Application of Malvern Laser Particle Size Analyzer in Measuring Size Distribution of 4A Zeolite
( Song Peng, Yang Yiliang, Zhang Wei)
Abstract: The method for determining the particle size distribution of 4A zeolite by Malvern laser particle size analyzer was introduced. The optimized test conditions were found by experimental comparison. In addition, according to the national standard (QB Plant I'1768-2003), the particle size distribution of 4A zeolite was also measured. By comparison, under the optimized test conditions, the particle size distribution results measured by the Malvern laser particle size analyzer can be matched with the test results of the national standard (QB/T1768-2003) to achieve the experimental purpose. The optimized test method is easy to establish, has high precision, has been applied, and has a good effect.
4A zeolite is synthetic crystal. It is widely used in detergent industry, petrochemical industry, pharmaceutical industry and environmental protection industry. Traditional detergent powder additive sodium tripolyphosphate is easy to cause environmental pollution, resulting in eutrophication of rivers and lakes. Since the 1970s, countries around the world have been looking for alternatives, and 4A zeolite has been the best so far. In recent years, water quality eutrophication has occurred in some inland lake areas, coastal economically developed areas and densely populated areas, which has attracted the attention of the environmental protection department. China has banned the use of phosphorus-containing detergents in some areas, and in the 21st century, it is necessary to gradually realize the non-phosphorization of washing powder. With the continuous development of China's economy, the improvement of people's lives, the popularity of household washing machines, detergents are growing rapidly, many times higher than the world average annual growth rate (4% 6%), but due to the low base and large population, The consumption of detergents will increase greatly, and accordingly, environmental protection is increasingly demanding the use of non-phosphorus washing, so the application of zeolite detergents is promising.
The determination of the zeolite particle size distribution is specified in the national standard (QB/T1768-2003). The zeolite particle size distribution measurement was carried out in accordance with the regulations using a CAPA-500 particle size analyzer manufactured by Hoifba Co., Ltd., Japan. Focus on the use of distilled water as the dispersion medium, discuss the application of Mastersizer2000 laser particle size analyzer in the determination of 4A zeolite particle size distribution. This method is easy to establish, has high precision, has been applied, and has a good effect.
1 experiment
1.1 Instruments and raw materials Mastersizer2000 laser particle size analyzer and Mastersizer2000 analysis software produced by Marlvern, UK; raw materials from China Daily Chemical Industry Research Institute; distilled water; CAPA-500 particle size analyzer produced by Japan Hofiba company. The UK's Marlvem Mastersizer 2000 laser particle size analyzer is suitable for particle size determination of micron-sized particles, making particle size analysis a simple and intuitive daily task.
1.2 Experimental methods
The 4A zeolite particles are uniformly dispersed in distilled water, and the circulation pump passes the distilled water at a certain flow rate through the laser beam at a certain rotation speed. The particle size is different, the diffraction angle is also different, the diffracted light is collected by the detector, and the received signal is converted into a particle size distribution curve to obtain relevant data.
1.3 Calibration of the instrument In order to better perform the experiment and make the results more convincing, the optical system was carefully and thoroughly cleaned, and the standard samples provided by Marlvern were used again to check the conformity of the test results. The repeatability of the test is determined by multiple analyses of a single standard . If the repeatability is within the precision range set by the instrument, the results do not match the Marlvern standard sample, indicating that the sample concentration and flow rate need to be reset until the result Corresponding to Marlvern's standard samples. The speed of the circulating pump corresponds to a certain flow rate. In the actual measurement, the speed of the circulating pump is set to set the flow rate. The appropriate rotation speed can not only make the sample not add obvious bubbles after the sample is added to the beaker, but also distribute the sample particles evenly in the distilled water without sedimentation. The final set circulating pump speed was 2000 rpm.
1.4 Test Procedure Check the sample for large particles before testing. If necessary, grind it. Inject 400 mL of distilled water into a 500 mL beaker, set the rotation speed of the circulating pump to 2000 rpm, start the circulation pump; start manual measurement, the software will automatically perform optical path correction and measure the background. When the test procedure prompts to add the sample, carefully add a small amount of 4A zeolite into the beaker with the sample spoon until the opacity reaches the prompt requirement; press the “Start†button to start the measurement. After the measurement is finished, the instrument automatically gives the particle size distribution map. It can also be measured after ultrasound.
