Photocatalysis in a novel semiconducting optical fiber monolithic reactor for wastewater treatment

The development of photocatalytic reactors is essential for the successful exploitation of heterogeneous photocatalysis on semiconductor particles, which has been shown to be an effective means of removing organic pollutants from wastewater streams. In this dissertation, a novel photocatalytic optical fiber monolith reactor (OFMR), which employed a ceramic multi-channel monolith as a support for TiO2 and quartz fibers inserted inside the monolithic channels as both a light-transmitting conductor and a support for TiO2, was developed for wastewater treatment by investigating the photocatalytic degradation of o-dichlorobenzene (DCB) and phenanthrene (PHE). This configuration provides a high surface area for catalyst coating per unit reactor volume, reduces the mass transport limitations, and allows for high throughput at low pressure drop. Using optical fiber to deliver UV light can remotely control the reactor.; The effects of water flow velocity, initial contaminant concentration, thickness of the TiO2 film on the optical fiber and incident UV light intensity were investigated and optimized. The results showed mass transfer effects could not be ignored due to the relatively low flow Reynolds number. Optimum thickness of TiO2 film on the optical fiber was found to be close to 0.4 mum in this study. The kinetics of DCB and PHE degradation were pseudo-first order. Greater apparent quantum efficiency was observed for the OFMR compared with that of the continuous annular reactor, which suggested that this novel reactor has the potential in photocatalytic applications.; The light distribution profile inside each cell of the monolith was quantitatively analyzed. The radiation field model with the fitting parameters was set up and validated. The two-dimensional heterogeneous convective-diffusion-reaction steady-state model of a multi-channel OFMR was developed by incorporating an empirical radiation field submodel, an annular flow dynamics model and a Langmuir-Hinshelwood kinetics submodel. Reasonable agreement was found between the model-predicted and experimentally observed photodegradation conversion data within the limits of experimental error, using the total rate constant as the only adjustable parameter. The model can be used to optimize the design parameters in an OFMR.