Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide an organic solvent moisture content determination method for accurately, quickly and conveniently determining whether the water content of an organic solvent meets the control requirement.
The purpose of the invention can be realized by the following technical scheme:
a method for determining the moisture content of an organic solvent comprises the following steps:
(1) quantitatively detecting the lowest color-developing water content of anhydrous copper sulfate changing into blue in each organic solvent by adopting a Karl Fischer titration method, and establishing a database;
(2) adding anhydrous copper sulfate powder into a certain organic solvent to-be-detected liquid, and oscillating to obtain a mixed liquid;
(3) comparing the mixed solution with a white background plate under illumination, judging whether the mixed solution turns blue or not, and comparing the mixed solution with the lowest color development water content in a database to finish the judgment of the water content of the organic solvent;
(4) filtering the mixed solution, drying and recovering copper sulfate;
(5) and (5) repeating the steps (2), (3) and (4) to finish the judgment of the moisture content of other organic solvents.
Further, the organic solvent includes an ester solvent, an alcohol solvent, an ether solvent or a hydrocarbon solvent.
Further, the ester solvent comprises ethyl acetate, butyl acetate or ethyl butyrate.
Further, the alcohol solvent includes methanol, ethanol or isopropanol.
Further, the ether solvent comprises methyl butyl ether, propylene glycol methyl ether or ethylene glycol ethyl ether.
Further, the hydrocarbon solvent comprises n-hexane, cyclohexane, n-heptane, toluene, xylene and trimethylbenzene.
Furthermore, the mass volume ratio of the anhydrous copper sulfate powder to the organic solvent is 0.3g:50 ml.
Further, the oscillation time is 15-20 s.
Further, in the step (3), if the anhydrous copper sulfate turns blue, the fact that the water content in the organic solvent is greater than or equal to the lowest color development water content does not meet the production standard.
Further, in the step (3), if the anhydrous copper sulfate does not change blue, it means that the water content in the organic solvent is less than the lowest color-developing water content, and the production standard is met.
The invention adopts the characteristics of strong moisture absorption and blue change when meeting water of anhydrous copper sulfate, and can accurately judge whether the water content of the solvent exceeds the standard. The color development sensitivity is high, the method is convenient and quick, and the copper sulfate can be recycled, so that the method has a high market application value.
Compared with the prior art, the invention has the following advantages:
(1) the invention only uses a Karl Fischer titration method once to detect the lowest color development water content which enables anhydrous copper sulfate to turn blue in each organic solvent, and establishes a database, and then only needs to use a simple judgment method to judge whether the water content in each organic solvent exceeds the standard, so that the method is simple and rapid;
(2) because only one Karl Fischer titration method is adopted, the produced sulfur pyridine waste liquid is very little and is environment-friendly;
(3) after the detection is finished, the anhydrous copper sulfate can be reused after being filtered and dried, so that the method has high market application value and is suitable for large-scale test.
Detailed Description
The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.
Quantitatively detecting the lowest chromogenic water content for changing anhydrous copper sulfate into blue in an organic solvent by adopting a Karl Fischer titration method, and establishing a database; the minimum water content of the anhydrous copper sulfate for each organic solvent was measured to be discolored as shown in the following table 1:
TABLE 1
Example 1
(1) Measuring 50ml of ethyl acetate solution to be detected, and putting the solution into a 100 ml conical flask;
(2) adding about 0.3g of anhydrous copper sulfate powder into the solution to be tested; shaking for about 15 seconds by hand to obtain a mixed solution;
(3) comparing the mixed solution with a white background plate under illumination, judging whether the mixed solution turns blue or not, and comparing the mixed solution with the lowest color development water content in a database to finish the judgment of the water content of the organic solvent; if the copper sulfate powder is changed from colorless to blue, the water content of the solvent is over the color development water content, namely the water content of the solvent is more than or equal to 2000ppm and does not meet the control requirement;
(4) filtering the mixed solution, drying and recovering copper sulfate.
Example 2
The difference from the example 1 is that the solvent to be tested is methanol, and if the copper sulfate powder is changed from colorless to blue, the water content of the solvent exceeds the color development water content, namely the water content of the solvent is more than or equal to 2500ppm, and the control requirement is not met.
Example 3
The difference from the example 1 is that the solvent to be tested is methyl butyl ether, if the copper sulfate powder is changed from colorless to blue, the water content of the solvent exceeds the color development water content, namely the water content of the solvent is more than or equal to 1000ppm, and the control requirement is not met.
Example 4
The difference from the example 1 is that the solvent to be tested is n-hexane, and if the copper sulfate powder is changed from colorless to blue, the water content of the solvent exceeds the color development water content, namely the water content of the solvent is more than or equal to 800ppm, and the control requirement is not met.