Figure 7

Optical absorbance spectrum and residue MB concentration. (A) The optical absorbance spectrum (in term of Kubelka-Munk equivalent absorbance units) of ZnO micro-tubes. (Note that the insert image demonstrates the Tauc Plot constructed from (A), and the band gap value is determined from the extrapolation of the linear Tauc Region line to the photon energy abscissa.) (B) The residue MB concentration as a function of treatment time for three different treatments: UV light illumination only (empty square), with ZnO micro-tubes but no UV illumination (empty inverted triangle), and with ZnO micro-tubes under UV irradiation (solid square).