Photodecomposition of phenol by silica-supported porphyrin derivative in polymer microchannel chips

Silica gel beads (diameter ∼10 μm) covalently modified with metal-free monopyridyltriphenylporphyrin (PyTPP) via a silane coupling reagent (PyTPP-SiO2) were introduced into a polymer microchannel and, the microchip was applied to photodecomposition of phenol under solution-flow conditions. The photodecomposition yield of phenol in the microchannel was dependent on the solution-flow rate (ν) and increased with decreasing ν. At ν = 0.5 μL/min, the decomposition yield was as high as 93% with the reaction time of 42 s, while that in a bulk aqueous PyTPP-SiO2 suspension was 73% with the reaction time of 2 h. In the microchannel chip experiments, furthermore, the yield increased with decreasing the thickness of the solution-flow layer above the PyTPP-SiO2 particles. On the basis of optical trapping-absorption microspectroscopy of single PyTPP-SiO2 particles before and after the photoreaction, we discuss characteristics of the photoreaction in the microchannel accommodated with PyTPP-SiO2 particles.