Recebido em 10/8/07; aceito em 31/1/08; publicado na web em 20/8/08PLASMA POLYMERIZED ACETALDEHYDE THIN FILMS FOR RETENTION OF VOLATILE ORGANIC COMPOUNDS. The aim of this work is the production and characterization of plasma polymerized acetaldehyde thin films. These films show highly polar species, are hydrophilic, organophilic and easily adsorb organic reactants with CO radicals but only allow permeation of reactants with OH radicals. The good step coverage of films deposited on aluminum trenches is useful for sensor development. Films deposited on hydrophobic substrates may result in a discontinued layer, which allows the use of preconcentration in sample pretreatment. Deposition on microchannels showed the possibility of chromatographic columns and/or retention system production to selectively detect or remove organic compounds from gas flows.
Simulation and experimental measurements were used aiming at better understanding flow behavior in planar and three-dimensional microchannels used for separation or preconcentration. Two different microchannels configurations were designed, manufactured in acrylic and the surface was modified to adsorb volatile organic compounds (VOCs). Both channels configuration are 73 cm long, 100 µm wide and 40 µm deep. Simulation was carried out in COMSOL (FEMLAB) 3.2 ® and COSMOS flow 5.0 ® programs, tracer visualization and quartz crystal microbalance data were evaluated according to chromatographic concepts. Due to the higher axial velocity, planar microchannels are more adequate for preconcentration whereas three-dimensional ones show a good performance in the separation process.Keywords: Microchannels; Planar, Three-dimensional, Preconcentration.
Resumo
Foram usadas simulações computacionais e medidas experimentais com o objetivo de compreender o comportamento de fluidos em microcanais tridimensionais e planares que foram testados na função de separação ou pré-concentração. Duas configurações diferentes foram projetadas, construídas em acrílico e tiveram sua superfície modificada para adsorver compostos orgânicos voláteis (COVs
Agradeço a Profa. Dra. Maria Lúcia Pereira da Silva pela orientação deste trabalho, como também pela amizade, confiança, incentivo, paciência e principalmente por ter me dado a oportunidade de realizar esse trabalho. Gostaria de agradecer à Rita Tereza dos Santos, do Lab. de Química do IFUSP, Neide Mitsue Fujiya, do LACE/IQUSP, pelos conselhos técnicos, acompanhamentos, discussões e pelas ajudas das mais diversas formas. À Alexandre Marques Camponucci, do LSI/EPUSP pelas medidas de MEV, Henrique Estanislau Maldonado Peres, do LME/EPUSP pelas medidas de espectrometria de massas. Aos colegas do grupo de tecnologias limpas (Alexsander, Antonio, Janaina, Rodrigo, Léo, Lílian, entre outros), pela amizade, apoio, companheirismo, discussões e por estarmos sempre trabalhando junto como um grupo que realmente quer vencer. Ao Laboratório de Sistemas Integráveis da EPUSP, pelo uso do perfilômetro e ao Laboratório de Microeletrônica pelo uso do equipamento de infravermelho.
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