Photocatalytic decolorization of reactive black 5 dye in aqueous TiO_2/ZnO suspension under UV light

摘要

The release of colored wastewaters in the ecosystem is a dramatic source of aesthetic pollution, eutrophication, and perturbations in aquatic life. Research devoted to the ill-effects caused by chemicals have acquired importance as a result of the increased care and attention paid to the environment and human health by international, socio-political, and legislative authorities. Compliance with strict quality standards is especially called for, in the case of handling and using toxic substances that affect the environment and health. Growing concern about environmental issues has prompted the industries to investigate appropriate and eco-friendly treatment technologies. The prime need of these industries is to have a simple but effective inexpensive technology for the treatment of wastewater. Photocatalysis is considered as an important part of emerging greener technology as it uses environmentally friendly oxidants (oxygen, hydrogen peroxide or ozone), photocatalysts (titanium dioxide, ferrous ions or its complexes), and ultraviolet (UV) radiation to degrade and mineralize the toxic organic pollutants. In this study, the photodecolorization of Reactive Black 5 dye has been performed using titanium dioxide (TiO_2 P-25 Degussa) and zinc oxide (ZnO) using a mixed batch reactor. The rate of degradation was studied in terms of changes in absorption spectra and reduction in chemical oxygen demand (COD). Various process parameters such as catalyst dose, pH, and dye initial concentration have been varied and their effect on the decolorization efficiency has been studied. The photocatalyst zinc oxide was found to be more efficient as compared with titanium dioxide.