JPS6359755B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a stable aqueous oxygen scavenger composition, and more particularly to a stable oxygen scavenger composition prepared by adding an aromatic compound having three or more hydroxyl groups to an alkali metal sulfite salt and forming an aqueous solution. Since alkali metal sulfites have high reactivity with oxygen, they are widely used as oxygen absorbers for boiler water, boiler feed water, and the like. Usually, deoxidation treatment is carried out using cold or hot water, but alkali metal sulfites have high reactivity with oxygen even at room temperature, which is considered to be a drawback.
In other words, regardless of when it is in powder form, when it becomes an aqueous solution, even if it is stored at room temperature (-10℃ to 35℃), oxygen in the air dissolves in the aqueous solution and reacts with the alkali metal sulfite in the solution, making it effective. Ingredients (sulfite ion)
The concentration of oxygen decreases, so that its oxygen scavenging capacity gradually decreases over time. When using an alkali metal sulfite salt as an oxygen scavenger, usually
The method used is to prepare an aqueous solution of about 1 to 10% by weight in advance and inject it using a chemical pump or the like. Therefore, if the deoxidizing ability of this aqueous solution decreases during storage, for example when used to deoxidize boiler water, there is a concern that the boiler will corrode due to lack of active ingredients, and to avoid this, the frequency of dissolution must be reduced. I didn't have to do much. When we tested the stability of aqueous solutions of alkali metal sulfite salts using various additives, we found that aromatic compounds with one hydroxyl group, such as carbolic acid, had no effect at all. Ta. Resorcinol and hydroquinone, which have two hydroxyl groups, also showed almost no stabilizing effect, and although catechol had a considerable effect, it was found to be unfavorable in terms of toxicity and other aspects. Thus, this invention utilizes alkali metal sulfite salts.
The present invention provides a stable aqueous oxygen scavenger composition characterized in that 0.01 to 10 parts by weight of an aromatic compound having three or more hydroxyl groups is added to 100 parts by weight to form an aqueous solution. The alkali metal salts of sulfite which are oxygen scavengers used in the composition of this invention include potassium,
Examples include sodium, lithium, and calcium salts, among which sodium and potassium salts are most commonly used, and these salts may be hydrated or anhydrous. Aromatic compounds having three or more hydroxyl groups (hereinafter referred to as aromatic compounds of the present invention) used in this invention include polyhydric phenols having three hydroxyl groups such as pyrogallol, hydroxyhydroquinone, and phloroglucin; gallic acid; Examples include derivatives of polyhydric phenol having three hydroxyl groups such as gallic acid amide; tannins such as quebratyotannin, katsuchitanin, and hamamelitannin. The most preferred of these are
In terms of marketability and price, these are pyrogallol, gallic acid, and tannins. In the composition of this invention, the aromatic compound of this invention is preferably 0.01 to 10 parts by weight based on 100 parts by weight of anhydrous alkali metal sulfite salt.
It is used by adding 0.5 to 3 parts by weight. The stable aqueous oxygen scavenger composition of the present invention is prepared by preparing a 1 to 10% by weight aqueous solution of an alkali metal sulfite, and adding the aromatic compound of the present invention in a predetermined weight ratio to the alkali metal sulfite to the aqueous solution. It is obtained by adding the compound as a solid or as an aqueous solution and stirring and mixing. Alternatively, the solid alkali metal sulfite salt and the solid aromatic compound of the present invention can be mixed in advance at a predetermined weight ratio, and the mixture can be prepared by dissolving the mixture in water. According to this invention, even if a concentrated aqueous solution of an alkali metal sulfite salt is stored at room temperature for a long period of time, the oxygen scavenging ability does not decrease and a stable state can be maintained. Furthermore, when this long-term stored solution is added to boiler water, etc. at a concentration of alkali metal sulfite in the range of 1 to 1000 ppm, immediately after dissolving only the alkali metal sulfite without adding the aromatic compound of this invention. It shows the same deoxidizing ability as when using an aqueous solution. Usually, the pH of these aqueous solutions is
Generally, it is 10 or more, but it can of course be used even if it is less than 10. The present invention will be explained in detail below with reference to Examples. Example 1 Air is blown into an aqueous solution of alkali metal sulfite,
Conditions were set to forcibly consume the active ingredient (sulfite ion), and the effects of various aromatic compounds having hydroxyl groups were determined. That is, 5% and 10% by weight aqueous solutions of anhydrous sodium sulfite were prepared, and a predetermined amount of the aromatic compound was added thereto. One portion of each of these solutions was placed in a beaker, and a ventilation tube was placed in the solution to aerate air at a ventilation rate of 1/min for 3 days at room temperature (23° C.). After the aeration was completed, the concentration of undecomposed sodium sulfite in the solution was measured, and the residual rate of sodium sulfite was calculated from the initial concentration measured in advance using the following formula. Note that the analytical method for sodium sulfite was based on JIS K 0101. The results are shown in the following table, and it can be seen that when the aromatic compound of the present invention was added, the residual rate of sodium sulfite was significantly higher. Sodium sulfite residual rate (%) = Sodium sulfite concentration at the end of aeration (%) / Initial concentration of sodium sulfite (%)
)×100

