Optofluidics-based membrane microreactor for wastewater treatment by photocatalytic ozonation

Abstract

Conventional photocatalytic ozonation usually suffers from the mass transport issue associated with low specific surface area and gas/liquid interface and liquid film. To address this issue, a new membrane microreactor based on optofluidics was developed for wastewater treatment by the photocatalytic ozonation in this work. The key component of the photocatalytic membrane was prepared by coating TiO2 onto carbon paper followed by the hydrophobic treatment with polytetrafluoroethylene. Such design offered several advantages such as large surface-area-to-volume ratio, enhanced mass transport, intense and uniform light irradiation, efficient separation of the liquid/gas phases, and good gas permeability. The performance of the developed microreactor was evaluated by methylene blue degradation, and the products were analyzed by the ion chromatography. Experimental results showed that because of these advantages, the optofluidic membrane microreactor not only yielded better performance but also showed more complete oxidation as compared to photocatalysis and ozonation. Parametric studies indicated that increasing the residence time and decreasing the methylene blue concentration could improve the degradation efficiency. High light intensity benefited photocatalytic ozonation. The obtained results demonstrate that the developed optofluidic membrane microreactor is feasible for wastewater treatment by photocatalytic ozonation. Besides, this new type of microreactor can also be applied to other photocatalytic systems.