Fabrication of Nanoporous Membranes of TiO2 on Different Substrates and their Application for Water Treatment

Abstract

This dissertation presents the mechanism for the fabrication of mechanically stable nanoporous membrane of TiO2 for water filtration antibacterial performance and dye degradation. Nanoporous membrane of TiO2 was fabricated on Ti and Si substrates to increase the mechanical strength specifically during filtration experiment. All the membrane samples were fabricated in constant anodization condition to attain the same geometry of pores and to easily compare the photocatalytic and flow through properties of all the fabricated samples of TiO2 nanoporous membrane. The free standing nanoporous membrane of TiO2 shows the best photocatalytic properties along with the maximum flux of 60 L/m2 h during water filtration experiment due to its maximum active surface area. The Ti and Si pillar support nanoporous membranes show comparatively less photocatalytic and flux values during filtration of water but these membrane samples exhibited almost double mechanical strength compared to free standing samples of TiO2 nanoporous membranes. Instead of performing all the anodization experiment on chemically polished Ti substrate some experiments of anodization were performed on unpolished Ti substrate. The electropolishing is an important task which greatly influence the geometrical variations in as-obtained nanoporous structure of TiO2. We reported dependency of geometrical parameters like pore diameter and cell size arises on nanoporous TiO2 membrane prepared by anodizing process on metallic Ti substrate, in the presence of fluoride ions based electrolyte on curved metallic surface. TiO2 membranes with uniform pores are formed on smooth Ti surface i.e., zero curvature. The pore diameter is bigger in case of negative curvature of Ti substrate, while it is smaller in case of positive curvature of metallic Ti substrate