CN114380278A - Method for removing trace sulfur dioxide in ultrapure sulfuric acid - Google Patents

Abstract

The invention provides a method for removing trace sulfur dioxide in ultrapure sulfuric acid, and relates to the technical field of chemical preparation. The method for removing trace sulfur dioxide in the ultra-pure sulfuric acid comprises the following steps: 1000g of ultrapure concentrated sulfuric acid is weighed through the accuracy, add into 200g 31% ultrapure hydrogen peroxide solution, its concentration is for about 5% to accurate demarcation, survey the sulfur dioxide content in the ultrapure sulfuric acid jar, according to the equal volume reaction principle of mole in the chemistry, calculate strictly required hydrogen peroxide solution molar quantity and required 5% hydrogen peroxide solution sulfuric acid solution volume, slowly add the hydrogen peroxide solution sulfuric acid jar above, the temperature is no longer than 50 degrees, the feeding finishes, it is even with the circulating pump circulation, most trace sulfur dioxide's content in the ultrapure sulfuric acid can be got rid of. By using hydrogen peroxide as an oxidant, a small amount of sulfur dioxide is oxidized into sulfur trioxide or sulfuric acid under certain conditions, so that the method is simple and convenient to operate, low in cost, strong in operability and suitable for industrial application.

Description

Method for removing trace amount of sulfur dioxide in ultrapure sulfuric acid

technical field

The invention relates to the technical field of chemical preparation, in particular to a method for removing trace amounts of sulfur dioxide in ultrapure sulfuric acid.

Background technique

The electronics industry, especially the modern chip industry, uses a large amount of ultra-pure sulfuric acid as a necessary chemical reagent in the process. In modern electronic chemicals, the control of various impurities, especially harmful impurities, is becoming more and more strict. For ultra-pure sulfuric acid, The content of sulfur dioxide in the product determines the grade of the product, and it is generally required to be controlled in the range of 1-5PPM. However, in the actual manufacturing process of ultra-pure sulfuric acid, it is difficult to control the sulfur dioxide to this level.

In the present invention, a scientific and simple method is found: using hydrogen peroxide as an oxidant, under certain conditions, a small amount of sulfur dioxide is oxidized into sulfur trioxide or sulfuric acid, so that the sulfuric acid product meets the specification requirements.

SUMMARY OF THE INVENTION

(1) Technical problems solved

In view of the deficiencies of the prior art, the present invention provides a method for removing trace sulfur dioxide in ultrapure sulfuric acid, which solves the problem that it is difficult to control sulfur dioxide at the level of 1-5PPM in the manufacturing process of pure sulfuric acid.

(2) Technical solutions

In order to achieve the above purpose, the present invention is achieved through the following technical solutions: a method for removing trace sulfur dioxide in ultrapure sulfuric acid, comprising the following steps:

S1. First accurately weigh 1000g of ultra-concentrated sulfuric acid, add it to 200g of 31% ultra-pure hydrogen peroxide solution, and accurately calibrate its concentration to be about 5%;

S2. Measure the content of sulfur dioxide in the ultrapure sulfuric acid tank again, and strictly calculate the required molar amount of hydrogen peroxide and the required 5% hydrogen peroxide sulfuric acid solution amount according to the reaction principle of molar equivalent in chemistry;

S3. Slowly add the hydrogen peroxide sulfuric acid solution prepared in step S2 into the sulfuric acid tank, the temperature does not exceed 40 ℃-50 ℃, and the feeding is completed, and the circulating pump is used to circulate evenly for 30-40min;

S4. Then test the surplus of sulfur dioxide in the sulfuric acid product in step S3, if it is less than 5PPM, it is judged as qualified.

S5. if the surplus of the sulfur dioxide in the sulfuric acid product in the step S4 is greater than 5PPM, the sulfuric acid product in the step S4 is heated to 120 ℃-150 ℃, and the sulfurous acid is decomposed, and the solubility of the sulfur dioxide in the sulfuric acid is decreased, thereby further reducing The remaining amount of sulfur dioxide in the sulfuric acid product, repeat step S4 to test the remaining amount of sulfur dioxide in the sulfuric acid product.

