TUS (Partner lead: IRIS)

Turbidity Spectrometry (TUS) is a flexible optical technique for monitoring the evolution of suspending particles which size ranges from approx. 100 nm up to few microns. The term “turbidity” describes the relative clarity of a sample due to particulates. The cloudiness or haziness of a fluid caused by individual particles (suspended solids) are generally invisible to the naked eye. The degree of turbidity can be measured from the amount of light scattered (i.e. diffused) by the materials in the sample using, for example, a UV-visible spectrophotometer in transmission or reflexion mode depending on the concentration’s level of nanoparticles. Multiple physical properties contribute to the collected signal, including scattering and absorption, so that with careful modelling of the optical interaction, including a comprehensive understanding of the material properties of the nanoparticles and the medium, and calibration to offline reference measurements, a wide range of particle sizes, material types and concentrations can be characterised. By establishing a close correlation between turbidity spectral features acquired from inline optics, and the nanoparticle synthesis processes under study, real-time process monitoring can be achieved.

In NanoPAT project, TUS will be applied for the nano-characterization of ceramic nanoparticle suspensions in electrolytes, silica nanoparticles and polymers dispersion. Following the nature of the materials and their refraction index behaviour, simultaneous characterization of the size, size distribution and concentration of the selected nanoparticles will be determined. Its suitability to measure individual diluted particles above 100 nm, as well as the size distribution of agglomerates up to several hundred nm, within less than 5 seconds (including data treatment time) will be demonstrated.

TUS has been selected as one of the three particle monitoring techniques in the project, because, being contactless and without sample preparation, it is suitable for inline processes. Furthermore, it can give access to the real-time analysis of various particle parameters.

As expected results, we want to be able to measure the nanoparticle parameters expected by each end user within their process duration, percentage of solid content, pH range, temperature and viscosity.

Figure 1: Turbidity Spectrometric system scheme