non-aqueous liquid containing a vaporizable component, passing a carrier gas through the other side, and guiding this to a detector. This measurement method continuously or intermittently measures the concentration of vaporizable components in a liquid that passes through the partition wall and diffuses into the gas. The present invention will be described in more detail below.

The shape of the continuous microporous porous partition used in the present invention includes a tube shape, a sheet shape, etc., and the material is a porous body using a liquid-repellent material or a porous body treated with a liquid-repellent material. It can be any of the following.

The material of the liquid-repellent continuous microporous porous partition body that can be used in the present invention includes synthetic resins such as halogenated ethylene resins such as fluorinated ethylene resins, halogenated vinylidene resins, polypropylene, polyester resins, vinyl chloride resins, etc. Examples include halogenated vinyl resin.

Examples of non-aqueous liquids referred to in the present invention include animal-based liquids,
Vegetable fats and oils, such as beef tallow, pork fat, fish oil, whale oil, saury, sardines, herring, sunflower, soybean,
These include corn, cotton, sesame, safflower, paulownia, rapeseed, rice bran, olive, camellia, cacao, shea, palm, coconut oil and mixtures thereof. Furthermore, there are liquid organic compounds, such as aliphatic hydrocarbons, alcohols, ethers, carbonyl compounds, carboxylic acids, aromatic hydrocarbons and their derivatives and mixtures thereof, and silicone oils. However, it is also possible to measure trace amounts of water contained in non-aqueous liquids by the method of the present invention. Next, the present invention will be explained according to the drawings.

Figures 1, 2, and 3 illustrate Example 1, and show a measurement method using a tube-shaped porous partition for liquid oil (rice oil) containing hexane, and Figure 4 illustrates Example 2.
This is an explanatory diagram showing a measurement method using a sheet-like porous partition wall for polyethylene glycol containing ethanol.

Figure 1 is an explanatory diagram of the flow of the measurement method of the present invention, Figure 2
The figure is a graph showing the response to step-like changes in the concentration of volatile components in a non-aqueous liquid containing volatile components according to the present invention. The vertical axis is the detector output, the horizontal axis is time, and the triangle marks are the volatile components. It's time to drip. FIG. 3 is a graph showing the relationship between the concentration of vaporizable components in the non-aqueous liquid and the output (peak height) of the measuring device.

FIG. 1 is a flowchart showing the principle of the measurement method of the present invention, in which 1 is a non-aqueous liquid, 2 is a continuous microporous porous partition, 3 is a measuring device, 4 is a carrier gas passage port, It is an entrance and an exit. A carrier gas, such as nitrogen or helium, is preferably passed on the gas side. Air may be used depending on the detector.

While the pressure and flow rate of the gas are desirably kept constant, for example, when a tube with an inner diameter of several mm is used, the flow rate of the gas is preferably kept constant at a value of about 40 to 80 c.c./min. It is desirable to keep the carrier gas temperature the same as the liquid temperature. And the differential pressure between the carrier gas and the non-aqueous liquid may be zero,
Further, either pressurization or negative pressure may be used. However, in the case of pressurization, if the pressure on the side of the gas to be vented is too high, the gas will blow out into the non-aqueous liquid through the pores of the porous body, which is not preferable. In short, the pressure should be maintained at a level that does not allow gas to blow out into the nonaqueous liquid through the pores. In the case of negative pressure, the differential pressure between the carrier gas and the dispersion liquid should be maintained at a negative pressure to the extent that the non-aqueous liquid does not seep into the inner wall through the pores of the partition.

Further, when using a tube, the pressure loss of the gas in the tube should be small, so the inner diameter of the tube is preferably several mm. However, in the case of a tube, if the tube is made too thin, the pressure may rise too much in some areas and blow out from the membrane, so it is desirable to determine the optimum value for the tube diameter within a range that does not cause this. Furthermore, the walls of the partition need to withstand a slight pressure difference, and on the other hand, if the walls are made thicker, the diffusion rate through the walls will be reduced, so the thickness is preferably about several hundred microns.
In addition, when using a tube, its length should desirably be long enough to bring the concentration of the vaporized component in the gas into equilibrium with the concentration of the same component in the non-aqueous liquid. For diameter tubes, 20~
30cm is sufficient. Regarding the pore size of the porous material, all commercially available porous materials with a pore size of 0.1 to 5μ can be used, and those with a pore size of >5μ can be used.
Alternatively, those with <0.1μ can be used as long as the usage conditions are selected. In addition, when selecting the material pore diameter etc. of the porous partition body of the present invention, based on the following relationship,
It may be selected according to each measurement condition. In other words, in the present invention, if the liquid permeates into the pores of the porous body, this measurement method no longer holds true, but how much pressure must be applied for the liquid to permeate into the pores is shown in the following equation. As described above, it is determined by the contact angle between the porous base material and the liquid, the interfacial tension, and the pore diameter, but the material, pore diameter, etc. may also be selected by taking into consideration the shape of the pores.

