JPS6126504A - Purification of sulfuric acid solution - Google Patents

Abstract

PURPOSE:A sulfuric acid solution is purified by precipitating and removing iron ions or copper ions existing in a sulfuric acid solution containing soluble organic materials reactive to hydrogen peroxide especially in an acidic range and promoting the decomposition of hydrogen peroxide. CONSTITUTION:Hydrogen ferrocyanide or hydrogen ferricyanide or their salts (e.g. potassium ferroxyanide, ammonium ferricyanide, etc.) are added to a sulfuric acid solution containing soluble organic materials containing iron ions and/ or copper ions, and the mixture is heated at <=60 deg.C to precipitate and remove the iron ions and/or copper ions. The amount of the hydrogen ferrocyanide, ferricyanide or their salt is dependent upon the amount of the iron ion or copper ion dissolved in the sufluric acid solution, and is determined based on the stoichiometric amount. Since the sulfuric acid solution usually contains a large amount of iron ion and little copper ion, the amount of the hydrogen ferrocyanide, etc. is determined based on the amount of iron ion.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for purifying a sulfuric acid solution containing iron ions and/or copper ions, and in particular a method for purifying a sulfuric acid solution containing soluble organic matter by reacting it with hydrogen peroxide in an acidic region. The present invention relates to a method for purifying a sulfuric acid solution in which iron and/or copper ions dissolved in the solution and promoting the decomposition of hydrogen peroxide are removed as precipitates.

[Prior art and problems]

Conventionally, heavy metal ions such as iron ions and copper ions are well known as representative substances that promote the decomposition of hydrogen peroxide in acidic solutions. A common method for inactivating or removing these heavy metal ions that promote the decomposition of hydrogen peroxide is to sequester the heavy metal ions with a chelating agent, phosphate, or the like. On the other hand, various reactions using hydrogen peroxide as an oxidizing agent under acidic conditions are also known. However, this method of sequestering metal ions is quite effective when only a small amount of metal ions are present, but for example, when a sulfuric acid solution containing soluble organic matter is reacted with hydrogen peroxide, In particular, when the sulfuric acid solution is recycled, metal ions that accelerate the decomposition of hydrogen peroxide accumulate in the sulfuric acid solution due to partial dissolution of reaction products and elution of metal ions during the reaction. As a result, the reaction of hydrogen peroxide is inhibited, resulting in various problems that are extremely inconvenient industrially.

Inactivating or removing these accumulated metal ions is one of the important issues in ensuring that the reaction proceeds smoothly and efficiently. One possible method to inactivate these accumulated metal ions is to sequester them with a conventional chelating agent, but even if this method is applied, it will require a large amount of expensive chelating agent. Not only is this necessary and economically disadvantageous, but it is also insufficient in terms of effectiveness and cannot be considered an appropriate means. Further, depending on the sulfuric acid solution to be treated, conventional chelating agents may not be able to be used.

There is still no industrially adequate means for removing or inactivating accumulated metal ions as hydrogen peroxide decomposition products dissolved in large amounts in the sulfuric acid solution used in the reaction with hydrogen peroxide. At present, there is no such problem, and the present invention aims to solve this problem.

[Means to try to solve problems]

In view of the above-mentioned circumstances, the inventors of the present invention have conducted various studies from various angles, and have found that the method of the present invention, which removes accumulated metal ions as a precipitate, is optimal. The present invention was made based on this.

That is, in the present invention, ferrocyanic acid or ferricyanic acid or a salt thereof is added to a sulfuric acid solution containing iron ions and/or copper ions and a soluble organic substance, and the mixture is treated at a temperature not exceeding 60°C to dissolve iron ions and/or copper ions. Another method is to remove copper ions as a precipitate.

Examples of the hydroferrocyanic acid or the salt of hydrocyanic acid used in the present invention include potassium ferrocyanide (anemic potassium) CK4Fe (C
N)s ・3 H2O), 7ethl Sodium cyanide (back soda) (Na4Fe(CN)e ・10H2
0), ammonium ferrocyanide (yellow blood ammonium) ((NH4) 4Fe(CN)s・3H20), potassium ferricyanide (K3 Fe (CN)s
), sodium ferricyanide [Na3Fe (CN
)6・H2O3, ammonium ferricyanide ((NH
4) nFe(CN)s) and the like. Among these, potassium ferrocyanide (anemic potassium), sodium ferrocyanide (back soda), etc. are preferred in terms of easy availability and ease of handling.

The amount of these ferrocyanic acid or ferricyanic acid or their salts to be added is determined by the amount of iron or copper ions dissolved in the sulfuric acid solution to be treated, and usually it is sufficient to add them on a stoichiometric basis. for example,
In the case of potassium ferrocyanide, it is 0.0 for iron ions.
The stoichiometric amount is 75 moles and 0.5 moles for copper ions.

In cases such as the sulfuric acid solution containing organic matter used in the present invention, iron ions are usually present in large amounts, and copper ions are relatively small (in such cases, it is sufficient to add them based on the amount of iron ions). , generally 0.6 to 1.0 mol/Fe (mol).However, if the amount of copper ions dissolved in the solution is present at a high level, it is It is preferable to add it within the above range.

According to the present invention, the temperature at which the sulfuric acid solution containing contaminants is treated must not exceed 60°C, preferably between room temperature and 50°C, and generally around the product temperature.

〔Effect of the invention〕

According to the method of the present invention, metal ions that act as catalyst components present in a sulfuric acid solution containing organic substances that participate in the reaction with hydrogen peroxide are It can efficiently and easily remove only the metal ions that promote the decomposition of hydrogen oxide, and can significantly suppress the decomposition of hydrogen peroxide during the reaction.

