The effect of stirring speed on the photocatalysed degradation
kinetics of 4-CP (initial concentration 1 × 10−5 mol/l) is shown
in Fig. 6b and, as observed for AO7, the 4-CP concentration vs.
time profiles all exhibited exponential decays. Although there is
strong increase in experimental rate constant when stirring is
applied (220 rpm), further increases in stirring speed (from 220 to
1160 rpm) did not produce a significant change in photocatalytic