ΔP=2γ・Cos θ/R ΔP: Pressure γ: Interfacial tension between the base material and the liquid θ: Contact angle between the base material and the liquid R: Pore radius As the measuring device, preferably, a gas chromatograph may be used.

If the gas contains multiple vaporized components, it is also possible to sample a certain amount of the carrier gas containing the vaporized components with a gas sampler, separate it with a column, and measure each amount with a detector. On the other hand, in gas,
Practically speaking, if only a single vaporized component is contained, there is no need to use a column to separate it, and the carrier gas containing the vaporized component can be detected by continuously flowing it directly to a flame ionization detector. good. In this case, since a column and a gas sampler are not used, it is mechanically simple and data can be obtained continuously, making it an extremely excellent measurement method for automatic control.

Next, the piping between the partition wall and the measuring device is desirably heated to a temperature higher than that of the non-aqueous liquid in order to prevent response delays due to condensation or adsorption of vaporized components.
It is preferable to maintain the liquid temperature at 5° C. or higher.

A feature of the present invention is that a liquid-repellent continuous microporous porous partition is used to quickly and continuously convert volatile components in a non-aqueous liquid into a gas that can be easily measured using a known measuring instrument, preferably a gas chromatograph. The purpose of this method is to measure the concentration of vaporizable components in the liquid using the above-mentioned measuring device by sampling periodically or intermittently using a simple mechanism.

On the other hand, for example, when a silicone tube without micropores is used for the purpose of the present invention, the mechanism by which vaporizable substances diffuse from the non-aqueous liquid to the gas in the tube is compared. In this method, the vaporizable substance dissolves and diffuses and moves into the gas inside the tube, whereas in this method, the vaporizable substance becomes a gas and diffuses in the pores of the porous body, so the mechanism is completely different. The diffusion rate of the latter diffusion mechanism is significantly higher.

The diffusion rate of the vaporizable substance into the liquid phase separated by the liquid-repellent porous material is expressed by equation (1).

(Here, J _A is the flux of component A, m is a constant representing the characteristics of the membrane, C is the molar concentration in the liquid phase, X _A is the molar fraction of component A in the liquid phase, R is the gas constant, T is temperature;
S _L is the solubility coefficient in the liquid phase, S _G is the solubility coefficient in the gas phase, H is Henry's constant, D _L is the diffusion coefficient in the liquid phase, and D _G is the diffusion coefficient in the gas phase).

The denominator of equation (1) is a term corresponding to the resistance to diffusion, and is composed of two elements: the first term, the resistance in the liquid side boundary film, and the second term, the resistance when passing through the pores of the porous body. Consisting of In general, the second term is much smaller than the first term, and the total resistance of both terms is almost dominated by the first term, that is, the resistance in the liquid-side boundary film.

On the other hand, in the case of a silicon film, vaporizable components dissolve and diffuse in the film, and the resistance thereof is generally much larger than the resistance in the liquid-side boundary film. Therefore, when comparing the diffusion rates of a liquid-repellent porous material and a silicon film, the former is dominated by the diffusion resistance due to the liquid-side boundary film, whereas the former is dominated by the dissolution diffusion resistance in the film, which is much larger than the liquid-side boundary film. The diffusion rate is faster than the latter. That is,
It can be said that the former has a faster response to changes in the concentration of volatile components in the liquid phase. According to this method, which uses a material with a high diffusion rate, a 90% response to changes in the concentration of volatile components in a non-aqueous liquid is around 1 minute, which is about 1 minute compared to when a silicone film is used. It exhibits a response speed of more than 10 times, indicating a significant superiority.

When carrying out the present invention, for example, when instruments that are immersed in liquid oil or fat are required to have, firstly, heat resistance that can withstand normal heat sterilization, and secondly, safety against foods and medicines. If a porous material such as tetrafluoroethylene is used as the material of the partition wall, these conditions can be fully satisfied, so that an excellent effect can be exhibited as a measuring method for the oil and fat industry.

Next, examples of the present invention will be described.

Example 1 The hexane concentration in rice oil was measured using a tube-shaped continuous microporous body made of tetrafluoroethylene. In other words, hexane was considered to be a substitute for odoriferous volatile components in fats and oils.

As shown in Figure 1, 500 c.c. of rice oil was placed in beaker 1 and stirred vigorously with a magnetic stirrer while maintaining a constant temperature. On the other hand, the tube was immersed in the liquid, N ₂ gas was passed through one end at a constant pressure and constant flow rate, the other end was led to a hydrogen flame ionization detector, and the output of the detector was continuously recorded with a recorder.

In the experiment, a fixed amount of hexane dissolved in rice oil was prepared in advance, and a fixed amount of this was dropped into a beaker at fixed time intervals to change the hexane concentration in the rice oil in steps. I looked at the device's response.

The tube has an inner diameter of 3.7mm, a wall thickness of 500μ, and a pore diameter.
0.1 μ, porosity 30%, tube length 30 cm, and the carrier gas was N ₂ gas at a flow rate of 60 c.c./min.
In this case, the pressure difference between the gas and rice oil is almost O
It was hot.

