Key Engineering Materials Vol. 314

Abstract: In this paper results of electrophoretically activated processes for domestic wastewater treatment in lab and field scale experiments are presented. The principal mechanisms of non-membrane and membrane based electrokinetic solid liquid separation by electrophoresis are described. In the case of non-membrane based electrokinetic wastewater treatment a modular processing scheme is suggested in order to achieve economically and ecologically suitable processing conditions based on colloidal wastewater characteristics. In the case of membrane based electrokinetic waste water treatment an effective anti-membrane fouling process is designed controlled by colloidal characteristics of the wastewater, especially zetapotential, as well as external field parameters and microfiltration module geometries. The specific energy input of the membrane based and non-membrane based electrophoretic waste water treatment methodologies are compared and future perspectives of electrokinetic activated waste water purification processes are proposed.

Abstract: Hydroxyapatite, porcelain and wollastonite coatings on stainless steel 316L were produced by electrophoretic deposition (EPD) in ethanol and acetone using a voltage between 200 and 1000 V during 0.5 to 60 s. The particle size distribution of the starting suspension was 0.3 to 4.9 microns with an average size of 1.5 microns. The coatings were analyzed using scanning electron microscopy. The amount of ceramic material on the surface of the metallic samples was evaluated by determining their difference in weight before and after the electrophoretic deposition process. The conductivity and zeta potential of the dispersing media were also evaluated. Dense, homogeneous and crack-free green coatings were obtained. The deposition rate was higher by using acetone as dispersing media. The higher zeta potential and the lower viscosity were attributed to be the cause of the better electrophoretic deposition of the acetone and methanol ceramic suspensions. Submicron particle coatings were then sintered between 800 and 1000 C during 2 h. The sintered coatings presented a very homogeneous polycrystalline structure free of cracks. The results show that the application of high voltage during short periods of time is an effective method to obtain ceramic coatings with good sinterability.