JPH0474501A - Deaerating agent - Google Patents

Abstract

PURPOSE:To make gas dissolved in a liquid adsorb on the surface of a deaerating agent and remove the gas by adding the deaerating agent of a polymer, cross-linked polymer, or polymer gel to the liquid. CONSTITUTION:A deaeratign agent of a polymer, cross-linked polymer, or polymer gel is added to a liquid in order to make a gas dissolved in the liquid adsorb on the surface and remove it. When the polymer, cross-linked polymer, or polymer gel shrinks, the temperature and concentration become not uniform in the periphery of the interfaces and thus the equilibrium of the liquid and the gas moves and conditions for generating bubbles are produced and sites where bubbles can grow are provided, so that the dissolved gas is adsorbed as bubbles on the shrinking interfaces and deaeration is carried out efficiently. In the case that, for example, hydrogel comprised of N-isopropylacrylamide as a main monomer and methylene bisacrylamide as a cross-linking agent is used, the gel shrinks and bubbles are adsorbed on the gel surface in water when the water is heated about at lowest 35 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a deaerator that adsorbs and removes gas dissolved in a liquid.

(Prior art and its problems) Conventionally, as a means for degassing gas dissolved in a liquid,
The main methods have been to reduce the pressure of the entire liquid, or to change the solubility of gas in the liquid by heating/cooling to degas it.

However, the method of reducing pressure has the disadvantage of requiring special equipment such as a vacuum pump. In addition, methods for heating/cooling liquids require heating/cooling means, and in some cases, it is necessary to heat the liquid to near its boiling point. It was not desirable in such cases.

Furthermore, dissolved gases are taken into the liquid again until they reach solubility when the pressure is returned from reduced pressure to normal pressure, or when the temperature is returned from heating/cooling to room temperature, so gases should be removed immediately before using the liquid. is preferable, but conventional methods requiring vacuum pumps and heating/cooling means have the drawback of not being simple.

It is also common practice to place a conventionally known porous material such as boiling stone into the liquid and use it in conjunction with a heating means. However, this is used in an auxiliary role to prevent bumping of porous materials, and in this case, the porous material is not used as a deaerator (but as a place to promote bubble growth). It's just there.

Additionally, when using a porous material as a deaerator, if the porous material is left in a liquid for a long time, the surface of the porous material will become wet with the liquid and it will no longer function as a deaerator. be.

Therefore, when using a porous material for degassing a liquid, it is not only complicated to add the porous material immediately before heating and degassing, but also because the porous material that has been used several times has to be used repeatedly. had the problem of requiring regeneration processing.

Examples of devices that require such a degassed liquid include liquid chromatography and inkjet printers that record by heating and foaming ink.

For example, liquid chromatography (hereinafter abbreviated as liquid chromatography)
In this method, a liquid is used as a carrier for flowing the sample, but if gas is dissolved in this liquid, the detector after chromatographic separation may malfunction or the S/N ratio may deteriorate.

That is, although optical means such as visible and ultraviolet are used in liquid chromatography detectors, they have been used when air bubbles are present, but deterioration over time after opening is unavoidable. In addition, since such printers are required to be small, lightweight, and low cost, it is difficult to provide a pressure reducing means such as the liquid black printer described above, and it is not possible to use ink while degassing.

Therefore, an object of the present invention is to provide an effective deaerator that solves the problems of the prior art described above.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention is a deaerator that is made of a polymer, a crosslinked polymer, or a polymer gel, and is characterized in that it adsorbs and degasses dissolved gas in a liquid.

(Function) According to the present invention, by introducing a polymer, a crosslinked polymer, or a polymer gel into a liquid, dissolved gases are adsorbed and removed on the surface of the liquid.

Furthermore, it is preferable to reuse the polymer gel or to control the amount of gas adsorbed/desorbed to the degassing agent by utilizing the fact that the polymer gel swells/shrinks and the amount of dissolved gas adsorbed changes. .

Since the blank cannot be distinguished from the sample or the optical density of the blank increases, the above-mentioned disadvantages occur. Therefore, in order to prevent this, the liquid may be pressurized and poured into a tube with high gas permeability such as a Teflon duplex, and the outside of this duplex may be depressurized and degassed, but this has the disadvantage of increasing the size of the device. there were.

Alternatively, statically, the liquid used as a carrier is sufficiently degassed by reducing pressure in advance and used immediately, but as time passes, the gas redissolves and changes over time occur. There was a drawback that it occurred.

