title: Binder-free carbon nanotube electrode for electrochemical removal of chromium.
abstract: Electrochemical treatment of chromium-containing wastewater has the advantage of simultaneously reducing hexavalent chromium (CrVI) and reversibly adsorbing the trivalent product (CrIII), thereby minimizing the generation of waste for disposal and providing an opportunity for resource reuse. The application of electrochemical treatment of chromium is often limited by the available electrochemical surface area (ESA) of conventional electrodes with flat surfaces. Here, we report the preparation and evaluation of carbon nanotube (CNT) electrodes consisting of vertically aligned CNT arrays directly grown on stainless steel mesh (SSM). We show that the 3-D organization of CNT arrays increases ESA up to 13 times compared to SSM. The increase of ESA is correlated with the length of CNTs, consistent with a mechanism of roughness-induced ESA enhancement. The increase of ESA directly benefits CrVI reduction by proportionally accelerating reduction without compromising the electrode's ability to adsorb CrIII. Our results suggest that the rational design of electrodes with hierarchical structures represents a feasible approach to improve the performance of electrochemical treatment of contaminated water.
authors.affiliation: Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame , Notre Dame, Indiana 46556, United States.
authors.forename: Haitao
authors.initials: H
authors.lastname: Wang
authors.forename: Chongzheng
authors.initials: C
authors.lastname: Na
keywords: Langmuir isotherm; carbon nanotube array; chromium electrosorption; chromium reduction kinetics; composite without polymer binder; industrial wastewater; three-dimensional electrode