(595f) Polyaniline Nanofiber Electrodes for Reversible Capture and Release of Mercury(II)

Highly effective removal of heavy metal ions especially mercury (II) from aqueous media is very important as release of those are only increasing. Traditional methods by adsorption mechanism include use of clay, activated carbons, zeolites. However, these method normally have low capacity and weak binding affinity. Metal organic frameworks and covalent organic frameworks have been explored as new type of adsorbents for mercury removal due to their easy synthesis, high surface area, and recyclability. However, they usually suffer from instability in water or aqueous solutions with a wide pH range and possess low adsorption capacity and weak affinity for Hg(II). Recently, beyond the traditional methods, electrochemical mediated capture and release of contaminants received the spotlight. Electrochemical separation and recycle method have distinctive advantages. It could be a general platform for selective ion recovery with high throughput and separation factors with advantages including fast kinetics, control by electrical potential, modularity, and reuse. Here we demonstrate that polyaniline nanofiber electrodes (PNE) can selectively adsorb mercury(II) from water and subsequent release of it can be controlled electrochemically through the redox processes. Our PNEs showed the fastest kinetics and the highest uptake capacity among known polyaniline adsorbents. This is the first demonstration of high performing redox active adsorbents for electrochemically controlled capture and release of mercury ions. Change of cyclic voltammetry is a simple and straightforward indicator for sensing mechanism.