CN112763433A

CN112763433A - Method for determining transparency of sulfuric acid by using turbidity meter

Info

Publication number: CN112763433A
Application number: CN201911064734.5A
Authority: CN
Inventors: 宋俊颢; 费建华; 黄振宇; 李家发; 宋任政
Original assignee: Baowu Carbon Material Technology Co ltd
Current assignee: Baowu Carbon Material Technology Co ltd
Priority date: 2019-11-04
Filing date: 2019-11-04
Publication date: 2021-05-07

Abstract

The invention discloses a method for determining the transparency of sulfuric acid by using a turbidity meter, which comprises the following steps: determining the transparency of a set of different sulfuric acid samples for calibration by a sulfuric acid transparency determination device; determining the turbidity of the set of different sulfuric acid samples using a turbidity meter; determining the relation between the transparency and the turbidity of the different sulfuric acid samples by comparing the transparency and the turbidity of the different sulfuric acid samples, wherein the relation is an inverse corresponding relation; measuring the turbidity of a sulfuric acid sample to be measured by using a turbidity meter; and determining the transparency of the sulfuric acid sample corresponding to the turbidity of the sulfuric acid sample to be detected according to the determined inverse proportion corresponding relation. The method can effectively reduce actual errors caused by transparency measurement among different operators, ensure the true and accurate analysis result, reduce the potential safety hazard of sulfuric acid operation, shorten the analysis time and improve the working efficiency.

Description

Method for determining transparency of sulfuric acid by using turbidity meter

Technical Field

The invention relates to a technology for determining the transparency of chemical product sulfuric acid, in particular to a method for determining the transparency of sulfuric acid by using a turbidity meter.

Background

And (3) measuring the transparency of the finished sulfuric acid, according to the national standard GB/534-.

FIG. 1 is a schematic diagram of a sulfuric acid transparency measuring apparatus.

In the actual operation process, if the sample is a sulfuric acid sample with a clear surface, the adding amount of the sulfuric acid in the fluoroscopy tube is increased. And if the surface of the sulfuric acid sample is turbid, injecting a certain volume of sulfuric acid into the glass perspective tube according to national standards, then placing the glass perspective tube on a transparency instrument, and observing the color change of the sulfuric acid liquid in the glass perspective tube in a overlooking manner until the color change is clear. Otherwise, the glass perspective tube is taken down, and the glass perspective tube is placed in a certain grid number and compared until the black and white are clear. The glass see-through tubes for determining transparency were arranged at 4mm intervals, and the difference between the front and the rear of each cell was 4 mm.

The difference of eye observation among people causes the error of the transparency measurement result of different people, particularly the error of the turbid sulfuric acid sample with low transparency is inevitable.

Table 1 lists the transparency measurements and errors for three specific sulfuric acid samples of different transparencies, four different operators:

TABLE 1

From this, it was found that the transparency observation results of the same sulfuric acid sample were different among different operators. The sulfuric acid samples with low transparency values have greater values of transparency errors.

The mass index in units used for different sulfuric acid samples is defined as follows:

index of sulfuric acid sample	Superior product	First-class product	Qualified product
				Transparency (mm)	Greater than or equal to 80	80-50	Less than 50

From the measurement results, it was found that:

(1) the sulfuric acid sample 1 was a clear and highly transparent sulfuric acid sample, and a certain amount of sulfuric acid was poured into a glass transtube according to the national standard for measurement. Its transparency is 160, and four operators agree to be a premium product without any objection.

(2) For the measurement of the sulfuric acid sample 2, there was a difference in judgment between persons with eyes, and the sulfuric acid sample 2 was between the first-class product and the superior product because the transparency of 50 to 80 was the first-class product and 80 or more was the superior product.

(3) The measurement of the sulfuric acid sample 3 was different between the workers in terms of the eye judgment, and the transparency 50 to 80 was an equal quality, and 50 or less was a non-defective product, so the sulfuric acid sample 3 was between the equal quality and the non-defective product.

It can be seen that there is an error in the measurement results due to the difference in the results of the transparency of sulfuric acid observed by the eyes of different persons, which affects the main factor of the transparency determination of sulfuric acid. No other method for determining the transparency of sulfuric acid has been found to be applicable at present through document retrieval.

Disclosure of Invention

The invention aims to provide a method for determining the transparency of sulfuric acid by using a turbidity meter, which comprises the following steps:

the method comprises the following steps: determining the transparency of a set of different sulfuric acid samples for calibration by a sulfuric acid transparency determination device;

step two: determining the turbidity of the set of different sulfuric acid samples using a turbidity meter;

step three: determining the relation between the transparency and the turbidity of the different sulfuric acid samples by comparing the transparency and the turbidity of the different sulfuric acid samples, wherein the relation is an inverse corresponding relation;

step four: measuring the turbidity of a sulfuric acid sample to be measured by using a turbidity meter;

step five: and determining the transparency of the sulfuric acid sample corresponding to the turbidity of the sulfuric acid sample to be detected in the step four according to the inverse corresponding relation determined in the step three.

