A NEW THEORETICAL APPROACH TO ELECTROOSMOTIC DEWATERING (EOD) BASED ON NONEQUILIBRIUM THERMODYNAMICS

A novel theoretical approach to electroosmotic dewatering (EOD), with or without a pressure gradient, of clays, sludges and other colloidal suspensions is proposed. The treatment is based on non-equilibrium the rmodynamics as developed in the work of Overbeek, De Groot and others. The interpretation of electrokinetic phenomena in terms of the concep ts of irreversible thermodynamics when combined with Onsager's relatio ns, it has been shown by Overbeek, provides a complete framework for u nderstanding all electrokinetic phenomena. We have applied this approa ch here to the electroosmotic dewatering, both in the presence and abs ence of applied hydrostatic pressure. The approach provides much clari fication on the nature and significance of currents and fluxes observe d during EOD: these are composed of three components, during combined pressure electroosmotic dewatering: (i) electrochemical/electrical cur rent; (ii) hydrodynamic flux; (iii) electroosmotic current. We have al so shown the manner in which the proposed new approach to EOD based on irreversible thermodynamics can be connected to the conventional appr oach based on the Heimholtz-Smoluchowski equation.