A Novel Metal-Free Robust Recyclable Electrosorbent for Removal Pb(II) from Low Concentrated Solutions in Complex Aqueous Matrices

We have developed a novel metal-free highly robust recyclable electrosorbent for removal Pb(II) from water. It is based on a cost-efficient and biocompatible conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) which is synthesized through a facile green chemistry route. This electrosorbent demonstrates superior adsorption-desorption properties and recyclability as compared to conventional lead adsorbents and the same sorbent but without electrostimulation. Specifically, its Pb(II) uptake (>800 mg/g without saturation in the presence of excessive NaCl, Ca and Fe) is three-fold higher, while adsorption and desorption kinetics at 400 ppb Pb(II) are faster than without electrostimulation. Importantly, the electrosorbent has 100% reversibility and excellent stability for at least 30 adsorption-desorption cycles and after one-month storage in water. Using XPS and Raman spectroscopy, we link the outstanding properties of the electrosorbent to its unique cation-exchange properties which are enhanced by applied potential. Our results demonstrate a novel strategy for facile manufacturing of cost-effective robust recyclable electrosorbents from conjugated conducting polymers, as well as advantages of electrochemical stimulation for achieving highly repeatable electrosorption and reclamation of valuable metals from their dilute solutions in complex aqueous matrices.