title: Photocatalytic degradation of the diazo dye naphthol blue black in water using MWCNT/Gd,N,S-TiO2 nanocomposites under simulated solar light.
abstract: A simple sol-gel method was employed to prepare gadolinium, nitrogen and sulphur tridoped titania decorated on oxidised multiwalled carbon nanotubes (MWCNT/Gd,N,S-TiO2), using titanium (IV) butoxide and thiourea as titanium and nitrogen and sulphur source, respectively. Samples of varying gadolinium loadings (0.2%, 0.6%, 1.0% and 3.0% Gd3+) relative to titania were prepared to investigate the effect of gadolinium loading and the amounts of carbon nanotubes, nitrogen and sulphur were kept constant for all the samples. Furthermore, the prepared nanocomposites were evaluated for the degradation of naphthol blue black (NBB) in water under simulated solar light irradiation. Higher degradation efficiency (95.7%) was recorded for the MWCNT/Gd,N,S-TiO2 (0.6% Gd) nanocomposites. The higher photocatalytic activity is attributed to the combined effect of improved visible light absorption and charge separation due to the synergistic effect of Gd, MWCNTs, N, S and TiO2. Total organic carbon (TOC) analysis revealed a higher degree of complete mineralisation of naphthol blue black (78.0% TOC removal) which minimises the possible formation of toxic degradation by-products such as the aromatic amines. The MWCNT/Gd,N,S-TiO2 (0.6% Gd) was fairly stable and could be re-used for five times, reaching a maximum degradation efficiency of 91.8% after the five cycles.
authors.affiliation: Department of Applied Chemistry, University of Johannesburg, Faculty of Science, P. O. Box 17011, Doornfontein 2028, South Africa; DST-NRF Centre of Excellence in Strong Materials, School of Physics, University of the Witwatersrand, Private Bag 3, WITS 2050, South Africa. Electronic address: gcmamba@gmail.com.
authors.forename: Gcina
authors.initials: G
authors.lastname: Mamba
authors.affiliation: Department of Applied Chemistry, University of Johannesburg, Faculty of Science, P. O. Box 17011, Doornfontein 2028, South Africa; DST-NRF Centre of Excellence in Strong Materials, School of Physics, University of the Witwatersrand, Private Bag 3, WITS 2050, South Africa.
authors.forename: Xavier Yangkou
authors.initials: XY
authors.lastname: Mbianda
authors.affiliation: DST-NRF Centre of Excellence in Strong Materials, School of Physics, University of the Witwatersrand, Private Bag 3, WITS 2050, South Africa; Nanotechnology and Water Sustainability Unit, College of Engineering, Science and Technology, University of South Africa, Florida Campus, Florida, Johannesburg, South Africa. Electronic address: ajaykmishra1@gmail.com.
authors.forename: Ajay Kumar
authors.initials: AK
authors.lastname: Mishra
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D002384:Catalysis; D004396:Coloring Agents / Q000737:chemistry; D005682:Gadolinium / Q000737:chemistry*; D015394:Molecular Structure; D053761:Nanocomposites / Q000737:chemistry; D037742:Nanotubes, Carbon / Q000737:chemistry*; D009282:Naphthalenesulfonates; D009284:Naphthols / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry*; D010782:Photolysis; D013455:Sulfur / Q000737:chemistry*; D013472:Sunlight; D014025:Titanium / Q000737:chemistry; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D037742:Nanotubes, Carbon; D009282:Naphthalenesulfonates; C558655:Naphthol Blue Black; D009284:Naphthols; D014874:Water Pollutants, Chemical; D014867:Water; C009495:titanium dioxide; D013455:Sulfur; D005682:Gadolinium; D014025:Titanium; D009584:Nitrogen
keywords: Gadolinium; MWCNTs; NBB; Simulated solar light; Tridoped titania