Abstract:
Photocatalysis is a green technology for the degradation of persistent organic compounds in water and has
been successful in the removal of several water pollutants. Degradation of organic compounds in water is often
accompanied by the formation of several intermediate compounds, some of which are feared to be more toxic
than the original compound being treated. In this study, aromatic intermediates formed during the photocatalytic
degradation of phenol were profiled in a batch system. The carbon-13 isotopic labelling technique was used to
track the degradation pathway. Photocatalytic degradation of phenol was conducted in 1L solutions of phenol
(20mg/L) in ultrapure water in a batch system. Catalyst concentration was constant at 8mg/L Titanium dioxide
(TiO2). Concentration of phenol and detection of the aromatic intermediates of phenol degradation were
monitored on a Waters High Performance Liquid Chromatograph (HPLC) and Gas Chromatogram- Mass
Spectrometer (GC-MS), respectively. Aromatic intermediates identified during the course of photocatalysis of
the phenol include hydroquinone, benzoquinone catechol and resorcinol. The concentration of phenol was
determined from the calibration curve of standards of phenol. Photocatalysis is a promising technology for the
complete mineralization of aromatic organic pollutants as it has been demonstrated that both the pollutant and
its direct intermediates can be completely removed from solution. Phenol degradation produces first aromatic
dihydroxy substituted compounds that are further degraded forming cycling compounds on cleavage of the
aromatic ring. The distribution of the degradation intermediates confirms that the dominant degradation pathway
is via hydroxyl radical mechanism.
