Synthesis and Applications of Discrete TiO2 Nanotubes in Water Treatment and Superhydrophobic Coatings

• Author / Creator

  Najia Mahdi

• TiO2 as an n-type semiconducting material is one of the most investigated transition metal oxides with a large bandgap of 3.2 eV that is environmentally friendly, chemically stable, biocompatible and have applications in photocatalysis, superhydrophobic coatings, antifouling membranes for water treatments, solar cells and biomedical technologies due to its physical, optical, chemical and electronic properties. The 1-D nanostructures of TiO2 such as nanotubes, nanorods, nanowires and nanofibers have been explored extensively due to their effective one-directional charge transport and large surface area when compared with bulk TiO2. Despite the advantages of 1-D nanotube arrays, to further understand and benefit from their properties in full potential, the discrete TiO2 nanotubes (d-TNTs) have gained attention specifically in applications where their porosity, hydrophilicity, adsorption capacity, large surface area and fast electron transport without any interruption matter.
  
  The present work described in this thesis is towards understanding the synthesis of TiO2 nanotubes for simpler discretization and their applications in two different projects; (1) antifouling and hydrophilic fabrication of polymer nanocomposite membranes to be used in water treatments, and (2) all-solution based, scalable superhydrophobic coatings to be used in oil and gas industry as well as two other projects proposed for future work investigating the fluorescent, electrical and optical properties of d-TNTs.
  In this thesis, d-TNTs are synthesized using three different organic electrolytes (ethylene glycol, EG-, dimethyl sulfoxide, DMSO-, and diethylene glycol, DEG-) containing fluoride ions to investigate their behavior in superhydrophobic coatings and antifouling polymer membranes. Amongst the other fabrication methods of TiO2 nanotubes, electrochemical anodization method is the simplest and cost effective method to synthesize TiO2 nanotubes with tunable properties such as length, diameter, wall thickness and barrier (oxide) layer thickness. In water treatment application, the hydrophilic TiO2 nanotubes with large area and high absorbance capacity are used as nanofillers in naturally hydrophobic PES polymer improving the rejection of organic content, water flux and antifouling properties in water filtration processes. In superhydrophobic coatings application, the hydrophobic properties of stainless steel is improved by coating a thick layer of d-TNTs solution due to nanotube’s porosity, mechanical strength, distance between nanotubes and inner microvoids that create a Cassie-Baxter state. To further improve the hydrophobicity and corrosion resistance of stainless steel, ODPA (octadecylphosphonic acid) SAMs is used to functionalize the surface of stainless steel after discrete nanotube coating is applied. The resultant surface presents a high contact angle (166±8º) with a good surface coverage and high corrosion resistance confirmed by electrochemical impedance spectroscopy and abrasion/adhesion tests.

• Subjects / Keywords

  • Water Treatment
  • Nanotube
  • Titania
  • TiO2
  • Superhydrophobic Coatings

• Graduation date

  Fall 2019

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-572z-mk95

• License

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