DT-1202 – Particle size and zeta potential measurement of concentrated dispersions

The DT-1202 combines both instruments, the acoustic attenuation spectrometer DT-100 and the elecotracoustic probe DT-300 in one device. Thus it is able to measure simultaneously particle size distribution and zeta potential of a liquid, concentrated dispersions in its original state without any modification like dilution!

To calculate the particle size distribution, the DT-1202 is measuring the sound speed and the attenuation of short ultrasound pulses for a set of frequencies, typically from 1 to 100 MHz (“transmission pulse technique” or “tone burst method”). The data will be recorded at different gaps between ultrasound sender and detector to improve the accuracy of the signals. Due to the wide frequency range of this unique technique, very small (< 100 nm) as well as coarse particles (>> 10 µm) can be measured with a high precision. The variable gap between sender and detector enables the characterization of diluted (< 1 vol.-%) and concentrated (up to 50 vol.-%) dispersions. The WINDOWS-bases software take into account the different ultrasound-wave-particle interactions as scattering, viscous losses and thermodynamic effects.

Zeta probe

Additionally, the DT-1202 is analyzing the zeta potential of a dispersion using its electroacoustic probe. Further colloidal parameters can be calculated like Debye-length, κa-value, Dukhin’sche number and surface charge density in case of strong non-polar solvents. Due to the smart design of the probe (pulse-echo method, smooth surface) it can be easily used both for laboratory experiments and for process-near online measurements.

Measuring principle of the DT-1202

Benefits and key features

• No dilution, no sample preparation
• Measurement of the acoustic attenuation spectrum from 1 to 100 MHz with highest accuracy and reproducibility
• Wide concentration range (0,1 – 50 Vol-%), due to variable sender detector gap
• Wide particle size range (5 nm – 1000 µm)
• Time of measurement: particle size: 1 – 10 min; zeta potential: < 1 min
• Sample volume: particle size: about 70 ml (optional < 5ml); zeta potential: > 0,5 ml
• Measurement of sedimenting and high viscous samples (up to 20000 mPas)
• On-line-measurement possible (by-pass setup)
• Fully automatic, quantitative titration experiments (acid/base, additives)
• Particle size and zeta potential can be measured simultaneously and separately

References and norms

/1/ ISO 20998-1 Measurement and characterization of particles by acoustic methods.
/2/ ISO 13099-3 Colloidal systems – Methods for zeta potential determination.
/3/ A. Dukhin, P. Goetz: Characterization of Liquids, Nano- and Microparticulates, and Porous Bodies using Ultrasound. 2nd Edition. Oxford: Elsevier, 2010.
/4/ PARTICLE WORLD 19; p. 18 – 19; “Characterization of liquids, dispersions, emulsions and porous materials using ultrasound”.

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