The key difference between zeta potential and point of zero charge is that zeta potential is the potential difference between the dispersion medium and the stationary layer of the fluid of a colloidal dispersion whereas point of zero charge is the pH of the colloidal dispersion at which the overall charge of the colloidal particles is zero.
Zeta potential and point of zero charge are important concepts in electrochemistry, regarding the properties of colloidal dispersions. A colloidal dispersion is a suspension where we can see soluble or insoluble particles are dispersed throughout a fluid.
CONTENTS
1. Overview and Key Difference
2. What is Zeta Potential
3. What is Point of Zero Charge
4. Side by Side Comparison – Zeta Potential vs Point of Zero Charge in Tabular Form
5. Summary
What is Zeta Potential?
Zeta potential is the electrokinetic potential of a colloidal dispersion. The name of this term is derived from the Greek letter “zeta”, and we usually call this electrokinetic potential as zeta potential. In other terms, zeta potential is the potential difference between the dispersion medium and the stationary layer of the fluid attached to the dispersed particle of the colloidal dispersion. Therefore, this term gives an indication of the charge present on the particle surface. There are two types of zeta potential as positive and negative zeta potential. Moreover, this potential is what we measure as the velocity of the particles in a d.c. electric field.
Figure 1: Variation of the Zeta Potential of a Particle in a Collodal Suspension with Distance from Particle Surface
Positive zeta potential indicates that the dispersed particles in the suspension in which we measure the zeta potential have a positive charge. In addition, considering the values, there is no significant difference between positive and negative zeta potential. Negative zeta potential indicates that the dispersed particles in the suspension in which we measure the zeta potential have a negative charge. Therefore, the charge of the dispersed particles is negative.
What is Point of Zero Charge?
The point of zero charge is the pH at which the overall charge of a particle is zero. This concept was developed in order to explain the colloidal flocculation. In electrochemistry, electric potential is a term similar to point of zero charge.
Figure 02: A Diagram of a Charged Particle in a Colloidal Suspension
In biochemistry, point of zero charge is the isoelectric point. Generally, this point is determined by acid-base titrations, where a neutralization reaction occurs. The analyte for this titration is a colloidal dispersion, and the procedure is carried out under monitoring of the electrophoretic mobility of particles in the dispersion.
What is the Difference Between Zeta Potential and Point of Zero Charge?
The key difference between zeta potential and point of zero charge is that zeta potential is the potential difference between the dispersion medium and the stationary layer of the fluid of a colloidal dispersion whereas the point of zero charge is the pH of the colloidal dispersion at which the overall charge of the colloidal particles is zero.
Moreover, another difference between zeta potential and point of zero charge is that zeta potential measures potential value while the point of zero charge measures pH value.
Summary – Zeta Potential vs Point of Zero Charge
Zeta potential and point of zero charge are important concepts in electrochemistry regarding the properties of colloidal dispersions. The key difference between zeta potential and point of zero charge is that zeta potential is the potential difference between the dispersion medium and the stationary layer of the fluid of a colloidal dispersion whereas the point of zero charge refers to the pH of the colloidal dispersion at which the overall charge of the colloidal particles is zero.
Reference:
1. Shen, Xiantao. “Molecularly Imprinted Photocatalysts.” Molecularly Imprinted Catalysts, 2016, pp. 211–228., doi:10.1016/b978-0-12-801301-4.00010-4.
Image Courtesy:
1. “Gold nanoparticle Zeta-potential” By Larryisgood – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Diagram of zeta potential and slipping planeV2” By Modified and converted to SVG by Mjones1984. Original work by Larryisgood. – Modified image based upon this. (CC BY-SA 3.0) via Commons Wikimedia
