ABSTRACT Photocatalytic remediation processes constitute a highly promising technique to degrade priority pollutants without the input of chemicals such as ozone and hydrogen peroxide. While gas phase based photocatalytic processes have already reached the commercial application stage, aqueous phase based photocatalytic processes in spite of their versatility in degrading a wide variety of organic compounds, still have to overcome low quantum efficiencies to favorably compete with other oxidation processes. Titania based catalysts have been shown to be the most active among the various catalysts investigated. This paper reviews the various aspects of the photocatalytic process which influence the quantum efficiency as well as the strategies proposed in the literature for its enhancement. These strategies include advanced photocatalyst designs such as the composite semiconductor oxides as well as new reactor designs that promote controlled periodic illumination of the photocatalyst. While three to five fold improvements in photocatalytic activity have been demonstrated by these individual approaches, no attempt has been made so far to combine the various strategies in the same system. A significant research and development effort is required to optimize the promising strategies reviewed in this paper for different target compounds in order to realize the full potential of the photocatalytic process.
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