Equating these 2 values of σ we can solve for ψo as a function of [H⁺]_B .

Let us look at some typical values:

Table 2: Effect of H⁺ ion concentration on zeta-potential

So we see that |ψo| decreases when [H⁺]_B increases.

What will be the effect if more salt is added?

(10.16)

In that case, value of κ will not be affected by [H+]B. Then the above done derivation does not hold.