Photocatalytic microfluidic reactors utilizing titania nanotubes on titanium mesh for degradation of organic and biological contaminants

Microfluidic reactors have gained considerable interest for photocatalytic degradation of contaminants in water. These systems have advantages such as large surface-area-to-volume ratio and high control of fluid flow, yet still suffer from drawbacks due to limited mass transport associated with laminar flow. The use of titania nanotubes synthesized on a mesh substrate shows improved photocatalytic performance in comparison to nanotubes synthesized on a foil substrate in a microreactor. At the lowest flow rate (25 mL/min), the area normalized fractional conversion of methylene blue increased from 20% for foil to 46% in the case of nanotubes on mesh. The enhanced photocatalytic performance of the mesh is due to shorter diffusion distance and induction of flow perturbation. Also, the radially outward oriented nanotubes formed over the circumference of the titanium wire leads to the efficient capture of both reflected and refracted light. The device was also applied for inactivation of Escherichia coli O157:H7. At a flow rate of 50 mL/min, the titania nanotubes on a mesh microreactor were able to achieve >99% inactivation of E. coli under AM 1.5 (approximate to 100 mW/cm(2)) simulated solar light. (C) 2015 Elsevier Ltd. All rights reserved.