The synthesis of titanium dioxide photocatalysts by sol-gel method: the effect of hydrothermal treatment conditions and use of carbon nanotube template

Download

index.pdf

Date

2009

Author

Yürüm, Alp

Metadata

Show full item record

Item Usage Stats

236
views

102
downloads

Titanium dioxide (TiO2), a semiconductor, has been used in many areas like heterogeneous photocatalysis. In the present study, the effect of hydrothermal treatment conditions and the use of carbon nanotubes on the photocatalytic activity of sol-gel synthesized titanium dioxide were examined. The anatase particles were transformed into layered trititanate particles with either nanotube or nanoplate structure by hydrothermal treatment under the alkaline conditions. Post hydrothermal treatment under neutral conditions was also applied and mesoporous particles were transformed into nanostructured, highly crystalline and ordered anatase particles. Photocatalytic activities of hydrothermally treated samples were determined against Escherichia coli under solar irradiation. Results showed that hydrothermal treatment under alkaline conditions improved the photocatalytic activity. However, although being highly crystalline, after post treatment, a limited activity was obtained because of dehydration of active (101) face of anatase. Nevertheless, TiO2’s initial inactivation constant rose from 0.6 to 2.9 hr-1 after regeneration of active sites in aqueous medium under solar irradiation. In order to enhance the surface area and improve activity, multi-walled carbon nanotubes were utilized during the synthesis of TiO2. The effect of calcination conditions and presence of sodium, iron and cobalt on the photocatalytic activity were also studied. For these samples, photocatalytic activities were tested with methylene blue solution under UV irradiation. It was observed that the utilization of CNTs enhanced both the surface area and the activity. Compositions with highest CNT content had better activities for their ability to delay charge recombination. While pure TiO2‘s initial decomposition constant was 0.8 hr-1, with sodium doping the best value of 1.9 hr-1 was achieved.

Subject Keywords

Chemical engineering., Carbon nanotubes.

URI

http://etd.lib.metu.edu.tr/upload/3/12610943/index.pdf
https://hdl.handle.net/11511/18972

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

A study of catalytic nanocarbon synthesis by means of quantum mechanical methods Tezsevin, İlker; Önal, Işık; Department of Chemical Engineering (2012) Throughout this thesis work, surface nanocarbon synthesis on metal catalyst surfaces was investigated as the first step of carbon nanotube production mechanism. Study was aimed to make a comparison between the performances of selected catalyst surfaces and to find most probable mechanism for the nanocarbon synthesis on the metal catalyst surface. Formation of nanocarbon from the acetylene as carbon source on the selected Fe(111), Ni(111) and Ni(100) surfaces were studied by means of quantum mechanics. Densi...
Production of nano alumoxane from aluminum hydroxide Sezgiker, Korhan; Gündüz, Güngör; Department of Chemical Engineering (2010) Alumina (Al2O3) is one of the most widely used engineering ceramic. It can be used in a wide range of applications like electrical/thermal insulation, wear resistance, structural refractories, cutting tools, abrasives, catalyst carriers and coatings. A traditional ceramic process has several steps (i.e. powder synthesis and processing, shape forming, drying, organic burnout and densification). Accessing powders with sizes in the range of a couple of micrometers down to several tens of nanometers is consider...
The Effects of Co-Mo/CaCO3 Catalyst's Calcination Temperature and Co/Mo Weight Ratio on Carbon Nanotube Production Hocaoglu, Caner; Sezgi, Naime Aslı (2015-01-01) Carbon nanotubes (CNTs) were synthesized in the temperature range of 500-700 degrees C over cobalt (Co)- and molybdenum (Mo)impregnated CaCO3 catalysts using acetylene gas. The effects of Co-Mo/CaCO3 catalyst's calcination temperature and Co/Mo weight ratio on the carbon deposition rate were investigated. The synthesized CNTs were multiwalled nanotubes with variable outer diameters. They exhibited Type II isotherm, and their surface areas were in the range of 24.8-89.9m(2)/g. It was concluded that the Co/Mo...
SYNTHESIS OF TiO2 NANOSTRUCTURES VIA HYDROTHERMAL METHOD Bilgin, Nursev; Agartan, Lutfi; PARK, JONGEE; Öztürk, Abdullah (2014-10-16) Titania (TiO2) nanostructures were produced via hydrothermal method using amorphous TiO2 powders synthesized by the sol-gel precipitation process. The hydrothermal system was isolated from the environment and hydrothermal reactions were allowed to execute at 130 degrees C for 36 h at autogeneous pressure, and at a stirring rate of 250 rpm. Scanning electron microscopy (SEM) analysis revealed that TiO2 nanofibers formed instead of nanotubes upon utilization of amorphous TiO2 precursor. After hydrothermal syn...
Production of boron nitride nanotubes and their uses in polymer composites Demir, Can; Sezgi, Naime Aslı; Bayram, Göknur; Department of Chemical Engineering (2010) Boron nitride nanotubes (BNNTs), firstly synthesized in 1995, are structural analogues of carbon nanotubes (CNTs) with alternating boron and nitrogen atoms instead of carbon atoms. Besides their structure, mechanical and thermal properties of BNNTs are very similar to the remarkable properties of CNTs. However, BNNTs have higher resistance to oxidation than CNTs. Also, BNNTs are electrically isolating. Therefore, they are envisioned as suitable fillers for the fabrication of mechanically and thermally enhan...

Citation Formats

A. Yürüm, “The synthesis of titanium dioxide photocatalysts by sol-gel method: the effect of hydrothermal treatment conditions and use of carbon nanotube template ,” Ph.D. - Doctoral Program, Middle East Technical University, 2009.