Process ultrasonic spectroscopy
The chemical industry plays a crucial role in the European economy. Although specialty chemicals account for only 26 % % of production, they are indispensable in numerous sectors, including the construction industry, cosmetics, the automotive industry, and the food industry. Titanium dioxide (TiO2) is an essential material whose properties depend greatly on the particle size. This is where the Ultrasound spectroscopy as an innovative method for process monitoring.
Titanium Dioxide and its Applications
Titanium dioxide is a widely used material that is used both as the main component and as an additive in products such as paints, sunscreens, toothpaste, and food. Additionally, around 1.5 million tons are produced worldwide annually, of which approximately 60 % are used in paints and coatings. This is where ultrasound spectroscopy can be applied.
The Particle size of TiO2 is a crucial factor in the properties of the final product. While sunscreen products require particle sizes of approximately 300 nm, transparent UV blockers require significantly smaller particles. The smaller the particles, the higher the manufacturing costs – these can be up to ten times higher.
TiO2 as a white pigment:
For TiO2 to be used as a white pigment, the particles must reflect visible light in the range of 440 nm to 700 nm. The optimal particle size for this reflection is approximately 300 nm. However, differences in particle size affect the color quality. If the majority of the particles are smaller than 300 nm, a blue tint is created, which is desirable for detergent products, but reduces the covering power for wall paints. Larger particles, on the other hand, result in a brown color tone and a loss of shine.
Challenges in process monitoring
The production of TiO2 requires precise process monitoring to achieve the optimal particle size of 300 nm. Since optical measurement techniques are unusable due to the low light transmission of TiO2 samples, samples have been taken, diluted, and analyzed with UV spectrometers until now. However, this method is time-consuming, error-prone, and highly dependent on the pH value of the samples, which means the use of ultrasonic spectroscopy.
Ultrasonic spectroscopy: An efficient solution
Ultrasonic spectroscopy therefore offers an innovative alternative to real-time particle size determination. In this method, a material is excited by high-frequency mechanical waves, whose response in turn depends on the thermo-physical properties of the medium. Furthermore, this method is:
- Non-destructive and non-intrusive
- Suitable for solid, liquid and opaque materials
- Easy to handle without manual intervention
- Applicable over a wide frequency range
The ITS Developed by U2S technology, ultrasonic measurements capture the particle size, distribution, and concentration in highly concentrated suspensions and are an example of a sophisticated application of ultrasonic spectroscopy.
Applications of ultrasonic spectroscopy
The U2S system allows the determination of the following material properties:
- Density and concentration of mixed liquids and suspensions
- Rheological properties such as flow behavior and deformation
- Changes in material composition due to changes in particle sizes
- Relaxation phenomena in biological materials and soft solids
An example application is the Concentration dependence of titanium dioxide. The graph shows samples with different concentrations (1 %, 3 %, 5 %, 10 %, 30 %, 50 %, 70 %). The results show how particle size and concentration affect the material properties, which illustrates why continuous monitoring by ultrasonic spectroscopy is necessary.
Summary
Ultrasound spectroscopy therefore revolutionizes process monitoring in the chemical industry. With this method, particle size, distribution, and concentration can be determined in real time – even in highly concentrated samples. Furthermore, this reduces production time, improves product quality, and minimizes costs. Finally, the U2S technology offers a reliable, efficient, and versatile solution for the requirements of modern industrial processes.