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Introduction to Microfuidics
Published in Simona Badilescu, Muthukumaran Packirisamy, BioMEMS, 2016
Simona Badilescu, Muthukumaran Packirisamy
In addition to being driven through electroosmotic force, motion could also be supplemented with pressure force, as shown in Figure 8.17. When there is a charge separation at the fluid-solid interface, pressure-driven flow results in a bulk motion of unbalanced charges in the fluid, leading to the generation of a net electrical current called streaming current (Istream), as shown in Figure 8.18. Streaming current under constant pressure gradient for a circular channel depends on several parameters, like Istream=εςΔPAμL where A is the cross-sectional area of the channel, ∆P = Pdownstream – Pupstream, and µ is dynamic viscosity.
Streaming Current or Particle Charge Analyzer
Published in Béla G. Lipták, Analytical Instrumentation, 2018
When studying the adsorption characteristics of colloidal suspensions, the knowledge of surface charges on the suspended particles is important. In water or waste treatment, the streaming current detector (SCD) can estimate treatment demand or continuously control the addition of coagulation chemicals by detecting the surface charge on particles. Less directly, it can compare the relative charge-influencing ability of alternative treating chemicals, or determine the effect of pH on a chemical’s ability to promote or enhance coagulation. Most effective use requires a recognition of the role of electrical charge in stabilizing suspensions.1
Mechanisms of Particle Removal from Liquid
Published in Maik W. Jornitz, Theodore H. Meltzer, Sterile Filtration, 2020
Maik W. Jornitz, Theodore H. Meltzer
The streaming current potential is useful because it provides a measurement of the net surface charge of the colloidal particles. This correlates with how much coagulant must be added to the colloidal suspension to cause it to agglomerate. The coagulant, such as alum, supplies multivalent cations, Al3+, to neutralize the negative charges of the first electrical layer. This charge neutralization destabilizes the colloidal suspension, reducing the double layer dimension and thus permitting the particles to agglomerate and to become large enough to be responsive to gravitational settling.
Photocatalytic removal of 2,4-Dichlorophenoxyacetic acid from aqueous solution using tungsten oxide doped zinc oxide nanoparticles immobilised on glass beads
Published in Environmental Technology, 2022
Yahya Zandsalimi, Afshin Maleki, Behzad Shahmoradi, Saeed Dehestani, Reza Rezaee, Gordon McKay
Zeta potential is very important for understanding and controlling the properties of colloidal suspensions. In general, the characteristics of the suspension can be identified by understanding how colloids interact. To measure the zeta potential, the undoped and doped zinc oxide samples were prepared by dissolving 0.01 g of sample in 5 ml distilled water at an optimum pH value. Before the measurement, each sample was sonicated for 15 min. It should be pointed out that the zeta potential was calculated from the determined streaming current by means of the Helmholtz–Smoluchowski equation, which is applicable for any surface conductivity [33]. The results are shown in Figure 10.