What is Helmholtz Smoluchowski velocity?
A well-known practical alternative that alleviates the above mentioned difficulties is the adoption of the Helmholtz–Smoluchowski velocity [3], which is an artificial slip velocity imposed at the solid surface to take care of the electroosmotic force in capillaries.
What is electrokinetic streaming potential?
A streaming current and streaming potential are two interrelated electrokinetic phenomena studied in the areas of surface chemistry and electrochemistry. They are an electric current or potential which originates when an electrolyte is driven by a pressure gradient through a channel or porous plug with charged walls.
How do you measure stream potential?
Streaming potential can be calculated experimentally by plotting the voltage difference across the membrane (or along the surface) over a range of flow rates (creating a range of pressure differentials) and a linear relation should be obtained, see Fig. 18.3.
What is electrokinetic phenomena in physical chemistry?
Phenomena associated with the movement of charged particles through a continuous medium or with the movement of a continuous medium over a charged surface. The four main electrokinetic phenomena are electrophoresis, electroosmosis, streaming potential, and sedimentation potential, or Dorn effect.
How zeta potential can be determined with the help of streaming potential?
Electrophoretic light scattering (ELS) In contrast to streaming potential measurements no movement of the liquid is generated, but the movement of the particles is induced. Therefore, an electric field is applied and the electrophoretic mobility of particles is used to calculate the zeta potential.
What is electrokinetic phenomena in colloids?
Electrophoresis, which is one of the electrokinetic phenomena observed in colloidal systems, is the motion of charged colloidal particles in a liquid medium under an applied electric field. The surface charge density σ of a charged particle can be calculated from the particle surface potential ψo.
What is electrokinetic force?
“Electrokinetics” refers to the study of electrically driven mechanical motion of charged particles or fluids. Sometimes it is used more narrowly for fluid or particle motion in electrolytes and ionic liquids (reserving the term “electrohydrodynamics” for weakly conducting dielectric liquids).
Can zeta potential be positive?
The magnitude of the zeta potential gives an indication of the potential stability of the colloidal system. Particles with zeta potentials more positive than +30 mV or more negative than -30 mV are normally considered stable.
What is electrokinetic effect?
Electrokinetic phenomena are a family of several different effects that occur in heterogeneous fluids, or in porous bodies filled with fluid, or in a fast flow over a flat surface. Influence of an external force on the diffuse layer generates tangential motion of a fluid with respect to an adjacent charged surface.
What are electrokinetic properties?
Electrokinetic properties of soils are the overall reflection of the distribution of various kinds of ions in the electric double layer of a soil-water system. They are related to both the characteristics of the soil and the nature of ions.
What if zeta potential is negative?
The negative symbol in front of the zeta potential means that the net charge of the scattering object (including up to the slipping plane) is negative. Different materials have different isoelectric points, and it is very typical to see a negative charge above the isoelectric point IEP of the sample.