Preferably, the method steps of testing the surplus of sulfur dioxide in the sulfuric acid product in the step S4 are as follows:

S1. Precisely measure 20ml of sulfuric acid product, place it in a two-necked 1000mL round-bottom flask, add 500-600mL of water and 8-10mL of 6molL ^-1 hydrochloric acid solution, introduce nitrogen into one neck to the bottom of the bottle, and connect the other to a reflux condenser and a condenser. , the upper end is connected with a trachea and introduced into the bottom of a beaker;

S2. Then add water and a few drops of starch solution in the beaker, add 0.01-0.02molL ^-1 iodine standard solution dropwise to make it blue, and heat the flask until the solution boils;

S3. Distillation and iodine in the beaker play a reducing role. With the decrease of the iodine concentration in the solution, the solution has a phenomenon of fading. After that, 0.01-0.02molL ^-1 iodine standard solution is added dropwise to supplement the consumed iodine, so that the solution returns to blue color, repeat until the solution in the beaker does not fade within 1-2min;

S4. Finally, the concentration of sulfur dioxide can be directly calculated by the amount of iodine liquid consumed.

Preferably, the hydrogen peroxide used in the step S1 is an ultra-pure product with a concentration of 30%-50%.

Preferably, when the sulfuric acid-containing oxidant and the sulfur dioxide-containing ultrapure sulfuric acid are mixed in the step S3, they must be fused in a clean and airtight container.

Preferably, the added amount of the hydrogen peroxide sulfuric acid solution in the step S3 must be strictly calculated, and the added amount cannot exceed 1-2% of the theoretical amount.

(3) Beneficial effects

The invention provides a method for removing trace sulfur dioxide in ultrapure sulfuric acid. Has the following beneficial effects:

The present invention measures the content of sulfur dioxide (generally 50-100PPM) in the ultrapure sulfuric acid tank by accurately weighing 1000g of ultrapure concentrated sulfuric acid, adding it to 200g of 31% ultrapure hydrogen peroxide solution, and accurately calibrating its concentration to be about 5%. According to the reaction principle of equivalent moles in chemistry, strictly calculate the required molar amount of hydrogen peroxide and the required amount of 5% hydrogen peroxide sulfuric acid solution, slowly add the above hydrogen peroxide sulfuric acid solution into the sulfuric acid tank, the temperature does not exceed 50 degrees, the feeding is completed, Using the circulating pump to circulate evenly for 30-40 minutes can remove most of the trace sulfur dioxide content in the ultrapure sulfuric acid, so that the residual amount of sulfur dioxide is less than 5PPM. Industrial application.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1:

The embodiment of the present invention provides a method for removing trace sulfur dioxide in ultrapure sulfuric acid, comprising the following steps:

S1. First accurately weigh 1000g of ultra-concentrated sulfuric acid, add it to 200g of 31% ultra-pure hydrogen peroxide solution, and accurately calibrate its concentration to be about 5%;

S2. Measure the content of sulfur dioxide in the ultrapure sulfuric acid tank again, and strictly calculate the required molar amount of hydrogen peroxide and the required 5% hydrogen peroxide sulfuric acid solution amount according to the reaction principle of molar equivalent in chemistry;

S3. slowly add the hydrogen peroxide sulfuric acid solution obtained in step S2 into the sulfuric acid tank, the temperature is not more than 40 ° C, the feeding is completed, and the circulating pump is used to circulate evenly for 30min;

S4. Then test the surplus of sulfur dioxide in the sulfuric acid product in step S3, if it is less than 5PPM, it is judged as qualified.

S5. if the surplus of the sulfur dioxide in the sulfuric acid product in the step S4 is greater than 5PPM, the sulfuric acid product in the step S4 is heated to 120 ° C, and the sulfurous acid is decomposed, so that the solubility of sulfur dioxide in the sulfuric acid is decreased, thereby further reducing the sulfuric acid product. For the remaining amount of sulfur dioxide, repeat step S4 to test the remaining amount of sulfur dioxide in the sulfuric acid product, if it is less than 5PPM, it is judged as qualified.

The method steps of the surplus of sulfur dioxide in the test sulfuric acid product in step S4 are as follows:

S1. Precisely measure 20ml of sulfuric acid product, put it in a two-neck 1000mL round-bottom flask, add 500mL of water and 8mL of 6molL ^-1 hydrochloric acid solution, introduce nitrogen to the bottom of the bottle in one neck, and connect the reflux condenser to the other, and the upper end is connected to a The trachea is introduced into the bottom of a beaker;

S2. Then add water and a few drops of starch solution in the beaker, add 0.01molL ^-1 iodine standard solution dropwise to make it blue, and heat the flask until the solution boils;

