Zeta Potential

Zeta potential is a parameter characterizing electrochemical equilibrium on interfaces. It depends on the properties of liquid as well as on properties of the surface. It plays an important role in theory of aggregative stability - DLVO theory. Electrostatic repulsion between particles depends on the value of zeta potential. The higher the zeta potential, the stronger the repulsion, the more stable the system becomes. For instance, high zeta potential of the fat droplets in milk prevents them against coalescence. Reduction of it due to addition of acid would lead to cheese formation from coalescence droplets.

More information: Streaming Current

Zeta Potential Analyzer

There are several different types of zeta potential analyzers. The older ones were based on the microelectrophoresis, the observation of particles motion in electric field using microscope. More recent methods of this type involve light scattering measurement. All methods that are based on light require extreme dilution of the samples. This is a major disadvantage of these methods. Dilution destroys zeta potential of the initial system because it changes the chemical composition of the liquid.

In contrary, our electroacoustic zeta potential probe is a new zeta potential analyzer that does not require dilution. The sample can be measured as is, in its natural conditions. This makes DT-300 much more suitable for many industrial applications.

The zeta potential analyzer DT-300 probe can be used also for monitoring sedimentation stability. It can be oriented in a way that the probe surface serves as a bottom of small cup. Then particles would settle on the surface of the probe when sedimentation stability is broken. Increasing concentration of the particles near the probe sensing surface would be reflected in the increasing magnitude of the measured signal. This is displayed on a special form of the DT-300 software.

In addition, this method is suitable for monitoring the presence of large particles in opaque dispersions of nano-particles. There are many instances when systems claimed as nano-dispersions contain large particles in addition to nano-particles. This method could verify such claims.

More articles to read:
Bulk Viscosity
Particle Size Measurement
Non-Aqueous Conductivity
Zeta Potential Analyzer