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Intensification of cross-flow membrane filtration using dielectrophoresis with a novel electrode configuration

Du, F., Ciaciuch, P., Bohlen, S., Wang, Y., Baune, M., Thöming, J.
Journal of membrane science 2013 v.448 pp. 256-261
artificial membranes, clay, dielectrophoresis, electric field, electric power, electrochemistry, electrodes, filtration, fouling, heat, porosity, temperature
Fouling can be a serious problem in membrane filtration processes. Here we present a solution that avoids addition of chemicals and allows for uninterrupted operation of cross-flow micro-filtration process. A novel electrode configuration is suggested for generating an inhomogeneous electric (ac) field for repelling particles from the membrane by means of dielectrophoresis (DEP). Undesired electrochemical reactions are avoided even in case of aqueous suspensions due to a sufficiently high frequency of the applied field (200kHz). The inhomogeneous electric field generated by interdigitatedly installed cylindrical electrodes (IDE) could move clay particles (size 100–3000nm) away from membrane (pore size 0.2µm), thereby reducing fouling in membrane filtration process. A specific cosine-wave like DEP force distribution induced by the IDE along the feed flow was observed to allow for enhancing the DEP fouling suppression by removing the particles agglomerate adhered to the membrane at lower electric field regions. The fouling suppression performance of this new DEP filtration process was revealed comparing experimentally the permeate flux using same membrane with and without electrical field. With continuous DEP operation period with more than 69% of initial permeate flux was 9 times higher. In this lab-scale process with feed flow rate of 12mL/min, Joule heating was observed elevating permeate temperature with rate of 3K/h indicating a demand for electrical power (dissipated as heat) of about 2.5W.