2 Results and Discussion The determination of the particle size distribution of 4A zeolite for detergents is specified in the national standard (QB/T1768-2003). The same sample was tested according to the regulations. It can be seen from the table that the 4A zeolite particles are The particle size is in the range of 1.000 m to 2.000 m, which is close to 50%; the particle size of less than 4 m is 99.71%. The CAPA-500 particle size analyzer manufactured by Horiba Company of Japan was used in the test, which is a traditional instrument.
The particle size distribution of the 4A zeolite was measured using a Mastersizer 2000 laser particle size analyzer, and the results should match the test results of the standard. The particle size distribution of the sample was determined using a Mastersizer 2000 laser particle size analyzer. The test conditions were mainly considered from the following aspects: flow rate, residence time of the same sample in distilled water, ultrasonic time and ultrasonic intensity. In addition, for samples with larger particles, pretreatment such as grinding is required to reduce sample dispersion time and improve the reliability of test data. The circulating pump has a rotational speed of 2000 rpm, and the rotational speed is not too high to prevent the generation of air bubbles and to avoid affecting the test results.
2.1 Ultrasonic time and ultrasonic intensity The purpose of ultrasound is to make the 4A zeolite more uniformly dispersed in distilled water while dispersing the "agglomerated" particles. Marlvem's Mastersizer 2000 laser particle size analyzer comes with ultrasound equipment and works well. The effect of ultrasound on the particle size distribution of 4A zeolite was observed by selecting the ultrasonic intensity value to the maximum and adjusting the ultrasonic time. Figure 1, Figure 2 and Figure 3 are the particle size distribution diagrams without ultrasound, ultrasound for 1 min, and ultrasound for 5 min, respectively.
As the ultrasonic time increases, the proportion of agglomerated particles in the 4A zeolite gradually decreases. After 5 minutes of ultrasonication, the 4A zeolite agglomerated particles have been reduced to the ideal condition. Therefore, the ultrasonic treatment has a significant effect on the uniform dispersion of 4A zeolite in distilled water and the elimination of the "agglomeration" of 4A zeolite agglomeration, but the ultrasonic time is not as long as possible. Comprehensive test cases to test other samples, the final selected ultrasonic time 5arin, then 4A zeolite is dispersed in distilled water is ideal, and asked for a further period of little significance when ultrasound.
2.2 The residence time of the same sample in distilled water after ultrasonication The repeatability of the 4A zeolite sample after sonication, whether the measured particle size distribution curve can be overlapped, is also an important basis for the test data to be convincing, This issue has also been examined. Table 2 shows the particle size distribution of the same 4A zeolite sample in distilled water after ultrasonication for different times. After sonication, the same sample has different residence time in distilled water, and has no effect on the particle size distribution of 4A zeolite, and the corresponding particle size distribution curve can be overlapped. This indicates that the 4A zeolite sample is already in a relatively stable state in distilled water.
2.3 Comparison with national standards A series of experiments were carried out. One of the purposes was to establish a test method using the Mastersizer 2000 laser particle size analyzer. The test results were compared with the national standard, and the test conditions were found to be matched. The same 4A zeolite sample was tested several times using the Mastersizer 2000 laser particle size analyzer during the experiment. The selected test conditions have been discussed previously. Table 2 shows the test results under this condition. Comparing Table 1 and Table 2, it can be seen that in the volume percentage of particle size less than 4 m, the national standard measured value is 99.71%, which is slightly larger than the result measured by the laser particle size analyzer.
3 Conclusion After the optimization of the test conditions, the obtained test results can be matched with the results of the national standard. At the same time, compared with traditional instruments, testing samples with laser particle size analyzer has the advantages of quickness and simplicity, and can better serve experiments and production. During the test, even a small amount of air bubbles will affect the analysis results. Increasing the dispersant and prolonging the stirring time can help prevent the generation of bubbles. In addition, each time the test is finished, it must be carefully cleaned to ensure that the optical system of the instrument is clean; the pipeline should be cleaned at regular intervals.
(Daily Chemicals Science)
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