S3. Distillation and iodine in the beaker play a reducing role. With the decrease of the iodine concentration in the solution, the solution will fade, and then add 0.01molL ^-1 iodine standard solution dropwise to replenish the consumed iodine, so that the solution returns to blue, Repeat this until the solution in the beaker does not fade within 1min;

S4. Finally, the concentration of sulfur dioxide can be directly calculated by using the amount of iodine liquid consumed;

Calculated as follows:

Wherein, A is the volume of the iodine titration solution consumed by the test product, ml;

B is the volume of iodine titrant consumed by blank, ml;

C is the actual concentration of iodine titrant;

W is the weight of the test product, g;

0.01 is the theoretical concentration of iodine titrant

0.6406 is the equivalent weight of sulfur dioxide per 1ml of iodine titration solution (1mol/L), g.

The hydrogen peroxide used in step S1 is an ultra-pure product with a concentration of 30%.

When the sulfuric acid-containing oxidant and the sulfur dioxide-containing ultrapure sulfuric acid are mixed in step S3, they must be fused in a clean and airtight container.

The addition amount of the hydrogen peroxide sulfuric acid solution in step S3 must be strictly calculated, and the addition amount cannot exceed 1% of the theoretical amount.

Embodiment 2:

The embodiment of the present invention provides a method for removing trace sulfur dioxide in ultrapure sulfuric acid, comprising the following steps:

S1. First accurately weigh 1000g of ultra-concentrated sulfuric acid, add it to 200g of 31% ultra-pure hydrogen peroxide solution, and accurately calibrate its concentration to be about 5%;

S2. Measure the content of sulfur dioxide in the ultrapure sulfuric acid tank again, and strictly calculate the required molar amount of hydrogen peroxide and the required 5% hydrogen peroxide sulfuric acid solution amount according to the reaction principle of molar equivalent in chemistry;

S3. Slowly add the hydrogen peroxide sulfuric acid solution prepared in step S2 into the sulfuric acid tank, the temperature is not more than 50 ° C, the feeding is completed, and the circulating pump is used to circulate 40min evenly;

S4. Then test the surplus of sulfur dioxide in the sulfuric acid product in step S3, if it is less than 5PPM, it is judged as qualified.

S5. if the surplus of the sulfur dioxide in the sulfuric acid product in the step S4 is greater than 5PPM, the sulfuric acid product in the step S4 is heated to 150 ° C, the sulfurous acid is decomposed, and the solubility of the sulfur dioxide in the sulfuric acid is decreased, thereby further reducing the sulfuric acid product. For the remaining amount of sulfur dioxide, repeat step S4 to test the remaining amount of sulfur dioxide in the sulfuric acid product, if it is less than 5PPM, it is judged as qualified.

The method steps of the surplus of sulfur dioxide in the test sulfuric acid product in step S4 are as follows:

S1. Precisely measure 20ml of sulfuric acid product, put it in a two-neck 1000mL round-bottom flask, add 600mL of water and 10mL of 6molL ^-1 hydrochloric acid solution, introduce nitrogen to the bottom of the bottle in one neck, and connect the reflux condenser to the other, and the upper end is connected to a The trachea is introduced into the bottom of a beaker;

S2. Then add water and a few drops of starch solution in the beaker, add 0.02molL ^-1 iodine standard solution dropwise to make it blue, and heat the flask until the solution boils;

S3. Distillation and the iodine in the beaker play a reducing role. With the decrease of the iodine concentration in the solution, the solution has a phenomenon of fading. After that, 0.02molL ^-1 iodine standard solution is added dropwise to replenish the consumed iodine, so that the solution returns to blue. Repeat this until the solution in the beaker does not fade within 2 min.

S4. Finally, the concentration of sulfur dioxide can be directly calculated by the amount of iodine liquid consumed.

The hydrogen peroxide used in step S1 is an ultra-pure product with a concentration of 50%.

When the sulfuric acid-containing oxidant and the sulfur dioxide-containing ultrapure sulfuric acid are mixed in step S3, they must be fused in a clean and airtight container.

The addition amount of the hydrogen peroxide sulfuric acid solution in step S3 must be strictly calculated, and the addition amount cannot exceed 2% of the theoretical amount.

