1 Introduction
During the recent years, photocatalysis has attracted a
continuous interest owing to its potential applications in fields
such as water and air purification[1,2], and also for the
preparation of organic compounds that are difficult to obtain
by alternative procedures[3,4]. Upon illumination of a
semiconductor with photons having energy higher than or
equal to the band gap energy of the semiconductor,
electron–hole pairs are generated and migrate to the external
surface of the bulk particle. Like many catalytic processes, the
overall photocatalysis consists of a series of independent steps:
(a) adsorption of reactants from the fluid bulk phase onto the
solid surface, (b) reaction in the adsorbed phase, and (c)
desorption of reaction products from the surface into the fluid
bulk phase. Material modification to increase substrate
adsorption in the photocatalytic sites can lead to a
photocatalyst with an enhanced efficiency.
The most widely used semiconductor is TiO2, which
offers a non-expensive, non-toxic, biocompatible, and high
reactivity for removal of inorganic and organic pollutants in
wastewater, particularly for organic compounds which can be
completely degraded under photocatalytic oxidation[5-10].
However, TiO2 powders have some disadvantages, such as
difficulty in separation of catalyst from the treated solution