3.3. Adsorption and photocatalytic activity of the samples
Rhodamin B is a widely used colorant in textiles and foodstuffs
and it can induce irritation to human skin, eyes and respiratory
tract. It is carcinogenic and chronically toxic toward human beings.
The decolorization of RhB is a probe reaction often cited to establish
the photocatalytic activity of photocatalyst [33,34]. The activity
of the sample is then evaluated by photodegradation of RhB.
Fig. 8a shows the absorbance spectra of the RhB solution in the
presence of the Fe3O4/SiO2/TiO2 catalyst (sample C2) during the UV
irradiation, with the wavelength covering 400–700 nm. With reaction
time up to 105 min, the intensity of the maximum peak at
about 553 nm decreased gradually without remarkable peak shift,
indicating the photodegradation of RhB by the Fe3O4/SiO2/TiO2
catalyst.