Wherein, step one includes:

pouring a sulfuric acid sample into a transparent glass tube with scales;

placing the transparent glass tube on a transparency measuring device;

observing the color change of the sulfuric acid liquid in the transparent glass tube until the black and white are clear;

the transparency value of the sulfuric acid sample was obtained by reading the scale number on the transparent glass tube.

Wherein, step two includes:

measuring the turbidity value of a sulfuric acid sample by using a 2100N type bench turbidity meter;

the turbidity value of the sulfuric acid sample was obtained by reading the value indicated on a desk-top turbidimeter model 2100N.

Preferably, in the method for determining the transparency of sulfuric acid using a nephelometer according to the present invention,

the second step comprises the following steps: turbidity values of 10 different sulfuric acid samples having a transparency of 50 and 10 different sulfuric acid samples having a transparency of 80 were respectively measured using a turbidity meter,

selecting the maximum value as the turbidity value of a sulfuric acid sample with the transparency of 50 and the turbidity value of a sulfuric acid sample with the transparency of 80;

the third step comprises: the inverse correspondence between the transparency and the turbidity of the sulfuric acid sample was determined according to the haze value of the sulfuric acid sample having a transparency of 50 and the haze value of the sulfuric acid sample having a transparency of 80 determined by the above methods.

The inversely proportional corresponding relationship between the transparency and the turbidity of the sulfuric acid sample determined in the third step is an inversely proportional straight line, and the slope of the inversely proportional straight line is determined by the transparency-turbidity relationship of the sulfuric acid samples having transparency of 50 and 80.

According to the method for determining the transparency of the sulfuric acid by using the turbidity meter, the corresponding relation between the transparency and the turbidity of the sulfuric acid sample is as follows: the transparency is more than 80mm, the turbidity is less than 37.2NUT, and the sulfuric acid sample is a superior product; the transparency is more than 50mm-80mm, the turbidity is between 37.2NUT-10.7EBC, and the sulfuric acid sample is an first-class product; the transparency is less than 50mm, the turbidity is more than 10.7EBC, and the sulfuric acid sample is a qualified product

The invention has the following advantages:

the turbidity of the sulfuric acid sample is measured by adopting a turbidity meter, and the transparency of the sulfuric acid sample is determined by utilizing the determined corresponding relation between the turbidity of the sulfuric acid and the transparency. The method can effectively reduce actual errors caused by transparency measurement among different operators, ensure the true and accurate analysis result, reduce the potential safety hazard of sulfuric acid operation, shorten the analysis time and improve the working efficiency.

Drawings

Other features, objects and advantages of the present invention will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a sulfuric acid transparency measurement apparatus;

FIG. 2 is a graph of transparency versus haze according to the present invention.

Detailed Description

The technical scheme of the invention is specifically explained in the following with the accompanying drawings of the specification.

The detailed features and advantages of the present invention are described in detail in the detailed description which follows, and will be sufficient for anyone skilled in the art to understand the technical content of the present invention and to implement the present invention, and the related objects and advantages of the present invention will be easily understood by those skilled in the art from the description, claims and drawings disclosed in the present specification.

The invention provides a method for determining the transparency of sulfuric acid by using a turbidity meter, which comprises the following steps:

Wherein, step one includes:

pouring a sulfuric acid sample into a transparent glass tube with scales;

placing the transparent glass tube on a transparency measuring device;

Wherein, step two includes:

According to the method for determining the transparency of the sulfuric acid by using the turbidity meter, the corresponding relation between the transparency and the turbidity of the sulfuric acid sample is as follows:

the transparency is more than 80mm, the turbidity is less than 37.2NUT, and the sulfuric acid sample is a superior product;

the transparency is more than 50mm-80mm, the turbidity is between 37.2NUT-10.7EBC, and the sulfuric acid sample is an first-class product;

the transparency is less than 50mm, the turbidity is more than 10.7EBC, and the sulfuric acid sample is qualified.

In order to implement the present invention, the inventors of the present application made the following works:

1. determination of the relationship between transparency and turbidity for different sulfuric acid samples:

by means of a turbidity instrument, we subject different sulfuric acid samples of known transparency to corresponding turbidity measurements and observe whether there is a relationship between them. The turbidity of the sulfuric acid samples corresponding to different known degrees of transparency was measured by a turbidity meter, and the measurement results are shown in table 2.

TABLE 2

According to the protocol of the instrument, EBC units are selected when the turbidity value is greater than 40 NUT.

