title: Electrocatalytic water treatment using carbon nanotube filters modified with metal oxides.
abstract: This study examined the electrocatalytic activity of multi-walled carbon nanotube (CNT) filters for remediation of aqueous phenol in a sodium sulfate electrolyte. CNT filters were loaded with antimony-doped tin oxide (Sb-SnO2; SS) and bismuth- and antimony-codoped tin oxide (Bi-Sb-SnO2; BSS) via electrosorption at 2 V for 1 h and then assembled into a flow-through batch reactor as anode-cathode couples with perforated titanium foils. The as-synthesized pristine CNT filters were composed of 50-60-nm-thick tubular carbons with smooth surfaces, whereas the tubes composing the SS-CNT and BSS-CNT filters were slightly thicker and bumpy, because they were coated with SS and BSS particles ~50 nm in size. Electrochemical characterization of the samples indicated a positive shift in the onset potential and a decrease in the current magnitude in the modified CNT filters due to passivation and oxidation inhibition of the bare CNT filters. These filters exhibited a similar adsorption capacity for phenol (5-8%), whereas loadings of SS and BSS enhanced the degradation rate of phenol by ~1.5 and 2.1 times, respectively. In particular, the total organic carbon removal performance and mineralization efficiency of the BSS-CNT filters were approximately twice those of the bare CNT filters. The BSS-CNT filters also exhibited an enhanced oxidation of ferrocyanide [FeII(CN)64-], which was not adsorbed onto the CNT filters. The enhanced electrocatalytic performance of the modified CNT filters was attributed to an effective generation of OH radicals. The surfaces of the filters were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy.
authors.affiliation: School of Architectural, Civil, Environmental, and Energy Engineering, Kyungpook National University, Daegu, 41566, South Korea.|School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA.
authors.forename: So Young
authors.initials: SY
authors.lastname: Yang
authors.affiliation: School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA.
authors.forename: Chad D
authors.initials: CD
authors.lastname: Vecitis
authors.affiliation: School of Architectural, Civil, Environmental, and Energy Engineering, Kyungpook National University, Daegu, 41566, South Korea. hwp@knu.ac.kr.|School of Energy Engineering, Kyungpook National University, Daegu, 41566, South Korea. hwp@knu.ac.kr.|Advanced Institute of Water Industry, Kyungpook National University, Daegu, 41566, South Korea. hwp@knu.ac.kr.
authors.forename: Hyunwoong
authors.identifier: http://orcid.org/0000-0002-4938-6907
authors.initials: H
authors.lastname: Park
mesh_terms: D002384:Catalysis; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D005295:Ferrocyanides / Q000737:chemistry; D005374:Filtration / Q000295:instrumentation; D008670:Metals / Q000737:chemistry; D037742:Nanotubes, Carbon / Q000737:chemistry; D010087:Oxides / Q000737:chemistry; D010636:Phenols / Q000737:chemistry; D017382:Reactive Oxygen Species / Q000737:chemistry; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*
chemical_list: D005295:Ferrocyanides; D008670:Metals; D037742:Nanotubes, Carbon; D010087:Oxides; D010636:Phenols; D017382:Reactive Oxygen Species; C020354:hexacyanoferrate II
keywords: Carbon nanotubes; Electrochemical filter; Hybrids; Metal oxides; Reactive oxygen species