In order to investigate the efficiency of the nanocomposite towards degradation of phenol under different flow rates, experiments are carried out with varying flow rates from 10 to 50 ml min−1 under similar conditions (Fig. 6). It is observed that at higher flow rate (50 ml min−1), the degradation phenol is almost
10% while at slower flow rate (10 ml min−1) it is around 70%. This observation can be attributed to mainly three factors; the induction period, contact time (residence time) and space time of the reactor for the reactant. Since the induction period at different flow rates are found to be almost similar (∼10 min), it seems that the contact time between reactant and photocatalyst has significantly contributed towards phenol degradation which has resulted in lesser amount of phenol removal. Similarly, space time in reactor calculated for flow rates such as 20 ml min−1 was found to be 50 min. These observations are suggestive of synergic effect of contact and space time that has resulted in the higher degradation of phenol at lower flow rate due to larger exposure of reactant molecules towards UV radiations in presence of a catalyst. Similar trends are also observed when the concentration of phenol is increased from 200 to 2000 mg L−1 (Fig. 7). Thus, the effectiveness of the photocatalyst is lower at both higher concentration of phenol and higher flow rate inside CSTR.