Visualization of the parietal mass transfer by using immobilized peroxidase

A new method is developed for direct visualization of the local mass transfer at solid liquid interfaces involving the chemiluminescent oxidation of luminol by H2O2 catalyzed by immobilized peroxidase. At low concentration of H2O2 (C less than 5 x 10(-5) M) this reaction is controlled by diffusion and it is possible to characterize the diffusion convection of H2O2 at each point of the tube as a function of the local hydrodynamic properties. These properties are characterized by pulsed Doppler ultrasound velocimetry. 1) The rate of light emission depends on Re1/3 for the laminar case and decreases when going downstream in accordance with the known theories of diffusion convection along tubes. 2)Downstream to a stenosis, a maximum of light appears which depends on the input Reynolds number in a manner similar to the reattachment point of the flow. This constitutes the first experimental confirmation of calculations on diffusion convection downstream to stenoses. These first experiments show the capacity of the method to detect the local properties of the parietal mass transfer phenomenon as a function of the geometry of the wall and the hydrodynamic properties of the flow.