Applied Catalysis A: General 389 (2010) 1–8 Contents lists available at ScienceDirect Applied Catalysis A: General journal homepage: www.elsevier.com/locate/apcata Review Immobilisation of titanium dioxide onto supporting materials in heterogeneous photocatalysis: A review Ang Ying Shan, Tinia Idaty Mohd. Ghazi ∗ , Suraya Abdul Rashid Department of Chemical and Environmental Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia article info Article history: Received 8 April 2010 Received in revised form 20 August 2010 Accepted 25 August 2010 Available online 9 October 2010 Keywords: Immobilisation Titanium dioxide Photocatalyst abstract The aim of this review is to offer an overview of the evolution in the use of different anchors (supports) for the immobilisation of a semiconductor photocatalyst, which is titanium dioxide (TiO 2 ). Several supports and immobilisation techniques that are commonly used for the removal of contaminants in wastewater are discussed. Generally, the immobilisation of a photocatalyst onto supporting material has largely been carried out via one of two major routes; physical (the thermal treatment method) route or chemical (the sol–gel method, chemical vapour deposition, electrodeposition, etc.) route. The benefits and drawbacks of various immobilisation techniques to obtain a high surface area TiO 2 support are also discussed. © 2010 Elsevier B.V. All rights reserved. Contents 1. Introduction .......................................................................................................................................... 1 2. Mechanism of photocatalysis ........................................................................................................................ 2 3. Photocatalyst structure .............................................................................................................................. 2 4. Photocatalyst supports ............................................................................................................................... 2 4.1. Glass .......................................................................................................................................... 2 4.2. Activated carbon .............................................................................................................................. 3 4.3. Silica materials ............................................................................................................................... 4 4.4. Polymeric materials .......................................................................................................................... 4 4.5. Other uncommon supports .................................................................................................................. 4 5. Various immobilisation techniques of TiO 2 onto supports .......................................................................................... 4 5.1. Sol–gel method ............................................................................................................................... 5 5.2. Thermal treatment method .................................................................................................................. 5 5.3. Chemical vapour deposition (CVD) .......................................................................................................... 6 5.4. Electrophorectic deposition .................................................................................................................. 6 6. Characterisation of immobilised TiO 2 ............................................................................................................... 6 7. Conclusion ............................................................................................................................................ 7 Acknowledgement ................................................................................................................................... 7 References ........................................................................................................................................... 7 1. Introduction Organic chemicals which may be present as pollutants in wastewater effluents from industrial or domestic sources must be removed or destroyed before the water can be discharged into the environment. The increased public concern over these envi- ronmental pollutants has prompted the need to develop effective ∗ Corresponding author. Tel.: +60 3 89464427; fax: +60 3 86567120. E-mail address: tinia@eng.upm.edu.my (T.I.Mohd. Ghazi). removal operations, which are known as advanced oxidation pro- cesses (AOPs). These processes are based on the production of hydroxyl radicals (OH • ) as strong oxidizing agents to mineralize the organic pollutants. Among the various AOPs, semiconductor mediated photocatalysis has been accorded great significance in recent times due to its potential to mineralize a wide range of recalcitrant organic pollutants at ambient temperature and pres- sures into harmless substances [1–5]. In the past, much research has been carried out into a slurry system (suspension of fine powdered TiO 2 ). However, the post-treatment removal of TiO 2 causes a sig- 0926-860X/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.apcata.2010.08.053