### Regarding how to convert from measured zeta potential to GeoDict's surface charg

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#### Syuhei

• Posts: 2
##### Regarding how to convert from measured zeta potential to GeoDict's surface charg
« on: August 17, 2022, 09:47:13 AM »
Dear GeoDict-Team,

How do they measure it in the laboratory that the amount of Filter Surface Charge at Movement subtab on Particles tab in  FilterDict-Media’s setting?
« Last Edit: August 17, 2022, 10:18:14 AM by Syuhei »

#### Liping Cheng

• Posts: 1
##### Re: Regarding how to convert from measured zeta potential to GeoDict's surface charg
« Reply #1 on: August 18, 2022, 04:08:32 PM »

Surface charge:
The electric charges are constrained on this 2-D surface, and surface charge density, measured in coulombs per square meter (C/m^2), is used to describe the charge distribution on the surface.

Zeta potential:
Zeta potential is the electrical potential at the slipping plane. The Grahame equation expresses the relation between surface charge and surface potential:
σ = Ɛ · Ɛ0 · Ψ0 / λ_d where Ɛ and Ɛ0 are the dielectric constants of two phases and λ_d is Debye distance up to which the ions get adsorbed on to the surface to meet the bulk liquid called the slipping plane where Ψ0 decreases to the value called Zeta potential so that above relation becomes:
σ = Ɛ · Ɛ0 · ζ / λ_d

https://www.researchgate.net/post/What_is_the_difference_between_surface_charge_and_zeta_potential
https://en.wikipedia.org/wiki/Surface_charge

« Last Edit: August 18, 2022, 04:13:30 PM by Liping Cheng »

#### Syuhei

• Posts: 2
##### Re: Regarding how to convert from measured zeta potential to GeoDict's surface charg
« Reply #2 on: August 19, 2022, 10:14:20 AM »
Dear Liping,