As can be seen from the table above, different degrees of transparency of sulfuric acid have corresponding haze values. The experimental data prove that: as the transparency of the sulfuric acid samples decreased, the corresponding haze increased continuously.

From this, we can preliminarily conclude that the transparency of the sulfuric acid sample is inversely proportional to the turbidity measured by the instrument.

2. The relationship between transparency and turbidity was determined for a sulfuric acid sample (i.e., first grade) having a transparency of 50mm to 80mm

Based on the above preliminary measurement results: the transparency of the sulfuric acid sample is inversely proportional to the turbidity measured by the turbidity meter, i.e., as the transparency of the sulfuric acid sample decreases, the corresponding turbidity increases continuously.

Since the measurement results should be judged to be consistent without any objection for the sulfuric acid samples having a transparency of 80mm or more. Next, we carried out turbidity measurement with a turbidimeter for sulfuric acid having a transparency of 50 to 80mm (i.e., first-class product), and the measurement results are shown in the following Table 3:

TABLE 3

As can be seen from the data in Table 3, haze below 40NUT gives transparency above 76mm, while haze above 40NUT increases in EBC haze, and correspondingly transparency below 76 mm. By measurement, we can determine that the turbidity of the sulfuric acid sample with the transparency of 50-80mm is between 37.2NUT and 10.7 EBC. Thus, the inverse relationship between turbidity and transparency of the sulfuric acid sample was again demonstrated.

3. For sulphuric acid samples (good) having a transparency of less than 50mm, the transparency dependence of turbidity is further demonstrated:

table 4 shows the relationship between transparency and haze for sulfuric acid samples having a transparency of less than 50 mm.

TABLE 4

Transparency (mm)	Corresponding turbidity (EBC)
		48	11.9
44	14.7
		40	18.5
36	19.3
		32	20.6
28	21.1
		24	22.0
20	23.2
		16	24.9
12	25.8
		8	27.0
4	28.8

As can be seen from the measurement results in the above table, the transparency was less than 48, and the haze was higher than 11.9EBC, which was a good product. When the transparency of the sample is less than 50mm, the transparency is relatively difficult to judge by the national standard method, and the result is different because the eyes of each person are different.

4. Sulfuric acid samples having transparency of 50mm and 80mm were selected as two key points for determining the correspondence between transparency and turbidity

In order to better judge the grade (qualified, excellent and first-class) of the sample, different sulfuric acid samples with the transparencies of 50mm and 80mm are measured again according to 37.2NUT and 10.7EBC measured by a turbidity meter to verify whether the transparence judgment accuracy is consistent with the measured result of the instrument.

4.1 turbidity measurements of different sulfuric acid samples having a transparency of 80mm are as follows:

sample number	Turbidity (NUT)
		1	36.8
2	37.2
		3	37.0
4	36.5
		5	37.1
6	36.9
		7	36.5
8	37.1
		9	36.6
10	37.0
		Mean value of	36.9
Maximum value	37.2
		Minimum value	36.5
Extreme difference R	0.7
		Standard deviation S%	0.26

As can be seen from the above table, the transparency of the various samples is 80mm and the haze is in

Between 36.5 and 37.2NUT, the turbidity measurement data has smaller error. It can therefore be concluded that the sulphuric acid sample transparency is greater than 80mm and its turbidity is greater than 37.2 NTU. The maximum value was chosen because the difference between the average and maximum values of the turbidity measurements was small.

4.2 turbidity measurements of different sulfuric acid samples with a transparency of 50mm are as follows: (since the scale of the transparency of the glass is not 50mm, the transparency 52mm is taken as an example)

From the above table, the transparency of the sample is 50mm, and the turbidity data measured with the sample has a small error. The haze is between 9.8 and 10.7EBC, the transparency is more than 50mm, and the haze is more than 10.7 EBC. Also, since the error between the average and maximum values of the turbidity measurements is small, we take the maximum value.

This gives the result: the transparency of the sulfuric acid is in corresponding relation with the turbidity, namely the transparency of the sulfuric acid sample is in inverse proportion to the turbidity measured by the turbidity meter.

With the above invention, in some cases where it is difficult to judge visually the transparency test piece, the transparency corresponding to the transparency is found from the correspondence between the transparency and the turbidity determined by measuring the turbidity value thereof with a turbidity meter. The invention provides a detection reference basis for judging the transparency of the sample. Therefore, errors caused by visual inspection are effectively reduced, and the accuracy and reliability of analysis results are improved.

Through a series of experimental data, according to the index of the transparency of the sulfuric acid, the corresponding relation between the transparency and the turbidity of the sulfuric acid sample is summarized as follows:

index of sulfuric acid	Superior product	First-class product	Qualified product
				Transparency	Greater than 80mm	50mm-80mm	Less than 50mm
Turbidity of water	Less than 37.2NUT	37.2NUT-10.7EBC	Greater than 10.7EBC

Safety factors are self-evident due to the strong corrosiveness of sulfuric acid. The invention reduces the potential safety hazard caused by the repeated acid discharge measurement with large sampling amount by adopting a national standard method (a glass perspective tube method).

