The purpose of this work is to develop a new method using
nano-TiO2 as an oxidizing photocatalyst for monitoring
COD. In a nano-TiO2–K2Cr2O7 system, where K2Cr2O7
is stoichiometrically involved, K2Cr2O7 can easily accept
photo-exited conduction band electrons and enhance the
ability of photocatalytic degradation of organic compounds.
Therefore, the COD of a given sample can be assessed by
tracing the change of the concentration of Cr(III) produced
by the photocatalytic reduction of K2Cr2O7. The optimization
of operation conditions was studied. When using
this method to determine real samples, it displays a short
analysis time, simplicity, and no requirement of expensive
and toxic reagents. The results were good as regards
to sensitivity and correlation according to the analysis of
a few real samples. Additionally, results obtained by the
method for determination of COD were in excellent correspondence
with the values obtained using the conventional
method.