Enhanced Photocatalytic Degradation of Methylene Blue and Methyl Orange Dyes via Transition Metal-Doped Titanium Dioxide Nanoparticles
Simon Bbumba *
Department of Chemistry, College of Natural Sciences, Makerere University, P.O. Box 7062, Kampala, Uganda and Department of Science, Faculty of Science and Computing, Ndejje University, P.O. Box 7088, Kampala, Uganda.
Moses Kigozi
Department of Chemistry, Busitema University, P. O. BOX 236, Tororo, Uganda.
Ibrahim Karume
Department of Chemistry, College of Natural Sciences, Makerere University, P.O. Box 7062, Kampala, Uganda.
Hussein Kisiki Nsamba
Department of Chemistry, College of Natural Sciences, Makerere University, P.O. Box 7062, Kampala, Uganda.
Chinaecherem Tochukwu Arum
Department of Materials Science and Explosives, Faculty of Science, Nigerian Defence Academy, Kaduna, PMB 2109, Kaduna, Nigeria.
Ivan Kiganda
Department of Chemistry, College of Natural Sciences, Makerere University, P.O. Box 7062, Kampala, Uganda.
Kato Maximillian
Department of Science, Faculty of Science and Computing, Ndejje University, P.O. Box 7088, Kampala, Uganda.
Resty Alexandra Nazziwa
Department of Chemistry, College of Natural Sciences, Makerere University, P.O. Box 7062, Kampala, Uganda.
John Ssekatawa
Department of Chemistry, College of Natural Sciences, Makerere University, P.O. Box 7062, Kampala, Uganda.
Collins Letibo Yikii
Department of Chemistry, College of Natural Sciences, Makerere University, P.O. Box 7062, Kampala, Uganda.
Muhammad Ntale
Department of Chemistry, College of Natural Sciences, Makerere University, P.O. Box 7062, Kampala, Uganda.
*Author to whom correspondence should be addressed.
Abstract
Herein, we reviewed the photocatalytic degradation of methylene blue and methyl orange using titanium dioxide nanoparticles. The nanoparticles normally face challenges due to electron-hole recombination effects and low surface area. Doping with transition metals such as copper (Cu), chromium (Cr), manganese (Mn), cobalt (Co) and nickel (Ni) is an alternative way of reducing the electron-hole recombination effects, improves structural and electronic properties but also reduces on the band gap energy below 3.0 eV. Photocatalyst which is an advanced oxidation process (AOP) is used as an alternative to remove both methylene blue and methyl orange dyes. This process produces highly reactive oxygen species (ROS) such as hydroxyl radical, sulphates and superoxide radical which create alternative pathways for the degradation of synthetic dyes to less toxic by-products which are water, hydrochloric acid and carbon dioxide. This review further discusses the synthesis techniques which include chemical vapor deposition, hydrothermal synthesis, sonochemical synthesis, sol-gel method, spray pyrolysis, etc that are commonly used in the preparation of pure and doped titanium dioxide nanoparticles.
Keywords: photocatalysis, titanium dioxide, methylene blue, methyl orange, sol-gel