Waste Water Remediation Using Electrochemically Cycled Extractants in Room Temperature Ionic Liquids

Abstract

This project involved preliminary development of an electrochemically activated, regenerable anion-exchange system for nitrate removal from waste water. The goal was to combine desirable features of liquid-liquid extraction, e.g., fast kinetics and process simplicity, with those of anion-exchange processes using resins. At the same time, volatile organic solvents would be eliminated and replaced with a regenerative medium. We developed a liquid-liquid extraction system using a non-volatile, water insoluble room temperature ionic liquid (RTIL) in place of the organic phase. Because RTILs are intrinsic electrolytes, they provide a ready method of in situ electrochemical activation and deactivation of redox-active extractants, such as ferrocenes. The redox-active extractant made nitrate recovery in a small volume possible, while avoiding consumable chemical oxidants and reductants and without generating large secondary waste streams, such as are obtained during regeneration of ion-exchange resins.