The sample solution and Cr(VI) solution were added to
the reactor with a predetermined amount of TiO2. The reactor
was water-jacketed to maintain constant temperature
and magnetic stirring was used through the experiment. The
pH value of the solution was maintained at a desired level
with KOH and H2SO4 and monitored by a Kyoto AT-400
autotitrator. The total volume of reaction solution was maintained
at 40 ml for each experiment. When the UV lamp
was turned on (λmax = 253.7 nm), photocatalytic oxidation
of the organic compounds began to occur, accompanying
an increase of Cr(III) concentration produced by the photocatalytic
reduction of Cr(VI). After 10 min irradiation reaction,
the aqueous samples were centrifuged by a centrifugal
presvac DCS-16 RV and filtered using a 0.22 m membrane