Decomposition of nonionic surfactant in a labyrinth flow photoreactor with immobilized TiO2 bed

The photocatalytic oxidation of nonionic surfactant polyoxyethylene nonyl phenyl ether (Rokafenol N9) in water in the labyrinth flow reactor with immobilized catalyst bed was investigated. Tytanpol A11 titanium dioxide supplied by Chemical Factory “Police” S.A. (Poland) was used as a photocatalyst. The influence of various factors, including reaction mixture flow rate, initial surfactant concentration and time of the process performance on the photodegradation of model compound were examined. It was found that the effect of the initial surfactant concentration on the effectiveness of Rokafenol N9 removal was practically negligible in the range of the investigation, whereas the reaction mixture flow rate has a significant effect on the effectiveness of Rokafenol N9 decomposition. The highest surfactant photodegradation (92%) was obtained at the solution flow rate equal to 11.98 dm3/h and the lowest (86%) at 1.64 dm3/h. The apparent rate constant k was linearly dependent on the reaction mixture flow rate. Extension of the reaction time from 5 to 60 h did not result in a complete mineralization of Rokafenol N9 to CO2 and water.