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Several pharmaceutical compounds have been detected in natural aqueous systems and ibuprofen (IBF), one of the most consumed medicament, has been detected in many countries. The degradation efficiency of IBF under TiO2/UV radiation was evaluated. Optimum degradation results were observed using 20 mg•L −1 of TiO2, pH 7.8 and 5 mg•L −1 of IBF. Under these experimental conditions total IBF removal was achieved in less than 60 min of irradiation. Although total IBF concentration was observed, the total mineralization of the compound was not achieved. The by-products generated during TiO2/UV reaction showed to be more toxic against Daphnia similis than the initial IBF present in aqueous solution.

Emerging contaminants including pharmaceuticals are a class of compounds that are causing great concern due to several environmental problems. Conventional water and wastewater treatments do not achieve high removal efficiencies for many of these drugs. Therefore, the present work investigated the removal of ibuprofen (IBP) by heterogeneous photocatalysis using TiO2 irradiated with artificial UV light or solar radiation. The treated solutions were tested against Daphnia similis and Raphidocelis subcapitata, which are species commonly used as bioindicators of environmental conditions. The results indicated that IBP removal reached 92 % after 1 h of treatment using artificial UV and 1000 mg L(-1) of TiO2, which was the optimum catalyst concentration in the range studied (20-1000 mg L(-1)). TOC removal reached up to 78 % after 60 min of treatment using TiO2/artificial UV. Ecotoxicological bioassays indicated that the treated solutions had acute effects, with 30 % immobilization of D. similis and 40 % growth inhibition of R. subcapitata.

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In the present work, the hybrid catalyst films of TiO 2 /CuO containing up to 10% in mol of copper were deposited onto glass surface. Precursor solutions were obtained by citrate precursor method. Films were porous and the average particle size was 20 nm determined by FEG-SEM analysis. The photocatalytic activities of these films were studied using Rhodamine B as a target compound in a fixed bed reactor developed in our laboratory and UV lamp. It was observed that the addition of copper to TiO 2 increased significantly its photocatalytic activity during the oxidation of Rhodamine B. The degradation exceeded 90% within 48 hours of irradiation compared to 38% when pure TiO 2 was used. Moreover, there was a reduction in the particles band gap energy when compared to that of pure TiO 2. These results indicate that the TiO 2 /CuO films are promising catalysts for the development of fixed bed reactors to be used to treat effluents containing azo dyes.

Recebido em 13/2/02; aceito em 3/6/02 PROPOSITION OF A PHOTOCATALYTIC REACTOR TO INACTIVATE AIRBORNE MICROORGANISMS. The TiO 2 /UV photocatalytic reactor was investigated as an alternative system to inactivate airborne microorganisms. The experiments performed in the absence of the catalyst showed that direct photolysis was not efficient to destruct microorganisms, with only 30% of inactivation. Similar inactivation percentage was obtained using TiO 2 in absence of UV radiation. The destruction of microorganisms present in a contaminated indoor atmosphere, using the combination of TiO 2 /UV was very efficient, reaching more than 98% of destruction.Keywords: microorganism inactivation; photocatalytic reactor; TiO 2 /UV irradiation. INTRODUÇÃOAntes da década de 70, os problemas de saúde relacionados com a poluição do ar de ambientes interiores chamavam pouca atenção da comunidade científica. O interesse por este assunto tem crescido nos últimos anos, uma vez que as pessoas têm passado a maior parte do seu tempo em ambientes fechados 1 . As causas da poluição do ar de ambientes interiores podem ser decorrentes da má ventilação, da presença de material particulado, da contaminação química, especialmente por compostos orgânicos voláteis e, também, devido à contaminação microbiológica. A melhora na ventilação e o emprego de filtros apropriados podem amenizar tais problemas. No entanto, a presença de compostos orgânicos voláteis e microrganismos (bacté-rias, fungos e vírus), ainda que em pequenas concentrações, causa grande preocupação 2,3 . Um grande número de sintomas está relacionado com a má qualidade do ar. O conjunto destes sintomas foi definido como Síndrome do Edifício Doente 3,4 . Os principais incluem dor de cabeça, náusea, irritação nos olhos, problemas no sistema respiratório, sonolência e fadiga 5 . Inúmeros métodos têm sido propostos com o objetivo de mitigar o problema da contaminação biológica do ar interno, incluindo filtros para a remoção de materiais biológicos. Os filtros têm sido utilizados devido ao baixo custo e fácil manuseio, apresentando, entretanto, a desvantagem de não destruírem os microrganismos, e sim transferi-los para outro meio 4 . Um processo alternativo para inativar os microrganismos, proposto no presente trabalho, emprega o sistema TiO 2 /UV. No início da década de 70, Fujishima e Honda 6 descobriram que a água era decomposta a hidrogênio e oxigênio na presença de um eletrodo de dióxido de titânio e luz UV. Quando o TiO 2 é irradiado com luz UV com energia igual ou superior ao seu "bandgap" o par elétron/lacuna positiva é gerado na superfície da partícula deste semicondutor. Como conseqüência, a lacuna positiva pode oxidar água adsorvida na superfície do TiO 2 , formando radicais hidroxila (HO • ). Estes radicais são altamente reativos 7-9 , possuindo um elevado potencial de oxidação. Dentre as possibilidades de aplicação deste sistema, o emprego na área ambiental tem merecido maior destaque devido, principalmente, à possibilidade de alcançar a mineralização completa de vá-rios com...

Emerging contaminants including pharmaceuticals are a class of compounds that are causing great concern due to several environmental problems. Conventional water and wastewater treatments do not achieve high removal efficiencies for many of these drugs. Therefore, the present work investigated the removal of ibuprofen (IBP) by heterogeneous photocatalysis using TiO2 irradiated with artificial UV light or solar radiation. The treated solutions were tested against Daphnia similis and Raphidocelis subcapitata, which are species commonly used as bioindicators of environmental conditions. The results indicated that IBP removal reached 92% after 1 h of treatment using artificial UV and 1000 mg L −1 of TiO 2 , which was the optimum catalyst concentration in the range studied (20-1000 mg L −1 ). TOC removal reached up to 78% after 60 min of treatment using TiO 2 /artificial UV. Ecotoxicological bioassays indicated that the treated solutions had acute effects, with 30% immobilization of D. similis and 40% growth inhibition of R. subcapitata.

The cultivation of strawberries generally requires substantial use of pesticides, and abamectin is the active principle of one of those most commonly employed. Conventional water treatment does not remove pesticides efficiently, so there is a need to investigate alternative procedures. The use of advanced oxidation processes (AOPs) can achieve good results in removal of toxic organic compounds present in aqueous solutions. The photo-Fenton process, one example of an AOP, was employed to study the degradation of abamectin. Results showed that when natural water samples contaminated with abamectin were treated using the photo-Fenton process, 70% of the initial amount of the compound was removed within 60 minutes of UV irradiation, and 60% mineralization was observed after 180 minutes of reaction.