What is zeta potential?

Zeta potential is the electric potential at the slipping plane surrounding a charged particle in a liquid. It reflects the degree of electrostatic repulsion between particles. A high absolute value means strong repulsion, which stabilizes the colloid against aggregation.

What zeta potential value indicates a stable colloid?

The widely accepted thresholds are: above ±30 mV is considered stable, above ±45 mV is very stable, and above ±60 mV is excellent. Values between ±10 and ±30 mV indicate incipient instability, while values below ±10 mV are considered highly unstable with rapid flocculation expected.

Can zeta potential be negative?

Yes. Zeta potential can be positive or negative depending on the surface chemistry of the particle and the pH of the medium. The sign indicates the polarity of the surface charge, but stability depends on the absolute magnitude.

How does pH affect zeta potential?

pH significantly influences zeta potential for amphoteric surfaces. At low pH, surfaces tend to be positively charged; at high pH, negatively charged. The pH at which zeta potential equals zero is called the isoelectric point (IEP), where the colloid is most unstable.

What instrument measures zeta potential?

Zeta potential is typically measured by dynamic light scattering (DLS) instruments with electrophoretic light scattering (ELS) capability, such as the Malvern Zetasizer. The instrument measures electrophoretic mobility and converts it to zeta potential via the Henry equation.

Is a higher zeta potential always better?

For electrostatic stabilization, yes. However, some systems use steric stabilization via polymer coatings and can be stable even at low zeta potentials. Context matters — always interpret zeta potential alongside particle size, PDI, and formulation chemistry.

Zeta Potential Helper

Name: Zeta Potential Helper
Availability: InStock
Author: Nham Vu

Enter a zeta potential value in millivolts to classify colloidal stability and get a plain-English interpretation.

Enter Zeta Potential

Zeta Potential (mV)

Stability Thresholds

Highly Unstable |mV| < 10

Unstable 10 – 20

Incipient Instability 20 – 30

Moderate Stability 30 – 45

Good Stability 45 – 60

Excellent Stability |mV| ≥ 60

Enter a zeta potential value and click Classify Stability.

Typical values range from -200 mV to +200 mV.

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Summary