Recovery TiO2 and sodium titanate nanowires as Cd(II) adsorbent from waste V2O5-WO3/TiO2 selective catalytic reduction catalysts by Na2CO3-NaCl-KCl molten salt roasting method

In this study, Cd(II) adsorbent has been recovered from waste and toxic WO3-V2O5/TiO2 Selective Catalytic Reduction (SCR) catalysts via a creative Na2CO3-NaCl-KCl (NNK) molten salt roasting method (MSM) followed by a leaching process to remove the toxic and valuable W and V. Such facile process enables a faster roasting reaction at a lower temperature compared to conventional roasting methods, achieving an optimized W and V leaching rate of 99.3% and 98.4%. The produced Cd(II) adsorbent mainly consists of TiO2 and sodium titanate nanowires (TiO2/STNWs) with a maximum Cd(II) adsorption capacity is 146.5 mg/g when the pH value is 6. The Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photo-electron Spectroscopy (XPS) analysis show that the adsorption of Cd(II) by our products can be ascribed to the Cd(II) ion exchange with Na ions and the hydroxyl groups. This study proposes a sustainable and economic approach for producing large scale and high-quality Cd(II) adsorbent via disposing waste SCR catalysts, which shows a great potential in the industrial applications. (C) 2018 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.