In addition, inkjet (which records by heating and foaming ink)
In the case of printers (hereinafter abbreviated as bubble jet), the presence of air bubbles in the ink reduces heat transfer efficiency and increases power consumption, and uneven foaming causes ink droplets to become uneven in size, reducing print quality. The problem arises.

In order to prevent this, measures such as storing the ink in a closed container with low gas permeability after degassing the ink at the time of shipment are recommended (preferred embodiment). .

Dissolved gas is a gas in contact with a liquid that has dissolved, and the amount of dissolved gas is determined by the solubility of the gas in the liquid, and is in equilibrium with the gas in contact with it. By shifting the equilibrium using a method such as depressurization, deaeration is performed by creating a state in which the gas is more stable outside the liquid than when it is inside the liquid.

In the method using reduced pressure, the number of gas molecules in the space in contact with the liquid is reduced, and the gas moves from inside the liquid to outside the liquid, which is used to degas the liquid.

Furthermore, the heating/cooling method utilizes the fact that solubility is determined by temperature. For example, when a liquid is combined with a gas exhibiting so-called positive solubility, in which the solubility of the gas in the liquid increases when the temperature is raised, the liquid is effectively degassed by cooling the entire liquid. Conversely, when the liquid exhibits so-called negative solubility, it is effective to heat the entire liquid.

Therefore, as mentioned above, if the equilibrium is shifted, the dissolved gas should come out of the liquid, but in this case, the size of the gas molecules may become a problem.In other words, the dissolved gas is solvated. Due to the large surface energy of one molecule or several molecules, it is difficult to combine with other dissolved gases or overcome the affinity with the liquid and come out of the liquid. It is well known that porous materials such as so-called boiling stones are effective in such cases.

However, as mentioned above, conventional porous materials have problems such as limited use conditions and generally cannot be reused.

A preferred deaerator of the present invention utilizes swelling/contraction of a polymer gel (or non-agglomeration/aggregation of polymers) to shift the equilibrium state between liquid and gas, and also uses shrinkage gel (aggregated polymer). This is a deaerator that uses the interface between the two as a place for bubble generation.

In other words, when a polymer, cross-linked polymer, or polymer gel contracts (agglomerates), non-uniformity in temperature and concentration occurs near the interface, which shifts the equilibrium between the liquid and gas, causing bubbles to form on the surface. As a result of research, we discovered that it can be adsorbed.

Conventionally, to degas the air in water, it was necessary to heat the water to nearly 100°C (100°C) to create foam, but according to the present invention, the temperature is 35°C.
At this relatively low temperature, the air dissolved in the water was degassed.

Furthermore, since there is no need to heat the liquid to near its boiling point, there is almost no change or denaturation of the liquid, which is particularly preferable for solutions that undergo thermal denaturation, such as protein solutions.

Furthermore, the degassing agent of the present invention is an economical degassing agent that can easily degas the liquid immediately before use without using special means such as a vacuum pump or other pressure reducing means. be.

(Example) Next, the present invention will be explained in more detail by giving examples and comparative examples.

Example 1 0.5 g of N-isopropylacrylamide, 13.3 mg of methylenebisacrylamide, N.

This creates conditions for bubbles to be generated, and provides a field where bubbles can grow, so dissolved gas is adsorbed as bubbles at the contraction interface (coagulation interface) and can be efficiently degassed.

In addition, the deaerator of the present invention utilizes the swelling/contraction of the polymer gel (non-aggregation/aggregation of the polymer), so if it is brought into the contracted state (agglomerated state) when degassing is desired, the wettability to liquid will be improved. It can form a low, clear interface and exhibit sufficient performance as a deaerator.

Therefore, unlike boiling stones, when placed in liquid, the surface will not become wet and the product will not function.

Furthermore, since the degree of shrinkage of the polymer gel can be controlled, the amount of degassing due to adsorption can be controlled arbitrarily by changing the wettability of the surface.

Temperature, electric field, current, salt concentration, etc. can be used to control this swelling/shrinkage (non-aggregation/aggregation).

For example, the present inventors found that in the case of a hydrogel with N-isopropylacrylamide as the main monomer and methylenebisacrylamide as a crosslinking agent, approximately 35
If the temperature is above .degree. C., the gel will shrink.N,N',N'-tetramethylethylenediamine (6 .mu..degree. C.) was dissolved in 9 m.beta. of distilled water and bubbled with nitrogen gas for 1 hour to prepare a monomer solution. Further, 1 mg of ammonium persulfate was dissolved in 1+nj2 of distilled water to prepare a polymerization initiator.

