Simulation and Optimization of a Multi-Annular Photocatalytic Reactor for Gaseous Tetrachloroethylene Degradation

IMOBERDORF, G.E.; CASSANO, A.E.; IRAZOQUI, H.A.; ALFANO, O.M.

Campinas (UNICAMP), SP Brasil

Workshop; III Encontro Sobre Aplicações Ambientais de Processos Oxidativos Avançados - III EPOA; 2005

UNICAMP

Volatile organic compounds (VOCs) are extensively used in numerous industrial processes as clean solvents or diluents for specific purposes. Among them, tetrachloroethylene or perchloroethylene (PCE) is toxic, carcinogenic and highly persistent in the environment. The environmental impacts of VOCs emission have become a major air pollution problem since last decade. A multi-annular photocatalytic reactor was conceived and designed, that consists of four borosilicate glass tubes (UV transparent) concentrically arranged, forming annular channels, where the polluted air flows. A black-light UV lamp, placed at the centerline of the photoreactor, is the source of near-UV radiation. The TiO2 photocatalyst was deposited as a thin film on the borosilicate glass tubes by means of a sol-gel technique. This configuration shares with monoliths their operating advantages (low pressure drop and good catalytic surface area per unit reactor volume), while showing a much better radiation distribution. The photoreactor shows good effectiveness for PCE removal from contaminated air streams (almost 100% PCE conversion was achieved under specific operating conditions), without stable intermediates species or sub products formation. A physical and mathematical model for the multi-annular concentric photoreactor was developed. It includes the kinetic model for PCE elimination from contaminated air presented in a previous work [1], as well as a radiation model and a mass transfer model. Predicted conversions show good agreement with experimental results with a RMSE (root mean square error) lower than 5%.