As a result, as shown in Fig. 2, it was found that the method had a good response time of about 2 minutes at 90% response to the step-like concentration change of hexane in rice oil. Furthermore, the hexane concentration in rice oil and the output of the detector had a linear relationship as shown in Figure 3, and had sufficient quantitative properties.

Example 2 As shown in FIG. 4, two beakers are immersed in a constant temperature bath, and polyethylene glycol 200 is added to both beakers, stirred, and maintained at a constant temperature. As shown in Figure 4, a sheet-shaped porous material made of tetrafluoroethylene resin attached to the top of a hollow container for sampling is placed in this beaker, and a carrier gas, _N2 , is supplied from one end of the container. It was fed at a constant pressure and a constant flow rate, and the other end was led to a hydrogen flame ionization detector.

Next, a fixed amount of ethanol pre-dissolved in polyethylene glycol 200 was dropped into the first beaker at fixed time intervals, and the response of the output of the detector to this was recorded.

By the way, since the hydrogen flame ionization detector also detects polyethylene glycol 200, the output of the pure liquid in the second beaker is blank, and the output of the first and second beakers is
The difference between the outputs of both detectors was taken as the output corresponding to the ethanol concentration. However, since polyethylene glycol has a low vapor pressure and therefore a low concentration in the carrier gas, even trace concentrations of ethanol could be sufficiently detected by this method.

Beaker capacity 1000c.c., liquid volume 800c.c., liquid temperature 20℃,
The carrier gas flow rate was 60 c.c./min, and the differential pressure with the liquid side was almost O. The sheet measures 2.0×
8.0cm, wall thickness 0.55mm, maximum pore diameter 2.0μ, porosity 62.0
% was used.

The amount of ethanol dropped at one time is determined by the concentration in the liquid.
It was set to 150ppm.

The hydrogen flame ionization detector used was the one attached to a Shimadzu gas chromatograph GC-6A.

As a result of the experiment, a 90% response time of about 50 seconds was obtained, and there was a linear relationship between the detector output and the ethanol concentration.

[Brief explanation of the drawing]

Figures 1 to 3 are explanatory diagrams of Example 1 of the present invention, with Figure 1 being a flow chart showing the principle of the measurement method, and Figure 2 showing the response to a step-like change in the concentration of vaporizable components in a non-aqueous liquid. The graph shown in FIG. 3 is a graph showing the relationship between the concentration of vaporizable components in the non-aqueous liquid and the output of the detector. FIG. 4 is a flow explanatory diagram showing the principle of the measurement method according to the second embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Non-aqueous liquid, 2... Liquid-repellent continuous microporous porous partition, 3... Measuring device, 4... Carrier gas, 5... Constant temperature bath, 6... Beaker.

Claims (1)

[Claims] 1. A non-aqueous liquid containing a vaporizable component is brought into contact with one side of a liquid-repellent continuous microporous porous partition, a carrier gas is passed through the other side, and the gas is introduced into a measuring device. The concentration of the volatile component in the non-aqueous liquid is measured continuously or intermittently by detecting the amount of the volatile component in the non-aqueous liquid that passes through the partition wall and diffuses into the gas. Measurement method. 2. The measuring method according to claim 1, wherein the continuous microporous porous partition body is tube-shaped. 3. The measuring method according to claim 1, wherein the continuous microporous porous partition body is in the form of a sheet. 4. The measuring method according to claim 1, wherein the material of the continuous microporous porous partition body is an oil-repellent porous body. 5. The measuring method according to claim 4, wherein the material of the oil-repellent partition wall is a porous body made of fluorinated ethylene resin. 6. The measuring method according to claim 1, wherein the material of the continuous microporous porous partition body is a porous body subjected to a liquid repellent treatment. 7. The measuring method according to claim 1, wherein the non-aqueous liquid is a liquid fat or oil. 8. The measuring method according to claim 1, wherein the non-aqueous liquid is a liquid in which a polymer such as an oligomer is suspended. 9. The measuring method according to claim 1, wherein the carrier gas is nitrogen. 10. The measuring method according to claim 1, wherein the carrier gas is helium. 11. The measuring method according to claim 1, wherein the differential pressure between the carrier gas and the non-aqueous liquid is zero. 12 Claim 1: The pressure is maintained relative to the liquid pressure to the extent that gas does not blow out into the non-aqueous liquid.
Measurement method described in section. 13. The measuring method according to claim 1, in which the non-aqueous liquid is maintained at a negative pressure relative to the liquid pressure to such an extent that the non-aqueous liquid does not seep into the inner wall of the partition wall in liquid form. 14. The measuring method according to claim 1, wherein the amount of vaporized components diffused into the carrier gas is intermittently measured by gas chromatography. 15 When the vaporized component in the carrier gas is substantially single, the concentration of the vaporized component in the non-aqueous liquid can be continuously determined by detecting the amount of that component using a flame ionization detector. The measuring method according to claim 1, which measures . 16. The measuring method according to claim 1, in which the piping that conveys gas from the partition to the measuring device is maintained at a temperature higher than the temperature of the non-aqueous liquid.