460 plus

Lignin (Lig) was purchased from Tokyo Chemical Industry Co., Ltd. (Tokyo, Japan). Calcined Lig at 200, 400, 600, 800, and 1000 °C was prepared by keeping it in a muffle furnace for 2 h (denoted as Lig200, Lig400, Lig600, Lig800, and Lig1000, respectively). Cadmium chloride was purchased from FUJIFILM Wako Pure Chemical Co. (Osaka, Japan).
The morphologies of each adsorbent were measured by scanning electron microscopy SU1510 (SEM, Hitachi High-Technologies Co., Tokyo, Japan). The specific surface area and pore volumes were analyzed using a specific surface analyzer NOVA4200e (Quantachrome Instruments Japan G.K., Kanagawa, Japan). The surface functional groups were analyzed by the Fourier-transform infrared (FT-IR) spectroscopy system 460Plus (JASCO Co., Tokyo, Japan). The binding energy and elemental distribution of the adsorbent surface were measured by the X-ray photoelectron spectroscopy system AXIS-NOVA (Shimadzu Co., Ltd., Kyoto, Japan) and electron microanalyzer JXA-8530F (JEOL, Tokyo, Japan), respectively.

The degree of crystallinity of the MWCNT/TiO₂ nanocomposites was investigated by the X-ray Diffraction spectroscopy (XRD) technique using a Schimadzu diffractometer (Model: XRD 6000) with Cu K (0.154 nm). The Fourier transform infrared (FTIR) spectra of the pristine and acid treated MWCNTs were recorded using the FTIR spectrophotometer (JASCO-460 PLUS, Japan). The morphology of the MWCNTs/TiO₂ composites were visualised using (JOEL 2010F UHR version electron microscope) (TEM) operating at an accelerating voltage of 200kV. Photoluminescence spectroscopy was performed on a Perkin Elmer LS 55 fluorescence spectrometer with different excitation wavelength at room temperature. The measurement accuracy of the recorded wavelengths was about ± 0.5 nm. The optical properties of the nanocomposites as well as their photocatalytic activities were studied using the Ultra violet visible spectrometer (UV-vis.) model (Shimadz-UV1650PC).