Zirconia and hafnia monoliths for the electrokinetic pumping of methanol

Silica based materials have been used predominantly to fabricate electrokinetic (EK) pumps capable to deliver solvent flow, mostly aqueous solutions. Methanol delivery by means of EK pumps based on silica has encountered some limitations. Electrochemistry of water and methanol results in by products that can adhere at the surface of the silica material resulting in a decreased in solvent flow. Metal oxides are stable at a wider pH range and can be used to design EK pumping systems. We have synthesized zirconia and hafnia monoliths and evaluated their electrokinetic pumping capabilities towards methanol. The electrokinetic pumping characteristics of monolithic structures of these oxides have been compared with those of silica based monolithic EK pumps. Hafnia and zirconia based EK pumps have generated higher flow rates of methanol than silica monoliths.