Conductive Adsorbent for Electrically Controlled Desorption and Sequential Release of Aqueous Mixture

Adsorption is a classical physicochemical process, widely used in heterogeneous catalysis, chemical engineering, and environmental science. Regenerating the exhausted adsorbents or reversible desorption is vital to achieving sustainable adsorption techniques, while the common chemical/thermal regeneration is energy-intensive and environmentally unfriendly. Given that the adsorbents’ surface physicochemical properties like surface charge and electronic structures, significantly affect adsorption capacity and kinetics, which offers opportunities for green desorption by tailoring surface chemical/electronic features. Since a certain adsorbate possesses specific adsorption energy on adsorbents, an electro-desorption idea is therefore proposed to electrically control the (sequential) release of aqueous substances by regulating the interfacial adsorption interaction above the corresponding threshold interfacial potential. Herein, as a proof-of-concept design, a sub-millimeter-sized carbon nanotube-reinforced conductive resin composite adsorbent with high conductivity and mechanical strength is developed, which demonstrates a high electro-desorption efficiency toward benzoic acid (94.1%; 3 V negative bias) and well-controlled electro-desorption kinetics by regulating the surface polarization. Using benzoic acid and terephthalic acid as a model of organic mixtures, the adsorbent exhibits an efficient bias-dependent sequential electro-desorption capability in separating mixtures. This work provides a promising efficient solution for green and efficient desorption/regeneration and a pioneering electrically-driven strategy toward aqueous mixture separation.