Abstract
Effect of HCl treatment on the hydrothermally prepared titanate nanotubes was studied. The pH and repeating times of acid treatment influenced both the microstructure and residual Na concentration of the titanate nanotubes. The lower pH and repeated acid treatment decreased residual Na ions in the titanate nanotubes, however, the acid treatment at much lower pH (pH 1) damaged the surface of nanotubes. The titanate nanotubes with almost no residual Na ions (i.e., less than the lower limit of detection by energy dispersive X-ray spectroscopy) can be obtained by hydrothermal method at 120°C for 72 h and H2O wash and subsequent HCl treatment at pH 2 for 3 times. The Na-free nanotubes (H2Ti3O7) were thermally unstable, and they changed into anatase particles at 500°C.
