1. Preface

Caprolactam is one of the important organic chemical raw materials. It appears as white powder or crystals and has an oily feel. The main application is to generate polyamide chips (commonly known as nylon-6 chips or nylon 6 chips) through polymerization, which can be further processed into nylon fibers, engineering plastics, plastic films, etc. Usually, in production and import and export trade, the moisture content of this product needs to be detected and controlled, and the relevant standard SN/T 2783-2011 has been formulated to guide the moisture determination of this product.

This method adopts the second Fagar in the standard. The Fischer determination method, compared with the first azeotropic method, is safe and easy to perform, has high detection efficiency, more accurate data, and good repeatability. It is suitable for detecting the moisture content of this product.

2 Instruments and equipment

2.1 Instruments

JH-V3 Karl Fischer moisture titrator (volumetric method), double platinum electrodes, 5mL titration unit.

2.2 Reagents

Karl Fischer titrant two-component.

3 Experimental Methods

3.1 Experimental Procedures

Through the liquid discharge device of the moisture titrator, the residual liquid is removed. Then, 40mL of solvent methanol is added to the titration cup, with the solvent covering the electrode. After setting the parameters, the instrument starts the pre-titration. When the instrument is in standby mode, click on the system injection, open the rubber stopper of the feeding port, and select the injection volume according to the volume of titration solution consumed by the sample. Quickly add the sample, immediately cover the rubber stopper, click "Start Measurement", and use Karl Fischer. Titrate with the titrant to the endpoint, input the sample weight, and calculate the moisture content of the sample.

3.2 Instrument Parameters

4 Results and Discussion

4.1 Experimental Results

Calculation formula:

In the formula:

X - represents the moisture content of the sample (%);

V1 - The volume (mL) of titration liquid consumed when titrating the sample;

m - The weighing amount of the sample (g);

T - represents the concentration of the titrant (mg/mL).

4.2 Conclusion and Discussion

The moisture content of caprolactam was measured by the JH-V3 Karl Fischer moisture titrator (volumetric method). The data repeatability was good, not exceeding the repeatability limit in the standard requirements. The difference between the two groups of data was 1%. Moreover, the operation was safe and the detection efficiency was higher, which was suitable for the rapid detection of the moisture content of caprolactam.

References

[1]GB/T 6283-2008 Determination of Moisture Content in Chemical Products - Karl Fischer Method (General Method)

[2] [2]SN/T 2783-2011 Determination of Moisture Content of Caprolactam