By accurately weighing 1000g of ultrapure concentrated sulfuric acid, adding it to 200g of 31% ultrapure hydrogen peroxide solution, accurately demarcating its concentration to be about 5%, measure the content of sulfur dioxide in the ultrapure sulfuric acid tank (generally 50-100PPM), according to According to the reaction principle of molar equivalent in chemistry, strictly calculate the required molar amount of hydrogen peroxide and the required amount of 5% hydrogen peroxide sulfuric acid solution, slowly add the above hydrogen peroxide sulfuric acid solution into the sulfuric acid tank, the temperature does not exceed 50 degrees, after the feeding is completed, use The circulating pump circulates evenly, so that most of the trace sulfur dioxide content in the ultrapure sulfuric acid can be removed, so that the remainder of the sulfur dioxide is less than 5PPM.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, and substitutions can be made in these embodiments without departing from the principle and spirit of the invention and modifications, the scope of the present invention is defined by the appended claims and their equivalents.

Claims (5)

1. The method for removing trace sulfur dioxide in the ultra-pure sulfuric acid is characterized by comprising the following steps: the method comprises the following steps:

s1, firstly, accurately weighing 1000g of ultra-special concentrated sulfuric acid, adding the ultra-special concentrated sulfuric acid into 200g of 31% ultra-pure hydrogen peroxide solution, and accurately calibrating the concentration of the ultra-special concentrated sulfuric acid to be about 5%;

s2, determining the content of sulfur dioxide in the ultrapure sulfuric acid tank, and strictly calculating the required molar quantity of hydrogen peroxide and the required 5% hydrogen peroxide sulfuric acid solution quantity according to a chemical molar equivalent reaction principle;

s3, slowly adding the hydrogen peroxide sulfuric acid solution prepared in the step S2 into a sulfuric acid tank, wherein the temperature is not more than 40-50 ℃, and after the addition is finished, circulating for 30-40min by using a circulating pump to be uniform;

and S4, testing the residual amount of the sulfur dioxide in the sulfuric acid product in the step S3, wherein if the residual amount is less than 5PPM, the judgment is qualified.

S5, if the residual amount of the sulfur dioxide in the sulfuric acid product in the step S4 is more than 5PPM, heating the sulfuric acid product in the step S4 to 120-150 ℃, so that the sulfurous acid is decomposed, the solubility of the sulfur dioxide in the sulfuric acid is reduced, and the residual amount of the sulfur dioxide in the sulfuric acid product is further reduced, and repeating the step S4 to test the residual amount of the sulfur dioxide in the sulfuric acid product, wherein the residual amount of the sulfur dioxide in the sulfuric acid product is less than 5PPM, and the judgment is qualified.

2. The method for removing trace sulfur dioxide in ultrapure sulfuric acid according to claim 1, wherein: the method for testing the residual amount of the sulfur dioxide in the sulfuric acid product in the step S4 comprises the following steps:

s1, precisely measuring 20mL of sulfuric acid product, placing the sulfuric acid product in a two-neck 1000mL round-bottom flask, adding 500mL of water and 600mL of water and 8-10mL of 6mol L^-1A neck of the hydrochloric acid solution introduces nitrogen to the bottom of the bottle, the other neck of the hydrochloric acid solution is connected with a reflux condenser tube, the condenser tube is connected with an air duct at the upper end and is introduced to the bottom of a beaker;

s2, adding water and a plurality of drops of starch solution into the beaker, and adding 0.01-0.02mol L^-1The iodine standard solution was blue colored and the flask was heated to boil the solution;

s3, distilling and reducing iodine in the beaker, leading the solution to have a fading phenomenon along with the reduction of the iodine concentration in the solution, and then dropwise adding 0.01-0.02mol L^-1Supplementing consumed iodine with iodine standard solution to make the solution turn blue, repeating the above steps until the solution in the beaker does not fade within 1-2 min;

and S4, finally, directly calculating the concentration of the sulfur dioxide by using the consumed iodine solution amount.

3. The method for removing trace sulfur dioxide in ultrapure sulfuric acid according to claim 1, wherein: the hydrogen peroxide used in the step S1 is an ultra-pure product with the concentration of 30-50%.

4. The method for removing trace sulfur dioxide in ultrapure sulfuric acid according to claim 1, wherein: the sulfuric acid-containing oxidizing agent and the ultra-pure sulfuric acid containing sulfur dioxide in step S3 must be mixed in a clean and sealed container.

5. The method for removing trace sulfur dioxide in ultrapure sulfuric acid according to claim 1, wherein: the adding amount of the hydrogen peroxide sulfuric acid solution in the step S3 must be strictly calculated, and the adding amount cannot exceed 1-2% of the theoretical amount.