Zeta potential (ζ-potential) is affected by various factors, including:

pH of the Medium:

· The protonation or deprotonation of functional groups changes the surface charge.

· At low pH, acidic groups (e.g., carboxyl) may become protonated, reducing negative charge.

· At high pH, basic groups (e.g., amines) lose protons, reducing positive charge.

Ionic Strength of the Solution:

· Higher ionic strength (e.g., high salt concentration) compresses the electrical double layer, decreasing the magnitude of zeta potential.

Nature of Functional Groups on the Surface:

· Sulfur-containing groups (e.g., thiols, sulfonates, sulfates) can be negatively charged, increasing negative zeta potential.

· Nitrogen-containing groups (e.g., amines, quaternary ammonium groups) can be positively charged in acidic conditions, increasing positive zeta potential.

Solubility of the Compound in Water:

· More soluble compounds tend to have better hydration shells, stabilizing charge distribution and increasing the absolute magnitude of zeta potential.

· Poorly soluble compounds may have surface aggregation, reducing charge mobility and decreasing absolute zeta potential.

Particle Size and Surface Chemistry:

· Smaller particles have a higher surface area-to-volume ratio, which can enhance charge accumulation and increase zeta potential.

Comparison of Compounds:

· If a compound contains nitrogen and sulfur groups and shows good solubility in water, it is likely to exhibit a higher absolute zeta potential (either more positive or more negative) than a compound that:

· Lacks these functional groups (no strong charged groups contributing to surface charge).

· Is not perfectly soluble in water, which may lead to aggregation and reduced charge stabilization.

Therefore, a water-soluble, nitrogen- and sulfur-containing compound will likely have a higher magnitude of zeta potential (more positive or more negative) compared to a less soluble, non-functionalized compound.

Sakshi Saini

Charalampos Tsekeridis

Zeta potential appears in dispersed systems. If your substance dissolves in a solvent, it means that it is distributed in it in the form of molecules or ions. Therefore, in such a system there will be no zeta potential.

That means if my compound will dissolve well, it doesn't show zeta potential, and I can not determine the stability of my compound. Yuri Mirgorod

Sakshi Saini

The stability of a compound with a chemical formula is determined by the standard change in the Gibbs energy of its production from simple substances stable under conditions of 298K and a pressure of 1 atm. If you mean the zeta potential, then you probably want to characterize the stability of a suspension, i.e. a dispersed system, by this parameter. But your compound, as you write, dissolves. Therefore, this is not a dispersed system, but a solution. Solutions are thermodynamically stable.

Thank you so much sir for the detailed answer Yuri Mirgorod