In addition, the invention shortens the analysis time, the previous method needs 7-8 minutes for analyzing the transparency of a sample, the analysis time for the sample which is difficult to judge is longer, and even more people are needed to participate. The analysis method for determining the transparency through the turbidity meter only needs 5 minutes of analysis time, so that the working efficiency is improved.

Example (b):

turbidity and transparency measurements and comparisons (i.e. effect checks) of the same samples by different persons:

1. measurement of superior products (1):

the sulfuric acid sample with the transparency of more than 80mm is easy to judge, and the measured error among different personnel is small. Therefore, from the above data, we judged the transparency of the sample to be 112 mm.

2. Measurement of superior products (2):

if the transparency of the sample is measured to be 84mm, or 74mm, according to the actual transparency visual inspection method (national standard method), according to the sulfuric acid transparency index: 50-80mm is first-class product; above 80mm is superior product. Then the sample is between premium and first-class. When the turbidity meter is used for measuring the sample, the error between different operators is obviously reduced compared with the transparency visual inspection method (national standard method). According to the data measured previously, the turbidity measured by the turbidity meter was 37.4NUT for a sample having a transparency of 80mm, from which the average value measured by the turbidity meter was:

37.1NUT, the sample was judged to have a transparency of 80mm, and the sulfuric acid sample was a superior product.

3. Measurement of first-class product:

if the transparency of the sample is measured to be 60mm by some operators and 48mm by some operators according to the actual operation transparency visual method (national standard method), according to the sulfuric acid transparency index: 50-80mm is first-class product; and when the thickness is less than 50mm, the product is qualified. Then the sample is between acceptable and first grade. When the turbidity meter is used for measuring the sample, the error between different operators is obviously reduced compared with the transparency visual inspection method (national standard method). According to the data measured previously, the turbidity of 9.7EBC was measured by the apparatus corresponding to the sample having a transparency of 56mm, from which the average value measured by the turbidity meter was: 9.2EBC, we judged the transparency of the sample to be 56mm, and the sulfuric acid sample was an aliquot.

4. Measurement of non-defective products

Since the transparency of the qualified product is reduced, the difficulty of visual inspection is increased, and the measurement error of different operators is increased. However, as a result of measurement of the turbidity by the turbidimeter, the transparency of the sample was judged to be 16 mm.

From the above series of sample data, the present invention can know that the transparency corresponding to the sulfuric acid sample and the turbidity measured by the apparatus have a corresponding relationship, that is, the corresponding turbidity is continuously increased as the transparency of the sulfuric acid sample is reduced. The inherent relationship between the transparency and turbidity of the sulfuric acid sample is preliminarily determined. According to the indexes of a company on a sulfuric acid product, different samples with the transparency of 50mm and the transparency of 80mm are subjected to instrument turbidity measurement, and through further data demonstration, the results show that the transparencies of the two key points correspond to the results measured by the instrument, the error is small, and the results are matched with the results of primary measurement. Thus consolidating our previous preliminary judgment. In the next practical application, the turbidity meter can be fully utilized to effectively measure the sulfuric acid sample to be measured under the condition that visual transparency judgment is inconsistent through measurement among different operators. And determining the transparency of the turbidity value corresponding to the turbidity value through data comparison. Thereby ensuring the true accuracy of the transparency analysis. Meanwhile, the measurement error caused by visual inspection of the transparency is reduced.

Finally, it should be noted that while the present invention has been described with reference to the specific embodiments thereof, it should be understood by those skilled in the art that the above embodiments are only for illustrating the present invention and are not to be construed as limiting the present invention, and various equivalent changes and substitutions may be made therein without departing from the spirit of the present invention, and therefore, it is intended that all changes and modifications to the above embodiments within the spirit and scope of the present invention be covered by the appended claims.

Claims

1. A method for determining the transparency of sulfuric acid using a turbidity meter, comprising:

2. The method of determining the transparency of sulfuric acid using a turbidity meter according to claim 1, wherein step one comprises:

pouring a sulfuric acid sample into a transparent glass tube with scales;

placing the transparent glass tube on a transparency measuring device;

3. The method of determining the transparency of sulfuric acid using a turbidity meter according to claim 1, wherein step two comprises:

4. The method for determining the transparency of sulfuric acid using a turbidity meter according to claim 1,

5. The method for determining the transparency of sulfuric acid using a turbidity meter according to claim 4,

6. The method for determining the transparency of sulfuric acid using a turbidity meter according to claim 1,

the corresponding relation between the transparency and the turbidity of the sulfuric acid sample is as follows: