Simple Fabrication of a Continuous-Flow Photocatalytic Reactor Using Dopamine-Assisted Immobilization onto a Fluoropolymer Tubing
Chetsada Khositanon, Siwada Deepracha, Suttichai Assabumrungrat, Makoto Ogawa, Nopphon Weeranoppanant
Abstract
A flow reactor has been found to be advantageous for a photocatalytic reaction due to enhanced transport phenomena and photon transfer. A fluoropolymer is a promising material for fabricating a photocatalytic flow reactor because it is transparent, commercially available, and inexpensive. However, its high hydrophobicity and chemically inert nature makes it difficult to coat photocatalysts. In this work, we successfully developed a protocol to immobilize photocatalysts (TiO2–P25) onto the wall of a perfluoroalkoxy alkane tubing. The immobilization was enabled by the initial depositions of polydopamine and polyethyleneimine (PEI) layers. Then, through an ionic interaction, P25 was immobilized onto the PEI layer. A layer-by-layer PEI–P25 assembly yielded a high photocatalyst loading, which in turn enhanced the photocatalytic activity significantly. A continuous-flow operation of the photocatalytic methylene blue decolorization was demonstrated with negligible leaching of the photocatalysts and minimal loss in activity over time. A transport phenomenon inside the tubular reactor was modeled to elucidate the effect of the process parameters on kinetic and adsorption parameters. This simply fabricated flow reactor shows a great potential for photocatalytic applications.