Photocatalytic oxidation of pharmaceutical micropollutants in a flow-through reactor
The presence of pharmaceutical micropollutants in drinking and natural waters has recently become increasingly publicized. The increased presence of pharmaceutical micropollutants in drinking water requires additional water treatment strategies. Diatrizoate, carbamazepine, sulfamethoxazole, and ibuprofen represent several classes of common drug compounds that are present in natural and drinking water and are not effectively treated by conventional methods. Past experiments with TiO2 suspensions as a photocatalyst show the potential for the degradation of these drugs using this method. The photocatalyst works by the excitation of electrons in the TiO2 semiconductor by photons with energy exceeding the materials’ band gap energy. The resulting valence band holes are strong oxidants that can directly react with contaminants or oxidize adsorbed water molecules to form hydroxyl radicals, which can then react with the micropollutants. However a continuous, rather than batch, method would be more desirable to the water treatment industry. Deposition of TiO2 in thin films on glass slides was used to develop a model flow-through reactor to study dynamic photocatalytic treatment processes. Light is supplied by black light bulbs, which emit light in the ultraviolet-A range. Experiments have shown this to be an effective method for degradation of these four drug compounds as they flow through the reactor. The drug compound entering the reactor experiences a rate of decay that leads to reasonable degradation of the drug at the effluent.
titanium dioxide photocatalysis for water treatment
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign