Electrochemical Probe for Frictional Force and Bubble Measurements in Gas-Liquid-Solid Contactors and Innovative Electrochemical Reactors for Electrocoagulation/Electroflotation

Abstract

Electrochemistry constitutes an important discipline that involves many phenomena as mass transfer, migration because of the presence of electric field, and hydrodynamic especially in reactor with large scale. In fact, electrochemical methods and electrochemical reactors have to be developed in order to resolve many problems in different area (mining, waste water treatment etc). For measurement by electrochemical methods, probes have to be developed. For example, knowledge of the magnitude of the frictional forces between the solids and the gas-liquid mixture is very important for design of bioreactors. The growth of biomass on solid surfaces may be sensitive to shear stress. In fluidized bed bioreactors the suspended carriers are used for microbial immobilization or enzyme encapsulation. The knowledge of shear stress is important because some micro-organisms and cells attached to microcarriers are sensitive to excessive friction. The aim is to develop and verify a fast and inexpensive method for measuring the frictional forces in multiphase reactors beds. On the other hand the performance of a multiphase reactor – for example, a bubble column- depends on the knowledge the bubble swarm properties as bubble shape, velocity allowing to determine the gas liquid mass transfer and liquid solid mass transfer. To establish direct local information and precise bubble dimensions, various probes were used. The electrical resistivity probe was developed to measure the velocity and diameter of a bubble in a conducting liquid medium. In a non-conducting medium, the optical probe is more appropriate. To ensure easy measurement of bubble sizes in a non transparent conducting medium and to establish direct local information in a reactor, the present work shows the possible use of electrochemical probe.