Influence of non-conducting suspended solids onto the efficiency of electrochemical reactors using fluidized bed electrodes

Fluidized bed electrodes combine the advantages of a high specific electrode surface and a tolerance to reaction solutions containing suspended solids. In contrast to conventional packed-bed electrodes, which tend to get blocked when challenged with suspensions, such reaction solutions can pass freely through fluidized bed electrodes. In recent studies, we were able to show that the electric contacting between magnetic electrode particles can be improved by superposition of an external magnetic field to the fluidized bed electrode. However, these studies were conducted with plain solutions and the effect of non-conducting suspended solids on the performance of conventional and magnetically stabilized fluidized bed electrodes remained unknown. In this work, we investigate the influence of such suspension on the electrochemical conversion as well as on the conductivity of a fluidized bed electrode. Furthermore, the effect of magnetic superposition is evaluated. The results confirmed that the application of a fluidized bed electrode enabled the operation of an electrochemical model reaction process throughout the whole investigated concentration range of suspended solids (up to 40 g/L). However, the suspended solids showed a negative influence onto the electric conductivity of the fluidiezed bed and on the electrochemical conversions achieved. Superpositioning the fluidized bed electrode with a magnetic field of 20 mT, was able to significantly improve the electrochemical yield of the system. Therefore, magnetically influenced fluidized electrodes can be an interesting reactor type for electrobiotechnological systems combining electrochemical reactions with high densities of suspended microorganisms.

Automated summary

Fluidized bed electrodes combine a high specific electrode surface and a tolerance to reaction solutions containing suspended solids, with the capability to improve electric contacting between magnetic electrode particles by superposition of an external magnetic field. However, suspended solids have a negative influence on the electric conductivity and electrochemical conversions of fluidized bed electrodes, which can be significantly improved by superpositioning the electrode with a 20 mT magnetic field.