JP2000044207A - Method for stabilizing aqueous persulfate solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize an aq. persulfate soln. over a long period of time and to make the soln. free from restriction in the use by adding sodium hydroxide, potassium hydroxide or ammonia to the soln. SOLUTION: An aq. persulfate soln. is stabilized by adding sodium hydroxide, potassium hydroxide or ammonia to the soln. Sodium hydroxide, potassium hydroxide or ammonia to be added is preferably correspondent to the persulfate. When the persulfate is sodium persulfate, sodium hydroxide is appropriately added. When the persulfate is ammonium persulfate, ammonia is appropriately added. The amt. of sodium hydroxide, potassium hydroxide or ammonia added is not particularly limited and the concn. of the persulfate is not also particularly limited but is about 1-70 wt.% in practical use. Since the additive is converted into sulfate by reaction with sulfuric acid formed by the hydrolysis of the persulfate, the aq. persulfate soln. can be used without restriction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for stabilizing an aqueous solution of persulfate. Persulfate aqueous solutions are widely and industrially used as desizing agents and dye oxidizing agents in the textile industry and as printed wiring board treating agents in the electronics industry.

[0002]

2. Description of the Related Art Persulfate aqueous solution is liable to undergo hydrolysis and its concentration decreases during transportation and storage until use. Therefore, in actual use, persulfate is dissolved immediately before use and the storage tank is cooled. And adding stabilizers. Cooling the storage tank slows down the hydrolysis,
Although the stability of the aqueous solution of persulfate is improved, it has drawbacks such as requiring a large amount of cooling water and limiting the temperature at which cooling is possible due to the saturated solubility of the persulfate.

As a stabilizer, a chelating agent for blocking metal impurities, a pH buffer, a radical scavenger and the like are used. Particularly useful stabilizers for practical use include phosphates or condensed phosphates, mixtures of phosphates and urea, and alkali borates. Phosphates or condensed phosphates are
Although the initial stability is good, it has a drawback that the stabilizing ability is reduced due to hydrolysis or the like over a long period of time.

JP-A-6-40708 describes a method for stabilizing an aqueous solution of persulfate by adding an alkali borate or a mixture thereof. Therefore, there is a disadvantage that the performance cannot be maintained for a long period of time. In addition, there is a disadvantage that the use of a component that cannot originally be present in the aqueous solution of persulfuric acid causes a restriction in use.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the method for stabilizing a persulfate aqueous solution, and provides a persulfate which is stable for a long period of time and which is not restricted in use. It provides an aqueous salt solution.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to overcome these drawbacks. As a result, by adding sodium hydroxide, potassium hydroxide or ammonia to a persulfuric acid aqueous solution, a persulfate aqueous solution was added. Have been found to improve the stability of the present invention, and have completed the present invention. That is,
The present invention relates to a method for stabilizing an aqueous solution of persulfate, which comprises adding sodium hydroxide, potassium hydroxide or ammonia to an aqueous solution of persulfate.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The sodium hydroxide, potassium hydroxide or ammonia added to the aqueous solution of persulfate preferably corresponds to the persulfate. For example, when sodium persulfate is selected as the persulfate, sodium hydroxide is preferably used. When ammonium persulfate is selected as the persulfate, ammonia is preferably used. There is no particular limitation on the amount of sodium hydroxide, potassium hydroxide or ammonia to be added. The concentration of persulfate is not particularly limited, but is practically 1 to 70% by weight.

[0008] The added sodium hydroxide, potassium hydroxide or ammonia reacts with sulfuric acid generated by hydrolysis of persulfate to form a sulfate, so that the aqueous solution of persulfate of the present invention is restricted in use. I will not receive it.

[0009]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. The decomposition rate in the examples is represented by (initial persulfate concentration-residual persulfate concentration) / (initial persulfate concentration) × 100%. In addition, all concentrations are indicated by weight%, and the concentration of persulfate was measured by a reverse titration method using potassium permanganate.

Example 1 An aqueous solution prepared by adding 200 g / l of sodium persulfate and an arbitrary concentration of sodium hydroxide and adjusting the remainder with ion-exchanged water was placed in a polyethylene container equipped with a pressure release structure, and kept at 40 ° C. It was left in the bath. Seven days later, the concentration of the remaining persulfate was measured, and the decomposition rate of sodium persulfate was compared. Table 1 shows the results.

[0011]

[Table 1]

Comparative Example 1 Japanese Patent Application Laid-Open (JP-A) No. 6-407, 200 g / l of sodium persulfate
A solution was prepared in accordance with the examples and comparative examples of JP 08-A-08-A, and the decomposition ratio was compared in the same manner as in Example 1 at 40 ° C for 7 days. Table 2 shows the results.

[0013]

[Table 2]

[0014]

As described above, according to the present invention, it is possible to prepare a persulfate aqueous solution which is stable for a long period of time and which is not restricted in use.

Claims (1)

[Claims] 1. A method for stabilizing an aqueous persulfate solution, comprising adding sodium hydroxide, potassium hydroxide or ammonia to an aqueous persulfate solution.