Visible Light-Induced Photocatalytic Elimination of Organic Pollutants by TiO2: A Review

This review is focused on studies related to the elimination of organic pollutants present in aqueous systems by titanium dioxide photocatalyst under visible light illumination. The titanium dioxide semi-conductor has emerged as a very promising technology for the oxidation and mineralization of aqueous organic pollutants because of its properties such as high stability, low cost and non-toxicity. This photocatalytic process has also been used for the oxidation of organic pollutants present in air and soil besides water, in addition to the production of electricity and hydrogen in photoelectrochemical cells fed with organic wastes which renders benefits to the environment. This work covers different approaches reported in the literature for the degradation of aqueous organic pollutants by heterogeneous titanium dioxide photocatalysis. With attention given to influencing parameters, such as catalyst preparation, modification, loading and phase, pH, annealing temperature, bias potential application and inorganic ions. Such parameters are paramount to the photoactivity of this semiconductor, particularly under visible light radiation; conditions of which are imperative for viable technological green application of the phenomena.