The above monomer solution was placed in a cubic mold, a polymerization initiator was added while cooling to approximately 5°C, and the mixture was allowed to stand for 1 hour under a nitrogen atmosphere to polymerize, and then removed from the mold to obtain a polymer gel. When this polymer gel was placed indoors at 20°C into distilled water saturated with air at 1°C, and the entire distilled water was heated to 35°C, the polymer gel contracted and bubbles were generated at the interface. did. When the bubbles were collected and analyzed, it was confirmed that they were composed of air.

When only distilled water was separated and collected and compared with distilled water that had not been treated with polymer gel, the amount of dissolved air in distilled water treated with polymer gel had decreased to below the detection limit.

Comparative Example 1 In Example 1, distilled water without polymer gel was used as a comparative sample. When this untreated distilled water was heated to 35°C, no bubbles were observed.

Furthermore, a comparative analysis of distilled water heated to 35°C and distilled water that was not heated revealed that there was no significant difference.

In addition, when untreated distilled water was heated to around 100°C (the boiling point of water), bubbles were generated as it boiled.As a result of analyzing the distilled water, it was found that the distilled water treated with the polymer gel of Example 1 It was confirmed that the air was degassed to the same extent.

Therefore, according to Example 1, the same effect as heating distilled water to near its boiling point could be achieved at a relatively low temperature of 35°C.

Example 2 An attempt was made to reuse polymer gel. Distilled water at 20°C without degassing the polymer gel used as a deaerator in Example 1 1
When poured into ρ, the polymer gel swelled and no air bubbles were observed on its surface.

Next, this was heated to 35° C. in the same manner as in Example 1 to obtain a polymer solution containing Ruamide as the main component. This is Example 1
Unlike polymer gels that are polymerized, it is not possible to maintain a gel-like structure because no crosslinking agent is added.

Add this to distilled water at 20℃ saturated with air, and
When heated to 5°C, the polymer aggregated and bubbles were generated on its surface.

Therefore, it was confirmed that deaeration, which is the object of the present invention, can be achieved even if the material is not in a gel state as in Example 1.

(effect) As described above, according to the present invention, the following effects are achieved.

(1) Easy degassing is possible without the need for large-scale equipment such as a vacuum pump.

(2) It saves energy because it can be degassed at a relatively low temperature, and the liquid is less likely to undergo thermal decomposition or change in physical properties due to heat during deaeration.

[Brief explanation of the drawing]

FIG. 1 shows that at the initial stage when the deaerator of the present invention was used, the polymer gel contracted and air bubbles were adsorbed on its surface. This indicates that the polymer gel can be repeatedly used as a deaerator by heating. It has also been found that this repeated use is possible any number of times and that no special recycling treatment is required. Example 3 When distilled water was saturated with nitrogen and subjected to the same treatment as in Example 1, nitrogen was degassed from the distilled water. Example 4 0.5 g of N-isopropylacrylamide, N, N, N
',N'-Tetramethylethylenediamine (6μβ) was dissolved in distilled water (9mρ), and nitrogen gas was bubbled through the solution for 1 hour to obtain a solution. Also, ammonium persulfate 1mg
was dissolved in 1+nJ2 of distilled water to prepare a polymerization initiator. It is a conceptual diagram showing a poly N-isopropyl acrylic state or a non-degassed state when a polymerization initiator is added to the above monomer solution while cooling it to about 5°C, and it is allowed to stand for one hour under a nitrogen atmosphere to polymerize. , FIG. 2 is a conceptual diagram showing a degassing state. 1': Container and the liquid contained therein, 2: Gas dissolved in the liquid (not actually visible), 3: Swollen polymer gel (or non-agglomerated polymer or crosslinked polymer) 4: A polymer gel in a contracted state (or a polymer in an aggregated state or a crosslinked polymer); 5: Dissolved gas adsorbed on the surface of a polymer gel in a contracted state.

Claims (2)

[Claims] (1) A deaerator consisting of a polymer, a crosslinked polymer, or a polymer gel, which adsorbs and deaerates dissolved gas in a liquid. (2) The deaerator according to claim 1, wherein the adsorption capacity changes as the polymer gel swells/shrinks.