Purification of titanate nanotubes using a mesh-stacked dielectrophoretic separator equipped with carbon nanotube electrodes

• Carbon nanotubes were grown on mesh-stacked electrodes for dielectrophoresis.
• Titanate nanotubes were purified by dielectrophoresis with developed electordes.
• Large bandgap energy titanate nanotubes were concentrated.

A mesh-stacked dielectrophoretic (MS-DEP) separator whose electrodes were covered with multi-walled carbon nanotubes (MWCNTs) was built to purify titanate nanotubes (TNTs) synthesized by hydrothermal conversion from anatase TiO2 powders. MWCNTs were synthesized directly on the surface of stainless mesh electrodes. It was experimentally observed that this MS-DEP separator could be useful to purify TNTs. It was found that relatively low frequency for AC voltage applied on the MS-DEP separator was preferable when it was required to collect TNTs possessing a large energy bandgap. In addition, a model calculation was carried out to qualitatively discuss the effect of MWCNT to enhance the electric field strength at MWCNTs, which could generate the strong DEP force on small particles.