Enhanced Electro-Fenton Mineralization of Acid Orange 7 Using a Carbon Nanotube Fiber-Based Cathode

Abstract

A new cathodic material for electro-Fenton (EF) process was prepared based on a macroscopic fiber (CNTF) made of mm-long carbon nanotubes directly spun from the gas phase by floating catalyst CVD, on a carbon fiber (CF) substrate. CNTF@CF electrode is a highly graphitic material combining a high surface area (~260 m 2 /g) with high electrical conductivity and electrochemical stability. One kind of azo dye, acid orange 7 (AO7), was used as model bio-refractory pollutant to be treated at CNTF@CF cathode in acidic aqueous medium (pH 3.0). The experimental results pointed out that AO7 and its organic intermediate compounds were totally mineralized by hydroxyl radical generated from Fenton reaction. In fact, 96.7% of the initial total organic carbon (TOC) was eliminated in 8 h of electrolysis by applying a current of −25 mA and ferrous ions as catalyst at concentration of 0.2 mM. At the same electrolysis time, only 23.7% of TOC removal found on CF support which proved the high mineralization efficiency of new material thanks to CNTF deposition. The CNTF@CF cathode maintained stable its activity during five experimental cycles of EF setup. The results indicated that CNTF@CF material could be a potential choice for wastewater treatment containing bio-refractory by electrochemical advanced oxidation processes.

Surface Chemistry Analysis of Carbon Nanotube Fibers by X‐Ray Photoelectron Spectroscopy

“…Their combination of high surface area (250 m 2 g −1 ), high electrical conductivity (3.5 × 10 5 S m −1 ) and mechanical toughness (fracture energy above 80 J g −1 ) makes them ideal electrodes, often as both active material and current collector . Amongst multifunctional devices, CNT fibers have been used in all‐solid and structural supercapacitors, electrocatalyst support/current collector, battery current collectors, and electrodes, and in a range of photoelectrochemical conversion devices, including counter electrodes in dye‐sensitized solar cells . In parallel, it has also been observed that the high quality and few layers of the CNTs lead to bulk electrodes with accessible quantum (chemical) capacitance, reminiscent of 1D confinement in the constituent CNTs and closely related to the electrode joint density of states .…”

Coupling cathodic electro-fenton with anodic photo-electrochemical oxidation: A feasibility study on the mineralization of paracetamol

“…When hydrogen peroxides are continuously electrochemically generated on-site at the cathode by the reduction oxygen at the cathode the process is termed electro-Fenton (EF) [12]. Electro-Fenton has been successfully applied for wastewater treatment to mineralise dyes, pharmaceuticals and other persistent pollutants [13][14][15][16]. Selection of appropriate cathodic material is a crucial factor in the construction of an efficient EF reactor and remarkable success has been reported with the use of carbon-based materials such as carbon sponge [17], carbon felt [18] and carbon nanofibers [19].…”

Fe-Nanoporous Carbon Derived from MIL-53(Fe): A Heterogeneous Catalyst for Mineralization of Organic Pollutants

“…Of particular interest to our research group was solving the problem of particle agglomeration and investigating strategies to minimize iron leaching into the solution. We have recently explored methods to alter cheap carbon felt electrodes in order to optimize their performance in the EF process and avoid the introduction of particles to solution—avoiding any occurrence of particle agglomeration [24,25]. Immobilizing the catalyst on the carbon felt surface has little impact on performance, since most of the reaction occurs at the solid-liquid interface [26].…”