Effect of silver on the photocatalytic degradation of humic acid

✍ Scribed by Ankesh Bansal; S. Madhavi; Timothy Thatt Yang Tan; T.M. Lim

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 673 KB
• Volume: 131
• Category: Article
• ISSN: 0920-5861
• DOI: 10.1016/j.cattod.2007.10.078

✦ Synopsis

In this study, humic acid was mineralized and degraded photocatalytically in presence of bare TiO 2 and silver loaded TiO 2 (0.5-5.0 at.% Ag). Xray diffraction (XRD) and inductive coupled plasma (ICP) analysis confirm the complete photodeposition of silver over TiO 2 by photodeposition method. X-ray photoemission spectroscopy (XPS) studies confirmed the presence of Ag 0 in all Ag-TiO 2 samples and the absence of Ag + ions. Silver loading over TiO 2 improved the rate of mineralization and degradation of humic acid with a maximum loading of 1.0 at.% Ag. Ninety percent carbon from humic acid was mineralized to CO 2 only after 60 min by using bare TiO 2 as a photocatalyst. However, this conversion was possible within 40 min by using 1.0 at.% Ag-loaded TiO 2 . This observation verifies that coating of metals like silver over TiO 2 acts as an electron sink and can improve the redox reaction by preventing electron-hole recombination reaction. The optimum 1.0 at.% Ag loading in the current work is indicative that the blocking of the TiO 2 surface active sites by silver also plays an important role in the photocatalytic mineralization and degradation of humic acid. As the silver loading is increased, less number of active site are available over the surface of photocatalyst TiO 2 for redox reaction. This finding was supported by the TEM analysis of the photocatalyst samples.