Superhydrophilic and superoleophobic meshes for on-site oil-water separation

Vaziri, Elaheh (2023) Superhydrophilic and superoleophobic meshes for on-site oil-water separation. Masters thesis, Memorial University of Newfoundland.

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Abstract

Oil spills are becoming a major cause of environmental damage on a worldwide scale. Effective ways to separate oil from water are needed to solve this issue. Meshes and membranes that are superhydrophilic/superoleophobic are promising materials for oil-water separation, but their actual utilisation still confronts several obstacles. In this work, we made oleophobic TiO₂ and SiO₂ nanoparticle-coated superhydrophilic stainless steel meshes. The coating was made by electrophoretically depositing positively charged nanoparticles of TiO₂ and SiO₂ on stainless steel meshes after treating of TiO₂ and SiO₂ with iodine in acetyl acetone solutions. To increase stability and oil-water separation performance, four different mesh counts (80, 120, 200, and 400) were created and put through sintering operations at various temperatures. X-ray diffraction (XRD), scanning electron microscopy (SEM), and contact angle (CA) measurements were used to explore the specific microscopic structural characteristics of these meshes. These meshes were evaluated for their ability to separate oil from water using gas florescence and ultraviolet-visible (UV-vis) spectroscopic methods. Our research has shown that the mesh created with 1% concentration of SiO₂ (SiO₂/TiO₂ = 0.01), mesh spacing 400, and sintering temperature 800 °C had the optimal oil-water separation performance. It is important to note that for hexane and Terra-Nova oil, this mesh exhibits outstanding surface hydrophilicity/oleophobicity with static contact angles greater than 170°. In this experiment Terranova oil used in prepared emulsion for oil-water separation tests and the efficiency calculated was 91%. Also, these coated meshes can be reused for at least five cycles, according to durability testing, which also minimises the cost of treating oily wastewater.

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