What is the particle size of colloidal particles?
Answers
1 nanometer to 1 micrometer
Explanation:
Colloids Applications
A colloid is typically a two phase system consisting of a continuous phase (the dispersion medium) and dispersed phase (the particles or emulsion droplets). The particle size of the dispersed phase typically ranges from 1 nanometer to 1 micrometer. Examples of colloidal dispersions include solid/liquid (suspensions), liquid/liquid (emulsions), and gas/liquid (foams). A more complete range of colloidal
Particle Interactions
As particle size decreases, surface area increases as a function of total volume. In the colloidal size range there is much interest in particle-particle interactions. Most colloidal commercial products are designed to remain in a stable condition for a defined shelf life. Milk is an example where homogenization is used to reduce droplet size to delay the onset of phase separation (i.e., creaming with the fat rising to the surface). Commercial suspensions may be formulated to keep particles in suspension without sedimenting to the bottom. Examples of phase separation mechanisms are shown below.
Zeta Potential
Zeta potential refers to the potential in the interfacial double layer (DL) at the location of the slipping plane versus a point in the bulk fluid away from the interface. In other words, zeta potential is the potential difference between the dispersion medium and the stationary layer of fluid attached to the dispersed particle. A classic example of colloid chemistry is to measure zeta potential vs. pH to determine the conditions where the zeta potential reaches zero, known as the isoelectric point.
Scientists working to improve colloidal stability measure particle size, zeta potential, or both. Various techniques are now capable of measuring particle size into the colloidal region including dynamic light scattering (DLS) and laser diffraction. The SZ-100 nanoPartica DLS system can measure particle size and zeta potential of colloidal dispersions and has the option of an automatic titrator for zeta potential vs. pH studies. The LA-960 laser diffraction particle size analyzer is the best choice when particles above 1 micron may also be present in the particle system.