【table】

[Table] Example 2 A stabilization test was conducted when the product was left at room temperature. 0.50 parts by weight of pyrogallol per 100 parts by weight of anhydrous sodium sulfite is added to a 10% by weight aqueous solution of anhydrous sodium sulfite (a in Figure 1), and quebratyotannin is added to anhydrous sodium sulfite.
1.0 parts by weight per 100 parts by weight (b in Figure 1), and sodium sulfite anhydrous salt
One part of each 10% by weight aqueous solution (c in Figure 1) was placed in one beaker, a watch glass was placed on the beaker, and the beaker was left at room temperature.
The concentration of sodium sulfite in the solution was measured at regular intervals, and the residual rate (%) was calculated. The results are shown in FIG. It can be seen that the addition of the aromatic compound of this invention significantly stabilizes the aqueous sodium sulfite solution. When actually using the
Usually, one lot of a 10% by weight aqueous solution is consumed within 1 to 3 weeks, so the stabilizing effect is sufficient. Example 3 The following three types of aqueous solutions were compared in their oxygen scavenging ability. (1) 10% by weight aqueous solution of sodium sulfite anhydrous immediately after preparation (2) Test solution in Example 2 (adding sodium sulfite to the 10% by weight aqueous solution of sodium sulfite anhydrous)
0.5 parts by weight of pyrogallol per 100 parts by weight) was left at room temperature for 49 days (3) Another test solution in Example 2 (10% by weight aqueous solution of sodium sulfite anhydrous, 100 parts by weight of sodium sulfite) An aqueous solution in which 1.0 parts by weight of quebratyo tannin was added) was left at room temperature for 49 days, i.e., Osaka city soft water (previously aerated to give a dissolved oxygen content of 8.0 ppm), was collected in beakers one by one. Add each of the above three types of aqueous solutions so that the sodium sulfite concentration is 65 ppm,
The rate of oxygen decrease was measured using a dissolved oxygen concentration meter (Desolve Oxygen Meter, model DO-1A manufactured by Toa Denpa Co., Ltd.). As a result, (1),
When adding liquids (2) and (3) respectively, 1
Dissolved oxygen reached 0ppm in minutes and 55 seconds. Note that the temperature during this treatment and measurement was 55°C. That is, the solution containing pyrogallol or quebratyotannin showed the same oxygen scavenging ability as the freshly prepared aqueous sodium sulfite solution even after being left for as long as 49 days.

[Brief explanation of drawings]

FIG. 1 is a graph showing the change over time in the residual rate of sodium sulfite when pyrogallol and quebratillotannin were added to a 10% by weight aqueous solution of anhydrous sodium sulfite. a... Pyrogallol, sodium sulfite 100
Aqueous solution with 0.50 parts by weight added to parts by weight, b...
An aqueous solution containing 1.0 parts by weight of quebratyo tannin per 100 parts by weight of sodium sulfite, c...
10% by weight aqueous solution of sodium sulfite anhydrous salt.

Claims (1)

[Claims] 1. For 100 parts by weight of alkali metal sulfite,
0.01~ for aromatic compounds having 3 or more hydroxyl groups
A stable aqueous oxygen scavenger composition, characterized in that it is made into an aqueous solution by adding 10 parts by weight. 2 An aromatic compound having 3 or more hydroxyl groups is
The oxygen scavenger composition according to claim 1, which is added in an amount of 0.5 to 3 parts by weight. 3. The oxygen scavenger composition according to claim 1 or 2, wherein the alkali metal sulfite is sodium sulfite or potassium sulfite. 4. The oxygen scavenger composition according to any one of claims 1 to 3, wherein the aromatic compound having three or more hydroxyl groups is pyrogallol, gallic acid, or tannin.