A Plackett–Burman design in hydrothermal synthesis of TiO₂-derived nanotubes

Abstract

In this paper, a screening approach, involving the use of Plackett–Burman experimental design, permitted the evaluation of effects of 8 parameters from hydrothermal synthesis of TiO₂-derived nanotubes such as raw material surface area, $m_{{{\text{TiO}}_{2} }} ,$ filling factor, temperature, time, aging, stirring, and HCl concentration on the physical properties. All variables were investigated at two widely spaced levels. According to the obtained results, the influences of different factors depend on the selected response. The study highlights the role of filling factor, stirring, temperature, raw material, and time conditions on the surface area response. Also, the study highlights the role of filling factor and stirring conditions on the pore size response. No factors influenced on the pore volume response. The effects of some parameters, such as aging, $m_{{{\text{TiO}}_{2} }} ,$ and HCl concentration, were negligible. These factors could be eliminated from hydrothermal synthesis. The low surface area of products related to the higher surface area of raw material and stirring condition. TEM micrographs showed that the morphologies for high, medium, and low surface areas of products are nanotubes, nanowires, and nanospheres, respectively.