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Microfluidic Tensiometry and Investigation of Nanoparticles Adsorption at Liquid/Liquid Interfaces

Arvahi, Milad | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50443 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Mohammadi, Ali Asghar
  7. Abstract:
  8. The present paper is an attempt to critically measure interfacial tension with microchannels and achieve the quantity of adsorption in the liquid – liquid interfaces and comparing the adsorption of surfactants and nanoparticles surface modificated as well. At this point we need to make emulsion and it is necessary for droplets to be monodispersed due to analyze these droplets in this paper. According to this condition for our droplets microsystems are the best options. As we know surfactants were already known as a stabilizing emulsion agent and in this paper nanoparticles are suggested as suitable alternatives for surfactants which can be absorbed as if they are in the water / oil interfaces and prevent droplet coalescence. Gibbs adsorption isotherm reduces the interfacial tension to the amount of molecule or absorbed particle at the interface, and the amount of adsorption is quantitatively investigated. By standardizing the microfluidic system, with the help of a system whose interfacial tension is known, it can be calculated for interfacial tension by measuring the diameter of the droplets for other systems that their interfacial tension in unknown and have the ability to form droplets in the microchannel. This new method of measuring tensions between surfaces that consumes very little of the material and at the same time has high accuracy. The results of the microfluidic method were compared with the ring method and its error value was less than 5%. In this study, ordinary silica nanoparticles did not form droplets but, by modifying their surface and depositing hydrophilic and hydrophilic agents on the surface of silica nanoparticles, they achieved Janus silica nanoparticles that makes the performance of nanoparticles similar to surfactants and finally droplets forming in the presence of Janus nanoparticles. Finally it can be said that Janus nanoparticles which the strength of the hydrophilic and hydrophobic agent is approximately equal have the best performance in adsorption to the boundaries. The adsorption level of ionic and nonionic surfactants, as well as of Janus nanoparticles, have been compared together at the end
  9. Keywords:
  10. Interfacial Tension ; Nanoparticles ; Janus Nanoparticles ; Microfluidic System ; Glasses Microchannel

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