The pH of a solution can significantly affect the zeta potential in a colloidal system. Zeta potential is a measure of the electrostatic repulsion or attraction between particles in a colloidal system, which plays a crucial role in the stability of colloidal dispersions. The zeta potential is influenced by the surface charge of the particles and the ionic strength of the surrounding medium.In a colloidal system, the particles often have charged functional groups on their surfaces, which can either donate or accept protons H+ ions depending on the pH of the solution. When the pH of the solution changes, the degree of ionization of these functional groups also changes, which in turn affects the surface charge of the particles and consequently the zeta potential.At low pH values, the functional groups on the particle surface tend to donate protons and become positively charged. As a result, the zeta potential becomes more positive. Conversely, at high pH values, the functional groups tend to accept protons and become negatively charged, leading to a more negative zeta potential.The point at which the zeta potential is zero is called the isoelectric point IEP or point of zero charge PZC . At this pH value, the colloidal particles have no net charge, and the electrostatic repulsion between particles is minimal. This can lead to particle aggregation and destabilization of the colloidal system. Therefore, it is essential to maintain the pH of a colloidal system away from its IEP to ensure its stability.In summary, the pH of a solution can significantly affect the zeta potential in a colloidal system by altering the surface charge of the particles. This change in zeta potential influences the stability of the colloidal system, and it is crucial to control the pH to maintain the desired stability and properties of the colloidal dispersion.