Abstract

Microfluidics for photocatalytic water purification: now and beyond

Xuming Zhang, Assistant Professor, Hong Kong Polytechnic University

Microfluidics handles small volume of liquid using microstructures and benefits the photocatalysis in various aspects in terms of large surface area, short diffusion length, uniform residence time, uniform illustration, short reaction time, long durability and more functionalities, etc. These would help solve the major problems of current photocatalysis technology such as mass transfer limitation, photon transfer limitation, electron/hole recombination problems. Over the years, there are mainly four types of microfluidic reactors: micro-capillary reactors, single-microchannel reactors, multi-microchannel reactors, and planar microreactors. Our work focuses mostly on the planar microreactor designs, which have progressively solved the problems of photocatalysis. On the application side, the microfluidic reactors could be scaled up for large-scale industrial uses. But more realistically, they may find niche applications for rapid characterization of expensive photocatalysts, parallel performance comparison of different photocatalysts and optimization of the operation condition. In summary, the microfluidics provides a versatile platform for photocatalysis and their synergy opens up new rooms for scientific research and real applications. ACKNOWLEDGEMENTS This work is partially supported by The Research Grants Council (RGC) of Hong Kong through the General Research Fund grants (PolyU 5327/11E, PolyU 5334/12E and N_PolyU505/13), The Hong Kong Polytechnic University (G-YN07), and National Science Foundation of China (no. 61377068).