The method of the present invention uses iron ions and/or iron ions, which are present as a substance that accelerates the decomposition of hydrogen peroxide in a sulfuric acid solution when producing azodicarbonamide by reacting hydrogen peroxide with hydrazodicarbonamide under acidic sulfuric acid, for example. Alternatively, it is one of the suitable methods for removing copper ions. Furthermore, this method is also suitable for purifying a sulfuric acid solution in cases where hydrogen peroxide is used as an oxidizing agent and the reaction is carried out under sulfuric acid acidity, and is an extremely significant method industrially.

〔Example〕

The method of the present invention will be explained below using examples.

Example 1 Ferric sulfate 4000 mg/#, copper sulfate 30 mg/I
tSoluble organic matter (azodicarbonamide) 560mg/
19 containing 15.8% of chromium sulfate (catalyst component)
．． Add 172g/l' back potassium solution to 20n+1 of 5% sulfuric acid solution in the amount shown in the table below per 1 mole of iron, stir for 10 minutes at a solution temperature of 30°C, and leave the solution for 20 minutes. It was filtered, and the iron, copper, and chromium contents in the filtrate were determined by the iodine method and the atomic absorption method. The results are shown in Table 1. As can be seen from the table, chromium ions as catalyst components were not removed at all, but iron ions and copper ions were efficiently removed.

Table 1 180g of the sulfuric acid acidic solution treated above was heated to 50°C, and 27.2g of a commercially available 60% hydrogen peroxide solution was added dropwise to it over 0.5 hours while stirring with a metering pump. After that, the hydrogen peroxide concentration was measured 1.5 hours later while maintaining the same temperature using a conventional method.As shown in Table 2, the residual rate of hydrogen peroxide was high when back potassium was added. The value was shown.

Table 2 Example 2 Ammonium sulfate 500 mg/β, ferric sulfate 40
mg/1. , 0.20% of pH 1.7 containing 100 mg/# of soluble organic matter (azodicarbonamide)
To 200ml of sulfuric acid solution, 16g/j7 of back soda solution was added to iron ion in the same manner as in Example 1, stirred at 40°C for about 10 minutes, left to stand for 1 hour, and then filtered to remove the iron present in the filtrate. Quantification was carried out in the same manner as in Example 1.

Table 3 Example 3 Ferric sulfate 10800 mg/A, copper sulfate 30 mg/β
, soluble organic matter (azodicarbonamide) 500mg/
j! , to 200 ml of 21% sulfuric acid solution containing 31.2% chromium sulfate, add 150 g/# of backside ammonium solution to 1 mol of iron ion in amounts of 0.75 mol, 0.90 mol, and 0.975 mol, respectively. was added, stirred at 30°C for 10 minutes, left to stand for 30 minutes, and then filtered.
℃ and add a commercially available 60% hydrogen peroxide solution 27.2
g was added dropwise with stirring using a metering pump, and the hydrogen peroxide concentration was measured 1.5 hours later by a conventional method.

This is shown in Table 4.

Table 4 Example 4 Ferric sulfate 108 mg/#, ammonium sulfate 1200
mg/n, containing 100e+g/n of soluble organic matter2
Add 1.5% ferrocyanic acid solution to 200n+1 of 1% sulfuric acid solution at a concentration of 0.75% per mole of iron ions in the solution.
After stirring for 5 minutes, the mixture was left to stand for 1 hour and filtered, and the amount of iron present in the filtrate was measured by atomic absorption spectrometry. This is shown in Table 5.

Table 5 Example 5 40% sulfuric acid solution containing 30% acetic acid, 4000 mg/ferric sulfate (1, 30 vag/j! of copper sulfate)
172g/j in 0m1! Iron ion 1 for yellow blood potassium anemia
The amounts of 0.6 mol, 0.75 mol, 0.90 mol and 0.975 mol based on the mole were added, stirred, left to stand for 2 hours, filtered, and the iron and copper content in the filtrate was measured. .

Table 6 Example 6 2 containing ferrous sulfate 10000 mg/it, ammonium sulfate 30000 mg/12, acetic acid 10%
200 g/jl in 200 mn of 0% sulfuric acid solution! Each 0.67% red blood potassium solution per 1 mole of iron ion
mol, 0.77 mol, 0.87 mol.
After stirring at 40° C. for about 5 minutes, the mixture was allowed to stand for 2 hours and then filtered, and the iron content present in the filtrate was determined in the same manner as in Example 1.

Table 7 Example 7 Ferrous sulfate 4000 mg/f, copper sulfate 30 mg/1
2. Vinegar @ 1% in 200m/21% sulfuric acid solution containing 1%
Add 30 g/E red face soda solution to 1 mole of iron ions in the amount shown in the table below, and after stirring for about 5 minutes,
After being left for 1 hour, it was filtered, and the iron content present in the filtrate was determined in the same manner as in Example 1.

Table 8 Patent applicant: Mitsubishi Gas Chemical Co., Ltd. Representative: Nagano Washo Patent applicant: Eiwa Kasei Kogyo Co., Ltd. Representative Yoshi 1) Iwao

Claims (1)

[Claims] Ferrocyanic acid or ferrichydrocyanic acid or their salts are added to a sulfuric acid solution containing soluble organic matter containing iron and/or copper ions, and treated at a temperature not exceeding 60°C to precipitate iron and/or copper ions. 1. A method for purifying a sulfuric acid solution containing soluble organic matter, the method comprising removing soluble organic matter as a sulfuric acid solution.