The removal of pollutants from wastewater is a major environ-
mental problem that is being addressed by a variety of disciplines.
Azo-dyes are a group of pollutants that require particular attention
because they are used in numerous areas and are highly toxic to
living organisms [1].
Although many methods have been used to remove organic
contaminants from the wastewater of the textile and dye indus-
tries, advanced oxidation processes such as photodegradation are
the most effective [2]. The initial step in the photodegradation of
an azo-compound usually involves a reductive cleavage of the azo-
bond, which leads to the formation of toxic aromatic amines. [3,4].
So, to control the wastewater toxicity, both the effectiveness with
which the azo-compounds are degraded and the absence of toxic
photodegradation intermediates need to be assessed.
Spectroscopic techniques such as UV–visible spectroscopy are
usually used to monitor the effectiveness of degradation while
chromatographic-mass spectrometry techniques are commonly
used for identifying subproducts [2]. In recent years [5–11]
methodologies based on the chemometric analysis of the data
obtained from spectroscopically monitoring degradation process
have proved to be very useful for extracting information about
kinetic aspects and the type of intermediate formed. In particular