In a typical photocatalytic run, 350 mL of the aqueous solution
containing the desired concentration of ERM in the range 2.5–
30 mg/L (these values are well below ERM solubility in water
which has been reported to be 2–2.1 g/L [7,16]) were loaded in the
reaction vessel. These concentrations, although considerably
greater than those typically found in environmental samples,
were chosen to allow (i) the assessment of process efficiency
within a measurable time scale and (ii) the accurate determination
of residual organic carbon with the analytical techniques
employed in this work. The solution was slurried with the
appropriate amount of catalyst and magnetically stirred for
30 min in the dark to ensure complete equilibration of adsorption/desorption
of ERM onto the TiO2 surface. After that period, the
UV-A lamp was turned on, while pure O2 was continuously sparged
(unless otherwise stated) in the liquid under stirring. During
photocatalytic experiments, temperature was maintained at 25 8C
with a temperature control unit. In most cases, experiments were
performed at ambient solution pH which was acidic in the order 4–
5.7 (depending on ERM initial concentration and type of catalyst)
and left uncontrolled during the reaction.